Inclusion Criteria:

• Subject has provided informed consent.
• Diagnosis of multiple myeloma per IMWG criteria(26)
• Patients must have progressive disease following 3 or more prior lines of therapy.
  • Prior treatment must include a proteasome inhibitor, an immunomodulatory agent (IMiD), and an anti-CD38 monoclonal antibody.
  • Patients must not be candidates for regimens known to provide clinical benefit in relapsed or refractory multiple myeloma based on the investigator's judgement.
  • If a patient declines such therapy, this must be recorded in the study files. 4. Subjects must have measurable disease, including at least one of the criteria below:
  • SPEP demonstrating M-protein quantities ≥ 0.5 g/dl
  • UPEP demonstrating monoclonal protein ≥ 200 mg/24hr
  • Involved serum free light chain levels > 100 mg/L and an abnormal kappa/lambda (κ/λ)ratio
  • For patients with immunoglobulin class A (IgA) myeloma whose disease can only be reliably measured by quantitative immunoglobulin measurement, a serum IgA level ≥ 500 mg/dl will qualify as measurable disease
  • Non-secretory participants are eligible provided the participant has > 20% bone marrow plasmacytosis
• Adequate organ function:
• • Absolute neutrophil count (ANC) ≥ 1.0 x 10^9/L without growth factor support for 7 days
  • Platelets (plt) ≥ 50 x 10^9/L without transfusion for 7 days.
  • Hemoglobin ≥ 8.0 g/dl, transfusion support permitted
  • Aspartate aminotransferase (AST/SGOT) and alanine aminotransferase (ALT/SGPT) ≤ 3.0x upper limit of normal (ULN)
  • Serum bilirubin ≤ 1.5 x ULN
  • Estimated serum creatinine clearance of ≥ 45 mL/min using the Cockcroft-Gault equation or directly calculated from the 24-hour urine collection method.
  • International normalized ratio (INR) < 1.5 x ULN and partial thromboplastin time (PTT) < 1.5 x ULN
  • Left Ventricular Ejection Fraction by ECHO or MUGA of ≥ 40%.
  • Participants must have a performance status of 0-2 based on ECOG criteria.
  • For women of child bearing potential negative serum or urine pregnancy test (sensitivity of at least 25 mIU/mL) at screening

Exclusion Criteria

• Known hypersensitivity or allergy to ascorbic acid or melphalan
• Participants must not have a concurrent malignancy unless it can be adequately treated by non- chemotherapeutic intervention. Participants may have a history of prior malignancy, provided they have not had any chemotherapy within 365 days of study entry AND their life expectancy exceeds 5 years with respect to the concurrent malignancy at the time of study entry.
• Participants must not have life-threatening comorbidities.
• Known human immunodeficiency virus(HIV) disease (requires negative test for clinically suspected HIV infection).
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, recent (within 6 months) myocardial infarction, uncontrolled or symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, uncontrolled hypertension on appropriate therapy or psychiatric illness/social situations that would limit compliance with study requirements.
• Concurrent use of Coumadin (warfarin)
• Patients with G6PD deficiency
• Patients with a history of oxalate renal stones or a known history of multiple renal stones
• Diabetic patients who rely on a glucometer to dose insulin as ascorbate can interfere with glucometer readings