What is Neural prolotherapy?
Neural prolotherapy is also known as subcutaneous prolotherapy or the Lyftogt technique. It is named after its founder, Dr. John Lyftogt of New Zealand, who has been using this method to treat musculoskeletal injuries and various pain conditions over the last decade with amazing results. Neural prolotherapy is the injection of dextrose or manitol just below the skin (subcutaneous) to promote healing of injured nerves and restoration of tissue function.
The rational for neural prolotherapy is based on Hilton’s Law. Dr. John Hilton was a British surgeon who mastered the anatomy and noted that the nerve that innervates a joint also innervates the skin over that joint and the muscles that move that joint. Based on this Dr. Lyftogt hypothesized that irritation to a nerve that supplies sensation to the skin over a joint may also cause dysfunction and pain to the muscles and tissue around that joint. Knowing that dextrose promotes tissue healing in connective tissue such as ligaments and tendons (traditional prolotherapy) and nerves contain connective tissue, Dr. Lyftogt postulated that dextrose could do the same for nerves. He injected small amounts of dextrose under the skin and noted decreased local swelling, and improvement of pain and function. Thus, he postulated that restoration of nerve function will lead to healing in deeper structures underlying those nerves and reduction in pain. Although more research is needed to prove this hypothesis, the anecdotal evidence is compellingly. The Lyftogt method is now being taught around the world because of its efficacy with minimal risk and side effects.
How does Neural prolotherapy relate to traditional prolotherapy?
Prolotherapy is deep injections to promote regeneration or repair of connective tissue (ie. ligaments and tendons) whereas neural prolotherapy is superficial injections that target subcutaneous nerves. Both modalities result in pain relief and functional restoration.
What is the solution that is injected?
Neural Prolotherapy solution contains either 5% Dextrose in water (D5W) or 5% Manitol in water (M5W). Manitol is a sugar alcohol derived from the desiduous tree called flowering ash and Dextrose is a natural sugar found in corn. D5W is the same solution used in IV bags in the emergency room and hospitals.
How does Neural prolotherapy work?
Tissue injury causes a release of proinflammatory substances (ie. Bradykinin, prostaglandins) that activate a nonselective cation channel on nerves called Transient receptor potential cation channel V1 (TrpV1), also known as the capsacin receptor. This in turn results in nerve release of substances that cause inflammation, like substance P and calcitonin gene related peptide (CGRP) leading to leaky blood vessels (swelling), hypersensitivity, burning and painful sensations. It is postulated that dextrose and manitol bind to and inhibit the TrpV1 nerve receptors, preventing this cascade and restoring normal nerve function.
Injury to nerves by stretching, constricting, or cutting them, also result in the release of these pro-inflammatory substances which can lead to chronic nerve dysfunction and “neurogenic pain”. Nervi nervorum are small nerves that connect with larger subcutaneous nerves. They are more sensitive to tissue tension changes that can result in nerve constriction, especially at sites where the nerves penetrate muscle or fascia. These potential chronic constriction sites are thought to cause abnormal nerve function and are the primary targets of subcutaneous prolotherapy.
Is Neural prolotherapy treatment painful?
At AcuProlo Institute we use the smallest possible hypodermic needle (30Gauge) to inject the neural prolotherapy solution just under the skin (subcutaneous) about ¾ inch deep. No local anesthetic is required because it is such a well tolerated procedure compared to other types of injections. Multiple injections are done along the subcutaneous nerves. Some insertion points may result in mild discomfort or a sensation of initial burning or stinging followed by resolution of pain.
How will I feel after a neural prolotherapy treatment?
Most patients get immediate significant pain relief after the treatment and some get complete resolution of pain. This analgesic effect may initially last anywhere between hours to weeks. With subsequent treatments less areas need to be injected because the tissue has healed and the pain free duration gets progressively longer.
How often do I need these treatments?
This is different for each individual. Some people may get permanent relief after just 2 or 3 treatments. Many require multiple injections every 1-2 weeks for 6-10 consecutive weeks.
Is neural prolotherapy safe?
It is safe when administered by a properly trained physician. With the proper technique the risk of infection and tissue injury is minimal to none. Possible adverse effects include local swelling, bruising and mild transient pain. The solution injected is very safe because it is the same solution used in IV bags in the hospital, sugar water (D5W).
What conditions will neural prolotherapy treat?
Neural Prolotherapy is very effective in treating nerve pain as well as any musculoskeletal injuries, including shoulder, knee and ankle tendonitis, neck and low back pain, migraines, temporal mandibular joint (TMJ), and many other conditions. Many people present to Acuprolo Institute with chronic pain for which they have “tried everything”, including surgery, and still have persistent pain. These people respond very well to neural prolotherapy.
Can neural prolotherapy be done on a child or an elderly person?
Yes! Since it is minimally invasive and utilizes a very natural solution, it is safe and effective in both the pediatric and geriatric population.
Will my insurance cover for neural prolotherapy?
Neural Therapy was originally developed in Germany by the Huneke brothers. It involves the injection of Procaine (also known as Novocain), a common local anesthetic, into various but very specific areas. Neural Therapy is based on the theory that trauma can produce long-standing disturbances in the electrochemical function of tissues. Among the types of tissues affected by trauma include scars, nerves or a cluster of nerves called ganglions. A correctly administered Neural Therapy injection can often instantly and lastingly resolve chronic longstanding illness and chronic pain. Although an estimated 35% of all West German physicians use Neural Therapy to some extent and in the rest of the Western World it has become one of the most widely used modalities in the treatment of chronic pain, most physicians in the United States are unfamiliar with Neural Therapy. Here in the United States, "trigger point injections" are commonly used for pain based on the work of Janet Travell, M.D. It is not widely known but Dr. Travell learned about trigger points while studying in Germany and then returned home to write the reference book widely used in the United States on Trigger Point injections. However, Trigger Point injections are just one type of Neural Therapy. Neural Therapy is also often very effective for other medical illnesses such as allergies, chronic bowel problems, kidney disease, prostate and female problems, infertility, tinnitus (ringing in the ears), and many other conditions.
How did Neural Therapy start?
The basis for Neural Therapy started with the use of cocaine as a local anesthetic in the late 1800's by the great scientists, Pavlov and Sigmund Freud. In 1906, the German surgeon, Spiess, discovered that wounds and inflammatory processes subsided more quickly and with fewer complications after injection with the newly discovered Novocain (procaine), which did not possess the addicting qualities of cocaine.
The famous French surgeon, Leriche, performed the first nerve block into the stellate ganglion in 1925 for the treatment of chronic intractable arm pain. He described the injection of Novocain as the surgeon's "bloodless knife." Ganglion blocks are now commonly used for the treatment of neck, shoulder, arm, leg, and low back pain. In addition, Procaine can be used directly in the nerves of the autonomic nervous system, peripheral nerves, scars, glands, acupuncture points, trigger points, and other tissues. Even intravenous Lidocaine has treated chronic somatic pain, including cancer pain. Modern Neural Therapy owes its discovery to an accident in 1925, observed and interpreted by two physicians, Ferdinand and Walter Huneke. They had for years
attempted in vain to help their sister, who often suffered severe migraine attacks. During one particularly violent attack, Ferdinand injected his sister intravenously with what he thought was a remedy for rheumatism. While he was still administering the injection, the blinding migraine headache simply vanished, together with the flashing sensation in ůont of her eyes, dizziness, nausea and depression. Her headaches never recurred! After witnessing this miraculous recovery, Ferdinand and Walter realized their sister's intravenous injection actually contained Procaine. After much further experimentation, it became clear that it was Procaine alone that had produced the startling cure, and therefore Procaine could also be used as a treatment remedy, as well as a local anesthetic.
How does Neural Therapy work at a site of disturbance?
A German neurophysiologist, Albert Fleckenstein, demonstrated that the cells in scar tissue have a different membrane potential normal body cells, functioning much like 1.5 volt battery implanted into the body. Whenever a cell has lost its normal membrane potential, ion pumps in the cell wall stop working. This means that abnormal minerals and toxic substances accumulate inside the cell. As a result, the cell loses the ability to heal itself and resume normal functioning. Procaine acts on the cell wall to allow the ion pumps to resume normal action and restore the membrane potential. This is how Procaine and other agents used in Neural Therapy correct the bioelectric disturbance at a specific site or nerve ganglion. By re-establishing the normal electrical condition of cells and nerves, the disturbed functions are also restored to normality, and the patient returns to health as far as this is anatomically still possible. The amazing part of Neural Therapy is that the site being treated can be very far away for the tissue in the body that is not functioning properly. For example, a scar on the chin can affect the low back. This is possible because of the vast network of nerves called the Autonomic Nervous System
What is the Autònomic Nervous System?
The nerves of your autonomic system provide a vast network of electrical circuits, having a total length of twelve times the circumference of the earth, and connecting every one of your 40 trillion cells to form a living whole human organism. This autonomic (or neurovegetative) system controls the vital processes everywhere in your body. It regulates your breathing, circulation, body temperature, digestion, metabolism, hormone formation and distribution. It causes your heart to beat and your lungs to breathe automatically, even when you are asleep. It does in fact control all of the numerous automatic processes without which you could not live. In other words virtually every cell in your body is connected not only to each other through the autonomic nervous system but is also in large part controlled by your autonomic nervous system.
