A Phase 2, Open Label, Multicenter, Single Arm Trial Evaluating the Activity and Safety of Abemaciclib + Aromatase Inhibitors (AIs) as Second-Line Treatment After First-Line Fulvestrant in Hormone-Receptor-Positive (HR+), Human-Epidermal-Growth-Factor-Receptor-Negative (HER2-) Metastatic Breast Cancer (MBC) Patients. Final Results of HERMIONE-7 Trial.

BACKGROUND AND PURPOSE

CDK 4/6 inhibitors with ET are the recommended choice as 1st-line therapy in HR+/HER2- MBC patients, however ET alone could remain an option for some of them. HERMIONE-7 is a multicenter, single-arm, Phase II study, aimed to evaluate Abemaciclib 150 mg BID + AIs, in patients who progressed on 1st line Fulvestrant.

MATERIALS AND METHODS

Primary aim was the efficacy of Abemaciclib + AIs in terms of Clinical Benefit Rate (CBR), secondary aims were Time to Progression (TTP), Overall Response Rate (ORR), duration of response (DOR), and safety.

RESULTS

From April 2020 to January 2022, we enrolled 31 patients. Median age was 72 years (range 47-86), 55% had < 2 comorbidities, mainly hypertension (12, 38.7%). Clinical Benefit Rate was 69% (95% CI, 49-85) and ORR was 21% (95%CI, 8-40). 1-year TTP and OS rates were 53.8% (95% CI, 38.6-74.9%) and 69.5% (95% CI, 54.8%-88.5%), respectively. Main adverse events remain diarrhea (80.6%), fatigue (54.8%) and nausea (35.5%), 3 patients (10.7%) had non drug-related fatal events.

CONCLUSIONS

HERMIONE-7 study showed that 2nd-line treatment with Abemaciclib + AIs is a feasible option in MBC patients who progressed on Fulvestrant in 1st-line setting and could be an alternative especially in terms of optimizing the cost-benefit ratio in some Countries.