– ADU-1805 is a potential best-in-class monoclonal antibody targeting SIRPα to block the SIRPα-CD47 checkpoint –

– Phase 1 study of ADU-1805 as a single agent and in a combination regimen in advanced solid tumors expected to begin second quarter of this year –

ALAMEDA, CA, USA & ROTTERDAM, The Netherlands I February 13, 2023 I Exelixis, Inc. (Nasdaq: EXEL) and Sairopa B.V. (Sairopa) today announced that the U.S. Food and Drug Administration (FDA) has cleared Sairopa’s Investigational New Drug (IND) Application to evaluate the safety and pharmacokinetics of ADU-1805 in adults with advanced solid tumors. As a monoclonal antibody active against all human alleles of SIRPα, ADU-1805 has the potential to address a broader patient population than other SIRPα-directed therapies.

“The clearance of this Investigational New Drug Application for ADU-1805 is an exciting milestone for our expanding biologics pipeline, marking the first of many anticipated advancements we expect this year,” said Vicki L. Goodman, M.D., Executive Vice President, Product Development & Medical Affairs, and Chief Medical Officer, Exelixis. “Based on its best-in-class potential and broad applicability, we look forward to learning more about ADU-1805 from the upcoming phase 1 trial across multiple tumor types, as we continue toward our goal of finding innovative solutions for patients with advanced cancers.”

By blocking SIRPα, a significant immune-suppressive component of the tumor microenvironment, ADU-1805 has the potential to improve the immune system’s ability to attack tumors. ADU-1805 has been optimized to bind preferentially to SIRPα compared with other SIRP family members, which may enhance its ability to stimulate immune cells.

Under the terms of the clinical development and option agreement announced in November 2022, Exelixis has the option to obtain an exclusive, worldwide license to develop and commercialize ADU-1805 and other anti-SIRPα antibodies upon review of data from prespecified phase 1 clinical studies of ADU-1805 to be completed by Sairopa during the option period. This IND clearance triggers a $35 million milestone payment to Sairopa which will be paid in the first quarter of 2023.

“Given the robust preclinical data generated, we are thrilled that ADU-1805 is now able to advance to the clinic,” said Laura Lassouw-Polman, Chief Operating Officer, Sairopa. “This is an important step forward in our partnership with Exelixis to explore the potential of ADU-1805, advancing our mission to develop therapies that modulate immune system activity to improve outcomes for cancer patients.”

About Exelixis

Exelixis is a globally ambitious oncology company innovating next-generation medicines and regimens at the forefront of cancer care. Powered by bi-coastal centers of discovery and development excellence, we are rapidly evolving our product portfolio to target an expanding range of tumor types and indications with our clinically differentiated pipeline of small molecules, antibody drug conjugates and other biotherapeutics. This comprehensive approach harnesses decades of robust investment in our science and partnerships to advance our investigational programs and extend the impact of our flagship commercial product, CABOMETYX® (cabozantinib). Exelixis is driven by a bold scientific pursuit to create transformational treatments that give more patients hope for the future. For information about the company and its mission to help cancer patients recover stronger and live longer, visit www.exelixis.com, follow @ExelixisInc on Twitter, like Exelixis, Inc. on Facebook and follow Exelixis on LinkedIn.

About Sairopa

Sairopa B.V. is a clinical-stage company that develops novel treatments for cancer by modulating the patient’s immune system. In April 2021 Sairopa acquired, backed by Van Herk Investments, a portfolio of therapeutic antibodies from Chinook Therapeutics, Inc. These antibodies were originally developed by BioNovion/Aduro Biotech Europe using the proprietary B-Select antibody platform that was also used to identify pembrolizumab (Keytruda™), BION-1301 and MK-5890 (Guelen et al., 2022). For more information about Sairopa, please visit www.sairopa.com.

SOURCE: Exelixis