Clinical Outcomes Associated with Drug-Drug Interactions of Oral Chemotherapeutic Agents: A Comprehensive...

Oral chemotherapy use is increasing due to new drug approvals as well as the convenience of the administration of oral drugs. This increased use also raises concern regarding drug-drug interactions (DDIs) with concomitantly administered drugs, resulting in loss of therapeutic effect, decreased tolerability, and/or increased toxicity.

The objective of this study was to review existing evidence of the clinical impact of DDIs with oral chemotherapeutic agents.

A comprehensive search of literature using PubMed was conducted in April 2018 for studies of DDIs associated with oral chemotherapy. Included studies were in English. We included randomized clinical trials, observational studies, and case reports evaluating a DDI between any oral chemotherapy drug and any other drug. Included studies needed to have at least one outcome of clinical relevance potentially attributed to the DDI, for example, effects on survival or toxicity. The quality of the articles was determined using published metrics appropriate for the study design.

There were 2626 studies identified in the initial search, of which 35 met all eligibility criteria. These included 15 retrospective cohort studies, 16 case reports or case series and four post hoc analyses of clinical trials. Among these, DDIs contributed to a statistically significant change in a clinical outcome in 12 studies. Eight of these studies evaluated overall survival and progression-free survival and found that the presence of the DDI was associated with reduced survival.

Our findings suggest that more real-world studies evaluating the association between oral chemotherapy DDIs and clinical outcomes are needed. The adverse clinical outcomes due to DDIs may be a reason for treatment failures and therapy discontinuation.