Real-life efficacy and predictors of response to immunotherapy in pituitary tumors: a cohort study.

Objective: After temozolomide failure, no evidence-based treatment is ava ilable for pituitary carcinomas (PCs) and aggressive pituitary tumors (APTs). To date, only 12 cases trea ted with immune-checkpoint inhibitors (ICIs) have been published, showing encouraging efficacy. Predictive factors of re sponse are lacking. Here, we aimed to assess the reallife efficacy and predictors of response to ICIs in PCs and APTs. Design and methods: This study is a multicentric, retrospective, observational coh ort study, including all PCs and APTs treated with ICIs in France up to March 2022. PD-L1 immunohisto chemistry and CD8+ T cell infiltration were evaluated centrally. Results: Six PCs (four corticotroph and two lactotroph) and nine APTs (five corticotroph and four lactotroph) were included. The real-life efficacy of ICIs was lower than previousl y published data. Three corticotroph tumors (33.3%) showed partial response, one (11.1%) stable disease, while five (55.6%) progressed. One lactotroph tumor (16.7%) showed partial response, one (16.7%) stable disease, while four (66.7%) progressed. PCs responded far better than APTs, with 4/6 PCs showing partial response compared to 0/9 APT s. Corticotroph tumors responded slightly better than lactotroph tumors. In the four responsive corticotroph tum ors, PD-L1 staining was negative and CD8+ T cell infiltration attained a maximum of 1% in the tumor center. Conclusions: Confirmation of the presence or absence of metastases is necess ary before starting ICIs. After temozolomide failure, ICIs appear as a good therapeutic option for PCs, especially for corticotroph carcinomas. Negative PD-L1 staining and very low CD8+ T cell infiltration in the tumor center should not preclude ICI administration in corticotroph carcinomas. [ABSTRACT FROM AUTHOR]