The future is now: Implementation of standard of care, preemptive pharmacogenomic testing in patients with gastrointestinal cancers.
Authors: Hearst Emily C , Martin James L , Crooks Kristy R , Greene Casey S , Hess Kaitlyn W , Johnson Natalie , Kao David P , Rafaels Nicholas , Carson Katelyn , Meguid Cheryl L , Taucher Kate , Davis S. Lindsey , Lieu Christopher Hanyoung , Aquilante Christina L 
Published: June 2024

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Background: Preemptive germline pharmacogenomic (PGx) testing provides insight into the safety of high-risk chemotherapy and effective use of supportive care medications in gastrointestinal (GI) cancers. Advances in clinical practice guidelines and clinician support have accelerated the appetite for PGx testing, particularly for drugs with severe adverse reactions. The objective of this study was to assess operational outcomes associated with end-to-end electronic health record (EHR) integration of standard of care, preemptive multigene PGx testing in patients with GI cancers. Methods: Patients in two UCHealth GI oncology clinics were tested for five PGx genes related to 5-fluorouracil (5-FU, DPYD), irinotecan ( UGT1A1), and supportive care therapies ( CYP2C19, CYP2D6, CYP2C9). The PGx test order was embedded in all GI oncology treatment plans. Patient samples were genotyped, and PGx results were returned as discrete data to the EHR. Automated clinical decision support (CDS) tools provided PGx-guided recommendations at the point of prescribing. We leveraged the EPIS process framework and evaluated operational outcomes such as number of patients tested, lab turnaround time, patients with actionable phenotypes, and number of CDS alerts and clinical actions. Results: The analysis included 89 patients who received results for DPYD/UGT1A1 and 83 patients who received results for supportive care genes. Among samples tested, DPYD/UGT1A1 and supportive care gene results were returned to the EHR in an average of 4.7 ± 2 days (range 1-8) and 17.3 ± 3 days (range 9-24), respectively. The number of patients with abnormal phenotypes, defined as poor metabolizers for UGT1A1 and any non-normal phenotypes for the other genes, were UGT1A1, n=10 (11.2%); DPYD, n=4 (4.5%); CYP2C19, n=43 (51.8%); CYP2D6, n=31 (41.3%; 8 uninterpretable results); and CYP2C9, n=19 (22.9%). This equated to 14/89 (15.7%) and 68/83 (81.9%) patients having an abnormal result for DPYD/UGT1A1 and at least one supportive care gene, respectively. CDS alerts fired for 32 drug-gene interactions for 25 distinct patients. Of the alerts, 7 (21.9%) were for 5-FU or irinotecan, which showed for 7/89 patients (7.9%); 25 (78.1%) were for supportive care medications, which showed for 23/83 patients (27.7%). There were 9 clinical actions taken in response to the PGx alerts, 7 (77.8%) for 5-FU or irinotecan and 2 (22.2%) for supportive care drugs. Appropriate clinical actions were taken for 100% of patients with 5-FU or irinotecan drug-gene interactions. Conclusions: End-to-end EHR integration of PGx testing and prescribing guidance facilitated clinician adoption of preemptive, standard of care multigene PGx testing, with test results driving important medication changes. Future studies will evaluate the impact of PGx testing on clinical outcomes and cost effectiveness metrics in this population.