by John Beeler, Ph.D., Vice President, Corporate and Business Development, Inivata
The promise of personalized medicine gained momentum with the publication of the human genome more than 13 years ago. Enthusiasm grew over the potential to decode the genetic basis of disease and enable efficient utilization of a new generation of genomically targeted therapies. Precision medicine, whereby genomic information is integrated into clinical decision-making, intended to realize a more personalized approach and treat the right patient with the right drug at the right time.
Despite clear examples of success illustrated by the development of molecular technologies to identify genomic alterations with high specificity and sensitivity and to guide the use of targeted therapies against altered genes, including EGFR, BRAF, ALK and others, there has been a growing chorus of skeptics who infer that application of these targeted therapies to a broader population harboring respective genomic alterations is nothing more than hype. According to these skeptics, one of the primary reasons that precision oncology medicine is an illusion is the lack of data from randomized clinical trials that support the use of genomically guided therapies in more tumor diverse populations. However, there are several factors that have contributed to the paucity of data supporting advances in precision oncology medicine, particularly in patients with advanced stage disease.
The lack of tumor tissue available for molecular profiling is a primary barrier to more robust clinical data. Reasons for the lack of tissue necessary for broad molecular profiling include poor performance status, which precludes patients from being subjected to the invasive procedure necessary for obtaining a tissue specimen. On other occasions, it has been noted that tumors are inaccessible for a biopsy (e.g. bone metastases) and even when obtained, the limited amount of biopsy material can be insufficient for molecular profiling. According to published reports, approximately one-third of advanced stage cancer biopsies deliver tissue specimens that are either poor quality or have insufficient tumor material for a molecular analysis to be performed.
Tissue-based biopsies are further constrained by spatial and temporal limitations that may provide an inaccurate representation of the heterogeneous nature of the malignant growth, which results in the treatment of a patient based on an inaccurate molecular diagnosis. Finally, tissue biopsies are not conducive to serial sampling and are thus incapable of monitoring the molecular evolution when a tumor progresses. The failure to obtain a high-quality tissue specimen that accurately reflects the complete tumor biology may be a contributing factor to the lack of data supporting the realization of precision oncology medicine.
Fortunately, we now find ourselves at a potential inflection point, capable of positively impacting the field of personalized medicine. Recent advances in the application of “liquid biopsies” and the potential to harness molecular information in circulating cell-free tumor DNA (ctDNA) from the convenience of a simple blood draw offers a “game-changer.” Analysis of ctDNA represents a new generation of molecular applications that are capable of producing data that was previously unavailable, thereby helping to deliver on the full promise of providing health care that is both more precise and personal.
First identified more than 60 years ago by Mandal and Metais, advances in genomics and molecular methods now allow analysis of cell free DNA with unprecedented sensitivity and specificity to expand the range of opportunities for liquid biopsy applications that will impact the major aspects of a patient’s care. Analysis of ctDNA can identify genetic alterations that enable therapy selection, quantitatively monitor treatment progress, including disease recurrence via serial sampling, and detect new resistance mutations as they emerge. This liquid biopsy approach has the potential to revolutionize cancer care and improve and/or resolve many of the limitations inherent in current tissue-based standard treatment protocols for providing a broad molecular profile.
This is particularly relevant in non-small cell lung cancer (NSCLC), where a significant number of patients with advanced NSCLC are not receiving molecular testing for first-line therapy and even less are receiving a molecular profile at disease progression following first-line therapy. The opportunity to improve the availability of a molecular profile when one is not otherwise obtainable and provide valuable molecular information that impacts clinical decision-making offers to help deliver on the promise of personalized medicine.
In contrast to the current state of euphoria generated by the liquid biopsy approach and analysis of ctDNA, there is still significant work to be done to generate data illustrating the benefits of ctDNA. The data is necessary to address the limitations of current tissue-based testing, to drive adoption and utilization of this innovative approach, and to improve trust in the regulatory and reimbursement landscape. At Inivata we believe it is vital to get this aspect correct, most importantly for cancer patients, to fulfill the promise of personalized medicine.