Inclusion Criteria:

          1. Able and willing to sign the ICF and comply with the protocol

          2. Male or female ≥ 18 years of age

          3. Eastern Cooperative Oncology Group (ECOG) performance status 0-1

          4. Agrees to bone marrow aspirates

          5. Must have pathologically confirmed multiple myeloma

          6. Has relapsed or refractory myeloma

          7. At least 2 prior systemic anti-cancer therapies for relapsed or refractory multiple
             myeloma, including an immunomodulatory agent and a proteasome inhibitor

          8. Meets all IMWG 2014 criteria at diagnosis

          9. Measurable disease

         10. If female, must be of non-childbearing potential or have a negative pregnancy test at
             screening and use adequate contraception throughout study until 90 days after last
             dose

         11. If male with partner of childbearing potential, be vasectomized or use adequate
             contraception throughout study until 180 days after last dose

         12. All previous therapy-related adverse events should have resolved, prior to Day 1, to
             Grade 1 or baseline value with the exception of alopecia (includes effects of
             radiotherapy)

         13. Adequate organ function as indicated by neutrophils, platelets, hemoglobin, eGFR,
             serum total and direct bilirubin, AST, ALT, INR, aPTT

        Exclusion Criteria:

          1. Received small molecule or tyrosine kinase inhibitor within two weeks or five
             half-lives (whichever is longer) prior to the first dose of study drug; chemotherapy,
             investigational drug or biological cancer therapy within three weeks prior to the
             first dose of study drug; nitrosourea or radioisotope within six weeks prior to first
             dose of study drug, non-recovery to the CTCAE v5 Grade 1 or better from the adverse
             events due to cancer therapeutics administered more than four weeks earlier.

          2. Received an anti-CD38 therapy within four months from first dose of study drug

          3. Inability to perform study baseline RBC type and cross-match, phenotype, genotype or
             lack of available baseline data on RBC phenotype or genotype

          4. Receiving other concurrent investigational therapies or have received investigational
             therapies within four weeks of the first dose of study drug or five half-lives, if
             known, whichever is shorter

          5. Currently receiving systemic steroids unless equivalent to 10 mg/day of prednisone or
             less for adrenal replacement only. At least two weeks since last dose of steroid
             therapy intended for the treatment of myeloma and the first dose of study drug.

          6. Non-secretory myeloma unless measurable plasmacytoma

          7. Known hypersensitivity to CID-103 or any of its excipients

          8. Baseline interval between Q and T wave on electrocardiogram > 480 msec using
             Fridericia's formula (QTcF)

          9. Requires renal dialysis

         10. Sensory or motor neuropathy ≥ Grade 3

         11. Known/clinically significant amyloidosis

         12. Known active central nervous system disease or leptomeningeal plasmacytoma.

         13. Presence of any other active malignancy requiring systemic therapy other than the
             disease under study

         14. Active infection requiring systemic therapy

         15. Active infection with human immunodeficiency virus and CD4+ T-cell count < 350/μL

         16. Active infection with hepatitis B (surface antigen); or infection with hepatitis C in
             absence of sustained virologic response

         17. Therapeutic anticoagulation, meaning any thromboembolic event within the last six
             months prior to first dose of study drug or anticoagulation with therapeutic
             (non-prophylactic) intent

         18. A history or evidence of cardiovascular risk

         19. History or clinical evidence of any surgical or medical condition which the
             investigator judges as likely to interfere with the results of the study or pose an
             additional risk in participating, particularly any pre-existing condition that would
             put the patient at additional risk should they experience an infusion-related reaction

         20. At the time of signing informed consent is a regular user (including
             "recreational/medical use") of any illicit drugs or had a recent history (within the
             last year) of substance abuse (including alcohol)