∙ In order to be eligible to participate in this study, an individual must meet all of the following criteria:

• Able to provide a signed Written Informed Consent: Voluntary written consent must be given before performance of any study-related procedure not part of standard medical care

• Male or female patients ≥18 years

• Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2

• Symptomatic MM having progressed on ≥2 prior line of therapies - including 1 proteasome inhibitor (bortezomib, carfilzomib etc.), 1 immunomodulatory drug (lenalidomide, pomalidomide, thalidomide etc.), and 1 CD38 targeting monoclonal antibody (daratumumab, isatuximab) either as monotherapy or in combination. Refractoriness (progression while on therapy or ≤60 days after discontinuation of therapy) to prior line of therapy is not required.

• Subjects who received BCMA-targeted immune-effector therapies like CAR-T cells and/or bispecific antibodies prior can be enrolled provided they are ≥60 days out of the treatment.

• Subjects must not be candidates for treatment regimens known to provide clinical benefit to be eligible for this study.

• Subjects must have measurable disease defined by at least 1 of the following 4 measurements:

‣ Serum M-protein \> 0.5 g/dL or Urine M-protein \> 200 mg/24 hours

⁃ Light chain MM without measurable disease in serum or urine: Serum immunoglobulin free light chain assay: involved free light chain level \>10 mg/dL (\> 100 mg/L) provided the serum free light chain ratio is abnormal

⁃ For oligo/non-secretory myeloma, measurable by standard imaging (PET/CT or MRI) ± bone marrow biopsy if myeloma biomarkers are inconclusive or non-contributory

• Able to swallow and absorb oral medication

• All previous therapies for cancer, including radiotherapy, major surgery and investigational therapies discontinued for ≥ 14 days before study entry, and all acute effects of any prior therapy resolved to baseline severity or Grade ≤ 1 Common Terminology Criteria for Adverse Events (CTCAE v5.0) excluding alopecia or fatigue.

• Adequate organ or marrow function

‣ CrCl (Cockcroft-Gault equation) ≥ 45ml/min

⁃ ALT/AST ≤2 times upper limit of normal

⁃ Total bilirubin ≤2 times upper limit of normal (\<3 x ULN for congenital hyperbilirubinemia states like Gilbert Syndrome)

⁃ Corrected serum calcium ≤12.5mg/dL or free ionized calcium ≤6.5mg/dL

⁃ ANC ≥1 x 109/L (prior growth factor permitted but must be without support 7 days before screening test)

⁃ Hemoglobin ≥8g/dL (without blood transfusion in 7 days prior to test, recombinant erythropoietin permitted)

⁃ Platelets ≥50 x 109/L

• No active infections (including but not limited to HIV, Hepatitis B, Hepatitis C, tuberculosis) or chronic health conditions which may interfere in the study in the opinion of the investigator.

• HIV: undetectable HIV viral load and CD4 counts \>200 for \>6 months on continuous antiretroviral therapy may be screened.

• Hepatitis B: If HbcAb positive and HBV PCR-, may be screened

• Hepatitis C: if completed anti-viral therapy and in sustained virological response \>6 months, may be screened

• Tuberculosis: Quantiferon or skin prick test positive but with negative chest imaging

• (CXR or CT) and asymptomatic, may be screened

• Note: A line of therapy consists of ≥1 complete cycle of a single agent, a regimen consisting of a

• combination of several drugs, or a planned sequential therapy of various regimens3.

• A treatment is considered a new line of therapy if any one of the following three conditions are met:

• Start of a new line of treatment after discontinuation of a previous line: if the treatment regimen is discontinued for any reason, and a different regimen is started, it should be considered a new line of therapy. A regimen is considered to have been discontinued if all the drugs in that given regimen have been stopped. The regimen is not considered to have been discontinued if some of the drugs of the regiment, but not all, have been discontinued.

• The unplanned addition or substitution of one or more drugs in an existing regimen: Unplanned addition of a new drug, or switching to a different drug, or combination of drugs due to any reason, is considered a new line of therapy.

• Stem cell transplant (SCT): In patients undergoing \>1 SCT, except in the case of a planned tandem SCT with a predefined interval such as 3 months, each SCT (autologous or allogeneic, should be considered a new line of therapy, regardless of whether the conditioning regime used is the same or different.