As Fleekenstein showed, scar tissue can create an abnormal electric signal. In turn this signal is transmitted throughout the rest of your body via the autonomic nervous system. Procaine delivered by direct injection to scars or through other nerves that travel into deeper scars through tiny tubules in the cellular matrix to these areas of bioelectrical disturbance for treatment. As a result, Procaine is capable of eliminating autonomic regulatory dysfunctions. Since the autonomic nervous system is the master controller of the body, Neural Therapy can have a profound impact on your condition and your ability to heal.
In 1940, Ferdinand Huneke observed the first "lightning reaction" or the "Huneke phenomenon," discovering that a scar can produce an "interference field." A patient presented to him with a severely painful frozen right shoulder that had been refractory to all kinds of therapies. Huneke injected the shoulder joint directly with Procaine without obtaining any pain relief. However, within several days of the shoulder injection, the patient developed severe itching in a scar in her left lower leg where she had surgery years prior and just before developing the painful shoulder. When she returned, Huneke injected Procaine into the itchy scar in her left leg. Almost immediately she obtained full and painless range of motion in her right shoulder joint. The shoulder problem never recurred. The leg scar injection had apparently "cured" her shoulder problem. This was the first observation of what Neural Therapy is capable.
What causes interference fields?
Why does Neural Therapy work?
I used to believe that if you get all the nutrients you need, avoid everything that makes you worse (allergens, alcohol, ete), and detoxify or get rid of anything that is preventing you from getting Well (mercury, yeast, abusive relationships), your body Will heal itself.
These were the three ingredients of attaining health However, for some individuals even when everything has been done in these three areas, something seems to be interfering with getting well. It turns out to be interference fields from sears, trauma, etc. that are disturbing the instructions of the autonomic nervous system to heal the body.
To understand this more fully, one has to understand that the autonomic nervous system is made up of two divisions. One is the sympathetic nervous system that is activated by stress. It speeds up your heart rate, makes you burn sugar more rapidly, tenses your muscles, and in general increases your ability to "fight or Flight." The other side of the autonomic nervous system is the parasympathetic nervous system. Its job is to promote healing, digestion, repair etc. It slows your heart rate down, increases mucus and digestion, etc.
The key features of the sympathetic nervous system is that it links all of the cells of the body together, regulates the contraction and expansion of blood vessels, regulates the activity of the connective tissue necessary for regenerating body systems, and it regulates the voltage (membrane potential) across the cell Wall in every cell in the body. While either the parasympathetic or sympathetic nervous system could be overly dominant and lead to symptoms, most people are stuck in an overly reactive sympathetic state. In other Words, the healing mechanism is impaired or "interfered with."
November 5, 2012
Chelation has long been favored by many integrative doctors. Now conventional cardiologists with vested interests in surgery and drugs are trying (and failing) to trash the study. What a surprise.
TACT, the Trial to Assess Chelation Therapy, is a seven-year study funded by the NIH and carried out by university cardiologists and experienced chelation physicians from around the United States. This randomized, double-blind study compared patients who were treated with medication and intravenous chelation therapy to those receiving medication but no chelation. The results of the study, announced Saturday at the annual meeting of the American Heart Association, shows important improvement in patients who had previous heart attacks and were already under cardiology treatment—especially patients with diabetes. The group treated with chelation had fewer subsequent surgeries than those who received a placebo. The findings were unexpected by the conventional medical establishment which long fought the funding and implementation of the study and which tried to undermine it over the years. Not surprisingly, the study authors noted that additional research will needed to explain the precise mechanisms at work. How does chelation therapy work? As we reported in February, one method involves injecting into the patient’s bloodstream organic chemicals, which can bind and remove the heavy metals in the bloodstream (metals which are toxic to humans and interfere with various physiological functions). There are also oral or suppository supplements for chelation, and some foods are natural chelators (e.g., cilantro and chlorella). In the TACT trial, patients were given an organic
molecule, EDTA (disodium ethylene diaminetetraacetic acid), which binds to (or “chelates”) the toxic minerals. Chelation therapy for heart and vascular disease has long been shown to be safe and statistically effective, and now the TACT trial has validated its promise.
Prolotherapy is a safe, non-surgical treatment for chronic pain and joint degeneration using injections to stimulate healing. We have been using prolotherapy for over thirty years and have studied with field leaders including Dr. Paterson and Dr. Bjorn Eck. We have participated in prolotherapy clinics in Europe, Venezuela and Tahiti. With over 34 years experience in nutritional medicine, we emphasize metabolic diet and nutrient therapies along with prolotherapy and platelet rich plasma therapy to optimize the body’s healing response in joints and ligaments.
When we see a new patient who is considering prolotherapy, we will take a thorough history: perform a physical exam as well as review diet and nutrients. The prolotherapy solutions we use are combinations of Dextrose, bicarbonate, Lidocaine or Xylocaine, and sterile water. Additionally, vitamin B complex, B12 , Folic acid and magnesium are added to stimulate a healing response. Platelet rich plasma is a so called “autologous” therapy or a treatment which uses the patient’s own blood serum to use naturally occurring growth factors and cytokines to stimulate the body’s own self repair processes and stem cells.
We will be happy to discuss your questions regarding prolotherapy, prolozone or platelet rich plasma therapy and look forward to introducing you to this very effective, natural therapy for chronic pain, joint degeneration of the neck, back, knees, feet, hips, sacroiliac, and shoulders.
LYME DISEASE- THE BIGGER PICTURE
Daniel J. Dunphy, PA-C, ND
Formulating a “bigger picture “ approach to managing Lyme disease syndrome both long term and in more biologically sustainable ways is a task that has taken me since the mid 1980’s to fully understand and formulate. I had a house in Cape Cod back then and saw the emergence of Lyme disease and subsequent Lyme related, immune deficiency, multiple infection and chronic fatigue syndromes. My observation is that one must take into account the symptoms associated with these various syndromes in the context of and integrative with hypo thyroid, hypoglycemia, stress, insomnia, hormone deficiencies and immune dysfunction.
In short, I do not see the world through Lyme colored glasses alone. To achieve long lasting success one must address heavy metal toxicity, immune deficiency/stress cortisol issues, focal inflammations, dysbiotic teeth, gums and gut as well as scars. All of these may allow activation of any chronic symbiotic virus or bacterial organism. Did you know that the human body has tens of trillions of bacterial forms, more then actual human body cells at any given moment of your life? So forget about eliminating bacteria and viruses by “bombing bugs”. If you only spray mosquitoes with DDT and leave the swamp as it was, the mosquitoes will come back only DDT resistant.
In a similar way, Lyme syndrome organisms, L- form bacterial microbes, aka “cell wall deficient forms” cannot be eliminated but rather will be encouraged by long term antibiotic use. So in treating Lyme syndromes with long-term antibiotics we may be both enabling the various species to develop resistance as well as forming more L forms, which is what physicians are purportedly trying to treat to begin with.
The science behind the objective testing and monitoring of these conditions still has a way to go before one can objectively state that the Borrelia organism is an actual cause of the syndrome vs. a player in a broader malaise. To date there is no balanced specific vs. sensitive test available to objectively monitor the effectiveness of antibiotic therapies for Lyme. What we have are shadow dances with the organism. A Lyme complex, antibody/ antigen complex, test was studied and developed at Johns Hopkins Medical School over seven years ago but shelved and never made publicly available even to Igenex Labs.
Ultimately, your Lyme physician is dependent upon subjective symptoms, which are also common to many other physiological imbalances, to determine clinical response to treatment.. Conditions such as hypo thyroid, hormone imbalance, hypoglycemia, insomnia, stress and immune deficiency must be addressed thoroughly in order to calm the waters enough to truly judge the effectiveness of Lyme syndrome treatments. Unless one eliminates some of the simpler causes of these myriad symptoms one can never be sure that what you perceive you have accomplished through antibiotics is, in fact, a clinical reality.
In approaching Lyme syndrome and the various ”co-infections” I believe three goals are necessary:
More Information on LymeThe History of Lyme disease
Many people know that Lyme disease takes its name from the town where it was first “discovered” – Lyme, Connecticut.
Lyme disease was officially discovered by the western medical community beginning in 1975, when a group of anxious mothers living in Lyme, Connecticut contacted public health authorities due to a rash of cases of joint inflammation in numerous children in their community. Thirty-nine children and twelve adults were studied by researchers at Yale University, and given a diagnosis for their mysterious ailment – “Lyme Arthritis.”
Eventually the bacteria, a spirochete similar to syphilis, was isolated in 1982 by researcher Willy Burgdorfer – an expert in spirochetal diseases – and was named “Borrelia burgdorferi” (Bb). The disease was determined to spread through the bite of a tick – specifically the “Ixodes” species of tick. As new cases continued to appear, health officials fought hard to find a treatment to kill the bacterial infection. Additionally, it was imperative to strengthen the patient’s immune system and alleviate the painful symptoms.
As the disease continued to spread, The Center for Disease Control (CDC) became involved and attempted to compile a standard for measuring the “epidemic.” Although their position paper clearly states that Lyme Disease is diagnosed by symptoms, using blood tests for support of diagnosis, the collection of statistics uses only those patients who have a certain level of antibodies in their blood, ignoring the presence (or lack) of symptoms. That fact -along with the long and difficult reporting for doctors, leads to gross under-reporting.
