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Precision Biologics to Unveil New ADC at SITC 2025

In a significant development in cancer therapy, Precision Biologics, Inc. has announced that it will reveal in vitro and in vivo efficacy data for its innovative tumor-specific antibody-drug conjugate (ADC), PB-vcMMAE-5, at the Society for Immunotherapy of Cancer (SITC) Annual Meeting 2025, held in National Harbor, MD. This groundbreaking ADC specifically targets human carcinomas that express truncated core 2 O-glycans, a modification often associated with cancer progression and poor prognosis.

Groundbreaking Data Presentation

The poster titled "In vitro and in vivo efficacy of the antibody-drug conjugate (ADC) PB-vcMMAE-5 against human carcinoma expressing truncated core 2 O-glycans" will be presented on Friday, November 7, 2025, during the SITC Annual Meeting. This ADC aims to overcome the resistance of solid tumors to immunotherapy, which has been a significant hurdle in clinical oncology.

Understanding PB-vcMMAE-5

PB-vcMMAE-5 comprises a monoclonal antibody (PB-223) that targets truncated core 2 O-glycans, specifically found on cancer cells but not on healthy tissues. This targeted approach minimizes damage to normal cells. PB-223 was developed following the affinity maturation of the clinical-stage antibody NEO-102 (Ensituximab), ensuring its binding specificity to cancerous tissues. The payload used in this ADC is Monomethyl auristatin E (MMAE), renowned for its potent antimitotic properties, which inhibit cell division by blocking tubulin polymerization.

The efficient design of this ADC features a cleavable linker (mc-vc-PABc), allowing for targeted delivery of the cytotoxic agent to tumor cells, enhancing therapeutic efficacy while reducing systemic toxicity. The drug-to-antibody ratio (DAR) of PB-vcMMAE-5 is 3.92, which is optimized for performance.

In Vitro Findings

The data set to be shared at SITC 2025 reveals the in vitro cytotoxicity of PB-vcMMAE-5 across nine human cancer cell lines, including aggressive forms such as triple-negative breast cancer (MDA-MB-231) and prostate cancer (LnCAP). These early results demonstrate that PB-vcMMAE-5 can effectively kill all tested cell lines, marking a promising advance in targeted cancer therapy. Notably, the highest efficacy was observed against MDA-MB-231, LnCAP, OV-90 (ovarian cancer), and NCI-H226 (lung cancer) cell lines, while the naked PB-223 mAb showed no significant cytotoxicity, underscoring the importance of the conjugation in enhancing therapeutic impact.

Promising In Vivo Results

Additionally, the safety profile of PB-vcMMAE-5 was established through studies in NOD-SCID mice bearing OV-90 ovarian cancer xenografts. The data showed that mice treated with PB-vcMMAE-5 did not experience significant weight loss or distress, indicating favorable tolerability. In vivo efficacy studies demonstrated significant tumor growth inhibition in a dose-dependent manner, revealing that the ADC effectively inhibited tumor growth with the most substantial effects seen at higher doses of 6 and 9 mg/kg. By day 45, histological analyses illustrated the absence of viable tumor cells in mice treated with the highest dosage, suggesting that PB-vcMMAE-5 could be a transformative option in treating malignancies expressing core 2 O-glycans.

Conclusion and Future Directions

The promising findings from Precision Biologics point towards a potential breakthrough in cancer treatment, especially for solid tumors that have been recalcitrant to traditional immunotherapy approaches. The data from SITC 2025 will provide vital insights into the clinical application of PB-vcMMAE-5, possibly paving the way for new therapeutic options for patients with advanced cancers. For further information and the full poster, interested parties can visit Precision Biologics' official website.

In conclusion, the developments surrounding PB-vcMMAE-5 showcase the potential this ADC has to revolutionize cancer treatment paradigms and enhance patient outcomes in the ongoing battle against cancer.