A Study Evaluating AB248 Alone or in Combination With Pembrolizumab in Adult Patients With Solid Tumors

Inclusion Criteria: * Age ≥18 years of age at the time consent is signed. * Has adequate end organ function per laboratory testing. * Pregnancy prevention requirements * Has measurable disease per RECIST 1.1 as assessed by the local site Investigator/radiology. * Has a performance status of 0 or 1 on Eastern Cooperative Oncology Group scale. * Histologic documentation of incurable, locally advanced or metastatic tumor of the type being evaluated in individual cohorts Exclusion Criteria: * Has a diagnosis of immunodeficiency. * Has a history of a previous, additional malignancy, unless potentially curative treatment has been completed, with no evidence of malignancy for 5 years. * Has known active CNS metastases and/or carcinomatous meningitis. * Has an active autoimmune disease that has required systemic treatment in the past 2 years. * Has an active infection requiring systemic therapy. * Inability to comply with study and follow-up procedures. * Has had a severe hypersensitivity reaction (Grade ≥3) to treatment with pembrolizumab, another monoclonal antibody, or has history of any hypersensitivity to any components of the study treatments or any of their excipients. * Has received prior systemic anticancer therapy including investigational agents within 4 weeks (or, if shorter, within 5 half-lives for kinase inhibitors) prior to first dose of study treatment. * Has received prior radiotherapy within 2 weeks of start of study treatment or has had a history of radiation pneumonitis. * Receiving chronic systemic steroid therapy or any other form of immunosuppressive therapy within 7 days prior the first dose of study treatment. * Has received previous treatment with another agent targeting the IL-2, IL-7, or IL-15 receptors. * Is expected to require any other form of antineoplastic therapy while on study