Ribociclib Plus Letrozole in Italian Male Patients with Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Advanced Breast Cancer: Case Studies of Phase 3b CompLEEment-1 Trial.

Abstract: Male breast cancer (BC) is rare, globally constituting only 0.5-1% of all patients with BC. In Italy, more than 2000 new male BC cases were registered between 2000 and 2014. The survival rate was lower in males than in females. Delayed diagnosis may be the reason for poorer outcome observed in male BC patients compared with female patients. Due to lack of substantial evidence and low availability of published data on male BC, the current treatment recommendations are based on evidence derived from trials on female patients. In Italy, most of the male BC patients are estrogen and progesterone receptor-positive. Targeted therapy in combination with endocrine therapy provides a clinically meaningful outcome in patients with hormone receptor-positive (HR-positive), human epidermal growth factor receptor 2-negative (HER2-negative) advanced BC. CompLEEment-1 is a single-arm, open-label, multicenter, phase 3b trial investigating the safety and efficacy of a CDK4/6 inhibitor, ribociclib, in combination with letrozole in men and women. Herein, we report the results from a retrospective analysis of five Italian male patients who completed the core phase. In this case series, the combination of ribociclib and letrozole was well tolerated and appeared to be effective in the male cohort with HR-positive, HER2-negative advanced BC in Italy. CompLEEment-1 trial representative of a real-world setting would add value by supporting the existing efficacy and safety profile of ribociclib in combination with letrozole in male patients with HR-positive, HER2-negative advanced BC. ClinicalTrialsgov Registration Number: NCT02941926.