First-line ribociclib plus endocrine therapy outperforms combination chemotherapy

Results from phase 2 RIGHT Choice trial, the first prospective, head-to-head study comparing a CDK4/6 inhibitor plus endocrine therapy versus combination chemotherapy, showed superior progression-free survival (PFS) of ribociclib plus endocrine therapy over combination chemotherapy in patients with aggressive, HR-positive/HER2-negative advanced breast cancer.

In patients with advanced breast cancer with aggressive disease features, like rapidly progressing or highly symptomatic disease, including life-threatening visceral crisis, combination chemotherapy is the standard-of-care [1]. The phase 2 RIGHT Choice trial (NCT03839823) compared the efficacy and safety of ribociclib plus endocrine therapy with combination chemotherapy in patients with aggressive, HR-positive/HER2-negative advanced breast cancer. Dr Yen-Shen Lu (National Taiwan University Hospital, Taiwan) presented primary results [2].

The trial randomised 222 patients with no prior systemic treatment for advanced breast cancer 1:1 to receive ribociclib plus letrozole or anastrozole or a physicians’ choice combination chemotherapy (docetaxel/capecitabine, paclitaxel/gemcitabine, or capecitabine/vinorelbine). The primary endpoint was PFS.

After a median duration of 24 months, 45.5% of patients in the ribociclib arm and 23.6% of patients in the chemotherapy arm were still on treatment. The median PFS was 24.0 months for patients treated with ribociclib plus endocrine therapy versus 12.3 months for patients treated with combination chemotherapy (HR 0.54; P=0.0007; see Figure). PFS benefit of ribociclib plus endocrine therapy was observed across most subgroups of patients. The median time to treatment failure was longer in the ribociclib than the chemotherapy arm (18.6 vs 8.5 months; HR 0.45). Time to onset of response, overall response rate, and clinical benefit rate were similar in both treatment arms.

Figure: Ribociclib plus endocrine therapy has greater PFS benefit than combination chemotherapy [2]



RIB + ET, ribociclib plus endocrine therapy; Combo CT, combination chemotherapy; PFS, progression-free survival; mo, months.

Based on these first results, Dr Lu concluded that “first-line ribociclib plus endocrine therapy offers an efficacious and clinically meaningful treatment option for patients with aggressive, HR-positive/HER2-negative advanced breast cancer.”

1. Cardoso F, et al. Ann Oncol. 2020;31:1623–1649.
2. Lu Y-S, et al. Primary results from the randomized phase II RIGHT Choice trial of premenopausal patients with aggressive HR+/HER2− advanced breast cancer treated with ribociclib + endocrine therapy vs physician’s choice combination chemotherapy. Abstract GS1-10, SABCS 2022, 6–10 December, San Antonio, TX, USA.

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Posted on 1 February 2023