The following article features coverage from the IASLC 2019 World Conference on Lung Cancer meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

No overall survival (OS) benefit was observed for the addition of the programmed cell death-ligand 1 (PD-L1) inhibitor, atezolizumab, to nab-paclitaxel and carboplatin chemotherapy in the intention-to-treat population (ITT) of the phase 3 IMpower131 trial of treatment-naive patients with stage IV non-small cell lung cancer (NSCLC) characterized by squamous histology. The findings from this analysis were presented at the IASLC 2019 World Conference on Lung Cancer hosted by the International Association for the Study of Lung Cancer held in Barcelona, Spain.1,2

The 3-arm, open-label IMpower 131 trial (ClinicalTrials.gov Identifier: NCT02367794) randomly assigned patients in a 1:1:1 ratio to receive atezolizumab, paclitaxel, and carboplatin; atezolizumab, nab-paclitaxel, and carboplatin; or nab-paclitaxel and carboplatin. The coprimary outcome measures of the trial were progression-free survival (PFS) and overall survival (OS), both in the ITT population. Secondary study end points included PFS and OS in patient subgroups defined by the level of PD-L1 in tumor.  

The median age of patients enrolled in the study was 65 years, and approximately 80% of participants were men; patients were treated with nab-paclitaxel and carboplatin with atezolizumab (343 patients) or without atezolizumab (340 patients). Patients receiving atezolizumab, paclitaxel, and carboplatin were not considered in this analysis.  

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Although a significant improvement in median PFS was observed with the addition of atezolizumab to first-line nab-paclitaxel plus carboplatin chemotherapy (6.5 months vs 5.6 months; hazard ratio [HR], 0.75; 95% CI, 0.64-0.88), median OS in the 2 study arms was not significantly different: it was 14.2 months and 13.5 months for patients receiving chemotherapy with or without atezolizumab, respectively (HR, 0.88; 95% CI, 0.73-1.05; P =.16).

These results contrast with the OS benefit recently reported for the first-line addition of atezolizumab to chemotherapy in patients with nonsquamous stage IV NSCLC.3

While inclusion criteria for the IMpower 131 trial did not limit patient enrollment according to tumor PD-L1 level, median OS in the subgroup of patients with a high tumor expression of PD-L1 was significantly higher for those patients receiving atezolizumab (23.4 months vs 10.2 months; HR, 0.48; 95% CI, 0.29-0.81). This OS difference was not observed in subgroups of patients with lower tumor PD-L1 levels.

Although no new safety signals were observed in this study, the incidence of grade 3/4 treatment-related adverse events was higher for patients who received atezolizumab compared with those who did not (68.0% vs 57.5%).  

“The strong benefit observed in high PD-L1 expressors highlights relevance of biomarkers for patient selection,” stated Federico Cappuzzo, MD from Azienda Unità Sanitaria Locale della Romagna, Ravenna/Italy.2

Read more of Cancer Therapy Advisor‘s coverage of the IASLC annual meeting by visiting the conference page.

References

  1. Cappuzzo F, Jotte R, Vynnychenko I, et al. IMpower131: Final OS results of carboplatin + nab-paclitaxel +/- atezolizumab in advanced squamous NSCLC. Presented at: IASLC 2019 World Conference on Lung Cancer hosted by the International Association for the Study of Lung Cancer; September 7-10, 2019; Barcelona, Spain. Abstract OA14.02
  2. International Association for the Study of Lung Cancer. IMpower131: Final overall survival results of carboplatin + nab-paclitaxel +/- atezolizumab in advanced squamous NSCLC [press release]. Published September 10, 2019. Accessed September 10, 2019.
  3. West H, McCleod M, Hussein M, et al. Atezolizumab in combination with carboplatin plus nab-paclitaxel chemotherapy compared with chemotherapy alone as first-line treatment for metastatic non-squamous non-small-cell lung cancer (IMpower130): a multicentre, randomised, open-label, phase 3 trial. Lancet Oncol. 2019;20(7):924-937.