A retrospective analysis of pembrolizumab plus chemotherapy versus pembrolizumab monotherapy for advanced or recurrent non-small cell lung cancer

Background Although clinical trials have investigated the addition of pembrolizumab to chemotherapy for non‐small cell lung cancer, none have investigated the addition of chemotherapy to pembrolizumab. Methods We conducted a retrospective study of 71 NSCLC patients including 33 treated with pembrolizumab plus chemotherapy (combination therapy group) and 38 treated with pembrolizumab monotherapy (monotherapy group) from 1 May 2016 to 31 August 2020. Results Eleven of 33 (33.3%) patients in the combination therapy group and 37 of 38 (97.4%) patients in the monotherapy group had programmed cell death ligand‐1 (PD‐L1) tumor proportion score (TPS) ≥50%. Objective response rate (ORR) and median overall survival (OS) were not significantly different between the combination therapy group and monotherapy group (54.5% vs. 47.4, p = 0.637 and 16.6 vs. 27.0 months, p = 0.463). In patients with PD‐L1 TPS ≥50%, ORR and median OS were not different between the combination therapy group and the monotherapy group (63.6% vs. 48.6%, p = 0.499 and not reached vs. 27.0 months, p = 0.976). Thirty‐three (100%) patients experienced adverse events (AEs) in the combination therapy group and 32 (84.2%) in the monotherapy group. Treatment discontinuation at 1 year due to AEs occurred more frequently in the combination therapy group (45.2%) than in the monotherapy group (21.1%). Conclusion There was no significant difference in ORR and OS between the two groups, and treatment discontinuation was more frequent in the combination group. A randomized controlled trial is needed to evaluate the addition of chemotherapy to pembrolizumab for first‐line treatment in patients with PD‐L1 TPS ≥50%.
There was no significant difference in clinical response and prognosis between the combination therapy group and the monotherapy group. We think that the higher frequency of treatment discontinuation due to adverse events in the combination therapy group compared to the monotherapy group is one reason why there was no significant difference in prognosis between the two groups.