KEY TAKEAWAYS
- The phase 3 study analyzed 1L LET + RIB or PBO in ML-2 subgroups with either de novo metastatic disease or late recurrence.
- This focused ML-2 analysis revealed an overall survival hazard ratio in line with the broader study.
In the ML-2 study, a combination of ribociclib (RIB) + letrozole (LET) showed a significant increase in overall survival (OS) compared to placebo (PBO) and LET (median [m] OS was 63.9 vs 51.4 months). This was observed in postmenopausal patients (pts) with HR+/HER2- advanced breast cancer (ABC) who had not received prior endocrine treatment for ABC. Those with prior (neo)adjuvant treatments were included, but a treatment-free interval (TFI) of more than 12 months was required for those who had used a nonsteroidal aromatase inhibitor. The current analysis focused on ML-2 subgroups with either de novo metastatic disease or late recurrence (TFI > 12 months).
Patients were evenly randomized to receive either 1L LET + RIB or PBO. Subgroups with de novo metastatic disease or late recurrence were examined for OS, progression-free survival (PFS), time to chemotherapy (TTC), and chemotherapy-free survival (CFS).
Of the 668 participants, 18.4% were excluded due to a TFI ≤ 12 months. Among the remaining 545 pts, 41.7% had de novo disease, and 58.3% experienced late recurrence. Baseline characteristics were balanced across treatment arms. The median OS was better in the RIB group at 69.2 months compared to 54.3 months in the PBO group (HR, 0.75 [0.60-0.93]; P = .005). Both TTC (54.1 vs 40.9 months, P = .004) and CFS (42.5 vs 36.1 months, P = .002) were improved with RIB over PBO. No new safety concerns were identified.
This focused analysis of ML-2 excluded pts with TFI ≤ 12 months and revealed that the OS hazard ratio was in line with the overall study population. The median OS was notably higher in the RIB group than in the PBO group, showing about a 15-month improvement.
Clinical Trial: https://classic.clinicaltrials.gov/ct2/show/NCT01958021
O’Shaughnessy, J., Beck, T., Chia, S., Isaacs, C., De Laurentiis, M., Kuemmel, S., Jhaveri, K., Janni, W., Rugo, H.S., Lteif, A., Sopher, G., Hu, H., Neven, P. 196P – Efficacy and safety of first-line (1L) ribociclib (RIB) + letrozole (LET) in patients (pts) with de novo metastatic disease and late recurrence from (neo)adjuvant therapy (tx) in MONALEESA (ML)-2. Annals of Oncology (2023) 8 (1suppl_4): 101223-101223. 10.1016/esmoop/esmoop101223
