Personalized Medicine - Where are We?

 

Despite the introduction of many new anticancer drugs, long term survival rates in most cancers - on a broad population basis - have remained largely unchanged.  And yet within these broad populations certain patients have benefited substantially from chemotherapy.  On an individual-patient basis, long-term remissions and cures are not unknown even within  poorer-prognosis cancers.  The highly-individualized patterns of treatment response commonly observed among cancer patients suggest that patients might benefit if cancer treatments were more highly tailored to each patient.  Among cancer physicians, there has been great interest in what is now called "personalized medicine."  As a goal, the concept is seen as a more rational, more humane, and potentially more effective approach to cancer treatment.  And yet today toxic cancer drugs typically are still assigned broadly to all patients within a specific cancer diagnosis group without first assessing the effectiveness of each drug against each patient's own tumor cells.  Despite all of the discussion, most cancer experts today recognize that personalized medicine remains an elusive goal.      

 

More Effective Use of New Drugs

 

Perhaps the most promising cancer treatment breakthrough in decades is the development of angiogenesis-inhibiting drugs.  These drugs work by attacking capillaries which carry oxygen and nutrients to cancer cells.  However, one problem with these drugs, in addition to their extremely high cost, has been determining in advance who will benefit from them.  The other problem has been learning how to make the drugs more effective by using them in combination. 

 

Cancer - A Controllable Illness?

 

Many cancer physicians predict that cancer will someday become a chronic illness, controllable through the use of combinations of targeted drugs, including angiogenesis inhibiting drugs.  The principle of improved therapy effectiveness brought about through the use of drug combinations is demonstrated by studies of anti-HIV drugs and also by studies of early angiogenesis-inhibiting drugs.  The latter studies were carried out in animal-tumor models.  In these studies, single agents produced only sporadic and temporary benefits.  However, the effectiveness of these drugs increased exponentially when they were combined with other drugs in various ways.  Therefore many investigators are working on ways to determine which combinations of anti-angiogenesis drugs might be effective for individual cancer patients.  However, no method has been reported to date which has the ability to do this reliably.

 

A Discovery which Resulted in an Invention

 

An article appearing in the Journal of Internal Medicine reports invention of what could be the first practical laboratory test to guide the use of anti-angiogenesis drugs.  The new test was developed by Larry Weisenthal, MD, PhD and is based upon his discovery that endothelial cells, which form capillaries that deliver nutrients and oxygen to tumor cells, can be identified and characterized in micro-clusters of living cancer cells.  The new test is called the Microvessel Vascular (MVV) assay.  The MVV assay assesses the effect of anti-vascular drugs upon endothelial cells.  The MVV assay is the first tool which potentially allows for discrimination between anti-vascular drug effects and anti-tumor drug effects within the same biopsy specimen.  It is the only known test which potentially has the ability to test the effectiveness of different combinations of angiogenesis-inhibiting drugs prior to administering the drugs to the patient.

 

Using the Invention to Improve Patient Outcomes

 

If this personalized approach to treatment selection were to help individual study participants to achieve improved outcomes it could demonstrate the principle that cancer patients can benefit when chemotherapy regimens are personalized for them using combined technologies - in this case the newly-developed MVV assay along with existing functional tumor cell profiling methods - to identify the most promising combination of anti-angiogenesis drugs, targeted anti-tyrosine kinase drugs, and standard chemotherapy agents.