Racial and ethnic disparities in enrollment for clinical trials of poly (ADP-ribose) polymerase (PARP) inhibitors in breast cancer treatment.

Poly (ADP-ribose) polymerase (PARP) inhibitors have shown promise in treating breast cancer with BRCA1/2 mutations, particularly triple-negative breast cancer (TNBC). There is limited data on the representation of different racial groups in PARP inhibitor clinical trials. We conducted a systematic review of phase II/III clinical trials using PARP inhibitors for the treatment of BRCA1/2-mutated breast cancers from 2016 to 2023, using PubMed, Embase, Scopus, CENTRAL, ClinicalTrials.gov, and Cochrane. Nine trials remained for analysis. Enrollment fraction (EF) was calculated by comparing the number of trial enrollees to the number of incident cancer cases. Logistic regression was used to determine the odds ratio (OR) of trial enrollment across racial groups. Overall, the trials included a total of 2845 White, 136 Black, 83 Hispanic, 662 Asian, and 247 Other racial group patients. Other group was excluded from further analysis due to unspecified racial makeup. Among breast cancer patients of any type, EF was the highest for Asian (0.85%), followed by White (0.47%), Black (0.12%), and Hispanic (0.06%) patients. Comparing to White patients, the enrollment ORs were 0.26 for Black, 0.12 for Hispanic, and 1.80 for Asian (p < .001). Analyses were repeated excluding the Asian group, as these patients were recruited from Asian countries rather than the Asian American population. The ORs for Black and Hispanic patients remained the same and significant. Our results show the significant under-representation of Black and Hispanic patients in PARP inhibitor trials in the U.S., raising concerns about equity and the generalizability of trial outcomes for these populations.