17 November 2020 - - Swedish biotechnology company Alligator Bioscience (NASDAQ Stockholm: ATORX) and US-based biotechnology company Aptevo Therapeutics Inc. (NASDAQ: APVO) have provided an update on ALG.APV-527, a novel immunotherapeutic bispecific candidate intended for the treatment of multiple solid tumors expressing 5T4, a tumor-restricted antigen, the companies said.

Aptevo and Alligator are advancing ALG.APV-527 into Phase I clinical development in a co-development 50/50 partnership. The companies anticipate filing a Clinical Trial Authorization during the first half of 2021 to initiate Phase I clinical development in multiple sites in the European Union. 

Aptevo and Alligator will continue to explore licensing opportunities as ALG.APV-527 moves into clinical development.

ALG.APV-527 is designed to simultaneously target 5T4 and the co-stimulatory receptor 4-1BB (CD137) to promote potent, tumor-directed immune T-cell activation.

5T4 is a well-defined tumor antigen expressed on many different types of malignancies including non-small cell lung, renal, pancreatic, prostate, breast, colorectal, gastric, ovarian and cervical cancers and mesothelioma. Conversely, 5T4 has limited expression on adult normal tissues, making it an attractive target for cancer immunotherapy.

As announced on Monday, November 9, Aptevo is presenting two new posters at the Society for Immunotherapy of Cancer's 35th Virtual annual meeting, including one on ALG.APV-527.

The poster will present preclinical data demonstrating that ALG.APV-527 has a potentially favorable safety profile with no indication of systemic immune activation or liver toxicity in NHP or murine models. ALG.APV-527 induces robust in vitro killing of tumors that is dependent on 5T4 engagement. 

In vivo, ALG.APV-527 augmented anti-tumor responses and promoted tumor-specific memory.
ALG.APV-527 is a novel immunotherapeutic bispecific candidate intended for the treatment of multiple solid tumors expressing 5T4, a tumor-restricted antigen.

5T4 is an antigen that is highly expressed in a large percentage of solid tumors, including, non-small cell lung cancer (NSCLC), head and neck cancer and mesothelioma.

ALG.APV-527 is designed to activate anti-tumor responses by inducing signaling through the co-stimulatory receptor 4-1BB (CD137), which is an immune receptor that is upregulated on activated T cells and natural killer cells.

Aptevo Therapeutics Inc. is a clinical-stage biotechnology company focused on developing novel immunotherapies for the treatment of cancer.

The company's lead clinical candidate, APVO436, and preclinical candidates, ALG.APV-527 and APVO603, were developed based on the company's versatile and robust ADAPTIR modular protein technology platform.

The ADAPTIR platform is capable of generating highly differentiated bispecific antibodies with unique mechanisms of action for the treatment of different types of cancer.

Alligator Bioscience AB is a clinical-stage biotechnology company developing tumor-directed immuno-oncology antibody drugs.

Alligator's pipeline includes the two key assets ATOR-1017 and mitazalimab. Furthermore, there are two partnered assets: ALG.APV-527 in co-development with Aptevo Therapeutics Inc. and AC101 in clinical development by Shanghai Henlius Biotech Inc.).

In addition, the company has developed a novel concept for more patient-specific immunotherapy: Neo-X-Prime. Alligator's shares are listed on NASDAQ Stockholm (ATORX). The company is headquartered in Lund, Sweden.