Toxicities were graded with the Common Terminology Criteria for Adverse Events CTCAE v5.0., the following toxicities were classified as DLTs: * Any treatment related grade 5 toxicity * Grade 4 neutropenia or thrombocytopenia * Febrile neutropenia * Grade 4 anemia * Grade 3 or 4 non-hematologic toxicity * Recurrent grade 2 pneumonitis * Any other toxicity requiring permanent discontinuation of AMG 404.

A TEAE is any adverse event (AE) starting on or after the first administration of investigational product (IP) and up to and including 140 days after the last IP dose date or end of the study, whichever occurs earlier. A TEAE with unknown/missing relatedness to AMG 404 is assumed as an event is related to AMG 404. A serious adverse event (SAE) is defined as an adverse event that: is fatal, is life threatening, requires in-patient hospitalization, results in persistent or significant disability/incapacity, is a congenital anomaly/birth defect, and other medically important serious event. A treatment-related AE (TRAE) is any TEAE that per investigator review has a reasonable possibility of being caused by the investigational product. In the unlikely event that the relationship is missing, the TEAE will be considered TRAE and documented in a footnote of the treatment-related summary.