Cancer treatment has evolved in recent years from broader cyctotoxic chemotherapies to much more focused immunotherapies and combinations of both therapies. With the sequencing of the genome in 2003 to the discovery of cancer biomarkers in efforts such as The Cancer Genome Atlas, pharmacogenomics has significant potential to positively impact cancer care and precision medicine today.
An article in Pharmacogenomics and Personalized Medicine, “Cancer pharmacogenomics, challenges in implementation, and patient-focused perspectives” (Mar 2016) offers an update on cancer pharmacogenomics, and highlights the challenges in applying pharmacogenomics to the clinical setting – with a review of patient perspectives on these developments.
With the evolutions of cancer care comes an acceleration in drug advancement and approval and concomitant diagnostic assays – which the author state are “critical in identifying predictive biomarkers that allow for a personalized approach to therapy selection,” Pharmacogenetics provides the opportunity to stratify patients into those likely to respond or not respond to therapy, or those likely to experience or not experience toxicity, according to the review.
For example, one of the most serious types of skin cancers, metastatic melanoma, carries the mutation BRAF. Once the BRAF mutation is activated, tumor growth will likely occur.
Dihydropyrimidine dehydrogenase (DPD) is the enzyme responsible for the most of the metabolism of Fluorouracil (an immunosuppressive agent that is used to treat many cancers that is included on the Rxight® panel). Variants in DPD result in cancer treatment inefficiency or, conversely, lead to adverse reactions. Understanding the patient’s DPD and other cell mutations leads to better treatment and helps prevent therapy toxicity, according to the article.
Key factors in the integration of pharmacogenetic testing into routine clinical practice is physician acceptance but also patient adoption and understanding of the risks and benefits of PGx testing, according to the review, which calls for further patient education on the benefits of pharmacogenomics and genomics-based medicine in the future.
“As our knowledge of cancer at the molecular level continues to expand, clinicians must understand the therapeutic implications of these pathways and the challenges involved with clinical implementation of pharmacogenomics,” according to the report. Elucidating these genetic difference will lead to the development of better cancer therapies but a larger scale implementation will be more difficult. More data needs be available and hospitals need to have quick access to such information to implement genetic testing on a wide scale.