Recommendation H:
41
C
onduct retrospective analyses of archival tumor samples from cancer patients treated with standard of care and whose outcomes are known in order to better understand and target the mechanisms driving individual tumor types. The Cancer Moonshot provides a unique opportunity for the cancer research and clinical trials communities to apply state-of-the-art technologies to analyze the tissues already collected from cancer patients for molecular, genetic, and cellular clues to explain why some patients respond well to standard of care while many others do not. The ability to identify and analyze the complex network of genes, proteins, inflammatory/immune signatures, and biochemical pathways regulating different cell types within tumors from patients with known treatment outcomes will help refine criteria on how to optimally classify tumors and to assess whether standard of care is likely to be beneficial and the potential benefit of experimental therapies based on their molecular, genetic, inflammatory/immune, and cellular signatures. Analysis of tumors from thousands of treated patients whose outcomes are known would allow for rapid development of hypotheses to be validated prospectively in clinical trials.What is the problem?
Many thousands of patients have been treated with similar standard of care regimens. Some have had outstanding responses with substantial prolongation of life or even a cure, whereas others did not respond at all. Some patients with early outstanding responses have ultimately relapsed or become resistant to continued therapy with the same agents and eventually succumbed to their disease. In some cases, patients resistant to standard chemotherapy who undergo immunotherapy subsequently respond to prior chemotherapies to which they had been resistant. The underlying molecular, genetic, inflammatory/immune, and cellular mechanisms that may distinguish these groups of patients—even if they initially fall within the same disease classification—remains poorly understood. There is now an appreciation of the complexities of the tumor and its surrounding tissue microenvironment, in terms of its cellular, genetic, inflammatory/immune, and molecular heterogeneity. However, how each of these components drives either sensitivity or resistance to therapy, and how these features evolve over time or in response to therapy, have been difficult to address due to the lack of appropriate technologies and biological platforms required to study them effectively. Ultimately, while development of new drugs is supported by the pharmaceutical industry, fewer resources are devoted to distinguishing which patients are most and least likely to respond to a given drug, including identification of which patients will respond best to different therapeutic approaches. This remains understudied and ill defined, and is a roadblock to developing more successful cancer therapies.
What are the challenges?
Several limitations, ranging from technological and infrastructural to educational and financial, have made it difficult to carry out large-scale retrospective analyses of tumor
samples. For instance, the technologies and high-throughput capabilities needed to visualize and analyze large numbers of tumor cells and tissues and determine their genetic and molecular makeup have only recently attained the degree of sophistication necessary to answer questions about tumor heterogeneity and evolution over time and after treatment.
Next-generation sequencing technologies are now available to quickly sequence and identify gene mutations and to identify changes in global gene expression that are associated
with different tumor types and stages of disease. Other complementary high-throughput technologies involving mass cytometry and multidimensional fluorescence microscopy are now accessible as well, with capabilities to study multiple simultaneous parameters associated with cancer cell physiology at the single-cell level. This includes the ability not only to characterize the composition of cells in tumor masses, but also to simultaneously monitor dozens of proteins and enzymes involved in regulatory pathways commonly altered in cancers and their surrounding supportive cells.
Additional barriers to obtaining the samples necessary for these analyses reflect issues with clinical infrastructure, medical oncologist reimbursement, and patient reluctance to enroll in trials. Recent implementation of the NCI’s National Clinical Trials Network (NCTN) has helped pave the way for these issues to be addressed head-on. While barriers exist, over 2000 institutions, consortia, and practices participate in the NCTN and meet the enrollment criteria for continued membership. This mechanism should be pursued in ongoing clinical research efforts, including better development of quality metrics, reimbursement of time, and inclusion of contractual and regulatory structures that are well established, functional, and inexpensive. The strengths of the system are the willingness of oncologists and patients to engage in clinical trials, the use of standard treatments as appropriate, uniform management of cancer care, agreed-upon standards, and tissue availability for research and diagnostic use.
NCTN has also focused on centralizing tissue banks, technology cores, and data management centers to facilitate access to clinical details on the research end and educational/
informational resources to patients and community health centers alike—which helps inform ongoing trials and on best practices for common and rare cancer types. NCTN may, therefore, set an exemplary framework for other groups to expand upon in the implementation of this recommendation.
An alarming limitation that affects the research and clinical communities across the board is the fact that only 5% of all cancer patients enroll in clinical trials. Many oncologists do not have the bandwidth to recruit more patients, and the low participation rates means that the diversity of patients in trials is limited. Challenges also result from potential inconsistencies in the collection of tumor specimens from treated patients, difficulties in sample preparation, and issues with shipping to central labs and conducting tumor assays. Without
more-coordinated efforts, the ability to successfully implement this recommendation and obtain meaningful large-scale information will remain a challenge.
43
Why is this important?
The reasons why cancer patients with similar disease and disease stage may end up with very different outcomes despite receiving the same standard of care remains an enigma.
This gap in our understanding costs lives and drains scarce resources. A thorough analysis of archival samples to determine the underlying cellular, genetic, inflammatory/immune, and molecular events that drive a tumor’s response or resistance to therapy will help refine patient sub-classification at the molecular level. It will also provide invaluable information on which patients are likely to benefit from standard of care and which patients require additional or novel interventions. Equally important, a retrospective analysis may also identify patient subgroups that may not need therapeutic intervention at all—patients who currently fall victim to “overdiagnosis” and are thus receiving the standard of care without significant benefit. A comparison of archived successes and failures will also set the framework to help inform ongoing and future clinical trials being carried out in pursuit of more effective treatments.
What will it achieve?
Implementation of this recommendation will establish expanded networks of cancer researchers and clinicians, similar to NCI’s NCTN, that can only be accomplished efficiently and effectively at this large scale through the coordination afforded by the Cancer
Moonshot. It will develop better risk stratification of cancers and allow tailored treatments to be developed for patients who are at high risk for relapse and would not likely benefit from standard of care alone. Having a trove of cellular, genetic, inflammatory/immune, and molecular parameters available will enable the clinical oncology community to define a patient’s risk category for therapeutic response and in so doing, enhance the cure rate for locally advanced cancers and anticipate how individual advanced-stage patients will respond to distinct therapies. Finally, this recommendation will help identify efficient ways to conduct faster and smaller precision-based trials on patients with the appropriate biological parameters.