A Study of XB628 Alone and in Combination With Zanzalintinib in Participants With Recurrent Advanced or Metastatic Solid Tumors

This study consists of a Dose-Escalation stage and a Dose Expansion stage. The primary purpose of the dose escalation stage is to determine the maximum tolerated dose (MTD) and/or recommended dosage(s) for expansion (RDE\[s\]); and the dose expansion stage is to evaluate the preliminary antitumor activity of XB628 as a single agent and in combination with zanzalintinib.

Key Inclusion Criteria: * Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1. * Minimum life expectancy of ≥ 12 weeks. * Have a recurrent advanced or metastatic solid tumor that is histologically or cytologically confirmed. * Adequate organ and marrow function. * Not amenable to curative treatment with surgery or radiation. * Received at least 1 line of prior systemic anticancer therapy in the recurrent or metastatic setting. * Acceptable alternative therapy was received, refused, intolerable, or no longer effective. * Capable of understanding and complying with the protocol requirements and provide signed informed consent according to the protocol and local requirements. Key Exclusion Criteria * Primary brain tumors or known active brain metastases. * Major surgery (eg, gastrointestinal surgery, removal or biopsy of brain metastasis) within 4 weeks before the first dose of study treatment. * Received radiation therapy within 1 week before the first dose of study treatment or clinically relevant ongoing complications from prior radiation therapy. * Received prior therapy targeting NK cells (eg, monalizumab). * A woman of childbearing potential has a positive serum pregnancy test within 7 days prior to study treatment. Note: Other protocol defined Inclusion/Exclusion criteria may apply.