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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
MINI03.03 - Pembrolizumab 2 mg/kg Q3W for Previously Treated, PD-L1-Positive Advanced NSCLC (ID 3024)
16:45 - 18:15 | Author(s): R. Hui
In patients with previously treated NSCLC enrolled in KEYNOTE-001 (NCT01295827), the anti–PD-1 antibody pembrolizumab (MK-3475) has demonstrated promising efficacy and manageable safety when given at dosages of 10 mg/kg once every 2 weeks (Q2W) or once every 3 weeks (Q3W). In a prospectively defined validation set from KEYNOTE-001, the greatest efficacy was observed in patients whose tumors expressed PD-L1 in ≥50% of tumor cells. Here, we present data for patients with previously treated, PD-L1–positive advanced NSCLC enrolled in a KEYNOTE-001 expansion cohort added to evaluate pembrolizumab 2 mg/kg Q3W.
Patients had measurable disease, ECOG performance status of 0 or 1, and adequate organ function. Prior therapy with ≥1 platinum-doublet chemotherapy regimen was required; an appropriate tyrosine kinase inhibitor was required for patients with sensitizing EGFR mutations or ALK translocations. All patients had PD-L1–positive tumors, defined as staining in ≥1% of tumor cells as determined by a prototype IHC assay using the 22C3 antibody. The percentage of PD-L1–stained tumor cells was also determined by a clinical trial IHC assay using the same antibody. Patients received pembrolizumab 2 mg/kg Q3W until investigator-determined progression according to immune-related response criteria, intolerable toxicity, patient withdrawal, or investigator decision. Response was assessed centrally every 9 weeks by RECIST v1.1.
Of the 55 patients enrolled, 41 (74.5%) received ≥2 prior therapies. Three (5.5%) patients experienced grade 3-5 drug-related AEs (grade 3 colitis and pneumonitis and grade 5 cardiorespiratory arrest). After a minimum of 27 weeks of follow-up by central radiology review of tumor imaging (median, 7.7 months; range, 6.4-9.7 months), confirmed overall response rate (ORR) in the 52 patients with centrally evaluable disease at baseline was 15.4% (95% CI, 6.9%-28.1%) and the disease control rate (DCR, complete response + partial response + stable disease) was 50.0% (95% CI, 35.8%-64.2%). At the time of analysis, all responses were ongoing, and the median response duration was not reached (range, 2.1+ to 6.2+ months). Median progression-free survival (PFS) was 3.3 months (95% CI, 2.0-6.0 months), with a 6-month PFS rate of 37.7%. Median overall survival (OS) was not reached, and the 6-month OS rate was 75.8%. In the 25 (45.5%) patients who had PD-L1 expression in ≥50% of tumor cells, confirmed ORR was 30.4% (95% CI, 13.2%-52.9%), DCR was 56.5% (34.5%-76.8%), median PFS was 4.2 months (95% CI, 1.9 months-NR), and 6-month PFS and OS rates were 49.0% and 81.8%, respectively.
In this previously treated cohort of patients with PD-L1–positive advanced NSCLC, pembrolizumab 2 mg/kg Q3W demonstrated robust and durable antitumor activity, with improved efficacy in patients with PD-L1 staining in ≥50% of tumor cells.