Background

Patients (pts) with a/mTNBC have limited treatment options and poor prognosis. Combining checkpoint inhibitors with 1L chemotherapy improves outcomes but only in PD-L1+ve a/mTNBC, emphasizing a critical need. Dato-DXd, a TROP2 antibody-drug conjugate (ADC) with potent topoisomerase (TOPO) I inhibitor payload, elicited a 34% objective response rate (ORR) in heavily pretreated a/mTNBC and 52% ORR in a subset naïve to TOPO I-based ADCs. In BEGONIA, an ongoing 2-part, open-label platform study, D (an anti-PD-L1 antibody) combined with other therapies, including ADCs, is being evaluated in 1L a/mTNBC (NCT03742102). Here, we report preliminary results of Dato-DXd + D.

Methods

Unresectable a/mTNBC pts eligible for 1L treatment, regardless of PD-L1/TROP2 status, received intravenous Dato-DXd 6 mg/kg + D 1120 mg every 3 weeks until progression or unacceptable toxicity. Primary endpoints are safety and tolerability. Secondary endpoints include investigator-assessed ORR (RECIST v1.1) and response duration. Data cutoff was Nov 2021.

Results

29 pts received Dato-DXd + D (24 ongoing), 27 had the opportunity to have 2 postbaseline scans. Median (range) follow-up was 3.9 (2–6) months. Confirmed ORR was 20/27 (74%; 95% CI, 54–89); 2 (7%) pts had complete and 18 (67%) had partial responses, all were in response at data cutoff. No dose-limiting toxicities were observed. 4 pts (14%) underwent 1 Dato-DXd dose reduction due to stomatitis, 4 (14%) had 1 Dato-DXd dose delay, and 4 (14%) had 1 D dose delay. No dose modifications were required due to diarrhea. Table: 166MO

Summary of adverse events (AEs), n (%)

Conclusions

Combination of Dato-DXd + D in 1L a/mTNBC demonstrated robust response rates with a manageable safety profile in this preliminary analysis, warranting further investigation. Additional enrollment and analysis of translational data is ongoing. Funding: AstraZeneca/Daiichi Sankyo.

Clinical trial identification

NCT03742102.

Editorial acknowledgement

Medical writing support, which was in accordance with Good Publication Practice (GPP3) guidelines, was provided by Nicole Seneca, PhD, of Parexel (Hackensack, NJ) and was funded by AstraZeneca.

Legal entity responsible for the study

AstraZeneca/Daiichi Sankyo.

Funding

AstraZeneca/Daiichi Sankyo.

