Abstract 662
Background
Pembrolizumab is currently approved for advanced non-small cell lung cancer (NSCLC) patients with programed death ligand-1 (PD-L1) expression ≥50% as first-line therapy. However, the efficacy or immune-related adverse events (irAEs) are unclear in patients with ultra-high PD-L1 expression.
Methods
We retrospectively analyzed patients with advanced NSCLC and PD-L1 tumor proportion score (TPS) of ≥ 50% who received pembrolizumab as first-line therapy at 11 institutions in Japan between February 2017 and January 2018. Patients were separated to TPS 50-74% cohort and TPS ≥75% (ultra-high PD-L1 expression) cohort. Early irAEs were defined as irAEs that occurred within 3 weeks after commencing pembrolizumab therapy.
Results
In total, 161 patients were included; 70 patients in TPS 50-74% cohort and 91 patients in TPS≥75% cohort. The patient characteristics and the frequency of irAEs were not different between both cohorts. The objective response rates (ORR) and disease control rates (DCR) were 54.3% (38/70) and 77.1% (54/70) in TPS 50-74% cohort, 47.3% (43/91) and 69.2% (63/91) in TPS≥75% cohort (P = 0.43, P = 0.29, respectively). Time to treatment failure (TTF) curve showed that TTF of TPS≥75% cohort was comparable to that of TPS 50-74% cohort within 4 months (hazard ratio [HR] = 1.19, 95% confidence interval [CI], 0.74-1.91; P = 0.47). However, TTF of TPS≥75% cohort showed the tendency to be longer in late phase (4 months or later) (HR = 0.48, 95% CI, 0.19-1.25; P = 0.13). In the patients who achieved complete response or partial response, TTF of TPS≥75% cohort was longer than that of TPS 50-74% (HR = 0.49, 95% CI, 0.23-1.03; P = 0.059). The medians of overall survival were not reached in both cohorts. The follow-up is ongoing.
Conclusions
The ORR and DCR of TPS≥75% cohort were comparable to those of TPS 50-74% cohort. However, the patients with ultra-high PD-L1 expression could continue pembrolizumab therapy long when they achieved objective responses.
Editorial acknowledgement
Clinical trial identification
Legal entity responsible for the study
Masaki Kanazu.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.