A Study of STI-3031 (an Anti-PD-L1 Antibody) in Patients With Selected Relapsed/Refractory Malignancies

This is an open-label, multicenter, global Phase 2 basket study to investigate the efficacy, safety, pharmacokinetics and pharmacodynamics of STI-3031 in patients with selected relapsed or refractory (R/R) malignancies. The study will be conducted as separate Phase 2, single arm substudies for each of the indications below: * Extranodal NK/T-cell lymphoma (ENKTL) * Peripheral T-cell lymphomas (PTCL) * Diffuse large B-cell lymphoma (DLBCL) with PD-L1 gene translocation, copy gain, amplification, polysomy detectable by a fluorescence in situ hybridization (FISH) assay or Epstein-Barr virus positivity (EBV+) as assessed by EBV-encoded small RNA (EBER) testing * Biliary tract cancers (BTC) (intrahepatic cholangiocarcinoma), extrahepatic cholangiocarcinoma or gallbladder cancer) All participants will receive the study intervention, STI-3031.