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 or refractory multiple myeloma, as well as to define the recommended Phase 2 dose.

Key Inclusion Criteria:

1. Relapsed/Refractory Multiple Myeloma

   1. Confirmed diagnosis and evidence of progressive disease or clinical relapse as defined by International Myeloma Working Group criteria and following prior therapy for multiple myeloma (MM)

   2. Relapsed or refractory MM requiring current treatment

   3. Previously failed ≥ 3 prior regimens (after at least 2 cycles of medication per regimen) and included at least 1 immunomodulatory drug, 1 proteasome inhibitor, and an anti-CD38 antibody agent

   4. Participants must have measurable disease as defined by at least 1 of the following:

      • Serum M-protein ≥ 0.5 grams/deciliter (dL) by serum protein electrophoresis or for immunoglobulin A (IgA) myeloma, by quantitative IgA; or
      • Urinary M-protein excretion at least 200 milligrams (mg)/24 hours; or
      • Serum free light chain whereby the involved light chain measures ≥ 10 mg/dL and with an abnormal ratio

2. Estimated life expectancy ≥ 3 months

3. 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

Key Exclusion Criteria:

1. Concurrent invasive malignancy
2. Participants who had an allogeneic stem cell transplantation and are still on immunosuppressive medications or corticosteroids above physiological dose within 4 weeks before agenT-797
3. Prior radiotherapy within 2 weeks of start of study treatment
4. Prior systemic cytotoxic chemotherapy, biological therapy, or major surgery within 3 weeks prior to dose of study drug