AEGERA THERAPEUTICS

In December 2007, we and Aegera Therapeutics Inc. completed a licensing and collaboration agreement providing us with exclusive worldwide rights (excluding Japan) to develop and commercialize HGS1029 and other small-molecule IAP inhibitors in oncology.

Under the agreement, we made an upfront payment to Aegera of $20 million as a licensing fee and for an equity investment. Aegera will be entitled to receive up to $295 million in future development and commercial milestone payments. Aegera will receive low double-digit royalties on net sales in the HGS territory. In North America, Aegera will have the option to co-promote, under which it will share certain expenses and profits (30%) in lieu of its royalties. Aegera retains the non-oncology rights to its IAP inhibitors that are not selected for development under this agreement.

Two Phase 1 clinical trials of HGS1029 are currently ongoing – one in patients with advanced solid tumors initiated in May 2008 and another in patients with advanced lymphoid tumors initiated in November 2009. We plan to develop our IAP inhibitors in combination with mapatumumab, our antibody to TRAIL receptor 1, and in combination with other therapeutic agents.

TAKEDA

We entered into an option and license agreement with Takeda, pursuant to which Takeda has exercised its option to develop and commercialize HGS-ETR1 in Japan.

KIRIN

In October 2002, we entered into a license agreement with the Pharmaceutical Division of Kirin Brewery Company, Ltd. relating to the development and commercialization of agonistic human antibodies to TRAIL receptor 2. Under the agreement, we will work together to identify and optimize the best candidate for clinical development. Kirin will develop and commercialize any resulting drug in Japan and Asia/Australasia. We will develop and commercialize any resulting drug in North America, Europe and the rest of the world.

DIADEXUS

In 2003, diaDexus announced that the FDA cleared its PLAC™ test for marketing as a diagnostic aid to help predict a person’s risk for coronary heart disease. The PLAC test measures the level of lipoprotein-associated phospholipase A2 (Lp-PLA2) in human blood. The PLAC test was discovered through the use of our technology, and we are entitled to receive royalties on sales of the PLAC test. diaDexus also received from GSK the right to develop products based on a number of diagnostic targets identified by HGS. We are entitled to royalties on the sale of any products developed from these targets. In 2003, we acquired exclusive worldwide rights from diaDexus to develop and commercialize diagnostic immunohistochemical tests based on the TRAIL receptor-1 and TRAIL receptor-2 proteins.

AMGEN

In January 2006, we announced a license agreement under which Amgen has acquired exclusive worldwide rights to develop and commercialize therapeutic biological products for human use, based on a human gene discovered by HGS that has potential applications in autoimmune diseases, immune deficiencies or suppression, and cancer. Amgen also has acquired non-exclusive worldwide rights for the development and commercialization of diagnostic products for human use based on the same gene. According to the terms of the agreement, we received an up-front payment and will receive certain annual fees, as well as development milestone payments and royalties on annual net sales for therapeutic and diagnostic products successfully developed and commercialized using such rights.

GENENTECH

In August 2003, we entered into an agreement with Genentech in which we granted to Genentech exclusive worldwide patent rights to develop and commercialize therapeutic biologic products for human use based on a human gene discovered by HGS that may have potential applications in immunology, oncology and neurology. We also granted non-exclusive, worldwide rights to the development and commercialization of diagnostic and small-molecule products for human use based on the same gene.