Real-World Efficacy and Safety Data of Immune Checkpoint Inhibitors in Turkish Patients with Metastatic Melanoma: A Turkish Oncology Group Retrospective Study

Abstract

In recent years, significant success has been achieved in the treatment of metastatic melanoma with the use of immune checkpoint inhibitors (ICIs), and it resulted in a remarkable increase in patient survival. However, there are only a few studies reflecting daily practice outside of clinical trials. The present study aimed to evaluate the effectiveness and safety of ICI therapy in Turkish patients with metastatic melanoma, including those with poor prognostic factors such as advanced age and brain metastasis. A retrospective analysis was conducted on 249 patients diagnosed with metastatic melanoma and treated with ICIs at 23 cancer centers in Turkey. The efficacy and safety of treatment were investigated, and prognostic factors were examined. The mean age was 59 years, and 64% of patients were male. A total of 28% had BRAF mutation. A total of 22% of the patients were >70 years of age and 26% had brain metastases. The objective response rate with ICI therapy was 37.7%. The median overall survival (OS) was 61 months (95% CI 47-74.9), and the median progression-free survival was 7 months (95% CI 5.9-8). Examining factors influencing overall survival, the difference in median OS was not statistically significant by sex and BRAF status, whereas there were statistically significant differences by age, objective response status, metastasis pattern, and presence of brain metastasis. Median OS was 35 months in patients >70 years when compared with 67 months in patients aged 70 years and younger (P=0.02). Median OS was 41 months in patients without objective response, whereas it could not be reached in patients with objective response (P<0.0001). Median OS was 35 months in patients with de novo metastatic disease compared with 78 months in patients with recurrent metastasis (P<0.0001). Moreover, median OS was 37 months in patients with brain metastasis in comparison with 67 months in patients without brain metastasis (P=0.006). Multivariate analysis revealed that absence of objective response, presence of de novo metastasis, and presence of brain metastasis were independent poor prognostic factors affecting survival. Grade 3-4 immune-related adverse effects were observed in 7.2% of patients, and treatment was discontinued due to adverse effects in 2.8% of patients. The present study demonstrated that real-world data on ICI therapy in Turkish patients with metastatic melanoma may slightly differ from the results of other studies due to Turkey's conditions. Additionally, the present study, which included non-clinical trial patients, revealed important prognostic factors.