The goal of this study is to evaluate the safety of a new type of CAR T-cell, UF-KURE-BCMA, for the treatment of patients with advanced multiple myeloma that has not responded to other therapies. The main question is whether the use of these new CAR T-cells is safe for patients with this condition. Secondarily, the study will also look at the response of myeloma to this therapy.

This is a Phase I, single-arm, open-label, dose-escalation study using a 3+3 design that evaluates the safety of UF (ultrafast)- KURE-BCMA for patients with relapsed/refractory multiple myeloma. Eligible patients are adults (≥18 years) with relapsed or refractory multiple myeloma after ≥3 prior lines of therapy, including a proteasome inhibitor, an immunomodulatory drug, and an anti-CD38 antibody. The study will accrue a total of 12 patients.

The primary objectives of this study are:

• To determine the recommended Phase 2 dose (RP2D) of UF-KURE-BCMA
• To establish the safety profile and identify dose-limiting toxicities (DLTs)

The secondary objectives:

• Manufacturing feasibility
• Overall response rate (ORR) per IMWG criteria
• Duration of response (DOR)
• Progression-free survival (PFS)
• Overall survival (OS)

The exploratory objectives include:

• CAR-T cell persistence and expansion
• Replication-competent lentivirus (RCL) testing
• Cytokine profiling
• CAR-T cell phenotype characterization
• Anti-BCMA CAR antibody development
• Spatial multi-omics analysis of the bone marrow microenvironment

The study endpoints include:

Primary Endpoint Incidence of dose-limiting toxicities occurring within 28 days of CAR-T cell infusion Secondary Endpoints

• Manufacturing success rate (≥75%)
• Treatment-emergent adverse events
• ORR, DOR, PFS, and OS per IMWG criteria

The Investigational Product is UF-KURE-BCMA, an autologous CAR-T cells manufactured using an ultra-fast process (approximately 17-20 hours), that targets specifically BCMA, a marker expressed on the surface of the myeloma cell. The study will evaluate 3 different dose levels:

• Level -1: 3 × 10⁶ cells (≥50 kg) / 2 × 10⁶ cells (<50 kg)
• Level 1 (Starting Dose): 10 × 10⁶ cells (≥50 kg) / 7 × 10⁶ cells (<50 kg)
• Level 2: 15 × 10⁶ cells (≥50 kg) / 10 × 10⁶ cells (<50 kg) Prior to the cell infusion, the patients will receive a chemotherapy regimen (lymphodepleting regimen) that includes: Cyclophosphamide 300 mg/m² IV plus fludarabine 30 mg/m² IV, administered daily for 3 days (Days -4 to -2) The study will last 28 days, which is Dose-limiting toxicity (DLT) observation period. The follow-up period is 24 months with a long-term safety follow-up of 15 years.

The study endpoints:

Primary Endpoint Incidence of dose-limiting toxicities occurring within 28 days of CAR-T cell infusion Secondary Endpoints

• Manufacturing success rate (≥75%)
• Treatment-emergent adverse events
• ORR, DOR, PFS, and OS per IMWG criteria

Statistical Methods A standard 3+3 dose-escalation design will be used. Safety and efficacy will be summarized using descriptive statistics. Time-to-event endpoints will be analyzed using the Kaplan-Meier method.

Inclusion Criteria:

Subjects must meet ALL of the following criteria to be eligible for study enrollment:

1. Age: ≥18 years at time of signing informed consent

2. Diagnosis: Documented multiple myeloma meeting one of the following:

   • Relapsed disease: Progression after achieving at least minimal response (MR) to prior therapy
   • Refractory disease: Non-responsive or progressive disease while on therapy or within 60 days of last treatment (in subjects who achieved ≥MR on prior therapy)

3. Prior Therapy:

   • Received ≥3 prior lines of anti-myeloma therapy
   • Prior therapy must include:

   At least one proteasome inhibitor At least one immunomodulatory drug (e.g., lenalidomide, pomalidomide, thalidomide) At least one anti-CD38 monoclonal antibody (e.g., daratumumab, isatuximab) o Prior anti-BCMA CAR-T therapy is permitted if subject achieved PFS ≥6 months post-infusion

4. Measurable Disease: At least one of the following at screening (for response assessment eligibility):

   • Serum M-protein ≥0.5 g/dL by protein electrophoresis (SPEP)
   • Urine M-protein ≥200 mg/24 hours by protein electrophoresis (UPEP)
   • Serum free light chain (FLC) difference ≥10 mg/dL with abnormal FLC ratio Note: Subjects with non-measurable disease may enroll for safety assessment

5. Performance Status: ECOG Performance Status 0-2 (see Appendix A)

6. Organ Function: Adequate organ function as defined by:

   Hepatic:

   o Total bilirubin ≤2× institutional upper limit of normal (ULN), except subjects with Gilbert's syndrome

   • AST and ALT ≤2.5× institutional ULN

   Renal:

   o Calculated creatinine clearance ≥30 mL/min (Cockcroft-Gault formula)

   Cardiac:

   o Left ventricular ejection fraction (LVEF) ≥45% by echocardiogram or MUGA

   Pulmonary:

   o ≤Grade 1 dyspnea

   o Oxygen saturation ≥92% on room air

   o If PFTs performed: FEV₁ ≥50% predicted and DLCO ≥40% predicted (corrected for hemoglobin)

7. Prior Therapy Washout:

   o ≥2 weeks since last radiation or systemic anti-myeloma therapy (standard agents)

   o ≥4 weeks since last investigational therapy

   o ≥6 weeks since autologous stem cell transplant

8. Informed Consent: Ability to understand and willingness to provide written informed consent

9. Contraception Requirements (for subjects of reproductive potential):

Female subjects:

o Women of childbearing potential must: Have negative serum pregnancy test at screening Agree to use highly effective contraception (failure rate <1% per year) from enrollment through 6 months post-CAR-T infusion

• Acceptable methods: bilateral tubal ligation, male partner sterilization, hormonal contraceptives that inhibit ovulation, hormone-releasing IUD, copper IUD
• Sexual abstinence is acceptable if consistent with subject's preferred lifestyle

Male subjects:

• Must agree to use condom plus effective contraception if partner is of childbearing potential
• Must refrain from sperm donation from enrollment through 6 months post-CAR-T infusion

Exclusion Criteria:

Subjects meeting ANY of the following criteria will be excluded:

1. Disease-Specific Exclusions:

   • Active CNS involvement by multiple myeloma
   • Plasma cell leukemia
   • History of allogeneic hematopoietic stem cell transplantation

2. Malignancy Exclusions:

   o Second active malignancy, except: Non-melanoma skin cancer Carcinoma in situ (cervix, bladder, breast) Stage 1 uterine cancer Localized prostate cancer

3. Cardiovascular Exclusions:

   • New York Heart Association (NYHA) Class IV congestive heart failure
   • Unstable angina pectoris
   • Clinically significant cardiac arrhythmias
   • Myocardial infarction, stroke, or TIA within 6 months of enrollment

4. Infectious Disease Exclusions:

   • Known HIV infection or AIDS-related illness
   • Active hepatitis B or C infection:

Positive HBsAg, or Positive anti-HBc or anti-HCV with detectable viral nucleic acid by PCR

• Active infection requiring systemic therapy 5. Neurological Exclusions:
• History of clinically relevant CNS pathology including:

Epilepsy or seizure disorders Paresis, aphasia Uncontrolled cerebrovascular disease Severe brain injury Dementia Parkinson's disease 6. Autoimmune Disease:

• Active autoimmune disease requiring systemic immunosuppression >15 mg/day prednisone equivalent within past 6 months
• Examples: rheumatoid arthritis, lupus