Dr. Jonathon Edlow at Harvard Medical School claims that actual numbers could be 10 times higher than the numbers the CDC publishes. Other sources place the number much higher due to hundreds and thousands of people who are misdiagnosed with rheumatoid arthritis, fibromyalgia, MS, chronic fatigue and even Lou Gherig’s disease, along with those patients who have symptoms outside the CDC targeted vectors. Some estimates approach 300,000 new cases per year, but the total national count is unknown.
There are 850 tick species, and approximately 100 can transmit disease. It is no wonder that Lyme is now a worldwide disease.
The Biology of Lyme diseaseLyme disease, simply stated, is a multi-systemic bacterial infection spread primarily through the bite of an infected tick. But there is nothing simple about this virulent organism. Its official name is Borrelia burgdorferi (Bb), and it was initially classified with protozoa because it is so unique. Borrelia possesses the largest number of DNA replicators making it amongst the most complex bacteria in the world.
To review, Borrelia burgdorferi is a spiral-shaped “spirochete’ when it enters the human blood stream, and uses that active form to quickly disperse throughout the body and the “tunnel” into soft tissue. This “smart” bacteria will quickly and easily change it’s genetic structure into two other cell forms: the “L” form and the “cyst” form; and will link up in different combinations of the three forms.
The following symptom list is extensive, and symptom combinations vary greatly from person to person.
The hallmark of Lyme disease is for symptoms to mysteriously appear and then disappear weeks later, or for pain to move around the body. It is important to note that you can be infected for years without becoming disabled due to the morphologic nature of the bacteria. In other words, the disease can lie dormant in your body for months or years, taking over when you are worn down physically or if your immune system is suddenly or gradually compromised.
The Tick Bite
Head, Face, Neck
Digestive and Excretory Systems
Respiratory and Circulatory Systems
Babesia is a protozoal parasite, much like malaria, infecting the red blood cells and eventually destroying them. There are 13 different types, although only three of them are known to infect people. The symptoms can include any or all of the following: fatigue, drenching night sweats, fever, chills, weakness, weight loss, nausea, abdominal pain, diarrhea, cough, shortness of breath, headache, neck and back stiffness, dark urine or blood in urine.
Until recently, Babesia was considered a rare disease because it was only diagnosed in extremely ill patients with high fevers (104+). The bacteria which invades the red blood cells, has been largely ignored by the medical community in part because there wasn’t a reliable test for diagnosing it, and in part because there has been so little information about the disease.
Now it is recognized as the most common co-infection of Lyme disease, and synergistically linked in a manner that makes it very difficult to get rid of one without treating both.
Babesia symptoms, which may go back ten years or more, include one or more of the following; listlessness, slow thinking, high fevers or unexplained fevers, reduced appetite, chills, sweats, headaches and/or migraines, fatigue, muscle and/or joint pain, depression, anxiety, panic, nausea, vomiting, shortness of breath, cough, dark urine, enlarged spleen and/or liver, jaundice, enlarged lymph nodes, memory loss, psychiatric illness, struggle organizing, urgency to sleep in day, waves of generalized itching, dizziness, chest wall pain, sensitivity to light, and abdominal pain.
BartonellaBartonella is a blood infection, commonly referred to as “Cat Scratch Fever”.
The symptoms for Lyme BLO may include any combination of the following:
Typically, a co-infection is suspected when treatment for Lyme disease fails.
EhrlichiosisEhrlichiosis refers to several tick-borne diseases caused by very small organisms called Ehrlichiae, which affect both humans and animals. Ehrlichiae are gram negative bacteria that infect and destroy white blood cells. Two human diseases are caused by varieties of Ehrlichiae found in the U.S.
· Human monocyte ehrlichiosis (HME) infects white cells known as monocytes.
· Human granulocytic ehrlichiosis (HGE) infects granulocyte white blood cells.
Ehrlichiosis usually develops rapidly. Patients who are infected with ehrlichiosis will begin to feel symptoms between 3 to 16 days after being bitten by an infected tick. A patient may feel fine early in the day only to experience very severe, debilitating symptoms a few hours later. While ehrlichiosis is often very mild, with only flu-like symptoms, in some cases, symptoms can be severe and even cause death.
About one-third of HME patients and a smaller proportion of HGE patients develop a rash. Other common symptoms may include:
Daniel Dunphy has been using Dr. Michael Giesing’s TIRNA (Tumor Induced RNA) blood test since 2005 . In this test, now done by RGCC labs in Greece, circulating tumor cells or micrometastatic cells are isolated from the patient’s blood, genetically finger printed and then pharmaco genetically tested to determine effectiveness of both commonly used chemotherapies and targeted therapies as well as over 40 nutrient based and herbal therapies. Additionally, the targeted oncogenes are identified for each effective item. With this basic information patients and their doctors can more objectively personalize the treatment while reducing the risk of stimulating an even more aggressive and resistant tumor expression. You may call Daniel at 415 971-3733 to inquire further about the RGCC blood test.
Daniel J. Dunphy, PA-C, ND – 06.30.2009
The long-awaited era of personalized genetic medicine is finally dawning for people with cancer. A little-known reality of current “standard of care” in oncology is that genetic analysis of a person’s individual cancer is an effective, but unusual, method of cancer treatment.
Having researched cancer testing for the last five years both in Europe and the US, the author would like to share his insights with fellow health care practitioners. At present, a European lab offers a blood test which filters and isolates circulating tumor cells (a.k.a. micrometastatic cells) from a patient’s blood, genetically fingerprints them, then pharmacogenetically tests the cells for the effectiveness of various medical therapies.
Therapies tested include traditional medical chemotherapeutic agents and new generation targeted therapies, such as monoclonal antibodies and tyrosine kinase inhibitors, hormone blocking therapies, and an array of over forty nutrient, biological and herbal therapies.
The results not only help the practitioner and patient choose an effective combination of therapies, but also helps them understand which cancer genes (oncogenes) are blocked by which treatments. It is important to block the activity of multiple genes to successfully regulate cancer expression because single therapies are extremely rare in cancer care, as they often allow the cancer genome to adapt and become more aggressive.
Genetic tumor analysis is also available. Ideally, a frozen tumor sample is preserved at the time of biopsy. The sample can then be used for oncogene analysis, as well as creating an autologous (made from the patient’s own tissue) vaccine. A growing number of labs in the US and abroad offer this level of testing. However, only a few places worldwide provide autologous vaccine development. With regards to cancer care, it often pays to think and to act outside of the box.
One of the major labs that provide individual genetic analysis is Research Genetic Cancer Centre Labs in Greece (www.rgcc-genlab.com). I am unaware of any lab in the States doing this full multi-level analysis of micrometastatic cells. However, a relatively new blood test is available in the US, called CellSearch® Circulating Tumour Cell Test (Tel: 303 933-9785).
This test filters circulating tumor cells from a patient’s blood sample and gives a numerical probability of metastasis for colon, breast, prostate and ovarian adenocarcinomas. The cost of the RGCC test is about €1200 or $1800 USD. Return time is two weeks. Treating a cancer without oncogenetic (cancer gene) analysis is like trying to tell where a ship is coming from when it is thirty miles from the shore, without a telescope.
You know the ship is there, but where it’s actually coming from and whether it’s friendly or hostile are complete guesses. Individual oncogene analysis provides the appropriate quantum of analysis to pinpoint a cancer patient’s specific needs for care. The goal is to gather as much data as possible before therapies are selected. If a patient is treated with a wrong or inadequate therapy, the cancer will grow more aggressive in time. Similarly, trying to annihilate the cancer often annihilates the patient in the process, whereas containing the cancer over time usually allows the patient to live longer and enjoy a good quality of life, in spite of the cancer.
Think about how a bacterial infection is treated. If a doctor treats a systemic infection without first doing a culture and sensitivity test to determine which bacteria is involved and which antibiotics the bacteria is sensitive to, then he might prescribe the wrong treatment and thereby strengthen the infection. It is the same for the treatment and regulation of cancer.
Cancer can be viewed as a genetic organism with specific needs, strengths and weaknesses. It has an archaic metabolism similar to yeast, growing rapidly in low oxygen environments, and making only two ATP energy molecules from a molecule of sugar, then throwing off waste which creates a moat of toxicity and protects the cancer cells from the body’s defenses.
In normal cells in the body, one molecule of glucose sugar is made into 37 ATP energy molecules. This is an oxygen-based, highly efficient process, unlike cancer cell metabolism. Cancer cells thrive where other cells suffer. A tumor is highly inefficient and dies as fast, if not faster then it can grow; therefore it must seed itself in other areas of the body to survive.
It is a stealth-like parasitic organism which, unlike most evolutionary life forms, has evolved to thrive on inefficiency. It is important to understand that cancer is a systemic illness and that a tumor is NOT the cancer but only a manifestation of it.
Cancer is a disease which occurs at the level of the genes. While arguably an environmental illness, it occurs in individuals; as such, individual genetic analysis is a more precise tool to develop successful treatments for our patients.
Today’s “standard of care” for cancer is simply unacceptable, given the advances in biological sciences.
It is all too often a “standard of carelessness.”
Daniel has been doing onco genetic testing for his patients since 2005 using Dr. Michael Giesing’s TIRNA (Tumor Induced RNA) blood test.* Currently, Daniel uses the RGCC lab test for circulating tumor cells (aka micrometastatic cells). In this test circulating tumor cells are isolated from the patient’s blood then genetically finger printed. The isolated cancer “seeds” are then pharmaco genetically tested for the effectiveness of commonly used chemotherapeutic agents, gene targeted therapies , monoclonal antibodies and tyrosine kinase inhibitors, as well as over 40 nutrient and herbal based natural therapies. This allows the patient and doctors to more objectively determine the potential effectiveness of therapies before they are used and helps reduce creating an even more aggressive tumor expression often caused by using the wrong agents. You may call Daniel at 415 971-3733 to schedule this test. Please write firstname.lastname@example.org to order your test kit.
