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Pharmacogenomics (PGx), the study of inherited genomic variation and drug response or safety, is a vital tool in precision medicine. In oncology, testing to identify PGx variants offers patients the opportunity for customized treatments that can minimize adverse effects and maximize the therapeutic benefits of drugs used for cancer treatment and supportive care. Because individuals of shared ancestry share specific genetic variants, PGx factors may contribute to outcome disparities across racial and ethnic categories when genetic ancestry is not taken into account or mischaracterized in PGx research, discovery, and application. Here, we examine how the current scientific understanding of the role of PGx in differential oncology safety and outcomes may be biased toward a greater understanding and more complete clinical implementation of PGx for individuals of European descent compared with other genetic ancestry groups. We discuss the implications of this bias for PGx discovery, access to care, drug labeling, and patient and provider understanding and use of PGx approaches. Testing for somatic genetic variants is now the standard of care in treatment of many solid tumors, but the integration of PGx into oncology care is still lacking despite demonstrated actionable findings from PGx testing, reduction in avoidable toxicity and death, and return on investment from testing. As the field of oncology is poised to expand and integrate germline genetic variant testing, it is vital that PGx discovery and application are equitable for all populations. Recommendations are introduced to address barriers to facilitate effective and equitable PGx application in cancer care.

Purpose: Precision medicine approaches, including germline pharmacogenetics (PGx) and management of drug-drug interactions (DDIs), are likely to benefit patients with advanced cancer who are frequently prescribed multiple concomitant medications to treat cancer and associated conditions. Our objective was to assess the potential opportunities for PGx and DDI management within a cohort of adults with advanced cancer., Methods: Medication data were collected from the electronic health records for 481 subjects since their first cancer diagnosis. All subjects were genotyped for variants with clinically actionable recommendations in Clinical Pharmacogenetics Implementation Consortium guidelines for 13 pharmacogenes. DDIs were defined as concomitant prescription of strong inhibitors or inducers with sensitive substrates of the same drug-metabolizing enzyme and were assessed for six major cytochrome P450 (CYP) enzymes., Results: Approximately 60% of subjects were prescribed at least one medication with Clinical Pharmacogenetics Implementation Consortium recommendations, and approximately 14% of subjects had an instance for actionable PGx, defined as a prescription for a drug in a subject with an actionable genotype. The overall subject-level prevalence of DDIs and serious DDIs were 50.3% and 34.8%, respectively. Serious DDIs were most common for CYP3A, CYP2D6, and CYP2C19, occurring in 24.9%, 16.8%, and 11.7% of subjects, respectively. When assessing PGx and DDIs together, approximately 40% of subjects had at least one opportunity for a precision medicine-based intervention and approximately 98% of subjects had an actionable phenotype for at least one CYP enzyme., Conclusion: Our findings demonstrate numerous clinical opportunities for germline PGx and DDI management in adults with advanced cancer., Competing Interests: Milan RadovichEmployment: Caris Life SciencesLeadership: Caris Life SciencesStock and Other Ownership Interests: LifeOmic, Macrogenics, Immunomedics, Tyme TechnologiesHonoraria: LillyResearch Funding: Lilly (Inst), Boston Biomedical (Inst), Foundation Medicine (Inst), Epic Sciences (Inst), Pfizer (Inst), Genentech (Inst)Patents, Royalties, Other Intellectual Property: Combination therapy for the treatment of TNBC with a PI3K pathway inhibitor that targets PI3KDelta and PI3KGamma (Inst)Travel, Accommodations, Expenses: LifeOmic, Caris Life Sciences Victoria M. PrattStock and Other Ownership Interests: Quest Diagnostics, LabCorpOther Relationship: Avalon Heathcare John T. CallaghanEmployment: IU healthStock and Other Ownership Interests: Lilly, Abbott/AbbVie, Stryker (I) Bryan P. SchneiderHonoraria: Lilly, Research to PracticeResearch Funding: Genentech/Roche, Pfizer, Foundation Medicine, Exact Sciences Todd C. SkaarHonoraria: Tabula Rasa HealthcareConsulting or Advisory Role: Indiana University HealthTravel, Accommodations, Expenses: Tabula Rasa HealthcareOther Relationship: NIHNo other potential conflicts of interest were reported.