NEW YORK – The US Food and Drug Administration alerted oncologists, researchers, and patients Tuesday afternoon that Genentech's atezolizumab (Tecentriq) plus paclitaxel did not benefit triple-negative breast cancer patients enrolled in the Phase III IMpassion131 trial.
The trial randomized 650 previously untreated, inoperable, locally advanced or metastatic triple-negative breast cancer patients to receive either atezolizumab plus paclitaxel or paclitaxel plus placebo. Genentech in August had revealed that this study had failed to meet its primary endpoint of progression-free survival in PD-L1-positive, metastatic TNBC patients.
In its safety alert on Monday, the FDA stated that not only did the atezolizumab-paclitaxel combination fail to significantly reduce the risk of cancer progression and death compared to the placebo arm in the PD-L1 positive group, the interim survival analysis appears to favor the paclitaxel-placebo arm in the PD-L1-positive subpopulation and in the overall population.
The FDA noted that it has not approved the atezolizumab-paclitaxel combination for metastatic TNBC. However, the agency has granted accelerated approval to atezolizumab in combination with paclitaxel protein-bound (Celgene's Abraxane), which is a different therapy, for PD-L1-expressing metastatic TNBC.
"Healthcare professionals should not replace paclitaxel protein-bound (Abraxane) with paclitaxel in clinical practice," the FDA cautioned.
The agency said it will review the findings from IMpassion131 and other breast cancer studies involving the atezolizumab-paclitaxel combo and communicate any potential prescribing changes.
"Patients taking atezolizumab and paclitaxel for other approved uses should continue to take their medication as directed by their healthcare professional," the agency said, and recommended that doctors and patients report adverse events related to this regimen to its MedWatch Adverse Event Reporting program.