OPERA-02
Research type
Research Study
Full title
A Phase 3 Randomized, Double-Blind, Active-Controlled Study of Palazestrant with Ribociclib Versus Letrozole with Ribociclib for the First-Line Treatment of ER+, HER2– Advanced Breast Cancer (OPERA-02)
IRAS ID
1012665
Contact name
Thomas Haberberger
Contact email
Sponsor organisation
Olema Pharmaceuticals, Inc.
ISRCTN Number
N/A
Clinicaltrials.gov Identifier
Research summary
Olema Pharmaceuticals, Inc. is conducting a research study to test an investigational (not yet approved) medicine called palazestrant (OP-1250) for people with a specific type of advanced breast cancer: oestrogen receptor-positive (ER+), human epidermal growth factor receptor 2-negative (HER2-). Palazestrant is a type of endocrine therapy, which aims to stop the growth of certain breast cancer cells that depend on oestrogen. Current treatments for ER+, HER2- breast cancer often include medications such as ribociclib, which help slow the growth of cancer cells, used together with endocrine therapies such as letrozole.
This study will test whether palazestrant + ribociclib is better or worse that the standard treatment for advanced breast cancer - letrozole + ribociclib. Letrozole and ribociclib are approved for use in ER+, HER2- breast cancer. Approx. 1,000 adults will take part worldwide. Participation may last ~2.5 years.
This study has 5 periods:
• Screening (~ 4 weeks): Initial tests and assessments
• Treatment (~2.5 years): The study is double-blind, meaning neither participant nor doctor will know which treatment is given. Participants will be randomised (randomly assigned—like flipping a coin) to one of two groups:
1. Palazestrant + ribociclib + placebo for letrozole
2. Letrozole + ribociclib + placebo for palazestrant
A placebo looks like the actual drug however it does not contain any active ingredients.
Regardless of which treatment participants are assigned to, the study treatment will be given in 28-day (4 week) cycles. Everyone who enrols in the study will receive treatment for their cancer.
• End of Treatment Visit: At the time that the study treatment is stopped.
• Safety Follow-Up: One visit ~6 weeks after the last study treatment
• Post Treatment Follow-Up (every 12 weeks): Phone calls or visits to monitor treatment related side effects (if any), check if the cancer is still responding to study treatment and record any new treatments.REC name
South Central - Hampshire A Research Ethics Committee
REC reference
25/SC/0379
Date of REC Opinion
7 Jan 2026
REC opinion
Further Information Favourable Opinion