The QS-21 Stimulon adjuvant platform is partnered with GlaxoSmithKline and Janssen. Several of those collaborations involve Phase 3 trials. Altogether, the company and its partners are sponsoring approximately 20 clinical trials of Agenus products. Merck: April 2014, Agenus announced a deal worth potentially $100 million with Merck. The deal involves the discovery and development of therapeutic antibodies to two undisclosed Merck checkpoint targets, both thought to be relevant for cancer treatment. Agenus will use its proprietary Retrocyte Display® platform to discover and optimize antibodies against the targets.  4-Antibody: February 2014, Agenus acquired European biotechnology firm 4-Antibody, along with its Retrocyte Display technology and a portfolio of checkpoint modulator antibody candidates . Ludwig Cancer Research: 4-Antibody had been working on the checkpoint targets for several years in collaboration with Ludwig Cancer Research, one of the world's most renowned institutions for research into cancer and the immune system. The leader of the Ludwig collaborative laboratory at Memorial Sloan Kettering Cancer Center, Jedd Wolchok, is recognized as one of immuno-oncology's leading pioneers. GlaxoSmithKline (GSK): March 2012, GSK paid Agenus $9 million to include additional rights to the two firms’ agreement around Agenus’ QS-21 Stimulon® adjuvant. The deal amended license and manufacturing terms. It also included royalty payments to Agenus for an undisclosed indication upon commercialization of a vaccine. Checkpoint Modulators (CPMs) interfere with cancers’ ability to “hijack” natural immune defense systems. To protect the body against disease, but without attacking healthy cells, the immune system uses multiple “checkpoint” systems. Some checkpoints stimulate immune responses while others inhibit them. Cancer cells can evolve means to evade checkpoints, and CPMs can reverse that effect, helping the immune system better fight the cancer. Agenus currently has programs targeting the checkpoint modulators GITR, OX40, CTLA-4, LAG-3, TIM-3 and PD-1. The company is expanding that portfolio by using its proprietary Retrocyte Display® discovery system to generate fully human therapeutic antibody drug candidates. The platform is a high-throughput approach incorporating IgG format human antibody libraries expressed in mammalian B-lineage cells. The Prophage Series of patient-specific cancer vaccine candidates can also enhance the immune system's response to tumors.