Résumé
Abstract only 1055 Background: Real-world evidence is important as it complements data from randomized controlled trialse report updated results from CompLEEment-1, a Phase IIIb trial evaluating RIB+LET in an expanded population, the largest CDK4/6i trial in ABC to date. Methods: Patients (pts) with HR+, HER2– ABC, ≤ 1 line of prior CT and no prior ET for ABC received RIB+LET. Study design has been reported previously (De Laurentiis, et al. ASCO 2019). Primary endpoints were safety and tolerability. Results: 3,246 pts received ≥ 1 dose of study treatment. Median duration of follow-up was 25.4 months (mos) (15 additional mos since interim analysis [De Laurentiis, et al. ABC5 2019]). Median treatment exposure was 17.8 mos. Baseline characteristics indicated a diverse population, including men (1.2%), premenopausal women (22.2%), and pts aged ≥ 70 years (19.5%); 112 (3.5%) pts had an ECOG PS of 2, 194 (6.0%) pts received prior CT for ABC, and 51 (1.6%) pts had stable CNS lesions. The most common adverse events (AEs) were neutropenia (61.1%), nausea (35.9%), and fatigue (23.4%). Grade 3/4 hematologic abnormalities ( > 5.0 %) were decreased neutrophils (54.8%), leukocytes (25.9%), and lymphocytes (12.6%). Grade 3/4 biochemical abnormalities ( > 5.0 %) were increased ALT (9.1%) and AST (6.7%). An increase of > 60 ms in QTcF interval from baseline occurred in 189 (5.9%) pts, while post-baseline QTcF of > 480 to ≤ 500 ms and > 500 ms occurred in 59 (1.8%) and 42 (1.3%) pts, respectively. Treatment-related AEs led to treatment discontinuation in 418 (12.9%) pts. Of 74 (2.3%) on treatment deaths, 38 (1.2%) were due to breast cancer. Median time to progression was 27.1 mos (95% CI, 25.7-NE), overall response rate was 43.6% (95% CI, 41.5-45.8%), and clinical benefit rate was 69.1% (95% CI, 67.1-71.1%) for pts with measurable disease at baseline. Conclusions: This analysis confirms the safety and efficacy of RIB+LET in a large, diverse cohort of pts with HR+, HER2– ABC (with no previous ET for ABC), closely resembling real-world clinical practice. Safety and efficacy data were consistent with those observed in the MONALEESA trials, supporting the use of RIB+LET in the first-line setting. NCT02941926. Clinical trial information: NCT02941926 .