Multicenter Retrospective Analysis of the Safety and Efficacy of Sacituzumab Govitecan Combined With Radiation Therapy: The French ATTENTION Study.

Abstract

Based on the results of the ASCENT trial, sacituzumab govitecan (SG) has been approved for the treatment of breast cancer. With the expanding indications across multiple cancers, data on its combination with radiation therapy (RT) are needed. ATTENTION is a retrospective multicenter study from 6 French institutions. Eligibility criteria included patients with breast cancer who received RT and SG between September 2021 and January 2025. Concomitant treatment was defined as RT administered within 4 days before or after SG administration. Data were collected through an online questionnaire and centralized after medical record review, and protocol validation by the local ethics committee. The primary endpoint was safety profiles according to the Common Terminology Criteria for Adverse Events, version 5.0. Secondary endpoints included treatment response, evaluated according to Response Evaluation Criteria in Solid Tumors, version 1.1 criteria and/or clinical symptom improvement. Assessment was performed 4-12 weeks after RT. Fifty-five patients (63 lesions) were included. The median age was 56 years (37-82). SG and RT were administered concurrently in 37 lesions (median, 3 days), sequentially in 26 lesions (median, 10 days). Subtypes included human epidermal growth factor receptor 2 (HER2)-/hormone receptors (HR)- (30%), HER2-/HR+ (27%), HER2-low/HR+ (24%), HER2-low/HR- (18%), and HER2+ (2%). SG was given as second-line in 16%, and ≥ fourth-line in 54%. RT was symptomatic in 57% and for progression in 43%, mostly targeting bone (49%) and brain (32%), using 3D conformal RT (52%), stereotactic body RT (40%), or intensity modulated RT (8%). With a median follow-up of 7.9 months (1.7-35.4), RT-related toxicities of grade 1-2 occurred in 17 cases (27%), (3 dermatitis, 4 esophagitis, and 1 brain radionecrosis). No grade ≥ 3 toxicity occurred with concomitant SG. The overall response rate was 25% complete and 80% partial responses. Median overall survival was 12.9 months (95% CI, 7.97-17.77). ATTENTION is the largest study that confirms the feasibility and promising efficacy of concurrent treatment, pending confirmation in prospective trials.