* see Daniel Dunphy’s Video page for segments of a lecture given by Dr. Giesing regarding his TIRNA test and its efficacy. See the -Micrometastatic circulating tumor cell- page on this website for more on Dr. Giesing’s research.
And here is a low dose approach to regulating cancer growth which is less likely to destroy the bone marrow and immune system, helps to regulate the caner genome for an individual and allows time to work on targeting immune function as well as detoxification and tonification of organs and adaptive immune system.
THE ANTI-ANGIOGENIC BASIS OF METRONOMIC CHEMOTHERAPY
Robert S. Kerbel 1&Barton A. Kamen 2 about the authors
1 Molecular and Cellular Biology Research, Sunnybrook and Women’s College Health Sciences Centre, S-217, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada.
2 Cancer Institute of New Jersey, Robert Wood Johnson Medical School, 195 Little Albany Street, New Brunswick, NJ 08901, USA.
correspondence to: Robert S. Kerbel RSKerbel@aol.com
In addition to proliferating cancer cells and various types of normal cells, such as those of the bone marrow, conventional cytotoxic chemotherapeutics affect the endothelium of the growing tumour vasculature. The anti-angiogenic efficacy of chemotherapy seems to be optimized by administering comparatively low doses of drug on a frequent or continuous schedule, with no extended interruptions — sometimes referred to as ‘metronomic’ chemotherapy. In addition to reduced acute toxicity, the efficacy of metronomic chemotherapy seems to increase when administered in combination with specific anti-angiogenic drugs. Gaining better insight into the mechanisms of these effects could lessen or even eliminate the empiricism used to determine the optimal dose and schedule for metronomic chemotherapy regimens.
For almost half a century, systemic therapy of cancer has been dominated by the use of cytotoxic chemotherapeutics. Most of these drugs are DNA-damaging agents or microtubule inhibitors that are designed to inhibit or kill rapidly dividing cells. They are often administered in single doses or short courses of therapy at the highest doses possible without causing life-threatening levels of toxicity — this is referred to as the ‘maximum tolerated dose’ (MTD). MTD therapy requires prolonged breaks (generally of 2–3 weeks in duration) between successive cycles of therapy. Despite the number of such chemotherapeutics and the huge number of clinical trials that have been undertaken to test them, progress has been modest in terms of curing or significantly prolonging the lives of patients with cancer — particularly those with advanced-stage or metastatic disease 1,2. Moreover, the progress that has been made in treating certain types of malignancy often comes at a high price, given the toxic side effects that are frequently associated with MTD-based chemotherapy. These include acute myelosuppression, hair loss, damage to the intestinal mucosa, nausea and mucositis, as well as the long-term cardiac, renal, neurological and reproductive consequences. Indeed, many of the recent pharmacological advances in oncology treatment involve growth factors and anti-nausea drugs, which are administered to patients with cancer to minimize the severity of, or accelerate recovery from, chemotherapy-induced toxicities. Such ‘supportive-care drugs’ can significantly add to the financial burden of cancer chemotherapy, and have their own side effects.
A reappraisal of the best ways of administering chemotherapy is underway. Instead of only using short bursts of toxic MTD chemotherapy interspersed with long breaks to allow recovery from the harmful side effects, there is now a shift in thinking towards the view that more compressed or accelerated schedules of drug administration using much smaller individual doses than the MTD would be more effective — not only in terms of reducing certain toxicities, but perhaps even improving antitumour effects as well 3-6 . Moreover, some of these dosing/scheduling strategies are ideally suited to combining chemotherapeutics with many of the new targeted and relatively non-toxic anticancer drugs that have been or are being developed. The most recent refinement of this concept is called ‘metronomic’ chemotherapy 3, which refers to the frequent, even daily, administration of chemotherapeutics at doses significantly below the MTD, with no prolonged drug-free breaks.
There are many different factors that have contributed to the line of reasoning that for chemotherapy, ‘the more frequent the better’ and that ‘less is more’. First, the opposite approach — using ‘high-dose’ chemotherapy with autologous bone-marrow stem-cell transplants (to replace the destroyed bone-marrow-derived stem cells) — has not provided the kind of survival benefits expected, at least when this treatment strategy is used for patients with metastatic breast cancer 7,8. This approach is also very expensive and highly toxic. Furthermore, ‘dose-dense’ chemotherapy, in which one or more chemotherapeutic is administered at more frequent intervals (that is, every other week), has shown clear benefits in randomized Phase III clinical trials 9-11 . This strategy is usually designed to administer at least the same amount or, more commonly, even a greater amount of drug in total over time. 9
So, if every other week is better than every 3 weeks, then why not administer weekly or even daily treatment? Indeed, it is becoming more common to administer taxane drugs to patients with certain types of cancer, such as breast cancer , on a weekly schedule 12-15 . Such dose density — which is allowable because of exogenously administered supportive-care growth factors, antibiotics and transfusion medicine — seems in some respects to be conforming to the metronomic-therapy theme, as discussed below.
METRONOMIC CHEMOTHERAPY can be viewed as a variation of dose-dense therapy with the exception that the cumulative dose with metronomic therapy might be significantly less than with MTD-based chemotherapy 15 ,16 . As metronomic therapy reduces the level of toxicity, it lessens or even removes the need for growth-factor support to accelerate recovery from myelosuppression. Moreover, despite lower cumulative doses of drug administration, the antitumour effects of this approach, in terms of prolonging survival times, might actually be superior to conventional MTD regimens, especially in some preclinical models 17-19 . Support for metronomic therapy also comes from mathematical modelling studies 20 ,21 . Unlike dose-dense chemotherapy, the main targets of which are presumed to be proliferating tumour cells, the main targets of frequent or continuous metronomic chemotherapy are the endothelial cells of the growing vasculature of a tumour 22 . In essence, chemotherapeutics are used as anti-angiogenic agents, therefore “redefining the target of chemotherapy”, to cite Miller et al .23 . This is also the reason that Browder et al .22 coined the term ‘anti-angiogenic chemotherapy’ to describe this treatment strategy.
Another advantage of metronomic chemotherapy is the possibility of combining it with anti-angiogenic drugs, as well as other types of targeted therapies — such those that target specific signal-transduction molecules — or with antitumour vaccines. It is ironic that targeted therapies were originally designed with the goal of replacing chemotherapy, to reduce the serious morbidities associated with standard MTD or high-dose chemotherapy. However, although they are less toxic, most of these rationally designed drugs were found to have very modest efficacy, at least when used as single agents in treating patients with advanced disease. They have therefore mainly been used in combination with standard chemotherapy or radiation protocols. An example of this is bevacizumab (Avastin) — a humanized monoclonal antibody against vascular endothelial cell growth factor ( VEGF ) — which is used in combination with 5-fluorouracil (5-FU)/leucovorin/irinotecan for the treatment of metastatic colorectal cancer 24 ,25 . Another example is trastazumab (Herceptin) — a humanized monoclonal antibody against the ERBB2 oncoprotein — which is combined with an alkylating agent or paclitaxel for the treatment of metastatic breast cancer 26 .
One of the proposed benefits of targeted therapies was reduced toxicity and improved quality of life. When these drugs are combined with MTDs of chemotherapy, however, these benefits are not realized. As it is likely that chemotherapy will continue to be the mainstay for systemic cancer therapy for many years to come, designing more effective ways of administering and combining such drugs with the newest generation of molecularly targeted drugs will become increasingly crucial.
Chemotherapeutics do not specifically target tumour cells, but rather interfere with cell division, such as by inhibiting enzymes involved DNA replication or metabolism (for example, topoisomerases and thymidylate synthase), or microtubules. These drugs therefore also damage the normal dividing cells of rapidly regenerating tissues, such as those of the bone marrow and gut mucosa, and hair-follicle cells. Host toxicity is therefore often only marginally less than antitumour efficacy, so creating a narrow therapeutic index.
But perhaps there is a silver lining in this otherwise dark cloud, in that dividing endothelial cells are present in the growing blood vessels that are found in tumours 27 and, like other normal dividing cells, should be susceptible to chemotherapeutics 28 . Elimination of these dividing endothelial cells, or inhibition of their division, would presumably lead to an anti-angiogenic effect. Moreover, as host vascular endothelial cells are assumed to be genetically stable and lack the diverse genetic defects characteristic of cancer cells that lead to drug resistance, the putative effects of chemotherapy might be more durable in the face of continued therapy. By way of example, successive cycles of MTD-based chemotherapy can cause myelosuppression each time, the extent of which does not change appreciably 28 . If normal bone-marrow-cell progenitors acquired resistance to chemotherapy in the same way that genetically unstable, highly mutable cancer cells do, myelosuppression would gradually decline and disappear. So, the cancer cells that are resistant to a particular chemotherapeutic agent might indirectly respond to that same drug through a ‘side effect’ — loss of or damage to its associated vasculature, as first proposed in 1991 (Ref. 29 ). Literature dating back to the mid-1980s shows that virtually every class of chemotherapeutic has anti-angiogenic effects or antivascular effects in various in vitro and in vivo assays 23 .
