Atezolizumab Improves Overall Survival Regardless of PD-L1 Expression in NSCLC
The phase 3 OAK trial demonstrated that previously treated patients with advanced NSCLC experienced prolonged OS with atezolizumab compared to docetaxel regardless of PD-L1 status.
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Patients with PD-L1 negative non-small cell lung cancer (NSCLC) treated with atezolizumab may experience an overall survival (OS) benefit regardless of the PD-L1 IHC assay utilized, according to a study presented at the European Society for Medical Oncology (ESMO) 2017 Congress.1
The phase 3 OAK trial (ClinicalTrials.gov Identifier: NCT02008227) demonstrated that previously treated patients with advanced NSCLC experienced prolonged OS with atezolizumab compared to docetaxel regardless of PD-L1 status. Researchers investigated whether these results would be consistent across patients who were confirmed to be PD-L1 negative by varying assays.
In this study, researchers determined PD-L1 expression in patients with NSCLC prospectively using the SP142 assay and then retrospectively with the Dako 22C3 pharmDx PD-L1 assay.
Of the 850 patients in the primary population, 400 patients were evaluable by the 22C3 assay. Seventy-seven percent of patients found to be PD-L1 negative by the SP142 were confirmed to not express PD-L1 by the 22C3 assay.
Patients who were PD-L1 negative in both arms experienced a comparable OS benefit once treated with atezolizumab. Patients with the highest levels of PD-L1 expressions also experienced an improved clinical benefit.
The authors of the study concluded that “These data provide evidence of [atezolizumab] OS benefit in [patients] with PD-L1–negative tumors irrespective of the PD-L1 IHC assay used.”
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- Gadjeel S, Kowanetz M, Zou W, et al. Clinical efficacy of atezolizumab (Atezo) in PD-L1 subgroups defined by SP142 and 22C3 IHC assays in 2L+ NSCLC: results from the randomized OAK study. Presented at: ESMO 2017 Congress; Madrid, Spain: September 8-12, 2017. Abstract 1296O.