PII-076 - ESTIMATED PREVALENCE OF ACTIONABLE EXPOSURES TO PHARMACOGENETIC SUPPORTIVE CARE MEDICATIONS AMONG PATIENTS WITH GASTROINTESTINAL CANCERS.

A. Radwan¹, J. Martin², C. Roeder³, H. Anderson⁴, E. Hearst^5,6, D. Kao⁷, C. Aquilante⁴; ¹University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences, Aurora, CO, United States, ²University of Colorado Anschutz Medical Campus, ³University of Colorado School of Medicine, Aurora, CO, United States, ⁴University of Colorado Skaggs School of Pharmacy and Pharmaceutical Sciences, ⁵UCHealth CARE Innovation Center, Aurora, CO, United States, ⁶Colorado Center for Personalized Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, United States, ⁷University of Colorado School of Medicine.

Background: Patients with gastrointestinal (GI) cancers are prescribed chemotherapy and supportive medications, many of which have pharmacogenetic (PGx) prescribing recommendations. Our objective was to estimate the prevalence of actionable exposures to supportive care drugs among patients with GI cancers.

Methods: We conducted a retrospective prescribing frequency study in adult patients with gastrointestinal cancers diagnosed between 1/2015 and 10/2022 who were treated with capecitabine, IV 5-fluorouracil, or irinotecan at UCHealth. We evaluated 14 PGx supportive care drugs: celecoxib, citalopram, codeine, escitalopram, ibuprofen, lansoprazole, meloxicam, metoclopramide, metoprolol, omeprazole, ondansetron, pantoprazole, sertraline, and tramadol. The primary outcome was the projected prevalence of actionable exposure to each medication calculated by multiplying the CPIC frequency of actionable phenotypes for each race by the number of patients with at least one prescription of the medication and summing across all races.

Results: The study included 3985 patients with GI cancers (55% men, 82.6% white, mean age at first chemotherapy order=60.8 ± 12.5 years). Most patients (92.5%) had at least one prescription of a PGx supportive care drug after their first administration of chemotherapy. The mean ± SD number of PGx supportive care drugs was 3.1 ± 1.9 (median=3; range=0-10). PGx supportive care medications prescribed to >25% of the cohort were ondansetron (88.2%), pantoprazole (49.3%), tramadol (34.5%), ibuprofen (25.3%), and omeprazole (25.3%). The projected prevalence of actionable exposure to these drugs is shown in the table.

Conclusion: PGx medications were prescribed often in our GI cancer cohort. Projected actionable exposure approached 30% for some genes, highlighting the potential clinical utility of multigene PGx testing to guide supportive care therapy in GI oncology.