Toxicity of PD-1/CTLA-4 inhibitor immunotherapy among elderly patients.

Abstract

e14139 Background: The use of Immune check point inhibitors in advanced metastatic melanoma is becoming increasingly common especially in the elderly population. With metastatic melanoma being mostly a disease of the elderly, the safety and toxicity profile of immune check point inhibitors in this population group continues to remain controversial. Prior studies have hypothesized that due to reduced immune responses in the elderly, toxicity to immune check point inhibitors is expected to be low. In this study we aim to analyze the association of check point inhibitor induced immuno-toxicity with age. Methods: We analyzed 108 patients with stage 4 metastatic melanoma who were treated with anti-PD1 and/or anti-CTLA-4 immunotherapy. Out of these patients, 58 (53.7%) were 65 or more years old and 50 (46.3%) were < 65 years old. Overall, 64 (59.3%) patients had autoimmune side effects; 35 (60.3%) were 65 years or older and 29 (48%) were < 65 years old. The most common side effects were dermatitis (n = 22, 20.4%) and colitis (n = 21, 19.4%). Incidences of various autoimmune side effects were calculated in both groups (65 years or older and < 65 years old). Fisher exact test was used to calculate p values Results: There was a significant difference between the incidence of dermatitis between the two groups. (51.4% in 65 years or older and 24.1% in < 65 years old group, p = 0.04). The incidence of colitis was more in the 65 years or older group (37.1%) as compared to < 65 years group (31.1%) however results were not statistically significant (p = 0.79). Similarly, there was no significant difference in other autoimmune side effects including hepatitis, arthritis, pneumonitis, thyroiditis, hypophysitis, adrenalitis, anemia and thrombocytopenia between the two groups. Also, there was no significant difference in the incidence of different grades of side effects (1 to 4) between the two groups. Conclusions: Patients who are 65 years or older can safely tolerate immunotherapy as compared to patients < 65 years old but with an increased risk of dermatitis. These data should be validated by a larger study population.