Clinical Trial Finder

Inclusion Criteria:

• - Age ≥18 years old, male or female; - Diagnosis of MM with relapsed or refractory disease; - Eastern Cooperative Oncology Group (ECOG) Performance ≤2 ; - Expected survival of at least 12 weeks; - Participant has measurable disease; - Adequate venous access for the apheresis of peripheral blood mononuclear cell; - Adequate organ function; - Able and willing to comply with the study protocol and follow-up plan, and sign the informed consent form in writing.

Exclusion Criteria:

• - Received any treatment that might influence the activity of CAR-T cells prior to the collection of peripheral blood mononuclear cells; - Have history of vaccination within the 4 weeks preceding the collection of peripheral blood mononuclear cells; - Have active bleeding or venous thromboembolic events requiring anticoagulation; - Have tested positive for cytomegalovirus and/or mycobacterium tuberculosis, or had any uncontrolled active infection within 14 days prior to the collection of peripheral blood mononuclear cells; - Subjects infected with active HBV or HCV, HIV, syphilis; - Subjects with known central nervous system disease or multiple myeloma involving the central nervous system (CNS) or presenting with CNS-related symptoms; - Patients currently experiencing active autoimmune diseases; - Diagnosed with immunodeficiency or receiving any other form of immunosuppressive therapy within 7 days prior to enrollment in this study.

• - Have following severe diseases: unstable angina, cerebrovascular accident or transient ischemic attack, myocardial infarction , New York Heart Association (NYHA) Class ≥ III, congestive heart failure, poorly controlled severe arrhythmias or other cardiac diseases requiring mechanical support; subjects with known chronic obstructive pulmonary disease (COPD) with a forced expiratory volume in 1 second (FEV1) < 50% of predicted normal; subjects with known moderate or severe persistent asthma, or a history of asthma within the past 2 years, or currently having any category of uncontrolled asthma; subjects requiring oxygen to maintain adequate oxygen saturation; subjects with hypertension whose blood pressure cannot be lowered to the following range despite treatment with two or more antihypertensive medications;.

• - Subjects with malignancies other than multiple myeloma; - Have any non-hematologic toxicity resulting from prior treatments that cannot be restored to ≤ grade 1 or baseline, excluding alopecia and grade 2 neuropathy; - History of alcohol abuse, drug addiction, substance abuse, or mental illness within the past year; - Presence of acute graft-versus-host disease (GVHD) or extensive chronic GVHD of Grade ≥ 2 requiring treatment within the 4 weeks before enrollment, or as judged by the investigator to likely require anti-GVHD treatment during the study; Subjects who had previously received BCMA-CD19 dual-target CAR-T cell products or autologous stem cell transplantation within 12 weeks before the collection of peripheral blood mononuclear cells; - Known allergy or hypersensitivity reactions to cyclophosphamide, fludarabine, dimethyl sulfoxide (DMSO), CD19, or BCMA-targeted drugs; - Subjects had participated in other clinical trials and used its investigational drugs within the 3 months prior to the collection of peripheral blood mononuclear cells.

• - Pregnant or lactating women.

- Any situation that the investigator believes may increase the risk of subjects or interfere with the results of clinical trials

Arms

Experimental: Phase 1: Low dose group

Infusion of KQ-2003 CAR T-cells by single dose of 1.0×10^6 CAR-T cells/kg

Experimental: Phase 1: Medium dose group

Infusion of KQ-2003 CAR T-cells by single dose of 2.0×10^6 CAR-T cells/kg

Experimental: Phase 1: High dose group

Infusion of KQ-2003 CAR T-cells by single dose of 3.0×10^6 CAR-T cells/kg

Experimental: Phase 2a: RP2D

After all subjects in the Phase 1 dose-escalation study completed DLT observation, RP2D was determined based on the analysis results for the phase 2a expansion study.

Interventions

Biological: - KQ-2003 CAR T-cells

KQ-2003 CAR T-cell therapy involves autologous chimeric antigen receptor T-cells, capable of targeting both human B cell maturation antigen (anti-BCMA CAR) and CD19 antigen molecules (anti-CD19 CAR) simultaneously as a cellular therapy.