Emulation of the MONALEESA-2 Trial Using Specialty Oncology Electronic Health Records Databases

Randomized controlled trials (RCTs) are generally regarded as the gold-standard of evidence for establishing efficacy of medical products. However, real-world data (RWD) are increasingly used to complement evidence from RCTs. Yet, to have confidence in the accuracy of non-interventional studies medical products and their outcomes in oncology, investigators need to know what questions can be validly answered, with which non-interventional study designs, and which analysis methods are appropriate, given the data that is available. Building on a process from the RCT DUPLICATE initiative1-4 EmulatioN of Comparative Oncology trials with Real-world Evidence (ENCORE) is part of the expansion project specific to oncology and aims to emulate 12 randomized oncology RCTs using multiple EHR data sources. The purpose of this protocol is to describe the emulation of the MONALEESA-2 trial. MONALEESA-2 was a Phase III, double-blind, randomized study assessing the efficacy and safety of ribociclib (600 mg orally once daily on days 1-21 of a 28-day cycle, followed by 7 days off) in combination with letrozole (2.5 mg orally once daily, continuously) versus letrozole alone in postmenopausal women with hormone receptor-positive \[estrogen receptor (ER) and/or progesterone receptor (PR)\], human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer who had not received prior systemic treatment for their advanced disease.