KEY TAKEAWAYS
- The phase 3b RIBECCA study aimed to investigate the real-world efficacy of ribociclib plus letrozole in postmenopausal women with HR+HER2- ABC.
- The primary endpoint was to determine CBR.
- Researchers concluded that in this diverse HR+HER2- ABC population, ribociclib plus letrozole demonstrated consistent efficacy and safety, mirroring pivotal trial outcomes.
In MONALEESA-2, combining ribociclib with letrozole demonstrated a substantial increase in progression-free survival (PFS) for postmenopausal women diagnosed with HR+HER2- advanced breast cancer (ABC).
Peter A Fasching and his team aimed to assess the RIBociclib for the treatment of advanCed breast CAncer (RIBECCA) study and its effectiveness of ribociclib plus letrozole in a patient population representative of routine clinical practice.
Researchers conducted an inclusive analysis in a multicenter, open-label, single-arm, phase 3b study. Patients diagnosed with HR+HER2-ABC, deemed ineligible for curative therapy, and possessing an ECOG performance status of ≤ 2, were enrolled. Ribociclib plus letrozole was administered in (cohort A: postmenopausal women and men in first-line; cohort B: pre-/perimenopausal women in first-line [B1], patients pretreated for advanced disease [B2]).
The primary endpoint focused on clinical benefit rate (CBR) by week 24, with secondary endpoints included overall response rate (ORR), PFS, overall survival (OS), and safety. Multivariable Cox regression analysis explored the association between patient and tumor characteristics with PFS.
About 487 patients were included in the efficacy evaluation, with 502 assessed for safety. By week 24, the CBR reached 60.8% (95% CI, 56.3-65.1), and the ORR was 19.3% (95% CI, 15.9-23.1). Median PFS was 21.8 months (95% CI, 13.9-25.3) for first-line postmenopausal patients and 11.0 months (95% CI, 8.2-16.4) for premenopausal and pretreated patients. The median OS was not reached.
Factors such as higher baseline ECOG performance status, elevated histological grade, and negative progesterone receptor status had an unfavorable impact on PFS. The most common adverse events (AEs) included neutropenia (50.0%), nausea (42.0%), and fatigue (39.2%).
The study concluded that in this diverse population of patients with HR+HER2- ABC, the efficacy and safety outcomes of ribociclib plus letrozole closely mirrored those observed in pivotal trials.
This study was sponsored by Novartis Pharma GmbH, Germany.
Clinical Trial: https://clinicaltrials.gov/study/NCT03096847
Source: https://pubmed.ncbi.nlm.nih.gov/38154393/
Fasching PA, Decker T, Hartkopf A, et.al (2024). Efficacy, safety, and prognosis prediction in patients treated with ribociclib in combination with letrozole: Final results of phase 3b RIBECCA study in hormone receptor positive, human epidermal growth factor receptor-2 negative, locally advanced or metastatic breast cancer. Eur J Cancer. 2024 Feb;198:113480. doi: 10.1016/j.ejca.2023.113480. Epub 2023 Dec 15. PMID: 38154393.
