ADAPTcycle: Adjuvant dynamic marker-adjusted personalized therapy (ADAPT) comparing endocrine therapy plus ribociclib versus chemotherapy in intermediate-risk HR+/HER2- early breast cancer (EBC)

TPS601 Background: The WSG ADAPT trial program represents the concept of individualization of (neo)-adjuvant decision-making in EBC in a subtype-specific manner. The first WSG ADAPT umbrella trial aimed to establish early predictive molecular surrogate markers for response after a short 3-week induction treatment. The goals of the WSG ADAPT trial program are early response assessment and subtype-specific therapy tailoring to those patients who are most likely to benefit. Methods: WSG-ADAPTcycle is a prospective, multi-center, interventional, two-arm, open-label, (neo)adjuvant, non-blinded, randomized, controlled phase III trial (NCT04055493). It investigates whether patients (pts.) with HR+/HER2- EBC identified during screening as intermediate risk (based on Oncotype DX and response to 3 weeks of preoperative endocrine therapy [ET]) derive additional benefit from 2 years of the CDK4/6 inhibitor ribociclib combined with ET compared to chemotherapy (CT) (followed by standard ET). Co-primary endpoints are disease-free survival (DFS) and distant DFS. It is planned to screen 5600 pts and to randomize 1670 pts in a 3:2 ratio (ribociclib + ET/CT). Study start was in July 2019 (80 sites, enrollment period 36 months) and until date of submission, 180 pts. have been screened and 40 randomized. Pts with HR+/HER2- EBC with clinically enhanced risk (cT2-4 or Ki67 20% or G3 or cN+) are eligible if they fulfill the ADAPT intermediate-risk group criteria: either Recurrence Score (RS) ≤25 and Ki67postendocrine>10%, RS >25 and Ki67postendocrinepostendocrine