This is a Phase 1, open-label study to explore the safety, tolerability, and preliminary clinical activity of agenT-797, an unmodified, allogeneic iNKT cell therapy, in participants with relapsed/refractory (r/r) solid tumors, as well as define the recommended phase II dose in solid tumors. This Phase 1 study will also explore the safety, tolerability, and preliminary clinical activity of agenT-797 in combination with approved immune checkpoint inhibitors (ICIs), including pembrolizumab and nivolumab, in participants with r/r solid tumors.

Inclusion Criteria:

• Histological or cytological evidence of relapsed or refractory solid tumor malignancy for which no standard therapy is available or standard therapy has failed
• Measurable disease per RECIST 1.1 as assessed by local site Investigator/radiology. Lesions situated in a previously irradiated area are considered measurable if progression has been demonstrated in such lesions
• Part 2 only, participants must have progressed per Investigator assessment on pembrolizumab or nivolumab, and agree and are able to continue on the inhibitor(s) while on study
• No other medical, surgical, or psychiatric condition (including active substance abuse) that would interfere with compliance to the protocol, as determined by the Principal Investigator

Exclusion Criteria:

• Concurrent invasive malignancy
• Brain and/or leptomeningeal metastases that are untreated or require current therapy
• Prior radiotherapy within 2 weeks of start of study treatment