Prevalence of Drug-Drug Interactions in Sarcoma Patients: Key Role of the Pharmacist Integration for Toxicity Risk Management

Background: The risk of drug drug interactions (DDI) has become a major issue in cancer patient care. However, data in sarcoma patients are scarce. We aimed to evaluate the frequency of DDI with antitumor treatments, identify the risk factors for DDI and evaluate the impact of a pharmacist evaluation before anticancer treatment. Patients and Methods We performed a retrospective review of consecutive sarcoma patients starting chemotherapy (CT) or Tyrosine kinase inhibitor (TKI). A pharmacist performed medication reconciliation and established an early toxicity risk assessment. Potential DDI with antitumor drugs were identified using Micromedex electronic software. Results: : One hundred twenty-two soft-tissue and 80 bone sarcoma patients (103 males, median age 50 years,) were included before chemotherapy (86%) or tyrosine kinase inhibitor (14%). The median number of medications was 3; 34 patients (22% of patients with medication reconciliation) reported complementary medicine use. 37 potential DDI classified as major, were identified (12% of the 243 pre-therapeutic assessments). In multivariate analysis, TKI (p<0.0001), proton pump inhibitor (p=0.026) and antidepressant (p<0.001) were identified as risk factors of DDI (p<0.02). Marital status (p=0.003) was the single factor associated with complementary medicine use. A pharmacist performed 157 medication reconciliation and made 71 interventions among 59 patients (37%). In multivariate analysis, factors associated with pharmacist intervention were: complementary medicines (p= 0.004), drugs number (p=0.005) and treatment with TKI (p=0.0002) Conclusions: : Clinical interventions on DDI are more frequently required among sarcoma patients treated with TKI than CT. Multidisciplinary risk assessment including a medication reconciliation by a pharmacist could be crucial to prevent DDI with TKI.