This study is evaluating how safe and effective a new drug (called ISB 1442) is in people with relapsed or refractory multiple myelomaA Phase 1/2, First-in-Human, Multicenter, Open-Label, Dose Escalation and Dose-Expansion Study of Single-Agent ISB 1442 in Participants With Relapsed/Refractory Multiple Myeloma

Inclusion

1. Male or female patients aged 18 years or older.
2. Be willing and able to provide written informed consent and any locally required authorization (eg, Health Insurance Portability and Accountability Act of 1996 [HIPAA]) prior to any protocol related procedures, including screening evaluations

3. Phase 1: Patients with pathologically confirmed multiple myeloma (MM) who have progressed on or after standard therapy (relapsed/refractory [R/R] patients):

   1. Must have received at least 3 prior lines of therapy, including PIs, IMiDs, and anti CD38 therapies either in combination or as a single agent; and must not be candidates for regimens known to provide clinical benefit. (Note: Patients in Australia may have received any of the therapies including PIs, IMiDs, and anti CD38 therapies either in combination or as a single agent; and must not be candidates for regimens known to provide clinical benefit ).
   2. Must have measurable M-protein (serum and/or 24-hr urine, or serum free light chains).

4. Phase 2: Patients with pathologically confirmed MM who have progressed on or after standard therapy (R/R patients):

   Cohort A: R/R MM

   1. Must have received at least 3 prior lines of therapy, including PIs, IMiDs, and anti CD38 therapies either in combination or as a single agent;

   2. Must have measurable disease defined by at least 1 of the following abnormalities (as per IMWG criteria):

      • Serum M-protein ≥ 0.5 g/L (IgA ≥ 0.5 g/L), or
      • Urine light-chain (M-protein) of ≥ 200 mg/24 hours, or
      • Serum free light chain (sFLC) assay: involved free light chain (FLC) level ≥ 10 mg/dL provided sFLC ratio is abnormal.

   Cohort B: R/R MM Post-T-Cell Directed Therapy

   1. Must have received at least 3 prior lines of therapy, including PIs, IMiDs and anti-CD38 therapies either in combination or as a single agent; and have relapsed and/or be refractory to a T-cell directed therapy including cellular therapies or T cell engagers.

   2. Must have measurable disease defined by at least 1 of the following abnormalities (as per IMWG criteria):

      • Serum M-protein ≥ 0.5 g/L (IgA ≥ 0.5 g/L), or
      • Urine light-chain (M-protein) of ≥ 200 mg/24 hours, or
      • sFLC assay: involved FLC level ≥ 10 mg/dL provided sFLC ratio is abnormal
5. Have a body weight ≥ 40.0 kg at screening.
6. Have an Eastern Cooperative Oncology Group (ECOG) performance status score of 2 or less.
7. Have life expectancy of at least 3 months (from date of informed consent signing).

8. Have adequate organ function, including:

   1. Aspartate aminotransferase (AST, GOT) and alanine aminotransferase (ALT, GPT) ≤3.0 × ULN; bilirubin ≤1.5 × ULN. Patients with Gilbert's syndrome may have a bilirubin level >1.5 × ULN, per discussion between the Investigator and medical monitor.
   2. Estimated creatinine clearance ≥45 mL/min as calculated using the Cockcroft-Gault formula or 24-hour urine collection.
9. Left ventricular ejection fraction (LVEF) ≥45% as assessed by echocardiogram (ECHO) or multiple gated acquisition (MUGA) scan.