Key clinical point: Exposure to antibiotics during neoadjuvant pembrolizumab treatment was associated with a high residual cancer burden (RCB) in patients with human epidermal growth factor receptor 2-negative (HER2−), stage II or III breast cancer (BC).
Major finding: During pembrolizumab treatment, antibiotic use was significantly correlated with RCB index (RCB index-coefficient 0.86; P = .01) and was associated with a higher mean RCB index compared with no use of antibiotics (1.80 vs 1.08).
Study details: This secondary analysis of the phase 2 I-SPY2 trial included 66 patients with HER2− stage II or III BC treated with pembrolizumab plus paclitaxel followed by doxorubicin plus cyclophosphamide, of which 27% of patients concurrently used antibiotics.
Disclosures: This study did not receive any funding. Amit A. Kulkarni declared receiving institutional research funding and serving on advisory boards for various sources. The other authors declared no competing interests.
Source: Kulkarni AA, Jain A, Jewett PI, et al, and the ISPY2 Consortium. Association of antibiotic exposure with residual cancer burden in HER2-negative early stage breast cancer. NPJ Breast Cancer. 2024;10:24 (Mar 26). doi: 10.1038/s41523-024-00630-w Source