• Transplant eligible patients with newly diagnosed multiple myeloma (NDMM).

• High-risk multiple myeloma\*

• Participants with disease response ≥ PR to induction therapy

• Age ≥ 18 and ≤ 75. Non-English-speaking participants are eligible.

• Karnofsky performance status ≥70 (Appendix A).

• Adequate liver function (total bilirubin ≤1.5X ULN; ALT ≤2.5 X ULN)

• Estimated creatinine clearance ≥40 mL/min. Creatinine clearance may be calculated using Cockcroft-Gault, estimated glomerular filtration rate (Modification of Diet in Renal Disease \[MDRD\]), or Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formula). \*

• Participant agrees to not donate blood while taking lenalidomide and for 28 days after stopping lenalidomide.

• Participant agrees to enroll in the lenalidomide REMS program.

⁃ Women of child-bearing potential (WOCPB) must abstain from heterosexual intercourse or agree to use a contraceptive method that is highly effective (with a failure rate of \<1% per year), preferably with low user dependency (as described in Appendix B), plus one additional effective method at least 28 days before starting therapy, during the intervention period, at least 28 days after the last dose of lenalidomide and at least 4 months after the last dose of elranatamab, and agrees not to donate eggs (ova, oocytes) for reproduction during this period. The investigator should evaluate the effectiveness of the contraceptive method in relation to the first dose of the study intervention. A WOCBP must have a negative highly sensitive serum pregnancy test (as required by local regulations) within 10-14 days and also within 24 hours before the first dose of the study intervention.

⁃ Non Nonchildbearing potential is defined as follows (by other than medical reasons):

‣ ≥ 45 years of age and has not had menses for \>1 year.

‣ Participants who have been amenorrhoeic for \<2 years without a history of a hysterectomy and oophorectomy must have a follicle-stimulating hormone value in the postmenopausal range upon screening evaluation.

‣ Post-hysterectomy, post-bilateral oophorectomy, or post-tubal ligation.

⁃ Male participant agrees to contraceptive use that should be consistent with institutional guidelines regarding the methods of contraception for those participating in clinical studies.

∙ Male participants are eligible to participate if they agree to the following during the intervention period and for 1 (for lenalidomide) to 4 (for elranatamab) months after the last dose of study treatment to allow for clearance of any altered sperm: - Refrain from donating sperm during treatment (including dose interruptions) and for 4 weeks after their last dose of lenalidomide and 4 months after the last dose of elranatamab.

⁃ PLUS, either:

‣ Be abstinent from heterosexual intercourse as their preferred and usual lifestyle (abstinent on a long term and persistent basis) and agree to remain abstinent. OR

‣ Must agree to use contraception/barrier as detailed in Appendix B. \*Definition of high-risk and ultra-high-risk MM15:

‣ High-risk MM:

∙ o Presence of a high-risk chromosomal abnormality (HRCA) including: 17p13 deletion; t(4;14); t(14;16); t(14;20); Gain or amplification 1q by FISH.

‣ Ultra-high-risk MM

• Presence of ≥2 HRCA.