Pharmacogenomic Testing for Cancer Patients: Breaking the Barriers!

The article “Overcoming Barriers to Discovery and Implementation of Equitable Pharmacogenomic Testing in Oncology,” by Shriver and colleagues, addresses the multifaceted challenges hindering equitable pharmacogenomic (PGx) testing and implementation in oncology. It underscores the impact of genetic ancestry on treatment outcomes. It highlights systemic and diversity-related obstacles that must be overcome to realize the full potential of PGx in cancer care.

Key Challenges of PGx Implementation in Oncology

• Bias Toward European Descent: There is a noticeable bias in PGx research and clinical practice favoring individuals of European descent, leading to disparities in the understanding, access, and application of PGx testing across different genetic ancestry groups.
• Access to Care: Various barriers, such as issues with payor coverage, PGx test usability, and result turnaround times, impede access to essential PGx testing in oncology settings.
• Data Collection and Diversity: More diverse databases are critical for advancing PGx discovery. This includes enhancing the diversity of genomic databases, integrating pharmacogenomic data with treatment and outcome information, and leveraging adverse event reporting systems.
• Drug Labeling and Treatment Guidelines: Effective PGx implementation requires the integration of PGx testing recommendations into treatment guidelines and improving drug labels to include clear, consistent, and accessible PGx information.
• Infrastructure and Resources: Developing the necessary infrastructure and resources is vital for successfully incorporating oncology PGx programs and addressing technological and systemic healthcare challenges.
• Equitable Discovery: Ensuring equitable discovery and implementation of PGx testing necessitates diversifying research participation and including relevant genetic variants in PGx tests to cater to a broad spectrum of populations.

Systematic Issues!

In addition to these challenges, the article also discusses broader systemic issues, such as:

• The limited availability of germline data in electronic health records (EHRs)
• The challenges in deploying clinical decision support (CDS) tools
• The lack of reimbursement mechanisms for PGx consultations.

These factors further complicate the landscape of precision medicine and equitable PGx testing in oncology. To address these challenges, the article proposes comprehensive strategies to promote fair PGx discovery and integration in cancer care, emphasizing the importance of considering genetic diversity and systemic healthcare barriers.

Important gene-drug interactions in oncology

This paper discusses several important examples of gene-drug interactions, including DPYD with FU and capecitabine, TPMT and NUDT15 with 6-MP, UGT1A1-irinotecan, and CYP2D6-tamoxifen. These gene-drug pairs have been designated clinically actionable by CPIC, with dosing guidelines available based on reviews of evidence from the literature. Still, the lack of diversity in research threatens the regularly tested variants in these genes, which put understudied populations at high risk of avoidable toxicities!

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