ALG.APV-527 is a bispecific agonistic antibody for tumor-directed immunotherapy co-developed with Aptevo Therapeutics

ALG.APV-527 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 is a bispecific antibody, where one part generates tumor-specific T cell responses via the costimulatory receptor 4-1BB (CD137), and the other binds to the 5T4 protein expressed on the surface of tumor cells. The 5T4 part guides the drug candidate to the tumor, where 4-1BB binding triggers a tumor control process.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.