Many tumours, however, are intrinsically drug resistant or rapidly acquire resistance after showing initial responsiveness to chemotherapy regimens. So it would seem that chemotherapy has minimal or negligible anti-angiogenic effects. Why is this? Perhaps the proportion of dividing endothelial cells in tumour-associated blood vessels is simply too low for chemotherapy to have a significant therapeutic impact. Alternatively, the endothelial cells might be protected from chemotherapy-induced cell death by high local concentrations of endothelial-cell survival factors such as VEGF, basic fibroblast growth factor ( bFGF ) and angiopoietin 1 (Refs 30 ,31 ). A third explanation, uncovered in a pioneering study from Judah Folkman’s laboratory 22 , is that the anti-angiogenic effects of chemotherapy are both masked and marginalized by the way chemotherapy is usually administered. In this case, the long breaks between drug administration that are necessary to allow the patient to recover from the harmful side effects of the MTD chemotherapy, especially from myelosuppression, reduce the anti-angiogenic effects of the drugs.
Timothy Browder and colleagues evaluated the anti-angiogenic and antitumour effects of the alkylating agent cyclophosphamide in immune-competent syngeneic mice that had been injected subcutaneously with various tumour types 22 . They found that this drug, when administered at the MTD, caused apoptosis of endothelial cells in the newly formed tumour microvessels 22 . A detailed temporal analysis showed that the endothelial cells were the first in the tumour to undergo apoptosis 22 . This anti-angiogenic effect did not, however, translate into a significant therapeutic benefit, apparently because the damage to the vasculature of the tumour was largely repaired during the long (2–3-week) rest/recovery periods between successive cycles of MTD-based therapy.
It was therefore proposed that if cyclophosphamide was given more frequently ( Fig. 1 ), such as once or more per week with no extended breaks, there would be significantly less opportunity for repair of the damaged endothelium and the anti-angiogenic effects of the chemotherapy would irreversibly accumulate. This, of course, necessitates lowering the dose of the drug administered with each injection. Browder et al . showed that this more frequent, regular, lower-dose therapy, which was administered at one-third of the MTD, had impressive anti-angiogenic and antitumour effects when tested on several mouse tumour cell lines grown subcutaneously in syngeneic mice 22 . This approach allowed even very large established subcutaneous tumours, previously selected in vivo for acquired cyclophosphamide resistance using a conventional MTD regimen, to respond to the same drug and almost completely regress. In short, a state of acquired drug resistance could be reversed simply by apparently shifting the focus of the treatment away from the drug-resistant cancer-cell population to the drug-sensitive tumour endothelium 3,22 .
Figure 1 | Different therapeutic regimens.
Metronomic chemotherapy regimens differ from the standard maximum tolerated dose (MTD) chemotherapy regimens that have been common practice in medical oncology for decades. a| In standard chemotherapy, a drug is typically given in a single bolus injection or infusion at the MTD, interspersed by a long break — for example, 3 weeks — before the next course of this therapy is administered. Doses that exceed the MTD (‘high-dose’ chemotherapy) must be accompanied by an autologous bone-marrow stem-cell transplant and supportive-care growth-factor drugs to prevent lethal bone-marrow failure. In band c, examples of metronomic chemotherapy regimens are shown where, for example, the chemotherapy drug is administered more frequently, such as weekly ( b) or daily ( c), with no prolonged drug-free interruptions. Drugs that can be administered orally, such as cyclophosphamide, capecitabine, etoposide (VP-16), UFT (uracil plus tegafur, a fluoropyrimidine antimetabolite), would be ideal for prolonged daily administration schedules. Omission of prolonged drug-free periods is a key aspect of the basis for the anti-angiogenic effects of low-dose metronomic chemotherapy regimens, as these breaks allow repair and recovery from the anti-angiogenic effects of chemotherapy drugs on developing tumour blood vessels.
These results have been confirmed by others 32 ,33 and have also been modified with daily oral administration of the drug through drinking water, which seems to be less toxic than the weekly regimen 19 ,34 . Indeed, a recent detailed analysis showed that long-term daily low-dose cyclophosphamide therapy did not cause significant toxicity to tissues or cells normally affected by MTD regimens of the same drug 35 ; lymphopaenia was the only toxic side effect noted 35 .
Clinical precedents for metronomic therapy
In retrospect, these preclinical results actually have many intriguing clinical precedents 4,36 . For example, 40% of patients with non-small-cell lung cancer (NSCLC) who showed no response to standard doses of intravenous etoposide administered intermittently did respond — that is, their tumours shrank by 50% of more in volume — to the same drug when it was given orally at a much lower dose using a much more frequent basis (every day or every other day), with only a 1-week break every month 37 . Similar results have been shown in patients who have been given other drugs, such as microtubule-inhibiting taxanes, for treatment of advanced metastatic breast or ovarian cancer . In these patients, weekly regimens of drug administration are being increasingly adopted, often using only 30–40% of the MTD given once every 3 weeks 38 . In women who had stopped responding to the MTD of paclitaxel or docetaxel given once every 3 weeks, tumours were found to respond in a high proportion of cases to a regimen of approximately 30–40% the MTD once every week 13 ,36 ,38-40 . However, for the most part, these are not standard-of-care regimens and their benefits remain to be validated in randomized prospective Phase III clinical trials.
Metronomic therapy is also similar in many ways to the various long-term ‘maintenance’ chemotherapy regimens 41-45 that are used to treat children with certain types of cancer, such as acute lymphoblastic leukaemia . Maintenance therapy in this case involves the administration of low doses of oral methotrexate on a weekly basis and 6-mercaptopurine on a daily basis for up to 3 years. This treatment follows short-term remission-inducing chemotherapy using standard regimens and higher doses of various chemotherapeutic drugs 42 ,45 . Several studies have indicated that the drugs used in this type of maintenance therapy have anti-angiogenic effects 46-48 . In the case of methotrexate, low doses have been shown to cause anti-endothelial/anti-angiogenic effects in in vitro and in vivo assays 46 ,47 . Furthermore, the maintenance therapy used to treat patients with acute lymphoblastic leukaemia has been shown to have anti-angiogenic effects in the bone marrow, reducing the number of blood vessels in this tissue compartment 49-51 . The success of following standard MTD ‘remission-induction’ chemotherapy with long-term metronomic therapy regimens highlights the possibility that these two types of dosing regimens are not mutually exclusive, but can be used sequentially in a beneficial and harmonious manner. This approach should also be considered for adults, especially when combined with a cytostatic agent for long-term therapy.
Combination with anti-angiogenic drugs
Clinical trials are underway to determine whether metronomic chemotherapy can prolong survival when compared with standard MTD regimens in patients with various cancers, including advanced prostate and ovarian carcinomas, as well as certain types of haematological malignancies 6,49-52 . Relapses, however, will undoubtedly occur in most patients who initially show some benefit from metronomic therapy 49 . It was partly for this reason that the metronomic-chemotherapy protocol of Browder et al . has been modified and combined with endothelial-cell-specific angiogenesis inhibitors such as anti-VEGF receptor 2 ( VEGFR2 , also known as KDR or FLK1) antibodies or TNP-470, a fumigillin analogue 22 ,53 . This combination approach might improve efficacy without significantly increasing host toxicity 16 .
The rationale for this strategy was based on several considerations. VEGF-receptor tyrosine kinases are expressed preferentially by endothelial cells of the growing neovasculature of a tumour, and VEGF is a key survival (anti-apoptotic) factor for the endothelial cells of newly formed vessels 54 ,55 . There are several signalling pathways and molecular effector mechanisms by which VEGF can inhibit apoptosis in endothelial cells 31 ,56-60 . For example, signalling through VEGFR2 can activate the phosphatidylinositol 3-kinase (PI3K)–AKT pro-survival signalling pathway. This or other pathways lead to subsequent upregulation of several anti-apoptotic effectors, including BCL2, A1, XIAP and survivin 31 .
There is evidence that the anti-proliferative 30 or pro-apoptotic actions of pacitaxel 31 , vinblastine, cisplatinum and adriamycin 31 , as well as of several other types of cytotoxic substances, on human endothelial cells in culture are suppressed by the presence of VEGF 30 ,31 . High local concentrations of VEGF in the tumour microenvironment might therefore induce or promote multidrug resistance, by inducing a highly specific chemoprotective effect towards the VEGFR2-positive endothelial cells of the tumour 30 ,31 ,61 . Chemotherapy itself might also induce or upregulate the expression of VEGF and other endothelial-cell pro-survival growth factors in tumour cells 62 . So, the combination of a chemotherapeutic agent with a drug that blocks VEGF or its receptor (VEGFR2) should selectively amplify the pro-apoptotic effects of the chemotherapeutic against activated endothelial cells, but presumably not against other types of dividing normal cells 16 . This would improve the therapeutic index.
Previous studies have shown that anti-angiogenic drugs can improve the effects of some standard chemotherapy regimens 63 ,64 , and these findings have been validated in the clinic 24 ,25 . For example, in a large, randomized, placebo-controlled Phase III clinical trial, the combination of a standard, approved chemotherapy regimen for metastatic colorectal cancer — consisting of 5-FU/leucovorin and irinotecan — with bevacizumab (the anti-VEGF antibody), caused a statistically significant prolongation of survival, compared with patients treated with only the chemotherapy regimen 25 . So, one might anticipate that anti-angiogenic drugs should also improve the efficacy of continuous low-dose chemotherapy regimens, for which the side effects would be much more tolerable, and that the two types of drug could be administered together for long time periods.
