Retrospective analysis of treatment-naive Slovenian patients with metastatic melanoma treated with pembrolizumab – real-world experience
Background. Based on recent data from clinical trials, the immune checkpoint inhibitor pembrolizumab in patients with advanced/metastatic melanoma prolongs survival and has a good toxicity profile. Whether these results are transmitted into daily clinical practice remains to be answered. Aim of this study was to assess the efficacy and toxicity of pembrolizumab in treatment-naive patient with metastatic melanoma in everyday clinical practice in Slovenia and compare it to the results from clinical trials.
Patients and methods. This observational retrospective cohort study included 138 consecutive metastatic treatment-naive melanoma patients treated with pembrolizumab at the Institute of Oncology Ljubljana in Slovenia from January 2016 to December 2018. Patient and treatment characteristics were retrospectively collected from hospital data base. Statistical data were obtained using the SPSS software version 22. Survival was calculated by Kaplan-Meier method. Observation period was between January 2016 and the end of June 2019.
Results. The estimated median overall survival (OS) was 25.1 months (95% CI, 14.6-35.6) and median progression-free survival (PFS) was 10.7 months (95% CI, 5.9-15.4). Among all patients, 29 (21.0%) achieved complete response, 31 (22.5%) partial response and 23 (16.7%) stable disease. The number of organs with metastatic involvement and level of baseline lactate dehydrogenase (LDH) concentration showed a significant influence on the survival. Immune-related adverse events (irAE) were reported in 88 (63%) of patients, grade 3-4 irAE occurred in 12 (8.7%). Due to toxicity, 16 (11.6%) patients discontinued the treatment.
Conclusions. Our real-world data, single centre retrospective analysis showed inferior median OS and similar median PFS compared to the results from clinical trials. Anyhow, patients with normal serum levels of LDH and small number of organs with metastatic involvement had comparable survival outcomes. Toxicity rate of pembrolizumab was quite similar.
Key words: immunotherapy, pembrolizumab, advanced/metastatic melanoma, treatment-naïve