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MINI 03 - PD1 Axis Inhibition and EGFR (ID 101)
- Event: WCLC 2015
- Type: Mini Oral
- Track: Treatment of Advanced Diseases - NSCLC
- Presentations: 1
MINI03.05 - Efficacy of Pembrolizumab in Key Subgroups of Patients with Advanced NSCLC (ID 3057)
16:45 - 18:15 | Author(s): G. Lubiniecki
The humanized anti–PD-1 monoclonal antibody pembrolizumab (MK-3475) has demonstrated robust antitumor activity and a manageable safety profile in patients with advanced cancers, including NSCLC. In the first 495 patients with advanced NSCLC enrolled in multiple expansion cohorts of the phase 1b KEYNOTE-001 study (ClinicalTrials.gov, NCT01295827), pembrolizumab provided an overall response rate (ORR) of 19.4%. In a prospectively defined validation set, a relationship between tumor PD-L1 expression and pembrolizumab efficacy was demonstrated, such that patients with PD-L1 expression in ≥50% of cells had a 45.2% ORR compared with 16.5% and 10.7% in patients with PD-L1 expression in 1%-49% and <1% of cells, respectively. Using the total population of 550 patients with NSCLC treated with pembrolizumab in KEYNOTE-001, we assessed the relationship between antitumor activity and the level of PD-L1 expression in key patient subgroups.
Patients with advanced NSCLC enrolled in the NSCLC-specific expansion cohorts of KEYNOTE-001 received pembrolizumab 2 or 10 mg/kg every 3 weeks (Q3W) or 10 mg/kg every 2 weeks (Q2W) until confirmed progression, intolerable toxicity, or investigator decision. Tumor PD-L1 expression was assessed by immunohistochemistry using a clinical-trial assay and scored as the proportion score (PS) (ie, percentage of tumor cells with membranous PD-L1 expression). Response was assessed every 9 weeks per RECIST v1.1 by central review. Patients evaluable for PD-L1 were those whose slides were prepared within 6 months of staining and for which a proportion score could be assigned.
ORR in the 550 patients who received ≥1 pembrolizumab dose was 18.9%. ORR was generally similar across subgroups (Table), although there may be a difference between ever and never smokers. Among the 409 patients evaluable for PD-L1 expression, ORR was highest in those with PS ≥50% as compared with PS 1%-49% or <1% (36.8%, 11.9%, and 10.0%, respectively). Within all subgroups, ORR was highest in patients with PS ≥50% (Table). Figure 1
Pembrolizumab provides antitumor activity in a broad selection of subgroups of patients with advanced NSCLC. Improved response in patients whose tumors express PD-L1 in ≥50% of cells was observed for all subgroups. Ongoing analyses are investigating the interdependency between PD-L1 status, mutational status, and smoking.
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