The purpose of the study is to find out whether a dietary intervention can affect treatment response and/or quality of life for people with newly diagnosed multiple myeloma receiving standard induction chemotherapy with daratumumab (or isatuximab), lenalidomide, bortezomib, and dexamethasone (DRVd). The researchers will measure quality of life by having participants complete questionnaires. The study will investigate the effects of diet on quality of life, treatment response, and other disease, microbiome, and immune markers.

Inclusion Criteria:

• Newly diagnosed multiple myeloma
• Patients must have pathologically confirmed multiple myeloma on bone marrow biopsy with cytogenetics via Florescence in Situ Hybridization (FISH) or SNP array or genomic sequencing report and evaluation of blood myeloma markers (quantitative immunoglobulins, free light chains, serum protein electrophoresis and immunofixation).
• Age ≥ 18 years
• Bone marrow involvement
• Planned for four 28-day cycles of daratumumab (or isatuximab), lenalidomide, bortezomib, dexamethasone (or any other steroid) (DRVd) induction chemotherapy (with once weekly bortezomib day 1, 8, 15 and lenalidomide 21/28 days).
• All 4 planned drugs initiated by C2D1.
• Must enroll before C1D21 of induction chemotherapy as study intervention starts at C2D1.
• Treatment at a site where treating oncologist has capability and plan to send for bone marrow MRD negativity by next generation sequencing at end of 4 cycles (EOI). To be confirmed with local oncologist at enrollment.
• Treatment at MSK or at a site that uses EPIC for electronic medical records and willing to share records with MSK through EPIC's Care Everywhere or through MSK's shared care network.
• Enrollment on another trial that allows for 4 cycles of 28-day DRVd is acceptable.
• Prior dexamethasone treatment is eligible.
• Patients who have received up to one cycle of cyclophosphamide and/or bortezomib with dexamethasone for disease control are eligible.
• Able to complete study procedures and visits.
• Patients on GLP-1 drugs are eligible if it has been started at least 3 months prior to C2D1 DRVd or if it has been started more recently for diabetes mellitus control but not weight loss. If it is medically indicated and started for diabetes mellitus control while on trial they will not be removed/excluded from trial.
• Participant or caregiver must be able to complete surveys.
• Baseline 24-hour dietary recall must consume <30 grams dietary fiber per day to be eligible.
• Patients that already follow a minimally processed (whole food) plant-based diet in the last 3 months are not eligible (ovo-lacto-vegetarian or processed junk food vegan diets are eligible).

Exclusion Criteria:

• Leptomeningeal/CNS involvement
• Prior cycles of combination cytotoxic infusion chemotherapy such as VDPACE or DCEP are not eligible.
• Patients with BMI ≤19 kg/m2 are excluded.
• If in the opinion of the investigator there maybe any concerns regarding the ability of the patient to complete the study safely or any contraindications.
• Severe allergy to any legume (such as anaphylactic shock) or allergies to multiple legumes or if cross-contamination is a risk are not eligible.
• Severe allergies such as anaphylactic shock to peanuts and/or tree nuts, such as cashews are not eligible.
• Enrollment onto concurrent therapeutic study that requires patient receives treatment other than 4 cycles of DRVd induction as described above.
• Concurrent weight loss or dietary programs will be ineligible if require a specific diet or weight loss supplements.
• Plan for prolonged travel during the study that would preclude adherence to prescribed diet. Willingness to comply during travel is not an exclusion.

Memorial Sloan Kettering Cancer Center supports the international committee of medical journal editors (ICMJE) and the ethical obligation of responsible sharing of data from clinical trials. The protocol summary, a statistical summary, and informed consent form will be made available on clinicaltrials.gov when required as a condition of Federal awards, other agreements supporting the research and/or as otherwise required. Requests for deidentified individual participant data can be made beginning 12 months after publication and for up to 36 months post publication. Deidentified individual participant data reported in the manuscript will be shared under the terms of a Data Use Agreement and may only be used for approved proposals. Requests may be made to: crdatashare@mskcc.org.