• Age ≥18 years.

• Eastern Cooperative Oncology Group (ECOG) Performance Status criteria of 0-2.

• Must have archival bone marrow sample at time of diagnosis that can be used for clonality identification for NGS if not already performed.

• Presence of residual bone marrow minimal residual disease (MRD) positivity by clonoSEQ® next-generation sequencing (NGS) 90-120 days post autologous stem cell transplantation.

• Histologically confirmed diagnosis of symptomatic multiple myeloma (patients with multiple myeloma with secondary amyloidosis are eligible, but no amyloid treatment will be allowed while on study).

• Received autologous stem cell transplant as upfront therapy for myeloma (defined as ASCT within one year of diagnosis of symptomatic MM).

• Adequate organ function as defined below:

‣ Absolute neutrophil count (ANC) ≥1,000/mm\^3.

⁃ Platelet count ≥75,000/mm\^3; platelet transfusions to help patients meet eligibility criteria are not allowed within seven days before study enrollment.

⁃ Total bilirubin ≤1.5 x the upper limit of the normal range (ULN)

⁃ Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤3 x ULN

• Pregnancy It is not known what effects this treatment has on human pregnancy or development of the embryo or fetus. Therefore, female subjects participating in this study should avoid becoming pregnant, and male subjects should avoid impregnating a female partner. Non-sterilized female subjects of reproductive age and male subjects should use effective methods of contraception through defined periods during and after study treatment as specified below.

• Female participants: A female participant is eligible to participate if she is not pregnant, not breastfeeding, and at least one of the following conditions applies:

⁃ Not a female of childbearing potential (FCBP), OR

⁃ A FCBP who must have a negative serum or urine pregnancy test with a sensitivity of at least 25 mIU/mL within 10-14 days prior to and again within 24 hours prior to starting study medication and before each cycle of study treatment and must either commit to continue abstinence from heterosexual intercourse or apply a highly effective method of birth control during the intervention period and for at least five months after the last dose of isatuximab treatment Male participants: A male participant, even if surgically sterilized (i.e., status post-vasectomy), must agree to use contraception during the intervention period and for at least five months after the last dose of isatuximab treatment and refrain from donating sperm during this period.

• All study participants must be registered into the mandatory Revlimid REMS® program and be willing to comply with its requirements.

⁃ Ability to understand a written informed consent document, and the willingness to sign it.