• Subjects must be ≥ 18 years of age.

• Subjects must have an Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 2

• Subjects must voluntarily sign and date an in-formed consent form

• Subjects must have had documented multiple myeloma requiring treatment as defined by the criteria below:

• Monoclonal plasma cells in the bone marrow \> 10% and/or presence of a biopsy proven plasmacytoma at some point in their disease history requiring treatment according diag-nostic criteria (IMWG updated criteria 2014, Rajkumar et al. 2014) with measurable dis-ease at screening (serum M-protein \> 500 mg/dL or urine M protein 200 mg/24h, in case of oligosecretory MM serum free light chain \> 10mg/dL and abnormal kap-pa/lambda free light chain ratio)

• Cytogenetics/FISH confirming t(11;14)

• Prior treatment requirements:

• a. Subjects must have received at least 1 prior treatment line (induction, high-dose, consolidation and maintenance is considered as one treatment line). All patients have to have received at least one proteasome inhibitor and at least one immunomodulatory agent and at least one anti-CD38 monoclonal antibody.

• b. Subjects must have documented evidence of progressive disease on or after the last treatment line.

• c. Subjects with a history of autologous SCT are eligible for study participation provided the following eligibility criteria are met: i. ASCT was \>100 days prior to initiating study treatment, and ii. No active bacterial, viral, or fungal in-fection(s) present.

• Subjects must have adequate organ function, defined as follows:

• a. Hemoglobin ≥8.0 g/dL (without transfusion of red blood cells for the past 14 days) b. Absolute neutrophil count ≥ 1.5 x109/L (with-out growth factor support for the past 14 days) c. Platelet count more or equal 75 x109/L (with-out growth factor or platelet stimulating agents for the past 14 days) d. Adequate hepatic function per local laborato-ry reference range as follows: i. Aspartate aminotransferase (AST) ≤ 2,5 x upper limit of normal (ULN); ii. Alanine aminotransferase (ALT) ≤ 2.5 x ULN iii. Total bilirubin ≤ 1.5 x ULN, except in subjects with congenital bilirubinemia, such as Gilbert syndrome (direct bili-rubin ≤ 1.5 x ULN). Isolated bilirubin ≥1.5xULN is acceptable if bilirubin is fractionated and direct bilirubin \<35%.

• e. Subjects must have adequate renal function as demonstrated by eGFR ≥30 mL/min/ 1.73 m2 as calculated by Modified Diet in Renal Disease (MDRD) formula f. Spot urine (albumin/creatinine ratios (spot urine) \<500 mg/g (56 mg/mmol) OR Urine Dipstick Negative/trace (if 1+ only eligible if confirmed \<500 mg/g (56 mg/mmol) by albumin/creatinine ratio (spot urine from first void) g. Corrected serum calcium ≤ 14 mg/dL (≤3,5 mmol/L); or free ionized calcium ˂ 6,5 mg/dL (˂1,6 mmol/L)

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

∙ Is not a woman of childbearing potential (WOCBP) OR

‣ Is a WOCBP and using a contraceptive method that is highly effective

• Male participants are eligible to participate if they agree to the refrain from donating sperm and either bei abstinent from heterosexual intercourse or agree to use a highly effective contraceptive method during the intervention period and for 6 months after the last dose of study treatment to allow for clearance of any altered sperm

⁃ All subjects must agree to refrain from donating blood while on study drug and for 28 days after discontinuation from this study treatment.

⁃ All subjects must agree not to share study medication.

⁃ All prior treatment-related toxicities (defined by National Cancer Institute- Common Toxicity Criteria for Adverse Events (NCI-CTCAE), version 5.0) must be ≤ Grade 1 at the time of en-rolment except for alopecia.