A Study of XmAb®18087 in Subjects With NET and GIST

This is a Phase 1, multiple dose, ascending dose escalation study; to define a MTD/RD and regimen consisting of a first "priming" dose and escalated subsequent doses of XmAb18087; to describe safety and tolerability; to assess PK and immunogenicity; and to preliminarily assess anti-tumor activity of XmAb18087 in subjects with advanced NET or GIST. The study will enroll dosing cohorts to establish a MTD/RD and regimen in subjects with advanced NET or GIST, then enroll additional subjects into separate NET and GIST expansion cohorts to collect additional data on safety and potential efficacy of XmAb18087.