Feasibility of preemptive pharmacogenetic testing in colorectal cancer patients within a community oncology setting.

Abstract

Pharmacogenetics, in hand with precision medicine in oncology, represents an opportunity to holistically tailor a patient's treatment regimen using both somatic and germline variants to improve efficacy and decrease toxicity. Colorectal cancer patients represent a population with frequent use of fluoropyrimidine and irinotecan and are an ideal opportunity for implementation of preemptive pharmacogenetics as evidence supports pharmacogenetic testing for DPYD and UGT1A1 to reduce fluoropyrimidine and irinotecan toxicities. This was a single arm proof-of-concept study at a large community-based health system. Participants provided samples for pharmacogenetic testing via an external vendor prior to chemotherapy initiation and an oncology pharmacist was responsible for pharmacogenetic interpretation and pharmacogenetic-guided therapeutic recommendation to the treating provider. A total of 24 (60%) participants had a UGT1A1 variant. All participants (100%) were DPYD*1/*1. Results were available and interpreted for 29/40 (72.5%) participants prior to scheduled chemotherapy initiation (p value <0.014). Of the participants whose results were available in 5 weekdays or less (n = 23), 20 (87%) were communicated with the treating provider prior to scheduled chemotherapy administration. A total turnaround time of 5 days or less was significantly associated with PGx feasibility in a community-based oncology clinic (p = 0.03). In conclusion, we were able to show that implementation of preemptive pharmacogenetic testing into a community oncology clinic with results interpretation available prior to scheduled initiation of chemotherapy was feasible. As pharmacogenetic testing in oncology expands, pharmacists should be prepared to optimize supportive medication regimens as well as chemotherapy with pharmacogenetic results.