RIbociclib plus goserelin with hormonal therapy versus physician choice chemotherapy in premenopausal or perimenopausal patients with HR+, HER2– inoperable locally advanced or metastatic breast cancer: RIGHT choice study

Abstract

Background: A high percentage of breast cancer patients in the Asia‐Pacific (∼42%) and Middle East (∼50%) regions are aged 50 years or younger. Although a high proportion of younger patients with endocrine‐responsive metastatic disease are treated initially with cytotoxic chemotherapy (CT) in routine general practice, data from phase III trials have shown higher response rates and longer progression‐free survival with endocrine therapy (ET) in combination with CDK4/6 inhibitor versus single agent ET. Due to lack of direct evidence, trials in pre‐/perimenopausal advanced breast cancer are thus necessary to assess the efficacy of ET in combination with CDK4/6 inhibitor vs CT in aggressive or high tumor burden setting where CT is clinically indicated. Trial design: The RIGHT Choice study (NCT03839823) is a randomized, open‐label, multination phase 2 study with a target enrollment (approximately 55 sites in 13 countries in the Asia‐Pacific and Middle East regions) of 222 pre‐/perimenopausal women aged 18‐59 years who have not received prior systemic ET or CT for advanced disease. Patients must have advancedHR+, HER2‐breast cancer not amenable to curative therapy (ie, symptomatic visceral metastases, rapid progression of disease or impending visceral compromise, or markedly symptomatic nonvisceral disease where combination chemotherapy is clinically indicated). Tumors must be estrogen receptorpositive ≥10%; and ECOG performance status ≤2. Exclusion criteria include pregnancy or lactation, and postmenopausal status. Patients will be randomized to receive ribociclib (600 mg, 3 weeks on/1 week off) in combination with letrozole or anastrozole plus goserelin or to investigator's choice of combination CT (docetaxel +capecitabine, paclitaxel + gemcitabine, or capecitabine+ vinorelbine). The primary endpoint is progression‐free survival. Secondary endpoints include time to treatment failure, overall response rate, clinical benefit rate, time to response, overall survival, patient global health status, and safety. Healthcare resource utilization will be evaluated as an exploratory endpoint.