Trastuzumab Deruxtecan in brain metastases from breast cancer: outcome analysis of real life population

Abstract Introduction. Tumor dissemination to the central nervous system (CNS) is almost a rule in the treatment journey of advanced HER2+ breast cancer (BC). Recent results from the DEBBRAH and TUXEDO trials demonstrated high intracranial efficacy with Trastuzumab Deruxtecan (T-Dxd), confirmed by a pooled analysis of DESTINY-BREAST 01, 02, and 03 trials. However, a real world evidence is lacking in literature. Methods. We conducted a multicenter, observational, and retrospective real-world analysis on cases collected at 12 Italian Oncological Units. Patients with brain metastases (BMs) from HER2+ BC treated with T-Dxd in various treatment lines were enrolled. Data were extrapolated from the original DE-REAL study database. Primary endpoint was the intracranial overall response rate (iORR). The main secondary endpoints were intra- and global progression free survival (iPFS - gPFS); Other secondary objectives were the intracranial disease control rate (iDCR), intracranial duration of response (iDoR), the intracranial clinical benefit rate at 6 and 12 months (iCBr), the overall survival, and the safety. Results. 39 patients were included in the final analysis. iORR was 59% (23), iPFS was 15.6 months (95% CI: 10.5-20.8), gPFS was 11.8 months (95% CI: 8.5-15.0). i DCR 94.9% (87.9-100.0), iDoR was 11.9 months (10.1-13.7), and iCBr at 6 and 12 months were 69.2% and 59%, respectively. OS was not reached, with an overall rate of 77.9% of patients alive at 12 months. No new safety concerns were reported. Conclusions. This study confirmed the high intracranial efficacy and manageable safety profile of T-Dxd in this first-ever real world analysis.