Affinity Biopharma, a clinical-stage, oncology-focused biopharma and platform company focused on Tumor MicroEnvironment Activated (TMEA) therapeutics and local drug activation, announced the abstracts publication and presentation in the Poster Session at the upcoming 2025 American Association for Cancer Research (AACR) Annual Meeting during April 25-30 in Chicago, Illinois. These abstracts cover the preclinical data of our novel tumor microenvironment-activated (TMEA) anti-CTLA-4 antibody and our dual-payload TMEA-ADC platform.

The following are the details for the abstracts and poster presentations:

Presentation Title: Dual-payload TME-activated ADC platform

Session Category: Experimental and Molecular Therapeutics
Session Title: Novel Drug Delivery Technologies
Time: 4/28/2025 9:00:00 AM - 12:00:00 PM
Location: Poster Section 23, Board #24

Key Findings: For dual-payload TMEA-ADCs, each hydrophilic TMEA linker is paired with two insoluble payloads. Compared to GGFG linkers cleaved by lysosomal enzymes such as cathepsins B and K, the TMEA linkers exhibited superior stability in human plasma, higher cleavage efficiency in tumor homogenates, and strong safety profile in primate models. In various PBMCs-CDX models, dual-payload TMEA-ADCs such as IMD526 (HER2-Toxin-ISAC Dual Payload ADC) and IMD2113 (EGFR&TROP2- Dual Payload ADC) have displayed significant dose-dependent antitumor activities and superior efficacy over two single-payload-ADCs with no observable toxicities. In tumor re-challenge studies, mice that were cured by IMD526 exhibited immune memory and were resistant to tumor re-inoculation.

Presentation Title: A novel chemical conjugated anti-CTLA-4 antibody with tumor microenvironment activation

Session Category: Clinical Research
Session Title: Therapeutic Antibodies, Including Engineered Antibodies 2
Time: 4/29/2025 2:00:00 PM - 5:00:00 PM
Location: Poster Section 35, Board #19

Key Findings: IMD-303 (CTLA-4 TMEAbody) demonstrated strong anti-tumor activities as single agent in MC38 murine colon cancer models and anti-PD-1 primary resistant EMT-6 models, and it displayed significant synergistic effects when combined with IMD101 (a TMEA-Cytokine releasing IL-2), in which IMD-303 can reduce the number of Treg cells in tumors that were slightly up-regulated by IMD101. Preclinical GLP toxicology studies showed that the MTD (maximum tolerated dose) was > 360 mg/kg for single-dose in SD rats, and the NOAEL (no-observed-adverse-effect level) was > 200mg/kg for 2-month repeat-dose in primate, which was over 8.7 times human equivalent dose of clinically effective dose.