Biostar Pharma Initiates Pivotal U.S. Trial for Utidelone in HER2-Negative Breast Cancer Brain Metastases
Key Insights
Biostar Pharma (search) has dosed the first patient in a pivotal U.S. clinical trial testing utidelone injection combined with capecitabine for HER2-negative breast cancer (search) brain metastases.
The two-stage study will enroll approximately 120 subjects across nearly 20 top-tier U.S. cancer centers with CNS objective response rate as the primary endpoint.
Previous Phase II studies demonstrated promising efficacy with CNS response rates of 67.6% and 42.6% in different combination regimens.
Biostar Pharma (search) has achieved a significant milestone in addressing one of oncology's most challenging treatment areas by dosing the first patient in its pivotal U.S. clinical trial of utidelone injection (UTD1) combined with capecitabine for HER2-negative breast cancer (search) brain metastases (BCBM). The study, designated NCT06764940, represents a critical step toward potentially providing the first approved therapy for this devastating condition.
Trial Design and Scope
The pivotal study employs a two-stage design and plans to enroll approximately 120 subjects across nearly 20 top-tier clinical institutes throughout the United States. Participating centers include MD Anderson Cancer Center, Johns Hopkins Sidney Kimmel Comprehensive Cancer Center (search), City of Hope-Duarte, Robert H. Lurie Comprehensive Cancer Center at Northwestern University, University of Colorado Hospital, Augusta University, and University of California Los Angeles.
The trial's primary endpoint is central nervous system objective response rate (CNS-ORR), a critical measure for evaluating treatment effectiveness in brain metastases. This endpoint selection reflects the unique challenges of treating intracranial disease, where conventional systemic response measures may not adequately capture therapeutic benefit.
Unique Mechanism and Blood-Brain Barrier Penetration
Utidelone's therapeutic potential stems from its distinctive physicochemical properties and insensitivity to P-glycoprotein (search)-mediated efflux, which enable it to cross the blood-brain barrier and prevent or treat brain metastases of solid tumors. This capability sets utidelone apart from taxanes, which are also microtubule (search) stabilizers but lack effective brain penetration.
The drug's ability to overcome the blood-brain barrier represents a crucial advantage in treating BCBM, where the barrier has historically prevented many effective systemic therapies from reaching therapeutic concentrations in the central nervous system.
Promising Phase II Results
Two Phase II clinical studies have demonstrated utidelone's therapeutic potential in HER2-negative BCBM. The first study, combining utidelone with bevacizumab and chemotherapy and enrolling 34 subjects, was presented orally at the 2025 ASCO Annual Meeting. Results showed a CNS-ORR of 67.6%, a central nervous system clinical benefit rate (CNS-CBR) of 88.2%, and a median central nervous system progression-free survival (CNS-PFS) of 15 months.
A second Phase II study, published in JAMA Oncology in 2025, evaluated utidelone combined with bevacizumab in 47 subjects with HER2-negative BCBM. This study achieved a CNS-ORR of 42.6%, a median CNS-PFS of 10.6 months, and a median overall survival of 15.1 months.
Importantly, both studies demonstrated favorable safety profiles, with most treatment-related adverse events (TRAEs) being Grade 1-2, controllable, and reversible.
Addressing Critical Unmet Medical Need
The clinical significance of this development becomes clear when considering the current treatment landscape for HER2-negative BCBM. Approximately 20-50% of advanced breast cancer patients develop brain metastases, with HER2-negative BCBM patients facing particularly poor prognoses and median progression-free survival of only 2-6 months.
Currently, no clearly effective drug therapy exists for HER2-negative BCBM, and no drugs worldwide have been approved for this indication, highlighting a significant and urgent unmet medical need. The U.S. FDA has recognized this gap by granting utidelone orphan drug designation for the treatment of breast cancer brain metastases (search).
Regulatory Recognition
The FDA's orphan drug designation for utidelone in breast cancer brain metastases (search) underscores the regulatory recognition of both the unmet medical need and the drug's potential to address this challenging condition. This designation typically provides development incentives and expedited review pathways for drugs targeting rare diseases or conditions affecting fewer than 200,000 patients in the United States.