LEONARDA-2: Lerociclib plus letrozole versus placebo plus letrozole in HR+/HER2- advanced or metastatic breast cancer.

• DOI: 10.1200/jco.2024.42.16_suppl.1052
• Publication Date: 2024-08-05T16:15:11Z
• Authors: Xichun Hu; Biyun Wang; Shusen Wang; Zhongsheng Tong; Tao Sun; Wei Li; Lihua Song; Xi Yan; Ying Cheng; Fuming Qiu; Xinshuai Wang; Weimin Xie; Bing Zhao; Xinlan Liu; Changlu Hu; Guie Lai; Jinke Pang; Tong Li
• Keywords: Letrozole

1052 Background: Following promising outcomes in hormone receptor (HR)-positive, HER2-negative endocrine-resistant advanced breast cancer (BC) with lerociclib plus fulvestrant, this study assesses the efficacy and safety of letrozole HR+/HER2- or metastatic BC. Methods: This randomized, double-blind, placebo-controlled phase III involved BC patients without prior systemic therapy for disease. Participants were allocated 1:1 to either (150mg twice daily) placebo letrozole. The primary endpoint was progression-free survival (PFS) as assessed by investigators. Secondary endpoints included PFS (assessed Blinded Independent Central Review (BICR)), response rates, overall (OS), safety. interim analysis planned approximately 80 events. Results: By September 20, 2023, 279 randomized (137 + letrozole, 142 letrozole), a median follow-up 12.91 months. Baseline characteristics comparable across groups. At data cutoff, 83 events reported. significantly improved versus (median: not reached (NR) 16.56 months; hazard ratio: 0.464; 95% CI: 0.293-0.733; p=0.0004). BICR confirmed these results NR NR; 0.457; 0.274-0.761; p=0.0011). Subgroup benefits consistent, including visceral metastases, extensive sites previous (neo)adjuvant endocrine therapy, etc. For measurable disease, showed higher objective rate (62.3%) compared group (48.5%). OS immature at cutoff. Adverse primarily hematological toxicity, incidences grade 3/4 neutropenia (grade 3: 41.6% vs. 0.7%; 4: 5.1% 0%) leucopenia 27.0% 0%; 1.5% group. All leukopenia considered be treatment related. Grade 3 diarrhea infrequent, only 1 case (0.7%) reported QTc prolongation between (4.4%, 3:1.5%) (3.5%, 3:0.7%). No venous thromboembolism Serious AEs slightly (13.1% 7.7%). Treatment discontinuation due rare (1 patient [0.7%]) lerociclib. Conclusions: Lerociclib had an excellent profile prolonged patients. benefit consistent all clinically relevant subgroups, suggesting viable first-line therapeutic option favorable benefit-risk balance. Clinical trial information: CTR20212139; NCT05851014.