ROTTERDAM, The Netherlands – October 20th, 2025
Sairopa, a clinical-stage biotechnology company developing innovative cancer immunotherapies, presented new clinical data on ADU-1604, its differentiated CTLA-4 blocking antibody, at the European Society for Medical Oncology (ESMO) Congress 2025, taking place October 17-21, 2025 in Berlin, Germany.
The company presented a scientific poster showcasing significant clinical advances with ADU-1604 in melanoma patients who had previously failed PD-1 inhibitor therapy (n=27). The poster presentation featured the full results from the SRP-21C101 Phase 1 combined dose escalation and dose expansion clinical trial. Clinical efficacy was observed in 4/27 patients indicative of efficacy similar to other CTLA-4 inhibitors. Importantly, ADU-1604 showed a significantly milder safety profile as compared to existing CTLA-4 inhibitors, as evidenced by the reduced severity of immune-related adverse events.
“We are excited to share the clinical results from ADU-1604 in PD1 relapse/refractory melanoma with the international oncology community at ESMO Congress,” said Laura Lassouw-Polman, Chief Operating Officer at Sairopa. “ADU-1604’s milder safety profile as compared to other CTLA-4 blocking agents will support its future use as combination agent, with PD-1 blocking agents and/or other agents. We are grateful to all patients, their families and investigators that supported our study.”
About ESMO Congress 2025
ESMO Congress is Europe’s leading oncology conference, bringing together over 25,000 oncology professionals from around the world to share the latest advances in cancer research and treatment. The 2025 congress features cutting-edge research presentations, educational sessions, and networking opportunities focused on improving cancer care globally.
About Sairopa
Sairopa is a biotechnology company dedicated to advancing novel treatments for cancer by modulating the patient’s immune system. ADU-1604 (anti-CTLA4 antibody) is evaluated in Phase 1 clinical trials in melanoma patients that failed PD-1 checkpoint therapy. ADU-1805 (anti-SIRP antibody) is evaluated in Phase 1 clinical trials in patients with solid advanced tumors, ADU-1805 is tested as monotherapy as well as in combination with PD-1 checkpoint therapies. Preclinically, Sairopa is developing a proprietary bispecific antibody that simultaneously targets two checkpoints. For more information, please visit Sairopa’s website or contact: Sairopa B.V. CIC Stationsplein 45 Unit A4.004 3013 AK Rotterdam The Netherlands info@sairopa.com
About Sairopα:
Based in Rotterdam, The Netherlands, Sairopα aims to revolutionize cancer treatment through groundbreaking immunotherapy research. Backed by Van Herk Investments, Sairopα’s innovative therapeutic pipeline aims to transform cancer treatment and improve outcomes for patients globally. Sairopα is developing proprietary ADU-1604 (anti-CTLA4) and ADU-1805 (anti-SIRPalpha) antibodies in Phase 1 clinical development as well as a yet undisclosed bispecific antibody in preclinical development.
For more information about Sairopa, please visit www.sairopa.com.
Contact Information:
For more information, please visit Sairopα’s website or contact:
Sairopα B.V. CIC Stationsplein 45 Unit A4.004 3013 AK Rotterdam The Netherlands info@sairopa.com