Experiments were undertaken to evaluate this combination treatment concept using xenograft models of neuroblastoma 16 ,melanoma , breast, prostate and colon cancers 19 ,65 . In one of these studies, a very low dose of vinblastine was administered twice weekly — which was about 1/10–1/20 the MTD for mice and therefore represents low-dose chemotherapy 66 ,67 — in combination with an anti-VEGFR2 blocking monoclonal antibody called DC101 (Ref. 70 ). This combination caused complete and sustained regression of large, established — but localized — neuroblastoma xenografts in severe combined immunodeficient (SCID) mice. The metronomic vinblastine treatment was preceded by a 3-week remission-induction schedule of higher cumulative doses of the drug 16 to reduce the large tumour burden. This combination treatment, in which the two different drugs were given twice a week with no breaks, could be maintained for these exceptionally long periods (7 months) because they were not toxic to the mice 16 . By contrast, treatment with either the vinblastine regimen or DC101 alone, although non-toxic, resulted in significant but short delays in the growth of the tumour in the growth followed by relapse, and the animals only survived 1–2 months after initiation of treatment.
Were the low-dose chemotherapy regimens used in these studies anti-angiogenic and, if so, was this was the only antitumour mechanism? To address this question, a quantitative in vivo blood-vessel PERFUSION ASSAY showed that the low-dose vinblastine protocol itself could significantly inhibit angiogenesis 16 . Similarly, Browder et al . tested the weekly low-dose cyclophosphamide regimen using a CORNEAL MICROPOCKET ASSAY to show that this metronomic therapy protocol inhibited angiogenesis 22 .
Other studies involved 65 human breast cancer cell lines that had been previously selected for resistance to agents such as paclitaxel, doxorubicin and vinblastine, as a result of overexpression of the multidrug resistance 1 ( MDR1 ) gene, which encodes the P-glycoprotein drug-efflux pump 65 . In some cases, these cells were resistant to 50–100-fold higher concentrations of drugs than normal cells 65 . In xenograft studies, the combination of DC101 plus metronomic chemotherapy slowed tumour growth, whereas DC101 treatment or metronomic chemotherapy alone resulted in only temporary tumour responses — or even no apparent primary tumour responses, as measured by decreases in tumour volume. Cancer-cell-specific effects of drugs are not sufficient to overcome this level of drug resistance, so some alternative mechanism, such as anti-angiogenesis, must be involved 65 . Furthermore, Browder et al . administered a combination of the angiogenesis inhibitor TNP470 with weekly doses of cyclophosphamide to treat large, established transplanted mouse tumours that were previously selected for resistance to cyclophosphamide. They found that the combined treatment could gradually cause marked and sustained regressions, if not complete disappearance of such tumours 22 .
The results of Browder et al . and Klement et al . have now been confirmed by many different groups using various empirical continuous or frequent low-dose chemotherapy regimens. These regimens included many different chemotherapeutic drugs, as well as several different anti-angiogenic agents 32 ,68-73 . A summary of the drugs, drug combinations and tumour models studied is shown in Table 1 (Refs 18 ,19 ,73 ,74 ). In some of these studies, an empirical metronomic dosing schedule was compared head-to-head with the respective MTD regimen of the same chemotherapeutic drug 17 ,19 ,20 ,71 ,72 . In all cases, the MTD regimens were found to be inferior to the metronomic treatments in terms of either toxicity or survival, or both. This also held for situations in which an anti-angiogenic drug was added to the MTD, compared with respective metronomic chemotherapy regimens 17 ,19 ,20 .
Table 1 | Preclinical examples of antitumour efficacy of metronomic chemotherapy
The number of such studies, however, is limited and these findings need to be confirmed using different chemotherapeutic agents. Moreover, as discussed above, there might be additional benefits to using standard MTD chemotherapy followed by a subsequent long-term metronomic regimen — especially when treating exceptionally large tumours that are known to be responsive to certain chemotherapy drugs administered in the MTD fashion. This approach was used in preclinical studies by Klement et al .16 and Bocci et al .34 . Whereas some of the preclinical studies reported exceptionally long-term tumour responses, and in some cases mice were even cured 16 ,22 , most mice eventually relapsed 75 ,76 . This indicates that some forms of acquired resistance occur — either at the host level (such as through altered drug metabolism), the tumour-cell level, (such as through selection for mutant tumour cells that can survive under the hypoxic conditions created by inhibition of angiogenesis) 75 or at the level of the endothelial cells or blood vessels (such as vascular remodelling into more mature vessels that are less responsive to anti-angiogenic treatment) 76 .
Much evidence, mostly in vitro , indicates that the ‘activated’ endothelial cells of newly forming blood-vessel capillaries are highly and selectively sensitive to very low doses of various chemotherapeutic drugs 47 ,77-81 . For example, several studies have been undertaken to test the antiproliferative, migration-inhibitory and sometimes cytotoxic effects of picomolar concentrations of chemotherapeutic drugs on various human cell types, including fibroblasts, lymphocytes, tumour cells, epithelial cells from various tissues, and microvascular or macrovascular endothelial cells. A summary of some of these studies is shown in Table 2 . Some of the most interesting studies involve various microtubule inhibitors, such as vinblastine, paclitaxel and docetaxel. In these experiments, ultra-low concentrations of these drugs were reported to inhibit proliferation or migration of endothelial cells, but not of other cell types examined. For example, Wang et al . reported that 10–100,000-fold higher concentrations of paclitaxel were required to inhibit proliferation and migration of human astrocytes, fibroblasts, mammary epithelial cells, keratinocytes, prostate epithelial cells or smooth-muscle cells, compared with epithelial cells 80 . Taxanes, however, must be formulated in certain vehicles for injection, to prevent their binding to serum proteins. Clinically relevant concentrations of these vehicles or binding proteins can significantly dampen the anti-angiogenic activity of taxanes, meaning that higher doses of such injectable taxanes would have to be used in vivo to induce anti-angiogenic effects 82 .
Table 2 | Sensitivity of human vascular endothelial cells to metronomic therapy
Most of these studies reported no cytotoxic effects, although we have found that if endothelial cells are continuously exposed to a low concentration of drug such as paclitaxel over a 6 day period (replicating metronomic therapy), endothelial cells, but not dermal fibroblasts or tumour cells, undergo apoptosis within about 5 days 78 . This delay in cytotoxicity indicates that the pro-apoptotic effects of low-dose metronomic chemotherapy on endothelial cells might not be direct, but could instead be a secondary result of some other process that is specific to the vascular endothelial cell. This concept is illustrated in Fig. 2 .
Figure 2 | Possible mechanisms of the anti-angiogenic basis of metronomic chemotherapy.
There are two routes by which metronomic chemotherapy could lead to growth arrest or apoptosis of endothelial cells in the tumour neovasculature. A ‘direct’ pathway (left) assumes that activated, differentiated endothelial cells are intrinsically sensitive to low-dose chemotherapy, for which there is some evidence 80-85 ; the same might be true for circulating endothelial progenitor cells 17 . The ‘indirect’ pathway (right) assumes that the levels of metronomically administered drugs are too low to induce growth arrest or apoptosis of endothelial cells. Instead, an endogenous inhibitor of angiogenesis, such as thrombospondin 1, is induced in certain cells by low-dose chemotherapy. This inhibits tumour angiogenesis and vasculogenesis, leading to a reduction in tumour neovascularization in the absence of side effects such as myelosuppression, hair loss, and nausea or vomiting.
Two recent studies implicate thrombospondin 1 ( TSP1 ) as a potential mediator of the effects of metronomic cyclophosphamide 33 ,34 . In one study, 5 days of exposure to low concentrations of various chemotherapeutic drugs caused a marked increase in TSP1 mRNA and protein levels in vascular endothelial cells in vitro (other cells were not tested). TSP1, a component of the extracellular matrix that can also be secreted and found in the circulation, is a well known endogenous inhibitor of angiogenesis 83 ,84 . It seems to act primarily by binding to CD36 receptors, which are expressed by endothelial cells 85 . This interaction blocks proliferation and induces apoptosis in endothelial cells 86 ,87 , but would not be expected to occur in CD36-negative cells, such as most bone-marrow-derived haematopoietic stem cells or hair-follicle cells. TSP1 can also bind and sequester VEGF, and therefore block its pro-angiogenic activity 88 .
Further evidence to implicate TSP1 as a secondary mediator of the anti-angiogenic properties of metronomic chemotherapy was obtained in experiments that compared the anti-angiogenic and antitumour effects of MTD cyclophosphamide with a continuous daily low-dose regimen of the same drug in wild-type or Tsp1 -null mice 34 . In these experiments, the drug was administered continuously in the drinking water 19 . The antitumour efficacy (tested on subcutaneously transplanted Lewis lung carcinoma tumours) and anti-angiogenic effects were lost in the Tsp1 -null mice, but not in the wild-type controls 34 ,78 . Raghu Kalluri and collaborators have also shown that weekly administration of low doses of cyclophosphamide leads to loss of the antitumour activity of this drug against the B16 mouse melanoma grown in Tsp1-deficient mice 33 . By contrast, the chemotherapy regimen retained its efficacy in mice that were unable to produce either endostatin or tumstatin — two other endogenous inhibitors of angiogenesis 33 . It therefore seems that these molecules are not involved in the anti-angiogenic effects of metronomic treatment with cylophosphamide. TSP1, however, is induced in the melanoma cells and infiltrating host (stromal) cells of the treated tumours 33 .
