ALG.APV-527 is a bispecific agonistic antibody for tumor-directed immunotherapy co-developed with Aptevo Therapeutics. It was generated by proprietary binding elements obtained from Alligator’s ALLIGATOR-GOLD® antibody library, which were produced as a bispecific compound using Aptevo’s bispecific technology platform. ALG.APV-527 is based on Alligator’s first generation bispecific antibody, ATOR-1016.

ALG.APV-527 targets 4-1BB (CD137), a member of the TNFR superfamily of co-stimulatory receptors found on activated T cells, and the tumor antigen 5T4. The co-stimulatory receptor 4-1BB is known to play an important role in modulating and augmenting the immune response to cancer by promoting the activation, expansion and enhanced effector function of tumor-specific T cells. It is, therefore, an especially promising target for new immunotherapeutic approaches for cancer treatment.

5T4 is a protein predominantly expressed on tumor cells. It is present at very low levels or not at all in normal tissue. This enables the immune-activating effect of ALG.APV-527 to be targeted specifically to the tumor and not against normal tissue, the goal being effective tumor-directed immune activation with minimal side effects. The 5T4 tumor antigen is present on a number of different solid tumors, including breast, cervical, non-small-cell-lung, prostate, renal, gastric, colorectal and bladder cancers, indicating that ALG.APV-527 may be used for the treatment of several different types of cancer.

By combining a tumor-binding and an immunomodulatory antibody in one molecule, Alligator and Aptevo have created a drug candidate whose effect is localized to the tumor area, activating the tumor-specific immune cells present there.

ALG.APV-527 is currently in the preclinical development phase and initial production activities for clinical trial materials have commenced.