Pharmacogenomics: Frontiers in drug therapeutics – A narrative review

Abstract Pharmacogenomics (PGx) works away from the concept of one size fits all, opening the prospects of personalized medicine. It integrates genomic information into therapeutic decision making to optimize drug efficacy and minimize adverse reactions. Clinically actionable variants across oncology, cardiology, psychiatry, infectious diseases, and neurology have been identified. Established examples include VKORC1 and CYP2C9 variants guiding warfarin dosing, CYP2C19 influencing clopidogrel and antidepressant response, CYP2D6 affecting antipsychotic metabolism and opioid activation, and HLA-B*15:02 predicting severe cutaneous reactions to carbamazepine. In oncology, molecular targets such as epidermal growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK), BCR-ABL, human epidermal growth factor receptor 2 (HER2), BRCA1/2, NTRK, RET, and FGFR have transformed treatment through targeted therapies and companion diagnostics. Cardiovascular PGx continues to expand with emerging markers including PCSK9, lipoprotein A, CYP4F2, and ABCB1, whereas in the central nervous system PGx incorporates newer targets such as OPRM1, COMT, HTR2A, BDNF, and SCN1A/SCN2A. Parallel advances in gene editing technologies, as well as ex vivo engineered cell therapies and digital health tools, promise to further enhance precision therapeutics. Despite these scientific advances, PGx implementation remains limited, particularly in low- and middle income countries. Key barriers include perceived lack of clinical utility, workflow disruption, inadequate infrastructure, limited reimbursement, absence of local guidelines, and financial constraints. Effective implementation requires coordinated engagement of regulators, hospital leadership, payers, laboratories, informatics teams, clinicians, and patients. Although preemptive PGx testing offers long-term benefits by enabling immediate genotype-guided prescribing, reactive point-of-care testing remains the predominant model due to cost and reimbursement challenges. This is a brief narrative review exploring the clinical applications of PGx.