KEY TAKEAWAYS
- The CARABELA phase 2 trial aimed to investigate and compare the efficacy of ET/ABE and CT in the NAT setting.
- The primary endpoint was RCB.
- The CARABELA study found preoperative ET/ABE did not match CT’s RCB 0-I rate but had similar outcomes.
Both chemotherapy (CT) and endocrine therapy combined with abemaciclib (ET/ABE) are recommended for high-risk HR+/HER2 early breast cancer (EBC). It remains unclear if 12 months of ET/ABE can replace CT.
Miguel Martin Jimenez and the team aimed to investigate this by comparing their efficacy in the neoadjuvant (NAT) setting.
The CARABELA (NCT04293393) is a phase II, randomized, open-label study comparing 12 months of ET with letrozole and LHRH analogs in premenopausal patients plus ABE versus 6 months of CT with standard anthracyclines and taxanes regimens as NAT for HR+/HER2-, Ki67 ≥20%, and stage II-III breast cancer. Stratification included TNM stage, menopausal status, and Ki67 levels (<30% vs. ≥30%).
The primary endpoint was the rate of residual cancer burden (RCB) 0-I. For patients requiring additional NAT, RCB III was assigned. Secondary endpoints included RCB class distribution, PEPI score 0, clinical response rate (CRR), and safety. A Bayesian method was used for sample size calculation, requiring over 80% probability for less than a 5% difference in RCB 0-I to confirm the similarity between ET/ABE and CT.
The results revealed that 100 participants per arm were recruited from 24 Spanish sites, with a median age of 53 years; 57% were postmenopausal, 79% had stage II breast cancer, 61% were N1-2, and 77% had Ki67 levels ≥30%. In the ET/ABE arm, 79% of participants completed 12 months of treatment, and RCB was assessed in 95% of participants.
About 7 participants in the ET/ABE arm receiving additional NAT prior to surgical resection were assigned RCB III. ET/ABE did not achieve a similar RCB 0-I rate compared to CT (13% vs. 18%). The CRR showed no significant difference between ET/ABE (78%) and CT (71%) (P=0.26). The PEPI score of 0 was 14% for ET/ABE and 26% for CT (P=0.03). Treatment discontinuation due to adverse events was higher in the ET/ABE arm (9%) compared to CT (4%).
The study concluded that the CARABELA trial did not achieve its primary endpoint, as 12 months of preoperative ET/ABE did not demonstrate a similar RCB 0-I rate compared to CT in individuals with highly proliferative HR+/HER2- breast cancer. However, ET/ABE showed RCB class distribution and clinical response rate (CRR) similar to CT.
The trial was sponsored by the Spanish Breast Cancer Research Group.
Source: https://cslide.ctimeetingtech.com/breast24hybrid/attendee/confcal/show/session/16
Clinical Trial: https://clinicaltrials.gov/study/NCT04293393
Martin Jimenez M, Guerrero Zotano AL, Perez ME, et al. (2024). “Neoadjuvant study of 12 months of abemaciclib plus letrozole vs chemotherapy in HR+/HER2– highly proliferative (Ki67=20%) breast cancer: CARABELA (GEICAM/2019-01) trial.” Presented at ESMO-BC 2024. (112MO, ID 165).
