Effectiveness and safety of trastuzumab-anns compared to reference trastuzumab among patients with HER2-positive breast cancer: A non-inferiority study

IntroductionThis study evaluated the real-world effectiveness and safety of biosimilar trastuzumab-anns to the reference trastuzumab in a United States (U.S.) population.MethodsThis observational, multicenter, non-inferiority cohort study used electronic medical records from an integrated U.S. healthcare system. Eligible patients were HER2 + breast cancer patients treated with trastuzumab-anns (August 2019-December 2020) or trastuzumab (March 2017-July 2018). Patients were stratified by treatment setting (curative or palliative) and followed for up to 12 months, death, or end of membership, whichever occurred first. The effectiveness outcome was treatment failure, a composite of all-cause mortality or treatment change. The NI margin was set with an upper limit of 5% and multivariate Cox proportional hazards models were used. The safety was assessed by the incidence of cardiomyopathy and neutropenia. Sensitivity analysis was conducted using stabilized inverse probability of treatment weighting.ResultsOf the 4,111 patients eligible, 1,784 met the inclusion criteria with 893 patients in the trastuzumab-anns group and 891 in the reference trastuzumab group. For the composite of treatment failure, trastuzumab-anns was non-inferior to trastuzumab at 7.7% and 5.6%, respectively (90% CI: 0.0% to 4.0%; p < 0.01). A two-way analysis with Cox proportional hazard models showed no significant difference in the risk of treatment failure (adjusted hazards ratio 0.88, 95% CI: 0.6 to 1.3; p = 0.52). Rates of cardiomyopathy and neutropenia were comparable between groups.ConclusionIn this real-world U.S. population, trastuzumab-anns was non-inferior to reference trastuzumab in the treatment of HER2 + breast cancer.