Astellas Pharma already has a presence in the antibody drug conjugate (ADC) market, a cancer therapy that has grown rapidly in recent years. The Japanese pharma giant partnered with US biotech company Seagen to develop Padcev, which is already approved to treat bladder cancer. Astellas hopes to take ADC’s targeted approach further and partner with another US company. The new alliance with Sutro Biopharma focuses on developing ADCs with additional anti-cancer effects using the biotech’s technology.
The agreement calls for Astellas to pay its new partner $90 million up front. The companies aim to develop ADCs to address three undisclosed biological targets.
ADCs are a type of therapy made by linking targeted antibodies to a payload of anticancer drugs. The targeting ability of the antibody is designed to deliver precise hits to tumors, thereby protecting healthy tissue. South San Francisco-based Sutro has the technology to add a second drug to the ADC molecule. This additional drug stimulates the immune system, triggering an immune response to targeted tumor cells. Sutro calls these drugs immunostimulatory ADCs, or iADCs.
“Our novel iADC is designed to deliver two different drugs directly to tumors that not only kill tumor cells but also locally elicit an immune response against patient-specific tumor cells,” the company said in its statement. 2021 Annual Report“We believe that our iADC approach creates new therapeutic opportunities by combining the best characterization of ADCs with the biology of personalized vaccines.”
There is more to the iADC method. One of the challenges of all cancer immunotherapy is that tumors have immunosuppressive characteristics that make them “cold,” meaning that tumors do not elicit a strong immune response. The partners say that Sutro’s iADC technology has the potential to convert cold tumors into hot tumors. In a prepared statement, Sutro CEO William Newell said the iADC study could lead to new treatment options for patients whose cancers do not respond to currently available immunotherapies.
Under the terms of the deal announced late Monday, Sutro could earn up to $422.5 million in milestone payments for each product candidate developed under the partnership. Additionally, if any of these iADCs hit the market, Sutro would receive royalties from the sale. The agreement is likely to be executed in a similar manner to the deal covering the development of Padcev, which was co-commercialized by Astellas and Seagen in the United States. Sutro has the option to share U.S. development costs with Astellas If the biotech exercises that option, U.S. development costs and profits (or losses) from commercializing the therapy will be split equally. The agreement does not prevent Sutro from developing additional iADCs for targets other than Astellas’ partners.
Astellas is the latest pharmaceutical partner to sign with Sutro. ADCs for multiple myeloma have entered early clinical development in collaboration with Bristol Myers Squibb. The alliance with EMD Serono focuses on bispecific ADCs for non-small cell lung cancer and esophageal cancer. Sutro’s state-of-the-art in-house program, STRO-002, has reached early-stage clinical trials in ovarian cancer in other types of solid tumors.
The area of ADC drug research facilitates deals and drug approvals.So far, the ADC drug class has about a dozen FDA-approved therapies from companies, including SiegenRoche, ADC therapyand Gilead Sciences. Drugmakers are also looking for opportunities to expand the use of approved products to more patients. For example, at the annual meeting of the American Society of Clinical Oncology earlier this month, AstraZeneca presents data showing how its approved drug Enhertu was able to reach a group of breast cancer patients previously thought ineligible for this type of targeted therapyOne of the problems with ADCs is that some of the drug payload is released before the drug reaches its destination, leading to off-target effects. ADC startups such as Mythic Therapeutics is developing technology designed to ensure more toxic drugs reach tumors rather than healthy cells.
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