Impact of antihistamine use on the survival outcomes of immune checkpoint inhibitors in advanced cancer patients

Histamine and H1 receptors play a crucial role in the tumor microenvironment. Preclinical data showed that concomitant use of antihistamines and immune checkpoint inhibitors (ICIs) might increase the effect of ICIs. This study aimed to evaluate the impact of antihistamines on the oncological outcomes of ICIs. This retrospective study was conducted in a tertiary cancer center. Advanced cancer patients treated with ICIs were included in this study. A total of 133 patients receiving ICIs in the metastatic setting were included. Melanoma (33.1%) was the most common tumor type. The most common ICI was nivolumab (63.2%). Fifty-five (38.4%) patients received antihistamines concomitantly with ICIs. The most common antihistamine was pheniramine (85.5%). The median progression-free survival (PFS) (8.2 vs. 5.1 months, P = 0.016) and overall survival (OS) (16.2 vs. 7.7 months, P = 0.002) were longer in patients receiving antihistamines concomitantly with ICIs. In multivariate analysis, PFS [hazard ratio (HR) = 0.63, 95% CI: 0.40-0.98, P = 0.042] and OS (HR = 0.49, 95% CI: 0.29-0.81, P = 0.006) were also better in those patients after adjusting for confounding factors, such as performance status, bone or liver metastasis, and concurrent chemotherapy. This study suggested that antihistamines may enhance the efficacy of ICIs in patients with advanced cancer. If validated in prospective trials, antihistamines and ICIs combinations might be new options to improve oncological outcomes.