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Genentech's Tecentriq, Paclitaxel Combo Fails to Improve PFS in PD-L1-Positive TNBC

NEW YORK – Genentech said on Thursday that its Phase III IMpassion131 trial, investigating atezolizumab (Tecentriq) in combination with paclitaxel as a first-line option for metastatic, PD-L1-positive triple-negative breast cancer failed to meet its primary endpoint.

The drug giant didn't report detailed findings but issued a statement that the 650-patient randomized trial failed to demonstrate that the atezolizumab-paclitaxel combination statistically significantly improved progression-free survival compared to just paclitaxel in PD-L1-positive, metastatic TNBC patients. 

The secondary, overall survival endpoint also showed a negative trend, but the study wasn't powered for survival and this data wasn't mature at the time of analysis, according to Genentech. Researchers will continue to track survival in patients until the planned final analysis. The study didn't identify any new safety signals with the atezolizumab-paclitaxel combination.

Atezolizumab in combination with nab-paclitaxel (a different formulation than paclitaxel) received accelerated approval from the US Food and Drug Administration in metastatic, PD-L1-positive TNBC. The IMpassion130 trial, which investigated this combination, showed a statistically significant progression-free survival benefit. 

"Today's results underscore the need to better understand the cancer and immune system interactions, including the chemotherapy backbone and associated regimens," said Genentech's Chief Medical Officer Levy Garraway. "We remain committed to finding optimal treatments for all people living with this aggressive disease."

Genentech is in discussions with regulators about the IMpassion131 results and will present the data at a future medical meeting. The company will also use the insights gleaned from this trial to inform the design of future TNBC studies exploring the atezolizumab-paclitaxel regimen.