Diagnostics follow therapeutics, goes the old industry axiom. When there is no therapeutic approach toward treatment of a disease or condition, it makes little sense to define the disease in detail. With the increase in genetic knowledge and the later rapid success of the Human Genome Project, the old axiom is being turned on its head.
As the field of nucleic acid therapeutics emerged, the link between genomic data and therapeutics grew stronger, and so did the idea that therapeutic problems can be solved by genomics and related biomarker testing. The pairing of a diagnostic test to a therapeutic, the essential element of theranostics or companion diagnostics, is in some cases already a reality and predictions are being made for its future success.
Theranostics are considered the pathway to what has been termed personalized medicine. This has given the diagnostics field a huge boost in terms of publicity/public attention, revenue potential, and investment interest. Still questions exist as to how extensive such testing will be and how soon we will see its growth in clinical application. There are many hurdles to overcome. Researchers are confident, however, that these can be handled.
It is now possible to characterize diseases, e.g., cancer, by their molecular profile. Historically, the diagnostic classification of cancer has been based on the organ or tissue location where it originated in the body, e.g., pancreas, lung, stomach. These days, cancers can be classified by the genes that are expressed, the tumor’s cell surface proteins, and other molecular attributes. Such information may provide keys to understanding how cancer may spread and which therapeutic route may be the most effective.
Many experts believe that if such testing is included in clinical practice, we could be looking at an entirely new era of healthcare delivery. Such testing may provide substantially more information about a patient’s condition, including disease susceptibility and progression and likely drug responses. Due to the potentially predictive nature of such testing, it may form the basis for preventive interventions, or it may not.
Challenges for Theranostics
Despite these promising benefits, the use of companion diagnostic for personalized medicine applications will not have an easy route to and through the market.
First, the molecular diagnostic tests associated with companion diagnostics face the challenge of a healthcare finance system that has become dependent on visible disease symptoms and gross clinical classifications.
Simultaneously, the ability to classify diseases into distinct molecular subcategories challenges traditional pharmaceutical business models that focus on one-size-fits-all drugs. As a result, the economic rationale for personalized medicine in healthcare decisions needs to be based on the cost-savings that result from proactive and preventive interventions.
Second, physicians have an uneasy relationship with clinical diagnostics as it is. Despite the fact that they need this information to properly diagnose their patients, it is an aspect of their practices that is beyond their control. Physicians, by their very nature, must feel in control of the patient’s care. What companion diagnostics and personalized medicine are asking them to do is to accept direction in prescribing for their patients. If that direction is contrary to their experience, it raises conflict.
The third key issue is that of privacy. Currently, the legal picture regarding medical privacy issues that may affect personalized medicine and companion diagnostics is a patchwork of federal, state, and local laws. HIPPA not withstanding, these offer various levels of protection against the misuse of genetic information.
Biomarker discovery is another issue. Companion diagnostics have largely been the product of biomarker discovery. The identification of biomarkers, however, has mostly been a one-at-a-time approach. Many of the well-known biomarker assays have been identified based on clear biological insight from genetics, physiology, or biochemistry. As a result, only a few markers at a time have been considered for development. While genomics and proteomics are providing strong bases for biomarker discovery, the process is still a laborious one that experiences significant technical difficulties.
Finally, at a time when the healthcare system is seeking cost containment, companion diagnostics introduce new complexity into successful diagnosis. Complex genetic relationships (i.e., multiple affected genes) and rapid mutational states present key problems for companion diagnostics.