Reinduction of Hedgehog Inhibitors after Checkpoint Inhibition in Advanced Basal Cell Carcinoma: A Series of 12 Patients

SIMPLE SUMMARY: For patients with advanced basal cell carcinoma (aBCC) limited treatment options are available. In this situation, hedgehog inhibitors (HHIs) are approved as first-line treatment. Upon treatment failure or intolerance, a second-line treatment with PD1 inhibitors (PD1i) is an option. However, no third-line treatment is established. Therefore, we collected data of patients with aBCC, who received HHI reinduction following PD1i-failure. In our cohort of 12 patients, initial HHI treatment led to partial response in 8 and disease stabilization in 4 patients. Eventual HHI discontinuation was mostly due to tumor progression. Second-line PD1i resulted in a partial response in only one patient. Four out of the twelve patients responded to HHI reinduction, with the longest follow-up period being 29 months. Thus, a sequential treatment with HHI reinduction can be a feasible treatment option in a subgroup of patients with aBCC after treatment failure of first-line HHIs as well as of second-line PD1i. ABSTRACT: For patients with advanced basal cell carcinoma (aBCC) first-line treatment with hedgehog inhibitors (HHIs) and second-line treatment with PD1 inhibitors (PD1i) is available, offering combination and sequencing options. Here, we focus on the efficacy and safety of HHI reinduction after PD1i failure. Retrospective data analysis was performed with 12 patients with aBCC (locally advanced (n = 8)/metastatic (n = 4)). These patients (male:female 6:6, median age 68 years) initially received HHIs, leading to complete/partial response (66%) or stable disease (33%). Median treatment duration was 20.8 (2–64.5) months until discontinuation due to progression (n = 8), adverse events (n = 3), or patient request (n = 1). Subsequent PD1 inhibition (pembrolizumab 42%, cemiplimab 58%) yielded a partial response (8%), stable disease (33%), or progression (59%). Median treatment duration was 4.1 (0.8–16.3) months until discontinuation due to progression (n = 9), adverse events (n = 1), patient request (n = 1), or missing drug approval (n = 1). HHI reinduction resulted in complete/partial response (33%), stable disease (50%), or progression (17%). Median treatment duration was 3.6 (1–29) months. Response duration in the four responding patients was 2–29+ months. Thus, a subgroup of patients with aBCC responded to reinduction of HHI following PD1i failure. Therefore, this sequential treatment represents a feasible treatment option.