This is a dose-escalation and expansion study of ASP1948 as a single agent and in combination with nivolumab or pembrolizumab. The study consists of 3 periods for monotherapy and combination therapy: screening, treatment and follow up, followed by an optional Re-treatment period for participants that qualify.~The escalation cohorts will evaluate escalating dose levels of ASP1948 in participants with locally advanced (unresectable) or metastatic solid tumor malignancies.~After discontinuation of study drug, all participants will complete an end-of-treatment visit, along with 30-day and 90-day safety follow-up visits from the last dose of study drug.~For dose expansion, the tumor-specific cohorts will include participants with squamous cell carcinoma of the head and neck (SCCHN), non-small cell lung cancer (NSCLC), metastatic castration-resistant prostate cancer (mCRPC), ovarian cancer, pancreatic cancer and breast cancer, as well as any tumor types that respond to study drug treatment during dose escalation.
The purpose of this study is to evaluate the tolerability and safety profile of ASP1948 when administered as a single agent and in combination with nivolumab or pembrolizumab in participants with locally advanced (unresectable) or metastatic solid tumors; characterize the pharmacokinetic profile of ASP1948 when administered as a single agent and in combination with nivolumab or pembrolizumab and determine the recommended Phase 2 dose (RP2D) of ASP1948 when administered as a single agent and in combination with nivolumab or pembrolizumab. This study will also evaluate the antitumor effect of ASP1948 when administered as a single agent and in combination with nivolumab or pembrolizumab.