Clinical Trial Finder

Inclusion Criteria:

• - Relapsed or refractory multiple myeloma after 3 or more prior lines of therapy, including proteasome inhibitor (e.g. bortezomib or carfilzomib), anti-CD38 therapy (e.g. daratumumab), and anti-BCMA therapies (e.g. BCMA bispecific antibodies or BCMA CAR-T) - Measurable disease, defined as meeting at least one of the following criteria: - Serum M-protein ≥ 0.5 g/dL.

• - Urine M-protein ≥ 200 mg/24 h.

• - Serum FLC assay: involved FLC level ≥10 mg/dL (100 mg/L) with abnormal serum FLC ratio.

• - A biopsy-proven plasmacytoma.

• - Bone marrow plasma cells > 30% of total bone marrow cells.

• - At least 18 years of age.

• - ECOG performance status ≤ 1.

• - Adequate renal, hepatic, respiratory, and cardiovascular function, as defined below: - Renal function: - calculated creatinine clearance ≥ 50 mL/min/1.73 m2 OR.

• - radioisotope glomerular filtration rate ≥ 50 mL/min/1.73 m2 OR.

• - normal serum creatinine based on age/gender per institutional normal range.

• - Hepatic function: - ALT (SGPT) ≤ 5 x ULN for age.

• - Total bilirubin ≤ 2.0 x IULN (unless the patient has Grade 1 bilirubin elevation due to Gilbert's disease or a similar syndrome involving slow conjugation of bilirubin) - Respiratory function: - Minimum level of pulmonary reserve defined as oxygen saturation > 91% measured by pulse oximetry on room air.

• - Cardiovascular function: - LVEF ≥ 45% confirmed by echocardiogram or MUGA within 28 days of screening.

• - The effects of CS1 CAR-T on the developing human fetus are unknown.

For this reason, women of childbearing potential and men must agree to use adequate contraception (at least 2 forms of contraception, including one barrier method) prior to study entry and for 12 months after CS1 CAR-T infusion. If a female subject or female partner of a male subject becomes pregnant during therapy or within 12 months following WS-CART-CS1 infusion, the investigator must be notified in order to facilitate outcome follow-up.

• - Ability to understand and willingness to sign an IRB-approved written informed consent document (or that of legally authorized representative, if applicable).

Exclusion Criteria:

• - Any prior systemic therapy for multiple myeloma within 14 days before planned day of leukapheresis.

• - A history of other malignancy with the exception of treated non-melanomatous skin cancers and malignancies for which all treatment was completed at least 2 years before registration and the subject has no evidence of disease.

• - Currently receiving any other investigational agents.

• - Receipt of any cellular therapy within 8 weeks prior to the planned start of conditioning.

• - History of CS1-directed therapies.

• - A history of allergic reactions attributed to compounds of similar chemical or biologic composition to CS1 CAR-T or other agents used in the study.

• - History of Grade 3 CRS or ICANS with other CAR-Ts (including BCMA CAR).

• - Active hepatitis B, active hepatitis C, any uncontrolled infection, or HIV infection.

• - Ongoing or active infection or other serious underlying medical condition that would impair the ability to receive protocol treatment.

• - Pregnant and/or breastfeeding.

Women of childbearing potential must have a negative pregnancy test within 14 days of study entry.

Arms

Experimental: Part A Dose Escalation: WS-CART-CS1

Undergo apheresis procedure for WS-CART-CS1 manufacturing. Anti-multiple myeloma therapy may be given after leukapheresis and up to one week prior to the start of lymphodepleting chemotherapy at the discretion of the treating physician. Lymphodepleting chemotherapy on days -5, -4, and -3. Three days following the last dose of lymphodepleting chemotherapy (on Day 0), WS-CART-CS1 will be infused. Part A is the dose escalation portion of the study with the starting dose of 0.5 x 10^6 cells/kg of WS-CART-CS1.

Experimental: Part B Dose Expansion: WS-CART-CS1

Undergo apheresis procedure for WS-CART-CS1 manufacturing. Anti-multiple myeloma therapy may be given after leukapheresis and up to one week prior to the start of lymphodepleting chemotherapy at the discretion of the treating physician. Lymphodepleting chemotherapy on days -5, -4, and -3. Three days following the last dose of lymphodepleting chemotherapy (on Day 0), WS-CART-CS1 will be infused. Part B is the dose expansion portion of the study. The dose of WS-CART-CS1 will be determined in Part A of the study.

Interventions

Biological: - WS-CART-CS1

-Subject will be hospitalized for 7 days

Drug: - Lymphodepleting chemotherapy

Cyclophosphamide 500 mg/m^2 IV on Days -5, -4, and -3 Fludarabine 30 mg/m^2 IV on Days -5, -4, and -3