Post hoc analysis of the CPS <1 and CPS 1-19 (CPS: combined positive score) subgroups of the phase III KEYNOTE-048 trial was presented at AACR 2020
The phase III KEYNOTE-048 trial (NCT02358031) released during AACR 2020 demonstrated results of post hoc analysis of subgroups CPS <1 and CPS 1-19 (CPS: combined positive score), which had not been defined prospectively so far.
Patients with recurrent or metastatic head and neck squamous cell carcinoma (HNSCC) and without previous systemic therapy were randomly assigned 1: 1: 1 to pembrolizumab (P), pembrolizumab + chemotherapy (P + C) or EXTREME regimen (E, chemotherapy + cetuximab).
Progression-free survival (PFS), objective response rate (ORR), and duration of response were assessed by RECISTv1.1 by blinded independent central review. Overall survival (OS) and PFS were estimated using the Kaplan-Meier method. Hazard ratios (HR) and the 95% confidence intervals were based on a Cox regression model.
The baseline characteristics of subgroups CPS <1, CPS 1-19 and CPS ≥20 were similar to those of the total population. In the subgroup CPS <1, the HR (95% CI) for SG was 1.51 (0.96-2.37) for P (n = 44) vs E (n = 45) and 1.21 (0, 76-1.94) for P + C (n = 39) versus E (n = 43).
In the CPS 1-19 subgroup, the HR (95% CI) for OS showed a small advantage of P (n = 124) vs E (n = 133) (0.86 [0.66-1.12]) and favored P + C (n = 116) versus E (n = 125) (0.71 [0.54-0.94]).
The authors conclude that there was evidence of greater efficacy of therapy with increased expression of PD-L1. In the CPS 1-19 subgroup, the results of P + C versus E were consistent with the benefit of treatment. The analysis of the CPS subgroup <1 was limited due to the small sample size of patients.
Burtness, B.et al. Efficacy of first-line (1L) pembrolizumab by PD-L1 combined positive score <1, 1-19, and ≥20 in recurrent and/or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC): KEYNOTE-048 subgroup analysis. Session LBPO.CL02 – Late-Breaking Research: Clinical Research 2. LB-258.