Washington, DC—
In a presentation at the recent virtual European Society for Medical Oncology meeting last month, primary results from IMpassion131, a double-blind, placebo-controlled, randomized phase III trial of first-line paclitaxel plus atezolizumab for unresectable locally advanced/metastatic triple-negative breast cancer (mTNBC), suggest that the combination did not improve overall survival or progression-free survival versus placebo.

Now the FDA has sent out an alert about the clinical trial. The agency points out that atezolizumab in combination with paclitaxel is not approved for use in breast cancer, adding, “However, atezolizumab in combination with paclitaxel protein-bound (Abraxane)—a different combination therapy—is currently approved for the treatment of adult patients with mTNBC whose tumors express PD-L1 (PD-L1 stained tumor-infiltrating immune cells of any intensity covering ≥1% of the tumor area), as determined by an FDA-approved test.”

The FDA advises that continued approval of atezolizumab in combination with paclitaxel protein-bound will be contingent on proven benefit of the treatment in additional trials.
Accelerated approval of that combination was granted on March 8, 2019. An article earlier this year in Clinical Cancer Research concludes, “Accelerated approval was appropriate taking into account the unmet medical need along with the immaturity of the OS results and potential for PFS in the PD-L1-expressing population to predict clinical benefit.”

At this point, clinicians are strongly urged not to replace paclitaxel protein-bound (Abraxane) with paclitaxel for breast cancer patients.

In IMpassion131, treatment with atezolizumab and paclitaxel did not significantly reduce the risk of  cancer progression and death compared with placebo and paclitaxel in the PD-L1-positive population, according to the FDA, which adds that interim overall survival results favored paclitaxel + placebo, over paclitaxel plus atezolizumab in both the PD-L1-positive population and total population.

FDA officials say they will review the findings of IMpassion131 and will communicate new information regarding those results and any potential changes to prescribing information.
At the same time, the agency advises that it is evaluating the use of atezolizumab and paclitaxel in ongoing clinical trials for breast cancer and will recommend additional changes as appropriate.

The communication emphasizes that patients taking atezolizumab and paclitaxel for other approved uses should continue to take their medication as directed by their healthcare professional.
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