8-K: Abpro & Celltrion Unveil Promising HER2CD3 Data

Abpro and Celltrion announced new preclinical data for their HER2CD3 T-cell engager, CT-P72/ABP-102, showing potent anti-tumor activity and a favorable safety profile, advancing it towards clinical trials.

Summary

• Abpro Corporation and Celltrion, Inc. will present new preclinical data for CT-P72/ABP-102, a tetravalent bispecific antibody targeting HER2 and CD3, at the SITC 2025 Annual Meeting from November 6-10, 2025.
• The CT-P72/ABP-102 poster was selected as one of the Top 150 abstracts out of over 1,300 submissions at SITC 2025.
• Key findings include selective tumor binding to HER2-high cells with reduced binding to normal tissues, and reduced CD3 binding affinity for enhanced safety.
• The molecule demonstrated potent and selective anti-tumor activity in vitro, including robust T-cell activation and PBMC-mediated cytotoxicity.
• Strong preclinical activity was observed in vivo, inhibiting growth in HER2-high BT-474 tumors and showing efficacy in Enhertu-resistant gastric cancer models (NCI-N87/hABCG2) and KPL4 xenograft models.
• A GLP repeated-dose toxicity study in cynomolgus monkeys showed good tolerability at all tested doses, up to 90 mg/kg, supporting a favorable safety profile.
• The data supports advancement toward clinical development, with plans to initiate first-in-human trials next year.

Sentiment

Score: 9

Explanation: The preclinical data for CT-P72/ABP-102 is exceptionally strong, demonstrating potent anti-tumor activity in challenging Enhertu-resistant models and a favorable safety profile. The recognition as a Top 150 abstract at SITC 2025 further validates its potential, indicating significant progress towards clinical development and a highly positive outlook for the program.

Positives

• CT-P72/ABP-102 poster selected as one of the Top 150 abstracts out of more than 1,300 submissions at SITC 2025, indicating high scientific merit.
• Demonstrates potent and selective anti-tumor activity in HER2-high models, including those resistant to Enhertu, addressing a significant unmet medical need.
• Dual-affinity engineering reduces on-target, off-tumor activity, supporting a favorable preclinical safety profile in non-human primates at doses up to 90 mg/kg.
• The preclinical data reinforces confidence in the program's clinical potential and supports advancement toward first-in-human studies.
• Leverages Abpro's proprietary DiversImmune platform, designed for improved selectivity and safety in next-generation antibody therapies.

Risks

• The timing and advancement of development programs, including the timing and availability of additional data, may differ from expectations.
• Abpro's ability to continue as a going concern is a risk.
• Abpro's ability to achieve compliance with Nasdaq listing standards.
• Expectations regarding the therapeutic benefit of Abpro's programs may not be realized.
• Final data from preclinical studies and completed clinical trials may differ materially from reported interim data from ongoing studies and trials.
• Abpro's ability to efficiently discover and develop product candidates.
• Abpro's ability to obtain and maintain regulatory approval of product candidates.
• Abpro's ability to maintain its intellectual property.
• The implementation of Abpro's business model, including strategic plans for its business and product candidates, may face challenges.

Future Outlook

Abpro and Celltrion plan to build upon this strong preclinical foundation to assemble a robust Investigational New Drug (IND) submission package and initiate the first-in-human trial for CT-P72/ABP-102 next year. The molecule is being advanced for HER2-positive breast, gastric, colorectal, and other solid tumors, including those resistant to existing antibody-drug conjugates.

Management Comments

• Miles Suk, CEO & Chairman of Abpro: "We are highly encouraged by the preclinical data emerging from our collaboration with Celltrion. CT-P72/ABP-102 has shown highly selective binding and compelling anti-tumor activity across HER2-high models, including Enhertu-resistant settings, while maintaining a favorable safety profile in non-human primates. We look forward to working with Celltrion to build upon this strong foundation to assemble a robust IND submission package and initiate the first-in-human trial for CT-P72/ABP-102 next year."
• Soo Young Lee, Senior Vice President and Head of New Drug Division at Celltrion, Inc.: "CT-P72/ABP-102 represents a significant advance in the field of bispecific antibodies for targeting solid tumors. By combining dual-affinity engineering with tetravalent design, we've achieved a molecule that maintains potent anti-tumor activity in HER2-high models, including those resistant to current therapies, while minimizing off-tumor effects. These preclinical results validate our approach and underscore the potential for CT-P72/ABP-102 to set a new standard for safety and selectivity in HER2-targeted immunotherapy."
• Miles Suk, CEO & Chairman of Abpro: "We deeply value our partnership with Celltrion, a global leader in biologics and a trusted collaborator in advancing antibody-based therapeutics. Together, we are working to develop safer, more precise treatments for patients with HER2-driven cancers worldwide."

Industry Context

This announcement highlights progress in the development of next-generation bispecific antibodies, a growing area in oncology. CT-P72/ABP-102's ability to demonstrate efficacy in Enhertu-resistant models positions it as a potential solution for patients who have exhausted current HER2-targeted therapies, addressing a critical challenge in the treatment of HER2-positive cancers. The focus on dual-affinity engineering to minimize off-tumor effects aligns with broader industry efforts to improve the safety profile of T-cell engager therapies.

Comparison to Industry Standards

• CT-P72/ABP-102's efficacy in Enhertu-resistant gastric cancer models (NCI-N87/hABCG2) suggests a potential advantage over existing antibody-drug conjugates like Enhertu (trastuzumab deruxtecan), which is a standard of care for HER2-positive cancers.
• The dual-affinity engineering approach aims to reduce on-target, off-tumor activity and cytokine-related toxicity, which are common challenges for T-cell engagers in the industry, potentially offering a safer profile compared to some current bispecific antibody platforms.
• The selection of the abstract as one of the Top 150 at SITC 2025, a major immunotherapy conference, indicates recognition of its scientific novelty and potential impact within the oncology research community.

Stakeholder Impact

• Shareholders: Positive impact due to significant progress in a key pipeline asset, potentially increasing company valuation and future revenue prospects.
• Patients: Potential for new, safer, and more effective treatment options for HER2-driven cancers, especially for those resistant to current therapies.
• Employees: Continued progress in drug development can foster a positive work environment and potential for growth.
• Regulatory Bodies: The advancement of a promising new therapy will be of interest to regulatory authorities as it moves towards clinical trials.

Next Steps

• Assemble a robust Investigational New Drug (IND) submission package for CT-P72/ABP-102.
• Initiate the first-in-human trial for CT-P72/ABP-102 next year (2026).
• Continue development for HER2-positive breast, gastric, colorectal, and other solid tumors.

Key Dates

Recommendation

The strong preclinical data for CT-P72/ABP-102, including its efficacy in Enhertu-resistant models and a favorable safety profile, significantly de-risks the program and supports its advancement to clinical trials. Being selected as a Top 150 abstract at SITC 2025 further validates its potential, making it a compelling investment opportunity for long-term growth in the oncology space, particularly given the unmet need for therapies in resistant HER2-positive cancers.

Keywords

Abpro, Celltrion, CT-P72/ABP-102, HER2, CD3, T-cell engager, bispecific antibody, immunotherapy, cancer, preclinical data, SITC, oncology, Enhertu-resistant