Immunotherapy and Breast Cancer – Recent Trials Raise Questions
The results from the Impassion130 and Impassion131 trials of atezolizumab in triple negative breast cancer provide an important reminder of how little is known about the role of immunotherapies in the treatment of breast cancer.
We all want immunotherapy to “work” for breast cancer patients, but NBCC expects that the evidence of that benefit will be shown by well designed, well-conducted prospective randomized clinical trials, sufficiently powered to support that result. The Impassion trials show us we are not there yet.
Not that long ago, many in the medical oncology community celebrated a “practice changing” result from Impassion130, a Phase III randomized clinical trial of atezolizumab (Tecentriq®), a PD-L1 immune checkpoint inhibitor, combined with nab-paclitaxel (Abraxane®) in patients with triple-negative breast cancer (TNBC).
That excitement was a reaction to an analysis of a subgroup of patients with PD-L1+ tumors that suggested a benefit in overall survival, which the trial was not powered to test because it didn’t include enough people to answer that question. Yet, the FDA approved the drug, which now costs around $13,450 per month depending on the dosage schedule. There are now over 70 breast cancer clinical trials registered on clinicaltrials.gov that include this checkpoint inhibitor.
One of them is the Phase III Impassion131 trial, which is testing atezolizumab or placebo combined with paclitaxel (chemotherapy) in first-line advanced or metastatic triple-negative breast cancer (TNBC). This trial recently has reported very different results from the previous trial, according to an August 6 Genentech (a subsidiary of Roche) press release.
The preliminary results showed that Atezolizumab plus paclitaxel failed to demonstrate improvement in its primary endpoint of progression-free survival (PFS) compared to paclitaxel alone. Moreover, the early results suggest that the treatment combination may have a negative or worsening impact on overall survival in TNBC patients, although the results are immature, and the investigators note that the study wasn’t powered to detect a change in overall survival.
Essentially, the results of Impassion131 present a complete reversal of findings reported in The Lancet in January 2020 from their Impassion130 trial. Read NBCC’s full statement on the recent trial here.
Under the current rules of accelerated approval, we call on the FDA to withdraw of approval for Atezolizumab in this particular setting until clear evidence of clinical benefit can be demonstrated. We also hope that this will trigger an important discussion about accelerated approval in general, the cost of therapies, and the evaluation of trials ongoing or planned to ensure that they are not endangering patients’ lives. NBCC will continue to provide objective education on how to interpret evidence for advocates everywhere.
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