Exelixis and STORM Therapeutics Enter into Exclusive Collaboration and License Agreement to Discover and Develop Inhibitors of Novel RNA Modifying Enzymes

ALAMEDA, Calif. & CAMBRIDGE, UK – October 14, 2021 – Exelixis, Inc. (Nasdaq: EXEL) and STORM Therapeutics (STORM) today announced that they have entered into an exclusive collaboration and license agreement under which the parties will discover and advance novel drug leads intended for the treatment of cancer. The collaboration will focus initially on ADAR1, advancing early work by STORM applying its proprietary RNA epigenetic platform, as well as explore an additional undisclosed target.

Under the terms of the agreement, Exelixis will pay STORM an upfront fee of $17 million in exchange for licensing two of STORM’s discovery programs targeting RNA modifying enzymes, including ADAR1, as well as provide funding for discovery research activities conducted or managed by STORM. Exelixis will be solely responsible for global development, manufacturing and commercialization activities of any resulting molecules. STORM will be eligible for development, regulatory and commercialization milestones, as well as tiered royalties on the annual net sales of any compounds that are successfully commercialized under the collaboration.

“ADAR1 holds tremendous promise as a novel target for cancer. However, discovery efforts to identify ADAR1 inhibitors have remained a challenge, notably the development of rigorous, relevant assays to support small molecule drug discovery,” said Peter Lamb, Ph.D., Executive Vice President, Scientific Strategy and Chief Scientific Officer, Exelixis. “STORM has extensive expertise in RNA-modifying enzymes and has successfully developed advanced mass spectrometry-based high-throughput screening assays and implemented a suite of technologies to enable the discovery of ADAR1 inhibitors. We believe this collaboration has the potential to expand our portfolio of differentiated small molecule therapies in the field of oncology and deliver a first-in-class ADAR1 inhibitor.”

“STORM has established industry-leading expertise and know-how through ground-breaking research on the discovery of small molecule therapies targeting RNA-modifying enzymes. This collaboration with Exelixis validates the significant value of our technology platform and expanding pipeline,” said Keith Blundy, Director and Chief Executive Officer, STORM Therapeutics. “Exelixis has a proven history of success in the discovery, development and commercialization of innovative small molecule cancer therapies to provide patients with clinically meaningful treatment options. Access to Exelixis’ development expertise and funding will enable more rapid advancement of our ADAR1 discovery program, as well as other target activities under the collaboration.”

ADAR1 edits double-stranded RNA (dsRNA) molecules, reducing their ability to activate innate immunity. Depletion or inhibition of ADAR1 can activate the innate immune response in tumor cells, which can trigger tumor cell death. Notably, up to 30% of tumor cells in The Cancer Genome Atlas have high interferon-stimulated gene signatures and may be dependent on ADAR1, suggesting that ADAR1-targeted therapies could have potential in a wide variety of solid tumors as a single agent therapy. In addition, ADAR1 inhibition may also sensitize tumors to immune checkpoint inhibition and overcome mechanisms of resistance to this class of therapies.