On November 4, 2025 Zetagen Therapeutics, a privately held clinical-stage biopharmaceutical company pioneering first-of-its-kind targeted therapies for both primary and metastatic breast cancer, reported that its abstract titled "Single Intratumoral Drug Injection Yields Complete Response (CR) in Metastatic Breast Cancer (MBC) Bone Lesions", has been accepted and will be presented at the 2025 San Antonio Breast Cancer Symposium (SABCS) on Wednesday, December 10, 2025.

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The abstract presents preliminary clinical data from a recently completed Phase 2a trial (NCT05280067) performed at the University of British Columbia evaluating ZetaMet (Zeta-BC-003) for safety and efficacy for the treatment of MBC lytic bone lesions in Stage 4 breast cancer patients. Phenotypes treated within the study, TNBC, HR+, HR+/HER2+, and HERS2+/HR-. Each patient underwent a single fluoroscopy-guided injection of ZetaMet while under sedation. All achieved a complete response (CR), ceased tumor activity, with no serious adverse events (SAEs), adverse events (AEs), or skeletal-related events (SREs) and many demonstrated a reconstitution of trabecular bone, which further underscores the potential of ZetaMet to not only halt disease progression but restore skeletal integrity.

The findings build on prior compassionate use cases published in peer-reviewed journals with two-year follow-up, reinforcing ZetaMet’s potential to prevent SREs and improve overall survival. The abstract will be published in SABCS 2025 Proceedings and featured in Clinical Cancer Research.

With the trial now complete and comprehensive analyses underway, this presentation at SABCS will represent the most detailed data release to date. A full report of the findings will also be submitted to Health Canada (HC) and the U.S. Food and Drug Administration (FDA) to inform future planning discussions.

Presentation Details:

Abstract Number: 3549
Presentation Number: PS1-13-18
Presentation Title: Single Intratumoral Drug Injection Yields Complete Response in Metastatic Breast Cancer Bone Lesions: Results from Phase 2a Trial
Poster Presentation: Wednesday, December 10, 2025, 12:30-2:00pm CST
"The promising Phase 2a findings for ZetaMet mirror our earlier peer-reviewed results, reinforcing the strength of our clinically validated strategy in treating metastatic breast cancer." said Joe C. Loy, CEO of Zetagen Therapeutics. "We observed that both treated and adjacent non-treated lesions within the same vertebral body achieved complete response, with no signs of tumor activity and no skeletal-related events—all using the same drug concentration validated in our preclinical studies—strongly affirming the scientific foundation of our approach".

About ZetaMet (Zeta-BC-003)
ZetaMet (Zeta-BC-003) is the first-of-its-kind, synthetic, small-molecule, administered intratumorally to minimize off target toxicity, delivered via a proprietary controlled-release carrier intended to resolve metastatic breast cancer bone lesions, inhibit pain while regenerating bone, with the potential to increase survival rates.

The US Food & Drug Administration (FDA) has recognized Zetagen’s discoveries with multiple Breakthrough Designations including ZetaMet.

Zetagen with FDA and Health Canada (HC) approval via the Expanded Access (Compassionate Use) program has treated eight (8) patients with ZetaMet (Zeta-BC-003) with results published multiple peer-reviewed journals.

Peer-reviewed 2-year follow up clinical data published in 2023 on ZetaMet (Zeta-BC-003) demonstrated resolution of seven (7) lytic lesions (radiated and non-radiated), reduction in pain, significant attrition of opioid pain medication (4-fold), prevention of vertebral fracture, and increased survival rate in a patient living with Stage 4 breast cancer.[i] To view this publication via open access, go to: View Source

(Press release, Zetagen Therapeutics, NOV 4, 2025, View Source [SID1234659381])