Nivolumab in Multiple Myeloma Patients After Idecabtagene Vicleucel

This study is designed to evaluate if treatment with adjuvant nivolumab improves depth of response in patients with relapsed refractory multiple myeloma (RRMM) who achieve a less-than-ideal response to idecaptagene vicleucel.

Inclusion Criteria: 1. Written informed consent and HIPAA authorization for release of personal health information signed by the participant or his/her legally authorized representative 2. Age ≥ 18 years at the time of consent 3. ECOG Performance Status (PS) of ≤ 1 at the time of enrollment. PS must be evaluated within 14 days prior to enrollment. 4. Measurable disease according to IMWG 2016 criteria present within 28 days prior to ide-cel infusion. Note that patients will NOT be required to have measurable disease at time of enrollment. Measurable disease is defined as: 1. Serum M-protein ≥1 g/dL (\> 0.5 g/dL for IgA or IgM) OR 2. Urine M-protein ≥200 mg/24 h OR 3. Involved free light chain (FLC) level ≥10 mg/dL provided serum FLC ratio is abnormal 5. Previous treatment with idecabtagene vicleucel according to the FDA approved US prescribing information with a response of CR/sCR, VGPR or PR by IMWG 2016 criteria evaluated no sooner than 3 weeks after idecabtagene vicleucel infusion when compared to baseline disease evaluations collected no earlier than 28 days prior to ide-cel infusion. Note: The 28-day window applies to all assessments, even if assessments were performed on different days. Note: Participants who received non-conforming idecabtagene vicleucel who were originally prescribed idecabtagene vicleucel according to the FDA approved label may be considered for inclusion per the investigator's discretion. 6. Participants must be enrolled no sooner than 3 weeks and no later than 6 weeks from the date of the idecabtagene vicleucel infusion. 7. Recovered from all non-hematologic reversible acute toxic effects of prior therapy (other than alopecia) to ≤ grade 1 or baseline. Participants with grade ≤ 2 treatment induced peripheral neuropathy are eligible. Participants with hematologic reversible acute toxic effects are allowed to participate if laboratory values meet eligibility parameters. 8. Demonstrate adequate organ function as defined in the table below; all screening labs to be obtained within 28 days prior to enrollment. The most recent labs prior to enrollment will be used to evaluate for eligibility if labs drawn more than once during screening. 9. Females of childbearing potential (FCBP) must have a negative serum pregnancy test within 72 hours prior to enrollment. NOTE: Females are considered of childbearing potential unless they are surgically sterile (have undergone a hysterectomy, bilateral tubal ligation, or bilateral oophorectomy) or are postmenopausal (at least 12 consecutive months with no menses without an alternative medical cause). FCBP must be willing to use a highly effective contraceptive method (i.e., achieves a failure rate of \10 mg daily prednisone equivalent) or other immunosuppressive medications within 14 days of C1D1 (Note: Inhaled or topical steroids, and adrenal replacement steroid doses \> 10 mg daily prednisone equivalent, are permitted in the absence of active autoimmune disease) 13. Prisoners or participants who are involuntarily incarcerated 14. Known history of myocarditis, regardless of etiology 15. Known history of allergy or hypersensitivity to study drug components 16. History of serious side effects to nivolumab or ipilimumab, as defined by the enrolling investigator