Orencia by the numbers Repligen scored an exclusive license to develop CTLA4, an immune system regulator, in the 1990s from the University of Michigan. Early work with the university and the U.S. Navy had shown promise for using a fusion protein containing the compound to treat autoimmune diseases. The company was awarded U.S. patent No. 6,685,941, although its work never entered into the clinic. Luckily, that single patent would not go completely to waste.