Merus Announces First Patient Treated in Phase 1 Clinical Trial for Advanced Solid Tumors

Merus N.V. recently announced the first patient has been treated in its Phase 1 trial evaluating safety, tolerability, and preliminary efficacy of MCLA-145 for the treatment of patients with advanced solid tumors. MCLA-145 is a potential first-in-class PD-L1 x CD137 Biclonics being developed in collaboration with Incyte for the treatment of solid tumors.

“We are very pleased to announce the initiation of our Phase 1 trial for MCLA-145,” said Andres Sirulnik, MD, PhD, Executive Vice President and Chief Medical Officer of Merus. “MCLA-145’s unique triple action is designed to recruit T-cells, activate T-cells and also prevent T-cell exhaustion.  Importantly, MCLA-145 has potential to overcome known systemic side effects of CD137 agonists currently in development through more targeted delivery to the tumor microenvironment, and to address a significant unmet need in patient populations not benefitting from current immunotherapeutic agents.”

The Phase 1, open-label, single-agent clinical trial of MCLA-145 consists of dose escalation followed by dose expansion. Primary objectives of the Phase 1 trial are dose finding, evaluation of safety and tolerability of MCLA-145 in patients with advanced solid tumors. The Phase 1 trial will also examine potential preliminary antitumor activity and functional target engagement of single-agent MCLA-145. More details of the trial can be found at

Discovered through an unbiased functional screening of multiple immunomodulatory target combinations, MCLA-145 is a Biclonics T-cell agonist that also blocks T-cell inhibitor signals, and binds with high affinity and specificity to human PD-L1 and CD137 in preclinical models. The unique immunostimulatory profile of MCLA-145 derives from the ability to potently activate immune effector cells in the context of the tumor microenvironment while simultaneously blocking inhibitory signals in the same immune cell population.

Merus is developing MCLA-145 as part of a collaboration entered into with Incyte in December 2016 to potentially develop and commercialize up to 11 bispecific and monospecific antibodies from the Merus Biclonics platform. Under the terms of the collaboration, Merus will retain all rights to develop and commercialize MCLA-145, if approved, in the US, while Incyte has rights to develop and commercialize MCLA-145, if approved, outside the US.

Merus is a clinical-stage immuno-oncology company developing innovative full-length human bispecific antibody therapeutics, referred to as Biclonics. Biclonics, which are based on the full-length IgG format, are manufactured using industry standard processes and have been observed in preclinical and clinical studies to have several of the same features of conventional human monoclonal antibodies, such as long half-life and low immunogenicity. For more information, visit