Sutro Biopharma (STRO) and Astellas Enter Global Collaboration to Advance Novel Immunostimulating Antibody-Drug Conjugates (iADCs)


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Astellas Pharma Inc. and Sutro Biopharma, Inc. (NASDAQ: STRO) today announced a global strategic licensing and collaboration agreement focused on the discovery and development of novel immunostimulatory antibody-drug conjugates (iADCs). The collaboration leverages the unique cancer-fighting potential of iADCs as a novel modality, made possible by Sutro’s ability to design complex antibody conjugates and Astellas’ global oncology R&D expertise.

“We are excited to work with Astellas, a leading biopharmaceutical company with considerable expertise in immuno-oncology, on this new modality,” said William J. Newell, Chief Executive Officer of Sutro. “iADCs show promise far beyond the current success of ADCs. Sutro’s unique conjugation technology allows for dual conjugations that specifically incorporate a potent cytotoxin that can directly kill tumor cells with an immunostimulatory component that has the potential to locally initiate an immune response to the patient’s particular tumor cells. We look forward to collaboratively exploring the potential of this approach to treat cold tumors and bring new drug therapies to patients who do not respond to existing immunotherapies.

Naoki Okamura, Chief Strategy Officer at Astellas, said, “Astellas views immuno-oncology as a key focus of its R&D strategy; our goal is to bring effective drugs to patients who do not respond to existing immune checkpoint inhibitors. Sutro is a leading company in the field of iADCs, a new modality, and has its own original iADC technologies. The strategic partnership with Sutro will help us expand our pipeline and broaden the choice of cancer immunotherapies.

A major challenge of cancer immunotherapies, including immune checkpoint inhibitors, is the tumor microenvironment*1 in cold tumors, creating barriers to immune cell infiltration and thus preventing healing. Immune checkpoint inhibitors approved to date are only effective as monotherapy in approximately 20% of cancer types, which vary widely*1.

This strategic partnership will engage in the development of iADCs, a next-generation modality with the potential for effective and efficient approaches for the treatment of cold tumors to bring new drug therapies to patients who are unresponsive to existing therapies. An iADC, which combines an antibody with a small molecule compound that induces immunogenic cell death*2 in addition to an immune activating molecule, has the potential to enhance anti-cancer action.

This partnership will allow Astellas and Sutro to leverage each other’s strengths in their respective fields to accelerate iADC development for three distinct biological targets; Sutro will engage in research and preclinical studies to identify candidate compounds, and then Astellas will pursue clinical development. Sutro has advanced technologies to bind drugs to antibodies and proprietary compounds, including candidate antibodies and bindable cytotoxins and immunostimulatory molecules. For the development of iADCs, Astellas will leverage its global R&D and commercialization capabilities in the area of ​​antibodies and small molecular compounds. These iADCs may have the potential to provide new therapeutic options for the treatment of cancers for which no widely effective therapy is currently available.

Under the terms of the agreement, Sutro will receive an upfront cash payment of US$90 million to develop iADCs for three biological targets and may be eligible to receive up to US$422.5 million in development milestones, regulatory and commercial for each product candidate, and at several levels. royalties ranging from low to mid-double digits on worldwide sales of any commercial product that may result from the collaboration, subject to Sutro’s US cost and benefit sharing option.

Sutro has the ability to share the costs and benefits of developing and commercializing product candidates in the United States. If Sutro exercises this option for a particular product candidate, Astellas and Sutro will equally share the costs of such co-development and co-commercialization, with profits/losses resulting from the co-commercialization also being shared equally to the States. -United.

*1: Cancer surrounds itself with an environment favorable to its own survival, ie to protect itself from the immune system and facilitate its own growth and metastasis. Such an environment is referred to as the “tumor microenvironment”.*2: Immunogenic cell death is the death of cancer cells through the “cancer immune cycle” by which cancer antigens released by chemotherapy are taken up by dendritic cells , then presented to activated T cells to kill the cancer cells. Regarding the “cancer immune cycle”, please refer to the Astellas R&D meeting papers (held in December 2020).(


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