Pharmacogenomics, CYP2D6, and Tamoxifen: A Survey of the Reasons Sustaining European Clinical Practice Paradigms

Healthcare professionals' and consumers' knowledge, attitudes, perspectives, and education needs in oncology pharmacogenomics: A systematic review

Clinical implementation of pharmacogenomic (PGx)-guided prescribing in oncology lags behind research evidence generation. We aimed to identify healthcare professionals' (HCPs) and consumers' knowledge, attitudes, perspectives, and education needs to inform strategies for implementation of scalable and sustainable oncology PGx programs. Systematic review of original articles indexed in EMBASE, EMCARE, MEDLINE, and PsycInfo from January 2012 until June 2022, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and using the Mixed Methods Appraisal Tool. PROSPERO registration number CRD42022352348. Of 1442 identified studies; 23 met inclusion criteria with 87% assessed high quality. Of these, 52% reported on HCPs, 35% on consumers, and 13% on both HCPs and consumers. Most were conducted in the United States (70%) and included multiple cancer types (74%). Across studies, HCPs and consumers mostly perceived value in PGx, however, both groups reported barriers to utilization, including cost, lack of consistent recommendations across guidelines, and limited knowledge among HCPs; test accuracy, clear testing benefits, and genomic information confidentiality among consumers. HCPs and consumers value and want to engage in PGx strategies in oncology care, however, are inhibited by unmet needs and practice and knowledge gaps. Implementation strategies aimed at addressing these issues may best support increased PGx uptake in oncology practice.

Pharmacogenomics of breast cancer: highlighting CYP2D6 and tamoxifen

PURPOSE

To review recent pharmacogenomics studies on breast cancer patients undergoing tamoxifen therapy, highlighting how our knowledge on cytochrome P450 2D6 (CYP2D6) can help to guide the development of adjuvant therapies for these patients.

METHODS

A comprehensive literature search was conducted. Articles reporting findings pertaining to the effect of CYP2D6 on the therapeutic efficacy of tamoxifen, those reporting how targeting CYP2D6 could inform tamoxifen-based therapy development, and those on the tamoxifen effects on cell lines and animal models were included in the review.

RESULTS

With CYP2D6 being the primary enzyme for tamoxifen metabolism, single-nucleotide polymorphisms (SNPs) in this gene were one of the determinants in the rate of tamoxifen metabolism, thereby potentially having an effect on the efficacy of tamoxifen-based therapies. Our review indicates the potential effectiveness of targeting these SNPs, including those for the CYP2D6*10 allele (c. 100C > T), in modifying the level of tamoxifen metabolism. These findings suggest the importance of pharmacogenomics research in our understanding of the efficacy of adjuvant therapies. However, the involvement of multiple enzymes in tamoxifen metabolism, dietary factors, ethnic differences in gene frequencies, and patients' compliance to tamoxifen therapies in studies do present challenges in pharmacogenomics research.

CONCLUSIONS

Pharmacogenomics could play important roles in mediating the advancement of tamoxifen-based adjuvant therapies. Research efforts should be directed towards the exploration of further SNPs of CYP2D6 that affect tamoxifen metabolism, as well as epigenetic changes in CYP2D6, enabling the design of precision medicine and confirming clinical validity in the use of pharmacogenomics for tamoxifen.