Utrecht, The Netherlands and Villejuif, France, January 4, 2016 — Merus B.V., a clinical-stage immuno-oncology company developing innovative bispecific antibody therapeutics, and Institut Gustave Roussy, a leading Comprehensive Cancer Centre in Europe, today announced entry into a strategic collaboration to jointly develop bispecific antibodies for therapeutic immuno-oncology applications.

Under the terms of the agreement, Merus and Gustave Roussy will collaborate on the design and conduct of basic, preclinical and translational research studies and early clinical studies leveraging Merus’ portfolio of therapeutic human bispecific antibody candidates, including bispecific antibodies in pre-clinical development targeting combinations of immunomodulatory molecules. In addition, Gustave Roussy will participate in clinical studies of Merus’ MCLA-128, a HER2xHER3 bispecific antibody candidate that is designed for the treatment of patients with HER2-expressing solid tumors, and Merus’ MCLA-117, a CLEC12AxCD3 bispecific antibody candidate that is designed to recruit and activate T-cells for the treatment of patients with acute myeloid leukemia.

“Gustave Roussy is an internationally renowned leader in cancer research, and we look forward to working with them to conduct early clinical trials and conduct preclinical research to further develop our understanding of how a patient’s immune system can be activated to eliminate cancer cells,” said Ton Logtenberg, Ph.D., Chief Executive Officer of Merus. “Gustave Roussy’s outstanding preclinical and clinical oncology teams, coupled with Merus’ bispecific antibody pipeline, create a powerful research platform capable of identifying important advancements in the area of immuno-oncology.”

“We are excited to expand our opportunities for collaboration in the development of bispecific antibodies for immuno-oncology,” said Professor Jean-Charles Soria, head of the Drug Development Department (DITEP) at Gustave Roussy. “We believe alliances such as this one with Merus will allow us to accelerate the development of promising, innovative cancer therapies for the patients who need them.”

“Our alliance with Merus illustrates our strategic commitment, as one of the leading Comprehensive Cancer Centres in Europe, to actively collaborate with biotech companies developing innovative therapeutic antibodies and biotechnological platforms in the field of precision medicine and immunotherapy,” said Professor Alexander Eggermont, General Director of Gustave Roussy.

About Gustave Roussy

Gustave Roussy is a leading Comprehensive Cancer Centre in Europe. It is a centre where all the skills in cancer care are focused on the patient. It comprises approximately 3,000 professional staff who are engaged in care, research and teaching.

About Merus B.V.

Merus is a clinical-stage immuno-oncology company developing innovative bispecific antibody therapeutics, referred to as Biclonics. Biclonics are based on the full-length IgG format, are manufactured using industry standard processes and have been observed in preclinical studies to have several of the same features of conventional monoclonal antibodies, such as long half-life and low immunogenicity. Merus’ lead bispecific antibody candidate, MCLA-128, is being evaluated in a Phase 1/2 clinical trial in Europe as a potential treatment for HER2-expressing solid tumors. Merus’ second bispecific antibody candidate, MCLA-117, is being developed as a potential treatment for acute myeloid leukemia, and Merus expects to initiate clinical trials of this candidate in the first quarter of 2016. The company also has a pipeline of proprietary bispecific antibody candidates in preclinical development, including Biclonics designed to bind to various combinations of immunomodulatory molecules, including PD-1 and PD-L1.

Contacts:

Merus B.V.

Shelley Margetson – s.margetson@merus.nl

+31 (0)30 253 8800

Argot Partners

Eliza Schleifstein – eliza@argotpartners.com

1-917-763-8106