A Dose Escalation and Expansion Study of TRX518 in Combination With Cyclophosphamide Plus Avelumab in Advanced Solid Tumors

This is a Phase 1b/2a dose escalation and expansion, multi-center study to be conducted in 2 phases: * Phase 1b * Dose Escalation Part 1 (Doublet Therapy) * Dose Escalation Part 2 (Triplet Therapy) * Phase 2a * Dose Expansion (Triplet Therapy) Approximately 125 adult patients with histologically confirmed advanced solid tumors requiring therapy will be enrolled in the study. It is expected that approximately 24 patients will be enrolled in up to 4 cohorts, 2 cohorts in Dose Escalation Part 1 and 2 cohorts in Dose Escalation Part 2, of up to 6 patients per cohort. Up to 98 additional patients will be enrolled in the Dose Expansion phase of the study to achieve 88 evaluable patients (i.e., received at least 1 dose of study drug(s) and have 1 evaluable post-baseline modified RECIST v1.1 tumor response assessment; for mCRPC, assessment of soft tissue response will be per modified RECIST v1.1 and bone progression assessment will be per PCWG3 guidelines or discontinued treatment due to death, toxicity, or clinical progression) over 4 independent expansion groups.In either phase (1b or 2a), patients discontinuing for reasons unrelated to study treatment toxicity prior to completion of Cycle (C) 1 may be replaced to achieve the number of required evaluable patients per cancer type following consultation with the Sponsor. Data from each cohort in the Dose Escalation phase will be evaluated independently for safety and dose limiting toxicities (DLTs) prior to dose escalation and again prior to the Dose Expansion phase.