Duality Biotherapeutics, Inc. (the “Company”) (Stock Code: 9606) announced updated results from a Phase 1/2 DB-1311-O-1001 study (NCT05914116) of DB-1311/BNT324, an investigational B7H3 antibody drug conjugate (ADC), in heavily pretreated metastatic castration-resistant prostate cancer (mCRPC). The data were shared during the American Society of Clinical Oncology Genitourinary (ASCO GU) Cancers Symposium 2026 in San Francisco, USA.

As of September 5, 2025 (data cut-off), 104 mCRPC patients had received DB-1311/BNT324 at doses of 6 mg/kg (68 patients) or 9 mg/kg (34 patients). At a median 9.20-month follow-up, 50% of the patients remained under treatment. In 58 patients evaluable for tumor response, an unconfirmed objective response rate (ORR) of 41.40% and a confirmed ORR of 34.50% were observed, with a disease control rate (DCR) of 87.90%. The median duration of response (DOR) was 10.20 months. Among 82 radiographic progression-free survival (rPFS)-evaluable patients, the median rPFS was 11.30 months, with 6-month and 9-month rPFS rates of 72.00% and 63.00%, respectively. The 6-month and 9-month overall survival (OS) rates were 91.70% and 88.20%. PSA50 response rate stood at 35.40%, with a median PSA duration of response at 8.40 months.

Among the 34 patients with prior lutetium 177 (177Lu)-PSMA-617 treatment, 10 were response evaluable, with a confirmed ORR of 30.00% and a DCR of 100. In response-evaluable patients without prior Lu 177, the confirmed ORR was 35.40%, with a DCR of 85.40%.

DB-1311/BNT324 is currently under global development across multiple tumor types, leveraging B7-H3’s widespread overexpression. It is being investigated in an ongoing Phase 3 trial (NCT07365995) in taxane-naïve mCRPC. Previously, the U.S. Food and Drug Administration granted DB-1311 Fast Track Designation for advanced or metastatic CRPC and Orphan Drug Designations for esophageal squamous cell carcinoma and small-cell lung cancer.

The Company highlights that there is no assurance DB-1311/BNT324 will ultimately be developed or commercialized successfully, and shareholders are advised to exercise caution when dealing in the Company’s shares.