WCLC 2021 | Atezo maintenance therapy improves survival in the IMpower133 trial of ES-SCLC
Martin Reck, MD, PhD, German Center of Lung Research, Grosshansdorf, Germany, shares the findings of an exploratory analysis of the IMpower 133 trial (NCT02763579), aiming to assess the efficacy of atezolizumab maintenance therapy in extensive-stage small-cell lung cancer (ES-SCLC). The trial randomized over 400 patients to receive carboplatin+etoposide (CP/ET) with atezolizumab or placebo, followed by maintenance therapy with atezolizumab or placebo until unacceptable toxicity, disease progression, or loss of benefit. When assessing patients who reached the maintenance phase, atezolizumab maintenance therapy was shown to improve progression-free survival and overall survival compared to the placebo arm. This interview took place during the IASLC World Conference on Lung Cancer (WCLC) virtual meeting 2021.
Transcript (edited for clarity)
So, dear colleagues, it’s my pleasure to talk to you about the exploratory analysis that we presented at the World Lung Cancer Conference this year, on the IMpower 133 trial. While the IMpower 133 trial was a trial investigating the combination of an immunotherapy atezolizumab together with chemotherapy in untreated patients with metastatic small cell lung cancer. In the trial, significant improvement of overall survival and progression-free survival in favor of the immunotherapy-containing regimen was demonstrated...
So, dear colleagues, it’s my pleasure to talk to you about the exploratory analysis that we presented at the World Lung Cancer Conference this year, on the IMpower 133 trial. While the IMpower 133 trial was a trial investigating the combination of an immunotherapy atezolizumab together with chemotherapy in untreated patients with metastatic small cell lung cancer. In the trial, significant improvement of overall survival and progression-free survival in favor of the immunotherapy-containing regimen was demonstrated. And now we were looking on the population who reached the maintenance part, the second part of therapy, and we were asking for factors leading to the maintenance part and we were asking on the activity that we could show in this population.
So when we talked about this maintenance population, these were roughly 80% of the patients and we could identify three factors which were prognostic for reaching the maintenance part and these were the same factors in both arms of the trials. So these were age, the LDH level, and the performance status.
Now, when we look on the activity that we did observed, there was a clear sign of efficacy that we could see for progression-free survival and overall survival, so we did observe an improvement of median overall survival from 8.4, going up to 12.5 months, assessed from start of maintenance therapy, corresponding to a hazard ratio of 0.6.
So when we put this data together, we can say there is a similar group of patients coming to the maintenance part of the study. The sign of efficacy is there and the question is what is contributing to the overall survival benefit that we have observed in the IMpower 133 trial? And it appears that both parts of the therapy are of importance; the induction treatment, the combination of chemotherapy and immunotherapy, but also the maintenance therapy. The maintenance treatment was atezolizumab, which continued after the induction therapy until progression of the disease, and I think this is the main result of our analysis.
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Disclosures
Honoraria: Amgen, AstraZeneca, Boehringer-Ingelheim, BMS, Lilly, Mirati, Merck, Novartis, Pfizer, Regeneron, Roche.
