Abstract GS2-06: Primary results of SOLTI-1402/CORALLEEN phase 2 trial of neoadjuvant ribociclib plus letrozole versus chemotherapy in PAM50 Luminal B early breast cancer: An open-label, multicenter, two-arm, randomized study

Background: Different approaches for treatment de-escalation are being investigated; however, the current ongoing phase III adjuvant trials with CDK4/6 inhibitors are not addressing the question if these drugs can replace multi-agent chemotherapy in high-risk early breast cancer. Here, we present the primary results of the CORALLEEN phase 2 trial, which evaluates the efficacy of ribociclib plus endocrine therapy (ET) as neoadjuvant treatment in patients with high-risk Luminal B disease. Methods: CORALLEEN is a parallel, multicenter, two-arm, randomized exploratory study in postmenopausal women with primary operable hormone receptor-positive (HR+)/HER2-negative breast cancer, Luminal B by Prosigna®. Other eligibility criteria include stage I-III operable breast cancer and ECOG 0-1. Patients were randomized 1:1 to receive either six 28-days cycles of ribociclib (600mg; 3-weeks-on/1-week-off) plus daily letrozole (2.5mg) or chemotherapy (CT): 4 cycles of AC (doxorubicin 60 mg/m2 and cyclophosphamide 600 mg/m2 every 21 days) followed by weekly paclitaxel (80 mg/m2) during 12 weeks. Baseline, Day 15 on-treatment, and surgical specimens were collected for molecular characterization and evaluation of response. The primary endpoint is the rate of PAM50 Risk of Relapse (ROR)-low disease at surgery in each arm. PAM50 ROR score integrates gene expression data, tumor size, and nodal status to define a low-risk group in the adjuvant setting (i.e. u003e90% distant relapse-free survival at 10 years). ROR-low was defined using the standard cutpoints as Citation Format: Joaquin Gavila, Cristina Saura, Tomas Pascual, Cristina Hernando, Montserrat Munoz, Laia Pare, Blanca Gonzalez Farre, Pedro Fernandez, Patricia Galvan, Xavier Gonzalez Farre, Mafalda Oliveira, Miguel Gil Gil, Miriam Arumi, Neus Ferrer Tur, Alvaro Montano, Yan Izarzugaza, Antonio Llombart Cussac, Raquel Bratos, Santiago Gonzalez, Eduardo Martinez, Sergio Hoyos, Beatriz Rojas, Juan Antonio Virizuela, Vanesa Ortega, Rafael Lopez, Pamela Celiz, Eva Ciruelos, Patricia Villagrasa, Aleix Prat. Primary results of SOLTI-1402/CORALLEEN phase 2 trial of neoadjuvant ribociclib plus letrozole versus chemotherapy in PAM50 Luminal B early breast cancer: An open-label, multicenter, two-arm, randomized study [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr GS2-06.