APN411 is a checkpoint blockade approach based on low molecular weight compounds to enhance the immune system against cancer. Together with Evotec, a primary HTS assay with 80.000 compounds was conducted with human PBMCs (peripheral blood mononuclear cells) to identify compounds that enhance cytokine production specifically of activated primary human T cells but not of resting cells. Three hit series have progressed into medicinal chemistry, all of which have shown excellent activities on key functions for anti-tumor immune responses of primary human T and NK cells and confirmed in vitro activity on murine immune cells.

As of August 2015, selected hit series have been included in a strategic collaboration with Evotec AG and Sanofi with the aim to jointly develop novel small molecule-based cancer immunotherapies. Based on a pre-negotiated license agreement, Sanofi may now fully overtake the program to advance it to the clinical stage.