Early Access Program Providing HER2/HER3 Bispecific Antibody, MCLA-128, for a Patient With Advanced NRG1-Fusion Positive Solid Tumor

Inclusion Criteria:

• Age 18 years or older

• At least one evaluable or measurable lesion according to RECIST v1.1

• Patient with advanced metastatic solid tumor with documented NRG1 fusion determinedin a qualified local laboratory by molecular profiling using methods such as nextgeneration sequencing [DNA or RNA] as routinely performed at CLIA or othersimilarly-certified laboratories.

• Treatment with anticancer medications or investigational drugs within the followingintervals before the first administration of MCLA-128:

1. At least 14 days for chemotherapy, targeted small molecule therapy, orradiation therapy OR

2. At least 5 half-lives have passed since discontinuation of the systemictreatment

• Eastern Cooperative Oncology Group (ECOG) performance status 0 to 2

• Adequate organ function at the time of initiation of treatment administration

• Negative pregnancy test results in women of childbearing potential (defined as women ≤50 years of age or history of amenorrhea for ≤12 months prior to study entry)

• Ability to give written, informed consent prior to treatment, with the understandingthat the consent may be withdrawn by the patient at any time without prejudice

• Not eligible or feasible to participate in a clinical trial

• Any condition that in the opinion of Merus may preclude appropriate use of theinvestigational medicine

Exclusion Criteria:

• Any untreated, symptomatic central nervous system (CNS) lesion

• Presence of an active and uncontrolled infection

• Leptomeningeal metastases

• Known hypersensitivity to any of the components of MCLA-128 or history of severehypersensitivity reactions to human or humanized monoclonal antibodies, includingtherapeutic antibodies

• Presence of LVEF <50% on the screening echocardiogram; or history or presence of anysignificant cardiovascular disease, including unstable angina or myocardialinfarction within 12 months prior to treatment, congestive heart failure (NYHA ClassIII or IV), or ventricular arrhythmia requiring medication

• Presence of any other medical or psychological condition deemed by the Physician tobe likely to interfere with a patient's ability to sign informed consent, cooperateor participate in the study, or interfere with the interpretation of the results.