IMpower131: Strongly PD-L1-positive NSCLC patients may benefit from atezolizumab–chemotherapy
medwireNews: The final analysis of the IMpower131 trial reveals an overall survival (OS) benefit with the addition of atezolizumab to carboplatin and nab-paclitaxel chemotherapy for treatment-naïve patients with stage IV squamous non-small-cell lung cancer (NSCLC) who strongly express PD-L1.
The findings were presented to the IASLC World Conference on Lung Cancer 2019 by Federico Cappuzzo, from Azienda Unità Sanitaria Locale della Romagna in Ravenna, Italy, following on from an earlier report which demonstrated a progression-free survival benefit with the combination strategy regardless of the biomarker’s expression.
After a median 25.5 months of follow-up, intention-to-treat analysis gave a median OS of 14.2 months for the 343 patients who were randomly assigned to receive four to six cycles of atezolizumab 1200 mg every 3 weeks with carboplatin and nab-paclitaxel followed by atezolizumab maintenance therapy.
This was comparable to the median 13.5 months achieved by the 340 patients given four to six cycles of chemotherapy only, followed by best supportive care, giving a nonsignificant hazard ratio (HR) for death of 0.88 in favor of the immunotherapy regimen after considering sex, PD-L1 expression, and liver metastases.
However, when assessing only the subset of patients with high PD-L1 expression – defined as TC3 or IC3 on an immunohistochemistry assay – the median OS increased to 23.4 months for the 47 patients given atezolizumab plus chemotherapy versus 10.2 months for the 44 patients who received only chemotherapy.
The HR for death of 0.48 in favor of atezolizumab use reached statistical significance and was a “meaningful survival difference,” Cappuzzo said, indicating that patients with strongly PD-L1-positive tumors might benefit from the addition of atezolizumab to chemotherapy.
No new or unexpected safety signals were identified, he added.
Session discussant Jay Lee, from the University of California, Los Angeles in the USA, compared the findings of IMpower131 with those of the KEYNOTE-407 trial of pembrolizumab with carboplatin and paclitaxel or nab-paclitaxel, also in a stage IV treatment-naïve squamous NSCLC population.
In that trial, OS data were significantly in favor of pembrolizumab use and this was “echoed across the board” for PD-L1 levels. Therefore, pembrolizumab plus chemotherapy “remains as the preferred combination regimen in this population,” Lee said.
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