publication date: Oct. 26, 2018
Long-awaited trial of checkpoint inhibitor in breast cancer produces 2-month PFS gain; no final OS advantage seen—yet
By Matthew Bin Han Ong
Tecentriq, Genentech’s PD-L1 checkpoint inhibitor, is the first immunotherapy agent to report positive outcomes in breast cancer in a phase III trial—providing proof of principle that these drugs are active in treatment of triple-negative breast cancer.
The findings from Genentech’s trial were published in the New England Journal of Medicine and the company has submitted approval applications for Tecentriq (atezolizumab) plus Abraxane (nab-paclitaxel) in the triple-negative breast cancer indication to regulatory authorities.
As they consider the results, breast cancer experts predict charged yet nuanced debates over definitions of clinical benefit and criteria for regulatory approval. One thing everyone can agree on is that the results of the IMpassion130 trial as they now stand aren’t slam-dunk.
IMpassion130, which tested atezolizumab plus nab-paclitaxel vs. placebo plus nab-paclitaxel, was initially designed to randomly assign approximately 350 patients for the evaluation of a primary endpoint of progression-free survival. During the course of the trial, enrollment was expanded to accommodate the addition of overall survival as a second primary endpoint.
The overall survival data in IMpassion130 are not yet mature—the trial did not reach statistical significance in overall survival. Because of the trial’s hierarchical statistical design, the company has to win on OS in the intention-to-treat population before it can declare OS advantage in any subset.
And that is what makes the story of Tecentriq in triple-negative breast cancer such a nail-biter.
The atezolizumab combination improved final PFS by up to 2.5 months in the PD-L1–positive subgroup, and 1.7 months in the overall experimental cohort.
Continue reading Long-awaited trial of checkpoint inhibitor in breast cancer produces 2-month PFS gain; no final OS advantage seen—yet
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