Disclosure

P. Schmid: Financial Interests, Personal and Institutional, Other, Employment, consulting or advisory role and research funding: Genentech; Financial Interests, Personal and Institutional, Other, Employment, Honoraria, consulting or advisory role and research funding: Roche; Financial Interests, Personal and Institutional, Other, Honoraria, consulting or advisory role and research funding: AstraZeneca; Financial Interests, Personal and Institutional, Other, Honoraria, consulting or advisory role and research funding: Novartis; Financial Interests, Personal and Institutional, Other, Honoraria and consulting or advisory role: Pfizer; Financial Interests, Personal, Advisory Role, Consulting or advisory role: Bayer; Financial Interests, Personal, Advisory Role, Consulting or advisory role: Boehringer Ingelheim; Financial Interests, Personal, Advisory Role, Consulting or advisory role: Celgene; Financial Interests, Personal, Advisory Role, Consulting or advisory role: Eisai; Financial Interests, Personal, Advisory Role, Consulting or advisory role: Merck; Financial Interests, Personal, Advisory Role, Consulting or advisory role: Puma Biotechnology; Financial Interests, Institutional, Funding, Research Funding: Astellas Pharma; Financial Interests, Institutional, Funding, Research funding: OncoGenex. K.H. Jung: Financial Interests, Personal, Advisory Role, Consulting or advisory role: AstraZeneca; Financial Interests, Personal, Advisory Role, Consulting or advisory role: Celgene; Financial Interests, Personal, Advisory Role, Consulting or advisory role: Eisai; Financial Interests, Personal, Advisory Role, Consulting or advisory role: MSD; Financial Interests, Personal, Advisory Role, Consulting or advisory role: Novartis; Financial Interests, Personal, Advisory Role, Consulting or advisory role: Roche; Financial Interests, Personal, Advisory Role, Consulting or advisory role: Takeda. P.J. Wysocki: Financial Interests, Personal and Institutional, Other, Honoraria and consulting or advisory role: AstraZeneca; Financial Interests, Personal and Institutional, Other, Honoraria and consulting or advisory role: Astellas; Financial Interests, Personal and Institutional, Other, Honoraria and consulting or advisory role: Amgen; Financial Interests, Personal and Institutional, Other, Honoraria and consulting or advisory role: BMS; Financial Interests, Institutional, Other, Honoraria: Gilead; Financial Interests, Personal and Institutional, Other, Honoraria and consulting or advisory role: IPSEN; Financial Interests, Personal and Institutional, Other, Honoraria, consulting or advisory role and research funding: Immunicom; Financial Interests, Personal and Institutional, Other, Honoraria and consulting or advisory role: Janssen; Financial Interests, Personal and Institutional, Other, Honoraria and consulting or advisory role: MSD; Financial Interests, Personal and Institutional, Other, Honoraria, consulting or advisory role and research funding: Merck; Financial Interests, Personal and Institutional, Other, Honoraria, consulting or advisory role and research funding: Pierre Fabre; Financial Interests, Personal and Institutional, Other, Honoraria and consulting or advisory role: Pfizer; Financial Interests, Personal and Institutional, Other, Honoraria, consulting or advisory role and research funding: Roche; Financial Interests, Personal and Institutional, Other, Honoraria and consulting or advisory role: Sanofi. J. Jassem: Financial Interests, Personal, Other, Personal fees: AstraZeneca; Financial Interests, Personal, Other, Personal fees: Pfizer; Financial Interests, Personal, Other, Personal fees: Roche; Financial Interests, Personal, Advisory Role, Consulting or Advisory role: AstraZeneca; Financial Interests, Personal, Advisory Role, Consulting or Advisory role: Pfizer; Financial Interests, Personal, Advisory Role, Consulting or Advisory role: Exact Sciences; Financial Interests, Personal, Other, Conference registration fee: Boehringer Ingelheim. C.X. Ma: Financial Interests, Personal and Institutional, Funding, Funding: Puma; Financial Interests, Personal and Institutional, Funding, Funding: Pfizer; Financial Interests, Personal, Advisory Role, Consulting Fees: Gilead; Financial Interests, Personal, Advisory Role, Consulting Fees: AstraZeneca; Financial Interests, Personal, Advisory Role, Consulting Fees: Athenex; Financial Interests, Personal, Advisory Role, Consulting Fees: Jacobio; Financial Interests, Personal, Advisory Role, Consulting Fees: Natera; Financial Interests, Personal, Advisory Role, Consulting Fees: Bayer Healthcare; Financial Interests, Personal, Advisory Role, Consulting Fees: Biovica; Financial Interests, Personal, Advisory Role, Consulting Fees: Eisai; Financial Interests, Personal, Advisory Role, Consulting Fees: Eli Lilly; Financial Interests, Personal, Advisory Role, Consulting Fees: Novartis; Financial Interests, Personal, Advisory Role, Consulting Fees: Phillips Electronics; Financial Interests, Personal, Advisory Role, Consulting Fees: Sanofi; Financial Interests, Personal, Advisory Role, Consulting Fees: Seattle Genetics; Financial Interests, Personal, Advisory Role, Consulting Fees: Pfizer. R. Fernandes: Financial Interests, Personal, Advisory Role, Consulting fees: Canadian Agency for Drugs and Technologies in Health (CADTH); Financial Interests, Institutional, Other, Honoraria: Bayer; Financial Interests, Institutional, Other, Honoraria: Pfizer; Financial Interests, Institutional, Other, Honoraria: Ipsen; Financial Interests, Institutional, Other, Honoraria: BMS; Financial Interests, Institutional, Other, Honoraria: Merck; Financial Interests, Institutional, Other, Honoraria: Novartis; Financial Interests, Institutional, Other, Honoraria: Janssen. R. Huisden: Financial Interests, Personal, Full or part-time Employment, Personal fees from AstraZeneca during the conduct of the study and outside the submitted work: AstraZeneca. R. Stewart: Financial Interests, Personal, Full or part-time Employment, Personal fees from AstraZeneca, during the conduct of the study and outside the submitted work: AstraZeneca; Financial Interests, Personal, Other, Personal fees from Pfizer, outside the submitted work: Pfizer. P. Vukovic: Financial Interests, Personal, Full or part-time Employment, Personal fees from AstraZeneca during the conduct of the study and outside the submitted work: AstraZeneca. A. Tablante Nunes: Financial Interests, Personal, Full or part-time Employment, Personal fees from AstraZeneca during the conduct of the study and outside the submitted work: AstraZeneca. Z. Nowecki: Financial Interests, Institutional, Other, Honoraria: AstraZeneca; Financial Interests, Institutional, Other, Honoraria: Sanofi Aventis; Financial Interests, Institutional, Other, Honoraria: MSD; Financial Interests, Institutional, Other, Honoraria: Roche.