Boan Biotech today announced that the preliminary results of the ongoing Phase I clinical study for its BA1301, an investigational antibody-drug conjugate (ADC), were recently presented at the 2025 Congress of the European Society for Medical Oncology (ESMO 2025). Targeting CLDN18.2, this investigational ADC is intended for the treatment of advanced solid tumors, including those found in advanced gastric cancer, gastroesophageal junction (GEJ) adenocarcinoma, and pancreatic cancer.
CLDN18.2 is a transmembrane protein involved in regulating the tight junctions between epithelial cells. It is highly expressed in gastrointestinal (GI) tumors in a consistent and stable manner. Studies have shown that CLDN18.2 is found in approximately 70% of gastric cancer patients, 50% of pancreatic cancer patients, and 30% of esophageal cancer patients, making it a new target of therapeutic value in GI malignancies.
BA1301, developed by Boan Biotech, utilizes C-Lock site-specific conjugation to link the tubulin inhibitor payload, Duostatin-5, with a CLDN18.2-targeting monoclonal antibody. This enables the precise delivery of the cytotoxic payload to tumors, maximizing the anti-tumor activity while reducing the off-target toxicity and widening the therapeutic window. In addition, the bystander effect of the ADC further enhances its efficacy against heterogeneous tumors in gastric cancer and other GI malignancies.
The study presented at ESMO 2025 is a first-in-human, multicenter, open-label, dose-escalation and dose-expansion Phase I clinical trial. It’s designed to evaluate the safety, tolerability, pharmacokinetics, and preliminary efficacy of the BA1301 monotherapy in patients with advanced solid tumors. At the data cutoff, 59 patients had received at least one dose of BA1301. Key findings are as follows:
●Therapeutic potential across GI tumors: In patients with advanced gastric cancer with moderate-to-high CLDN18.2 expression, the 2.0 mg/kg dose cohort achieved an objective response rate (ORR) of 30.8% and a median progression-free survival (mPFS) of 6.1 months. Encouraging efficacy was also observed in other cancer types, including pancreatic cancer and advanced cholangiocarcinoma.
●Favorable safety and tolerability: The overall incidence and severity of hematologic and gastrointestinal adverse events were generally low. Among drug-related Grade ≥3 adverse events (AEs), the incidence of anemia and a decreasing neutrophil count was both 1.7%, while the incidence was 1.7% for vomiting and 0% for nausea, showing a clear superiority over other investigational CLDN18.2-targeting ADCs. The incidence of serious adverse events (SAEs) was only 8.5%, and no treatment-related deaths occurred.
●Better Stability of the ADC molecule: Based on its pharmacokinetic profile, at a dose of 2 mg/kg, the area under the curve (AUC) of Duostatin-5 was approximately 0.002% of that of the total antibody of the BA1301, an indication of low payload dissociation in plasma, which highlighted the advantage of the C-Lock site-specific conjugation approach.
BA1301 is currently undergoing dose expansion as a monotherapy in the Phase I study in China. It has been granted orphan drug designation in the U.S. for gastric cancer (including gastroesophageal junction adenocarcinoma) and pancreatic cancer.
Dr. Changlin Dou, President of R&D and Chief Operating Officer at Boan Biotech, said:“There are still substantial unmet medical needs for advanced gastrointestinal tumors, such as gastric and pancreatic cancers. Precision therapy targeting CLDN18.2 provides a novel approach for treating them. Employing site-specific conjugation, BA1301 has demonstrated a low payload dissociation, a high homogeneity, an encouraging preliminary efficacy, and a favorable safety profile in our ongoing Phase I study. Beyond monotherapy, we will evaluate the combination of BA1301 with Boan’s PD-1 inhibitor BA1104 (nivolumab biosimilar) and expand its development into additional tumor types, aiming to maximize clinical benefit for patients.”
BA1301 is Boan Biotech’s first in-house developed ADC candidate. Supported by three proprietary drug discovery platforms—the ADC Technology Platform, the Human Antibody Transgenic Mouse and Phage Display Platform, and the Bispecific T-cell Engager Technology Platform—the company has established a robust pipeline of innovative biologics. In addition to BA1301, key candidates also include BA1302 (CD228-targeting ADC), BA1304 (EGFR/B7-H3 dual-targeting ADC), PR201 (PD-1/IL-2 antibody-cytokine fusion protein), PR203 (TL-1A/IL-23 bispecific antibody), and BA1106 (non-IL-2-blocking anti-CD25 antibody), forming a comprehensive portfolio of investigational therapies.
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