Prospective observational study of atezolizumab plus nab-paclitaxel in patients with metastatic triple-negative breast cancer: JBCRG-C08/ATTRIBUTE.

The JBCRG-C08/ATTRIBUTE (UMIN000041747) study assessed atezolizumab plus nab-paclitaxel's safety and effectiveness in a metastatic triple-negative breast cancer population, including IMpassion130-ineligible patients. The primary outcome was incidence of investigator-assessed adverse events (AEs). Safety and full analysis populations included 149 and 148 patients, respectively; 4.0% of the full analysis population had Eastern Cooperative Oncology Group performance status ≥2 and 7.4% had a history/comorbidity of autoimmune disease (AID) at baseline. AEs occurred in 96.6% of the safety analysis population; serious AEs (SAEs), in 16.8%; and immune-related AEs (irAEs), in 30.9%. irAE incidence was 45.5% in patients with a history/comorbidity of AID. Notable SAEs included pneumonitis (3.4%), diarrhoea, pyrexia, adrenal insufficiency and cardiac failure (1.3% each). Two cases of Grade 5 pneumonitis occurred. Regarding effectiveness, median progression-free survival was 5.6 months (95% confidence interval, 4.2-6.7). This first analysis found no new safety concerns with atezolizumab combination therapy, although patients with AID require careful monitoring.