So, metronomic chemotherapy might not necessarily act directly on endothelial cells, but might instead act by inducing endothelial-cell-specific inhibitors, such as TSP1. This could explain why metronomic chemotherapy regimens do not increase the usual harmful side effects of chemotherapy, such as myelosuppression, despite the elimination or shortening of long, drug-free break periods. It is also interesting to note that other anticancer drugs that have anti-angiogenic ‘side effects’ could also work by a similar mechanism. For example, in 1997 trastazumab, a monoclonal antibody against ERBB2, was implicated to have anti-angiogenic properties 89 , as it inhibits VEGF expression. Furthermore, it can induce TSP1 in tumour cells 90 .
As previously discussed, one crucial aspect and advantage of metronomic therapy is that it prevents the repair to the tumour vasculature that occurs between sessions of MTD therapy. What is the basis of this apparently robust and highly specific repair process? Part of the answer might lie in the effects of metronomic chemotherapy regimens on the mobilization, levels and viability of bone-marrow-derived circulating endothelial progenitor cells (CEPs). These cells contribute to some forms of angiogenesis, such as development of the vasculature in early embryonic development, as well as tumour angiogenesis, essentially constituting a form of ‘systemic’ vasculogenesis and angiogenesis, in contrast to the local division of differentiated endothelial cells in pre-existing vessels. Until 1997, it was thought that all new endothelial cells were derived through the latter process 91 , but there are reports that claim that up to 50% of the endothelial cells in newly forming blood vessels come from CEPs 92 . These cells can be mobilized from the bone marrow by growth factors such as VEGF, and then enter the peripheral-blood circulation. There, they can migrate to sites of ongoing angiogenesis and differentiate into mature endothelial cells 20 ,91 ,93 .
Bertolini et al .17 showed that in immune-deficient mice that were previously injected subcutaneously with human lymphoma cells, the increased levels of CEPs detected in the blood circulation of the mice sharply declined shortly after the mice were treated with a cycle of MTD cyclophosphamide. The number of these cells quickly and sharply rebounded during the drug-free break period, presumably as the result of a compensatory haematopoiesis-like effect 17 . By contrast, when cyclophosphamide was administered at lower doses on a weekly basis or continuously in drinking water, the numbers of CEPs gradually declined, as did their viability, and no compensatory rebound was observed 17 . If CEPs make a significant contribution to tumour angiogenesis — and this remains a point of continuing debate 94 ,95 — the ‘rebound’ of these cells during the long break periods after MTD chemotherapy could contribute, at least in part, to the repair process that occurs in the damaged tumour endothelium. This would explain the inability of MTD chemotherapy to inhibit tumour angiogenesis in a sustained, and therefore therapeutically effective, manner.
These studies call into question the use of growth factors as supportive measures to accelerate recovery from the myelosuppression-inducing effects of high-dose, standard MTD or dose-dense chemotherapy regimens. For example, both erythropoietin and granulocyte colony-stimulating factor ( G-CSF ) are often given to patients to help them recover from anaemia and myelosuppression, respectively, which are induced by MTD chemotherapy regimens. This is because they promote the mobilization of marrow progenitor cells into the peripheral circulation, where they can differentiate into mature white blood cells such as neutrophils or red blood cells, and have been shown to increase the mobilization of CEPs 96 ,97 . This, in turn, can stimulate vasculogenesis/angiogenesis, leading to tumour growth 98 ,99 , and could provide one explanation for the fact that treatment of patients with recombinant erythropoietin after standard chemotherapy is associated with a worse outcome, in terms of survival, in some clinical trials 100 .
Clinical trials of metronomic chemotherapy
Phase II clinical trials have been initiated to test the possible benefits of metronomic chemotherapy regimens — particularly when these are combined with an anti-angiogenic drug. Several of these trials are summarized in Table 3 . Most of these involve chemotherapy regimens in which cyclophosphamide is administered orally on a daily basis, sometimes for up to 2 years, with no break periods. In some cases, oral low-dose methotrexate is also given on two consecutive days on a weekly basis. The targeted drugs that are used include a cyclooxygenase-2 ( COX2 )-specific inhibitor such as celecoxib, which is administered on a daily basis, or a humanized anti-VEGF monoclonal antibody (such as bevacizumab), which is administered intravenously every 2 weeks. Celecoxib was selected for inclusion in the trial because of its commercial availability, ease of administration, excellent side-effect profile and putative anti-angiogenic effects 101 ,102 .
Table 3 | Clinical trials involving metronomic chemotherapy
The combination of cyclophosphamide and methotrexate has already been tested in a clinical trial in Italy, and has spurred additional trials that are underway 49 . Sixty-four women with progressive, advanced and refractory breast cancer received low doses of oral cyclophosphamide on a daily basis and oral methotrexate was given twice per week. Most of the patients had progressive metastatic disease when the trial began and had also previously received first-, second- or third-line treatments. An overall response rate of 32% was observed, which included two complete responders, 10 partial responders and 12 patients with stable disease lasting 6 months or longer 49 . No high-grade adverse events were reported, despite the fact that many patients had previously been treated with chemotherapy. This compares favorably with the standard third-line chemotherapy regimens used in this treatment setting, at least in terms of toxicity. The estimated cost of this outpatient therapy was about US$10 per month 49 .
In another recently reported trial, Glode et al . treated 32 patients with advanced androgen-independent metastatic prostate cancer. These patients received daily oral doses of cyclophosphamide and dexamethasone 52 . Dexamethasone, in addition to other properties, has been reported to have some anti-angiogenic effects 52 . In this small study, almost 70% of the patients showed a decrease in serum prostate-specific antigen levels of 50% or more. Although such preliminary results are encouraging, they need to be confirmed in much larger, controlled and prospective clinical trials 103 .
It is also very difficult to determine conclusively whether these therapies have anti-angiogenic effects that contribute to their putative antitumour efficacy. In this regard, Colleoni et al . reported that serum VEGF levels declined in patients who responded to therapy 49 . Bertolini et al . reported a reduced number of bone-marrow-derived CEPs in the blood of patients with lymphoma and breast cancer who received daily low-dose cyclophosphamide therapy 104 , similar to that observed in patients with rectal carcinoma who are treated with the anti-VEGF monoclonal antibody bevacizumab 105 . Nevertheless, the therapies obviously have other effects that contribute to their efficacy — this is especially true for drugs such as celecoxib and dexamethasone. For example, COX2, which is inhibited by celecoxib, can be expressed by tumour cells as well as by activated endothelial cells 101 . It is also known that low-dose chemotherapy, can stimulate the immune system in some cases, 106 ,107 , making it a potentially useful addition in combination with tumour vaccines or other types of immune-therapy approaches. Indeed, some studies indicate that metronomic chemotherapy using cyclophosphamide can increase the efficacy of immunotherapeutic vaccines in preclinical models 108 ,109 .
Metronomic therapy might also have some direct effects on tumour cells, such as induction of cell differentiation, although there is not yet any evidence for this. Continuous-chemotherapy regimens could also prevent a rebound in tumour-cell division known as ‘repopulation’, which can take place during the rest periods between cycles of MTD chemotherapy. Repopulation kinetics can become increasingly more aggressive with successive cycles of MTD pulsatile chemotherapy 110 , so shortening or eliminating the drug-free break periods might prevent this ‘kinetic drug resistance’.
Several successful paediatric chemotherapy approaches resemble metronomic therapy, as discussed above, in that they involve daily administration of low doses of cytotoxic drugs over prolonged periods of time, as so-called ‘maintenance’ therapies, and have minimal toxicity ( Table 4 ). Paediatric oncologists have shown that daily adminstration of cyclophosphamide along with weekly administration of Vinca alkaloid drugs, such as vincristine or vinblastine, is effective in treating patients with diseases such as neuroblastoma 111 . Weekly administration of Vinca alkaloids is also a key component of therapy for patients with Wilms’ tumour and rhabdomyosarcoma . Paediatric ‘CHOP’ (cyclophosphamide, adriamycicin, vincristine and prednisone) therapy, which is used to treat patients with non-Hodgkin’s lymphoma , is also conceptually similar to metronomic therapy. Aggressive fibromatosis can also be controlled with low-dose vinblastine and methotrexate treatment 112 . Other low-dose chemotherapy regimens that are being tested in children, with some hints of success, include low-dose cyclophosphamide treatment and low-dose vincristine therapy to treat infants with localized, unresectable neuroblastoma 111 .
Table 4 | Metronomic chemotherapy in paediatric oncology
The oral fluoropyrimidine 113 agent, UFT (uracil plus tegafur) — a prodrug mixture that is metabolized to 5-FU and two other metabolites, -butyrolactone (GBL) and -hydroxybutyric acid (GHB) — represents another chemotherapeutic that might be applied metronomically 74 ,111 ,114 . This drug is approved for treatment of certain cancers in Japan and throughout Europe, but not in the United States 115 . Recent randomized Phase III ADJUVANT clinical trials have been undertaken in patients with resected early-stage NSCLC of the adenocarcinoma variety. These patients were given daily low doses of oral UFT for 2 years, resulting in both a survival benefit and very little toxicity, despite the chronic nature of the treatment 116 . 5-FU, GBL and GHB have all been shown to have anti-angiogenic activity in an in vivo assay 74 ,117 , as well as to inhibit growth and migration of endothelial cells in culture 74 ,117 — especially when they are administered continuously at low doses 74 . Could the anti-angiogenic effects of this drug contribute to its clinical efficacy? Could this efficacy be increased by combination therapy with a targeted anti-angiogenic drug? Further studies are necessary to answer these questions. The trial of UFT in patients with lung cancer, however, shows the potential of oral long-term metronomic chemotherapy as an adjuvant therapy to treat patients who could have microscopic, early-stage recurring tumours.
