Improved survival in several cancers with use of H-antihistamines desloratadine and loratadine.

Background: We have previously shown an association with substantially improved survival in breast cancer and melanoma for desloratadine and loratadine users, and set out to find whether an improved survival can be seen in tumors with and without a known response to immune checkpoint therapy, such as anti-CTLA-4 or anti-PD-1.

Methods: We investigated survival and use of six common H-antihistamines (cetirizine, clemastine, desloratadine, ebastine, fexofenadine and loratadine) in a nation-wide cohort of all 429,198 Swedish patients with ten types of immunogenic (gastric, colorectal/anal, pancreatic, lung, breast, prostate, kidney, and bladder cancer, melanoma and Hodgkin lymphoma) and six non-immunogenic (liver, uterine, ovarian, brain/CNS, and thyroid cancer and non-Hodgkin lymphoma) tumors diagnosed 2006-2017. Follow-up was until 2019-02-24.

Findings: Desloratadine use was associated with an improved survival for all immunogenic tumors, but not for the non-immunogenic ones. Loratadine use was associated with improved survival for some tumors. Use of the other antihistamines could not be shown to be consistently associated with improved survival to a statistically significant degree.

Interpretation: Our hypothesis is that our findings result from immune checkpoint inhibition, and we believe both desloratadine and loratadine should be tested in randomized clinical trials as treatment of immunogenic tumors, with priority given to trials of desloratadine as treatment of tumors with few therapy options and dismal prognoses, such as pancreatic cancer. If our results can be confirmed in a clinical setting, new, potentially curative, therapies could result for several tumors, including ones with dire prognoses and limited treatment options.