Abstract GS02-01: Randomized phase 3 study of datopotamab deruxtecan vs chemotherapy for patients with previously-treated inoperable or metastatic hormone receptor-positive, HER2-negative breast cancer: Results from TROPION-Breast01

Abstract

Abstract Background: The global, phase 3 TROPION-Breast01 trial (NCT05104866) assessed the TROP2-directed antibody-drug conjugate (ADC) datopotamab deruxtecan (Dato-DXd) compared with investigator’s choice of chemotherapy (ICC) in patients (pts) with inoperable or metastatic hormone receptor-positive, HER2-negative (HR+/HER2‒) breast cancer (BC). Primary results were presented at ESMO 2023 (Bardia A, et al. Abstract LBA11). Here we report expanded data from TROPION-Breast01. Methods: Pts aged ≥18 years who had inoperable or metastatic HR+/HER2‒ BC, had disease progression on endocrine therapy (ET) and for whom ET was unsuitable, and had received 1‒2 prior lines of systemic chemotherapy (CT), were eligible. Pts were randomized 1:1 to Dato-DXd (6 mg/kg Q3W) or ICC (eribulin, vinorelbine, capecitabine, or gemcitabine) until progression or unacceptable toxicity. The dual primary endpoints were progression-free survival (PFS) by blinded independent central review (BICR) per RECIST 1.1, and overall survival (OS). Results: In total, 732 pts were randomized: 365 to the Dato-DXd arm and 367 to ICC. At data cut-off (Jul 17, 2023), 93/39 pts in the Dato-DXd/ICC groups were ongoing treatment. Pts receiving Dato-DXd had significantly improved PFS vs ICC (HR 0.63 [95% CI 0.52‒0.76]; p<0.0001). Hazard ratios for PFS favored Dato-DXd over ICC across prespecified pt subgroups, including prior lines of CT in the metastatic setting (1 vs 2), prior use of CDK4/6 inhibitor (≤12 months vs >12 months), prior use of endocrine therapy in the metastatic setting ( <6 months vs ≥6 months) and brain metastases (yes vs no). OS data were not mature at this data cut-off. In the Dato-DXd vs ICC arms, 192 (53%) vs 247 (67%) pts had received a subsequent therapy after study treatment discontinuation, including 15 (4%) vs 52 (14%) who received subsequent ADC therapy, and 165 (45%) vs 186 (51%) who received subsequent CT. Median time to first subsequent therapy was 8.2 months in the Dato-DXd arm vs 5.0 months in the ICC arm (HR 0.53 [95% CI 0.45–0.64). Overall, rate of grade ≥3 treatment-related adverse events (TRAEs) with Dato-DXd was less than half that with ICC. The secondary patient-reported outcome endpoints showed that time to deterioration in physical functioning, pain, and global health status/quality of life were delayed in the Dato-DXd arm compared with ICC. Conclusions: TROPION-Breast01 met its dual primary endpoint of PFS, demonstrating statistically significant and clinically meaningful improvement in PFS with Dato-DXd compared with ICC across all subgroups. Overall, the safety profile and QoL with Dato-DXd was favorable compared with ICC. These data support Dato-DXd as a potential new therapeutic option for pts with inoperable or metastatic HR+/HER2‒ BC who have received 1‒2 prior lines of CT. Citation Format: Aditya Bardia, Komal Jhaveri, Seock-Ah Im, Michelino De Laurentiis, Binghe Xu, Sonia Pernas, Giuliano Borges, David Cescon, Masaya Hattori, Yen-Shen Lu, Noelia Martínez-Jáñez, Erika Hamilton, Shusen Wang, Junji Tsurutani, Kevin Kalinsky, Lu Xu, Sabrina Khan, Neelima Denduluri, Hope Rugo, Barbara Pistilli. Randomized phase 3 study of datopotamab deruxtecan vs chemotherapy for patients with previously-treated inoperable or metastatic hormone receptor-positive, HER2-negative breast cancer: Results from TROPION-Breast01 [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr GS02-01.