Phase 1, Safety and Tolerability Study of XmAb541 and XmAb808 in Advanced Solid Tumors

The primary purpose of this study is to determine whether the combination of the investigational drug XmAb541 in combination with the investigational drug XmAb808 is safe and well tolerated, and to determine an optimal and safe dose(s) for further study. The study will also evaluate the effect of XmAb541 in combination with XmAb808 on participants' tumor outcomes.

Inclusion Criteria: * Age ≥ 18 years. * CLDN6+ tumor * Histological or cytological documentation of locally advanced, recurrent, or metastatic high grade serous ovarian carcinoma (HGSOC) including fallopian tube or primary peritoneal origin * Adequate Eastern Cooperative Oncology Group performance status * Life expectancy ≥ 3 months * Adequate organ function Exclusion Criteria: * Prior exposure to a CLDN6 targeting immune cell engager * Patients with treated brain metastases may participate, provided they are radiologically stable. * Active known or suspected autoimmune disease * Have any condition requiring systemic treatment with corticosteroids, prednisone equivalents, or other immunosuppressive medications within 14 days prior to first dose of study drug * Clinically significant cardiovascular, pulmonary or gastrointestinal disease * Active viral hepatitis B or hepatitis C