Frontline Atezolizumab Plus Paclitaxel Misses Primary End Point in TNBC Trial

August 7, 2020

The phase 3 IMpassion131 trial investigating atezolizumab plus paclitaxel versus placebo plus paclitaxel did not its primary end point of progression-free survival and was not statistically significant in the first line for patients with metastatic triple-negative breast cancer who had PD-L1-positive disease.

The phase 3 IMpassion131 (NCT03125902) trial investigating atezolizumab (Tecentriq) plus paclitaxel (Abraxane) versus placebo plus paclitaxel did not its primary end point of progression-free survival (PFS) and was not statistically significant in the first line for patients with metastatic triple-negative breast cancer (TNBC) who had PD-L1-positive disease, according to a press release from Roche.

“While we are disappointed by the results from the IMpassion131 study, we are grateful for all the patients, families and physicians who were involved in the study," Levi Garraway, MD, PhD, Roche's CEO and head of Global Product Development, said in a statement. "Today’s results underscore the need to better understand the cancer and immune system interactions, including the chemotherapy backbone and associated regimens. We remain committed to finding optimal treatments for all people living with this aggressive disease.”

The investigators of this study also observed that the secondary end point of overall survival (OS) showed a negative trend, but the study was not powered for OS and at the time of the analysis, the data were immature. A follow-up for the OS in these patients is planned to continue until the final analysis.

When looking at the toxicity of atezolizumab and paclitaxel, it was shown to be consistent with the previously established safety profile of each agent, and no new safety signals were seen.

IMpassion131 is a multicenter, randomized, double-blind clinical trial looking at the efficacy and safety of the atezolizumab combination compared with placebo in 651 patients with previously untreated, inoperable, locally advanced or metastatic TNBC. These patients were randomized 2:1 to either 840 mg of atezolizumab intravenously on days 1 and 15 of a 28-day cycle plus 90 mg/m2 of paclitaxel on days 1, 8, and 15 or to placebo and paclitaxel on the same dosing schedule. Treatment continued until disease progression or unacceptable toxicity.

The full results from this study will be presented at an upcoming medical meeting after being reviewed by global health authorities. These findings will inform current and future trials for patients with TNBC who are or will receive atezolizumab and paclitaxel.

In the trial preceding this, IMpassion130 (NCT02425891), atezolizumab and nab-paclitaxel exhibited a PFS benefit that was statistically significant, at 7.2 months over 5.5 months with placebo for patients with metastatic TNBC who had tumors had PD-L1 expression of more than or equal 1% (HR, 0.80; 95% CI, 0.69-0.92; P =.002). There were clinically meaningful improvements in OS as well, even though it was not formally tested in that study.

Atezolizumab, an anti-PD-L1antibody, in combination with nab-paclitaxel is approved for the treatment of adult patients with unresectable locally advanced or metastatic TNBC whose tumors express PD-L1 of more than or equal 1% in over than 70 countries.

Reference:

Roche provides update on Phase III study of Tecentriq in combination with paclitaxel for people with metastatic triple-negative breast cancer. News release. Roche. August 6, 2020. Accessed August 7, 2020. https://bit.ly/30AQwBI