Duality Biotherapeutics, Inc. (HKG: 9606) announced that the U.S. FDA granted Fast Track Designation (FTD) to DB-1310, its next‑generation HER3‑targeted antibody‑drug conjugate (ADC), for treating adult patients with advanced/unresectable or metastatic HR+/HER2‑negative breast cancer after prior endocrine therapy, CDK4/6 inhibitor, and chemotherapy. This marks DB‑1310 as the world’s first HER3‑ADC to receive FTD for this indication.
Regulatory Milestone
Item
Details
Approval Date
18 Dec 2025
Agency
U.S. FDA
Product
DB‑1310 (HER3‑targeted ADC)
Designation
Fast Track Designation (FTD)
Indication
HR+/HER2‑negative (IHC 0, 1+ or 2+/ISH‑) metastatic breast cancer post‑endocrine/CDK4/6i/chemotherapy
Significance
First HER3‑ADC globally to receive FTD for this indication
Previous FTD
Granted for nsqNSCLC with EGFR exon 19 deletion/L858R mutations (May 2025)
Novel target in breast cancer; limited HER3‑directed therapies
Payload
Topoisomerase inhibitor
Potent cytotoxic agent
Innovation
Next‑gen HER3‑ADC with improved selectivity and safety
Addresses unmet need in HR+/HER2‑ breast cancer
Clinical Stage
Phase II/III trials ongoing
FTD accelerates development timeline
Market Opportunity
Metric
Value
Context
HR+/HER2‑ Breast Cancer
~70% of all breast cancers; 30‑40% develop metastasis
Large patient population
Post‑CDK4/6i Market
$3‑5 billion global market for later‑line therapies
High unmet need after progression on endocrine/CDK4/6i
HER3‑ADC Competition
Limited; only DB‑1310 and other early‑stage candidates
First‑mover advantage if approved
Peak Sales Potential
$500‑800 million (global estimate)
Addresses niche but high‑value metastatic segment
FTD Benefit
Expedited FDA review, potential for accelerated approval
Shortens timeline to market
Strategic Implications
For DualityBio:Second FTD validates DB‑1310’s potential across multiple indications; HER3‑ADC first‑mover status strengthens IP and competitive moat; positions for global partnership or licensing.
For Patients:New therapeutic option in heavily pretreated HR+/HER2‑ breast cancer; HER3 targeting may overcome resistance to HER2‑directed and endocrine therapies; ADC mechanism offers potent tumor killing.
For Market:HER3‑ADC class emerges as promising niche; FTD in breast cancer broadens DB‑1310’s oncology footprint; DITAC platform may yield additional ADC candidates for other targets.
Forward‑Looking Statements This brief contains forward‑looking statements regarding DB‑1310’s clinical development, timeline, and market potential. Actual results may differ due to regulatory feedback, clinical risks, or competitive dynamics.-Fineline Info & Tech
By Fineline Cube 