Collaborating to Compete: Blood Profiling Atlas in Cancer (BloodPAC) Consortium
Thanks to these significant scientific advances, we know that tumors shed cells and a variety of chemical signals into the bloodstream, leaving behind small hints that can identify the cancer phenotype and genotype, the organ of origin, and the evolutionary state of cancer as a result of its natural progression and/or treatment pressures. For this reason, researchers are especially interested in developing new technologies to use this knowledge to transform how we detect and diagnose cancer, and how we predict and monitor response to therapeutic intervention. This provides the foundation for a future where simple blood draws could help physicians and patients more accurately and successfully detect and manage the disease. This approach, commonly described as liquid biopsies, provides a less invasive, more easily replicable, and potentially more informative alternative to standard tissue biopsies. Liquid biopsies are experienced by the patient as a simple blood test as compared to an often painful bone biopsy or more invasive open biopsy under anesthesia.
The value of blood profiling measurements in assessing and monitoring cancer patient status includes: repeated access to tumor material when tissue biopsies are impractical, more comprehensive assessment of tumor biology compared to sampling of one specific tumor locus, and more practical assessment of the molecular evolution of cancer throughout a patient's treatment. There has been significant academic and commercial activity in the development of liquid biopsies that are both cell‐based, such as circulating tumor cells (CTC), and cell‐free, such as circulating tumor DNA (ctDNA), isolation and analysis platforms, as well as technologies to assay for exosomes and other extracellular vesicles.
At this time, two liquid biopsies have been clinically validated and approved by the US Food and Drug Administration (FDA) as a companion diagnostic. Both test for mutations in the EGFR gene for patients with metastatic non‐small cell lung cancer (NSCLC). The cobas EGFR Mutation Test v2 (Roche Molecular Systems, Nutley, NJ) tests for exon 19 deletions or exon 21 (L858R) substitution mutations in the EGFR gene to identify patients eligible for treatment with Tarceva (erlotinib).2 The same test also can detect the T790M mutation in the EGFR gene to identify patients for treatment with Tagrisso (osimertinib).3
Clinicians are currently restricted in their ability to include liquid biopsy analysis as a part of clinical care (e.g., for serial monitoring), other than for ctDNA single draws, due to lack of sufficient evidence for payer reimbursement. There is growing concern that ctDNA analysis may follow the same path as first‐generation CTC methods4 because the data needed to demonstrate the level of evidence that the FDA and payers believe is needed for clinical efficacy currently exists for only the two indications just mentioned.