Oct 10 2017
Clinical efficacy of atezolizumab in PD-L1 selected subgroups defined by SP142 and 22C3 IHC assays in 2L+ NSCLC: results from the randomized OAK trial [1296O], Shirish Gadgeel, et al
The objective of this analysis is to evaluate PD-L1 expression in patients using the two FDA-approved PD-L1 IHC diagnostic assays, SP142 and 22C3 and to evaluate atezolizumab efficacy in populations defined as PD-L1-negative by each assay.
In addition to SP142 assays, 400 patients samples (biomarker-evaluable population [BEP]) from OAK were available for retrospective analysis by the 22C3 assay.
The majority (77%) of SP142 PD-L1 negative patients were also negative by the 22C3 assays.
- OS was improved with atezolizumab in the subgroup defined as PD-L1 low/negative, as measured by either assay:
- OS in TPS<1% (22C3) subgroup: HR = 0.61 (0.45, 0.84)
- OS in TC0 and IC0 (SP142) subgroup: HR = 0.55 (0.37, 0.80)
These results demonstrate that atezolizumab improves survival in patients with PD-L1 negative tumors irrespective of the assay utilized and also confirm the primary results from the OAK trial that atezolizumab provides survival benefit in all patients with NSCLC regardless of PD-L1 status.