NewLink Genetics and Genentech of S. San Francisco entered a collaboration in October worth in excess of $1 billion to develop NewLink's immune checkpoint inhibitor. Genentech is paying the Austin, Texas–based biotech $150 million upfront for an exclusive license to develop NLG919, an indoleamine 2,3-dioxygenase (IDO) pathway inhibitor, currently in phase 1 in solid tumors. IDO is one of several immune response checkpoints that may be involved in tumor immune escape. Increased IDO expression by antigen-presenting cells leads to tryptophan depletion, resulting in antigen-specific T-cell anergy and recruitment of T regulatory cells. NewLink's IDO blockers are small molecules that can be used alone or in combination with other cancer therapies. NewLink is also actively enrolling patients for phase 2 trials with indoximod, another IDO pathway inhibitor, in combination with Taxotere (docetaxel) in metastatic breast cancer and prostate cancer.