Companion Diagnostics: Lessons Learned and the Path Forward From the Programmed Death Ligand-1 Rollout.

CONTEXT.­: Programmed death ligand-1 (PD-L1) immunohistochemistry companion diagnostic assays play a crucial role as predictive markers in patients being considered for immune checkpoint inhibitor therapy. However, because of a convergence of several factors, including recognition of increased types of cancers susceptible to immunotherapy, increasing numbers of immune checkpoint inhibitors, and release of multiple PD-L1 immunohistochemistry antibodies with differing reporting systems, this complex testing environment has led to significant levels of confusion for pathologists and medical oncologists. OBJECTIVE.­: To identify which processes and procedures have contributed to the current challenges surrounding programmed death receptor-1 (PD-1)/PD-L1 companion diagnostics and to propose potential remedies to this issue. This is based upon input from key industrial stakeholders in conjunction with the College of American Pathologists Personalized Health Care Committee. DESIGN.­: A meeting of representatives of pharmaceutical and in vitro diagnostic companies along with the Personalized Health Care Committee reviewed the process of release of the PD-L1 companion diagnostic assays using a modified root cause analysis format. The modified root cause analysis envisioned an ideal circumstance of development and implementation of a companion diagnostic to identify shortcomings in the rollout of the PD-L1 assay and to suggest actions to improve future companion diagnostic assay releases. RESULTS.­: The group recommended improvements to key principles in companion diagnostics implementation related to multi-stakeholder communication, increased regulatory flexibility to incorporate postapproval medical knowledge, improved cross-disciplinary information exchange between medical oncology and pathology societies, and enhanced postmarket training programs. CONCLUSIONS.­: The rapidly changing nature of and increasing complexity associated with companion diagnostics require a fundamental review of processes related to their design, implementation, and oversight.

Getting Your Laboratory on Track With Neurotrophic Receptor Tyrosine Kinase.

CONTEXT.­: Neurotrophic receptor tyrosine kinase (NTRK) fusion testing has both diagnostic and therapeutic implications for patient care. With 2 tumor-agnostic US Food and Drug Administration-approved tropomyosin receptor kinase (TRK) inhibitors, testing is increasingly used for therapeutic decision making. However, the testing landscape for NTRK fusions is complex, and optimal testing depends on the clinicopathologic scenario. OBJECTIVE.­: To compare different NTRK testing methods to help pathologists understand test features and performance characteristics and make appropriate selections for NTRK fusion detection for their laboratory and individual patient specimens. DATA SOURCES.­: A literature search for NTRK gene fusions and TRK protein was performed, including papers that discussed treatment, testing methodology, and detection or prevalence of fusion-positive cases. CONCLUSIONS.­: As standard of care in some tumor types, next-generation sequencing (NGS) panel testing is a cost effective and reliable way to detect a broad range of NTRK fusions. The design of the panel and use of DNA or RNA will affect performance characteristics. Pan-TRK immunohistochemistry may be used as a rapid, less expensive screen in cases that will not undergo routine NGS testing, or on specimens unsuitable for NGS testing. Fluorescence in situ hybridization may be appropriate for low-tumor-content specimens that are unsuitable for NGS testing. Quantitative reverse transcription polymerase chain reaction is best suited for monitoring low-level disease of a specific, previously identified target. This information should help laboratories develop a laboratory-specific NTRK testing algorithm that best suits their practice setting and patients' needs.

Preanalytics and Precision Pathology: Pathology Practices to Ensure Molecular Integrity of Cancer Patient Biospecimens for Precision Medicine.

Biospecimens acquired during routine medical practice are the primary sources of molecular information about patients and their diseases that underlies precision medicine and translational research. In cancer care, molecular analysis of biospecimens is especially common because it often determines treatment choices and may be used to monitor therapy in real time. However, patient specimens are collected, handled, and processed according to routine clinical procedures during which they are subjected to factors that may alter their molecular quality and composition. Such artefactual alteration may skew data from molecular analyses, render analysis data uninterpretable, or even preclude analysis altogether if the integrity of a specimen is severely compromised. As a result, patient care and safety may be affected, and medical research dependent on patient samples may be compromised. Despite these issues, there is currently no requirement to control or record preanalytical variables in clinical practice with the single exception of breast cancer tissue handled according to the guideline jointly developed by the American Society of Clinical Oncology and College of American Pathologists (CAP) and enforced through the CAP Laboratory Accreditation Program. Recognizing the importance of molecular data derived from patient specimens, the CAP Personalized Healthcare Committee established the Preanalytics for Precision Medicine Project Team to develop a basic set of evidence-based recommendations for key preanalytics for tissue and blood specimens. If used for biospecimens from patients, these preanalytical recommendations would ensure the fitness of those specimens for molecular analysis and help to assure the quality and reliability of the analysis data.