Atezolizumab + nab-paclitaxel as first line therapy in Japanese patients with TNBC: A subgroup analysis of IMpassion130

Abstract

Background: IMpassion130 is randomized, double‐blind, phase III study to evaluate efficacy and safety of atezolizumab (ATZ)+nab‐paclitaxel (nPTX) vs placebo (Pla)+nPTX in patients (pts) with treatment‐naive locally advanced or metastatic triple‐ negative breast cancer (TNBC). We report the results of Japanese subgroup. Methods: Pts were randomized 1:1 to Pla or ATZ (840 mg, q2w)+nPTX (100 mg/m2, 3 weeks on/1 week off). Progression‐free survival (PFS) and overall survival (OS) as coprimary endpoints were assessed in intent‐to‐treat population and programmed deathligand 1 positive (PD‐L1+) population. Results: Among 902 enrolled pts, sixty five pts were from Japan (34 pts with ATZ+nPTX, 12 of them PD‐L1+; 31 pts Pla+nPTX, 13 of them PD‐L1+). Median PFS was 7.4 months (mo) in ATZ+nPTX, as compared with 4.6 mo in Pla+nPTX [hazard ratio (HR), 0.47; 95% confidence interval (CI), 0.25‐0.90]. In the PD‐L1+ population (n=25), median PFS was 10.8 mo in ATZ+nPTX, as compared with 3.8mo in Pla+nPTX (HR, 0.04; 95%CI, <0.01‐0.35). Median OS was not reached in ATZ+nPTX, as compared with 16.8mo in Pla+nPTX (HR, 0.44; 95% CI, 0.16‐1.24). In the PD‐L1+population, median OS was not reached in ATZ+nPTX, as compared with 13.3 mo in Pla+nPTX(HR, 0.12; 95%CI, 0.01‐0.99). Adverse events (AE) leading to any treatment discontinuation occurred in 5.9% in ATZ+nPTX and in 0%in Pla+nPTX. AE that led to the dose reduction or interruption occurred in 64.7% of ATZ+nPTX and in 56.7% of Pla+nPTX. Adverse event of special interest (AESI) occurred in 61.8% of ATZ+nPTX and in 50.0% of Pla+nPTX. The incidence of typical AESI was hepatitis (20.6% vs 26.7%), hypothyroidism (17.6% vs 3.3%), hyperthyroidism (5.9% vs 0%) and pneumonitis (2.9% vs 0%) in ATZ+nPTX and Pla+nPTX, respectively. The incidence of AESI was similar to that of overall study population. Conclusion: The efficacy and safety of ATZ+nPTX as first line therapy in Japanese pts with TNBC were consistent with those of overall study population.