Further experiments are required to determine whether other chemotherapeutics that can be orally administered on daily schedules for extended periods of time, such as the topoisomerase enzyme inhibitor etoposide (VP-16) or the alkylating agent temozolamide 118 , also have anti-angiogenic effects 119 that contribute to their antitumour efficacy. There are several other situations in which prolonged oral administration (4–5 weeks) of relatively low doses of chemotherapeutics is already in use, such as administration of etoposide 37 ,120 , razoxane 121 or temozolamide 122 ,123 to treat malignant melanoma and non-Hodgkin’s lymphoma. These are palliative-like regimens that are less toxic and are sometimes used to treat elderly patients, who are less able to cope with toxic MTD chemotherapy. It will be important to determine if anti-angiogenic effects contribute to the efficacy of such protocols — there is already some preliminary evidence that this is the case 119 ,121 . These studies could also accelerate the development of oral taxanes and other microtubule inhibitors for metronomic therapy 124 . Another approach involves the use of injectable chemotherapeutics that are incorporated into endothelial-targeted liposomes to increase the half-life of the drug in the circulation 125 .
Other types of metronomic therapy
The metronomic approach is not only used with chemotherapy, but also with radiation therapy. Sometimes, radiotherapy is administered at lower than normal doses, known as ‘hyperfractionated radiation’ 92 . In this regard, Garcia-Barros et al . have shown that the antitumour effects of irradiation can be mediated through a primary event that involves damage or destruction of the neovasculature of a tumour, followed by the death of tumour cells that surround the affected vessels 92 . This could help to explain the increased therapeutic efficacy of combining radiation therapy with endothelial-cell-specific anti-angiogenic drugs such as angiostatin or anti-VEGF antibodies 126 ,127 .
The cytokine intereferon- (IFN- ) also has anti-angiogenic effects, and is used effectively to treat paediatric patients with haemangiomas or giant-cell tumours when administered in small daily doses over prolonged periods of time 128 ,129 . This might be considered to be another example of the efficacy of anti-angiogenic metronomic therapy. Preclinical studies from Isiah Fidler’s group have also shown that metronomic administration of IFN- therapy is significantly more effective as an anti-angiogenic and antitumour treatment strategy in mouse xenograft models of cancer 130 . They have shown that daily administration of 10,000 units of IFN- was more effective than 70,000 units administered once a week as an anticancer therapy 130 .
Although we have explained the potential benefits of metronomic chemotherapy regimens — especially when used in a combination-therapy context with targeted anti-angiogenic agents — there are several significant challenges that must be overcome to increase the chances of success in the clinic. Foremost among these is the current empiricism associated with trying to determine the optimal dose and schedule for administration of chemotherapeutics. Other medical subspecialties have defined minimally inhibitory concentrations, such as those used to treat patients with infectious diseases or epilepsy.
It seems that there are two main approaches to administering chemotherapy. Perhaps a useful analogy is to compare these approaches to radio airwaves. ‘Amplitude modulation’ (AM) involves increasing the dose, but this requires increasing the time between the doses, whereas ‘frequency modulation’ (FM), involves decreasing the amplitude (the unit dose/time). There are some obvious advantages to FM, such as reduced acute toxicity and the ability to combine the drug with targeted therapeutics for prolonged periods. The challenge therefore is to find the smallest dose that will control the target cells and then the most frequent dosing that will maximize this control. This type of problem is obviously not unique, as many molecularly targeted drugs do not produce their maximum therapeutic effects at the MTD, and some do not even have dose-limiting toxicities 131 ,132 . Similarly, determining the biological activity of such agents in the absence of acute tumour regression can be difficult.
These problems might eventually be overcome through the discovery and application of novel molecular or functional surrogate markers, to guide dose selection and to monitor antitumour activity. The same could be the case for metronomic chemotherapy. So, detecting changes in levels of circulating TSP1 levels in serum or plasma after administration of various low doses of chemotherapeutics might be useful in determining the optimal low dose for a drug such as cyclophosphamide 34 . Another possibility is the application of functional imaging approaches, such as those used to detect changes in tumour blood flow. For example, Walter Wolf and colleagues recently reported that administration of docetaxel on either a once-every-week schedule, or a once-every-3-weeks schedule, resulted in reductions in tumour blood flow in several patients with breast cancer, as determined by dynamic-contrast magnetic-resonance imaging. Moreover, there seemed to be a strong correlation between this change and tumour response 133 . This is strikingly similar to the results of a clinical study involving administration of an anti-angiogenic drug called PTK787 — a small-molecule antagonist that blocks several receptor tyrosine kinases, including VEGFR2 in patients with colorectal carcinoma 134 . So, chemotherapeutics could have significant antivascular properties, which in some cases might be their primary effector function in terms of tumour destruction.
Another promising approach to determining the optimal low dose for a given metronomic chemotherapy regimen is evaluation of the activities of CEPs or circulating endothelial cells (CECs). As previously discussed, CEPs mobilization from the bone marrow into the peripheral circulation is strongly inhibited by low-dose cyclophosphamide, as is CEP viability 17 . So, there could be a direct relationship between the relative efficacy of different (low) doses of metronomic chemotherapy and the ability of these doses to reduce levels of CEPs in the peripheral circulation (Y. Shaked & R.S.K., unpublished observations). Furthermore, assays have been developed to detect the presence of CECs and CEPs in blood samples, such as by performing RT-PCR to detect the mRNA for the vascular endothelial cell-adhesion molecule VE-cadherin 135 . It is therefore encouraging that infusion of bevacizumab in patients with rectal carcinoma was recently found to lead to a rapid decline of both CECs and CEPs in the peripheral blood, as these assays might be exploited not only to monitor anti-angiogenic drug or treatment activity, but to help determine the optimal dose.
A second challenge is the prospect of delayed side effects, including secondary neoplasms, when administering protracted regimens of DNA-damaging agents or other types of genotoxic agents, although it might be argued that these are not a serious concern when treating patients with advanced-stage cancers. But it is certainly a concern in adjuvant-therapy settings for patients with early-stage disease, many of whom are already cured.
As for toxic side effects, although these might be delayed, they might nevertheless be significant. We have found that mice treated with protracted daily oral low-dose cyclophosphamide can eventually develop lymphopaenia 35 . Similarly, patients treated with extended low-dose temozolamide for successive cycles of 6 weeks with 2-week breaks can develop immunosuppressive T-cell lymphopaenia 136 . In this regard, the minimal-toxicity profile observed in patients with early-stage resected NSCLC who were given low doses of UFT every day for 2 years is encouraging — grade 3 toxic effects occurred in only 10/482 (2%) of patients 116 . This is particularly important because anti-angiogenic drugs and metronomic chemotherapy regimens might work best, and sometimes only, in patients with low-volume disease burden. This is true for almost all anticancer drugs and treatment strategies, for various reasons. These include reduced drug access to larger tumours, as well as reduced oxygen levels (hypoxia), which can attenuate the toxic effects of radiation or chemotherapy. It might be possible to treat early-stage disease with long-term combination therapies, but this clearly necessitates the use of non-toxic and less expensive drugs.
Hopefully, some of the clinical trials that are underway, especially those that are prospective and randomized 103 , will better indicate the potential promise of this therapeutic strategy — particularly when such metronomic chemotherapy regimens are integrated with new molecularly targeted drugs. In particular, there is a need to learn more about which chemotherapeutics are the most effective for metronomic dosing regimens, what combinations and sequences might be best to use, and what mechanisms of resistance might develop over time 75 ,76 . Furthermore, it will be important to determine the types of cancer that might be the most responsive to these therapeutic approaches. There is already some data available for the treatment of breast cancer 137 and tumours of the central nervous system 138 using this approach. As scientists carrying out basic research perform more preclinical studies this approach and begin to work more closely with clinical investigators that are leading metronomic chemotherapy-based clinical trials, there should be significant progress towards answering these questions over the next few years.
Cancer.gov: acute lymphoblastic leukaemia |breast cancer |colorectal cancer |melanoma |neuroblastoma |non-Hodgkin’s lymphoma |non-small-cell lung cancer |ovarian cancer |prostate cancer |rhabdomyosarcoma
Entrez Gene: angiopoietin 1 |bFGF |CD36 |COX2 |ERBB2 |G-CSF |IFN- |MDR1 |TSP1 |VE-cadherin |VEGF |VEGFR2
OMIM: Wilms’ tumour
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We are grateful to C. Cheng for her excellent secretarial and editorial assistance. We thank U. Emmenegger for critical reading of the manuscript. R.S.K. is a Canada Research Chair in Molecular Medicine whose research is supported by grants from the National Institutes of Health (USA), the National Cancer Institute of Canada, and the Canadian Institutes of Health Research. B.A.K. is an Amercian Cancer Society Clinical Research professor. This review is dedicated to T. Browder, whose pioneering studies in the laboratory of J. Folkman opened up the area of anti-angiogenic metronomic chemotherapy.
Competing interests statement. The authors declare competing financial interests .
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