Camizestrant in combination with capivasertib for women with ER-positive, HER2-negative advanced breast cancer: results from SERENA-1

Background Camizestrant, the next-generation oral selective estrogen receptor degrader and complete estrogen receptor (ER) antagonist, has previously demonstrated superiority over fulvestrant in patients with ER-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer. Capivasertib is a selective AKT inhibitor recommended with fulvestrant for patients with PIK3CA / AKT1 / PTEN -altered ER-positive, HER2-negative advanced breast cancer. Here, we report data from Parts I and J of SERENA-1 (NCT03616587), evaluating the safety, tolerability, pharmacokinetics and efficacy for the combination of camizestrant and capivasertib. Patients and methods SERENA-1 is a phase I, open-label, multi-part trial of camizestrant alone and in combination with other anticancer agents in women with ER-positive, HER2-negative advanced breast cancer. In parts I and J, participants received oral camizestrant 75 mg (once daily) in combination with oral capivasertib 400 mg (4 days on, 3 days off). Results Participants ( n = 29) had a median of two previous lines of therapy in the advanced setting; 55.2% had received fulvestrant and 89.7% had received a cyclin-dependent kinase 4/6 inhibitor. Camizestrant in combination with capivasertib had a well-tolerated safety profile, with diarrhea (75.9%) and nausea (44.8%) being the most common adverse events. Median t max was achieved ∼4 hours and ∼2 hours post dose for camizestrant and capivasertib, respectively. Clinical benefit at 24 weeks was seen in 51.7% of participants, and median progression-free survival was 8.3 months. Conclusion In these pretreated participants, camizestrant 75 mg in combination with capivasertib 400 mg was well tolerated, with a side effect profile consistent with each drug as monotherapy, and showed encouraging evidence of clinical efficacy.