Patient-Reported Outcomes and Progression-Free Survival Findings from the 5th Interim Analysis of the RIBANNA Trial in Patients with HR-Positive/HER2-Negative Advanced Breast Cancer

The oral, selective, cyclin-dependent kinase 4/6 inhibitor ribociclib has demonstrated significant overall survival and progression-free survival (PFS) benefits in combination with aromatase inhibitor fulvestrant in the 3 pivotal phase 3 MONALEESA trials in patients with HR-positive/HER2-negative advanced breast cancer. The RIBANNA trial is an ongoing, prospective, non-interventional study assessing the real-world efficacy and safety of first-line (1L) ribociclib with fulvestrant (or alternative endocrine therapy [ET]) with an estimated completion of February 2025. Results from the 5th interim analysis, comprising patient-reported outcomes and effectiveness of therapy sequences, were reported.

All patients with disease progression on 1L therapy were given subsequent lines of treatment per physician choice. 1L and second-line (2L) PFS were analyzed using the Kaplan-Meier (KM) method. Adherence was measured using various patient questionnaires. Time to deterioration (TTD) by 10% was calculated and analyzed using the KM method.

By the cutoff date of September 6, 2022, data were available for 2581 enrolled patients; the majority were on ribociclib and ET combination therapy (n = 2163), followed by ET (n = 237) and chemotherapy (CT; n = 237). Of the 2163 patients receiving ribociclib plus ET, 2085 (96.4%) were treated in the 1L setting. Overall, discontinuation rate was 42.1%, 44.3%, and 65.2% in the 1L ribociclib plus ET, ET alone, and CT cohorts, respectively, with death and lost to follow-up as the most common reasons for study discontinuation across the 3 cohorts. A total of 719 patients received 2L therapy, including 27%, 29.5%, and 35.4% of patients from the 1L ribociclib plus ET, ET, and CT cohorts, respectively.

The unadjusted KM estimate for median PFS (mPFS) for 1L treatment was 32.2 months (95% confidence interval [CI], 29.3-34.8) in the ribociclib plus ET cohort, 35.2 months (95% CI, 23.9-44.2) in the ET cohort, and 16.7 months (95% CI, 9.9-17.5) in the CT cohort. In the 2L setting, the KM estimate for mPFS was 7.5 months (95% CI, 6.5-8.5), 4.9 months (95% CI, 3.5-6.1), and 8.0 months (95% CI, 5.4-12.1), in the ribociclib plus ET, ET, and CT cohorts, respectively.

Adherence rates in the overall population at baseline were 87.9%, 91.6%, and 91.6% for EORTC QLQ-C30, QLQ-BR23, and HADS-D, respectively. MMAS-8 score analysis revealed a constant adherence pattern after 10 months of ribociclib plus ET therapy. Similar TTD was observed among the 1L ribociclib plus ET, ET, and CT cohorts; however, the “physical functioning” scale (median TTD [95% CI]) showed minor deterioration (P = .0009) in the 1L ribociclib plus ET cohort (12.3 [11.5-14.9]) versus 1L ET (9.1 [6.0-15.3]) or CT (6.0 [3.6-13.4]) over the treatment period. Analysis of the EORTC QLQ-C23 questionnaire revealed no clinically meaningful differences in the median TTD by 10% of the majority of subscales among the 1L ribociclib plus ET, ET, and CT cohorts; however, in the “body image” subscale, minor deterioration was found for ribociclib plus ET and ET versus CT. No meaningful differences in the depression and anxiety subscales of HADS-D were found between the cohorts.

Investigators concluded that this real-world study across a diverse patient population demonstrated that treatment with ribociclib elicits PFS benefits and maintains or improves patient quality of life, indicating substantial clinical benefit in patients with HR-positive/HER2-negative advanced breast cancer.

Source:

Fasching PA, Brucker C, Decker T, et al. Progression-free survival and patient-reported outcomes in HR+, HER2- ABC patients treated with first-line ribociclib + endocrine therapy (ET) or ET monotherapy or chemotherapy in real-world setting: 5th interim analysis of RIBANNA. San Antonio Breast Cancer Symposium 2022. Abstract P4-01-03.