Safety and Efficacy of CS1 CAR-T (WS-CART-CS1) in Subjects With Multiple Myeloma

April 24, 2026 updated by: Washington University School of Medicine

Phase 1 Dose-Escalation and Dose-Expansion Study of the Safety and Efficacy of CS1 CAR-T (WS-CART-CS1) in Subjects With Multiple Myeloma

Despite recent therapeutic advances, multiple myeloma (MM) remains an incurable disease. Although survival has improved, there are nevertheless diminishing durations of response to each subsequent line of therapy. This highlights the need for further therapeutic innovation. BCMA-targeting CAR-T cells show impressive response rates; however, their median duration of response is disappointing. The investigators propose that CS1(SLAMF7)-targeting CAR-T cells will fill a gap in the MM armamentarium.

CS1 is an attractive target in MM because it is expressed in most patients. Elotuzumab (Empliciti®), an approved anti-CS1 antibody, has proven the clinical efficacy of this target. CAR-T cells are an ideal modality to target CS1, given that two approved treatments, ide-cel (idecabtagene vicleucel, AbecmaTM) and cilta-cel (ciltacabtagene autoleucel, Carvykti™), have proven the potential for cellular immunotherapy in MM.

The investigators are testing the safety and preliminary anti-myeloma efficacy of WS-CART-CS1, a CAR-T cell therapy targeting CS1.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
25

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • Missouri
      • St Louis, Missouri, United States, 63110
        • Recruiting
        • Washington University School of Medicine
        • Sub-Investigator:
          • Feng Gao, M.D., Ph.D.
        • Sub-Investigator:
          • Ramzi Abboud, M.D.
        • Sub-Investigator:
          • Mark A Schroeder, M.D.
        • Sub-Investigator:
          • John F DiPersio, M.D., Ph.D.
        • Sub-Investigator:
          • Keith Stockerl-Goldstein, M.D.
        • Sub-Investigator:
          • Ravi Vij, M.D.
        • Principal Investigator:
          • Armin Ghobadi, M.D.
        • Contact:
        • Sub-Investigator:
          • Matthew J Christopher, M.D., Ph.D.
        • Sub-Investigator:
          • Zachary D Crees, M.D.
        • Sub-Investigator:
          • Mark A Fiala, MSW, Ph.D.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

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
    • In patients without measurable serum and urine M-protein levels, the difference between involved and uninvolved FLC levels (absolute increase) must be >10 mg/dL for consideration of defining progression before enrollment
    • 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.
  • 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.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Sequential Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
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.
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
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.
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

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Part A: Frequency and severity of treatment-emergent adverse events
Time Frame: From leukapheresis through 24 months after WS-CART-CS1 infusion (approximately 24 months and 1 week)
  • Graded by CTCAE v 5.0.
  • Adverse events will be tracked at the time of leukapheresis through 28 days post leukapheresis, to capture any AEs related to leukapheresis only.
  • Adverse events will then be collected beginning with lymphodepletion chemotherapy and continue through Day 100 post WS-CART-CS1 infusion or until initiation of another anticancer therapy, whichever occurs first.
  • After Day 100, only targeted AEs will be reported through 24 months after WS-CART-CS1 infusion or until disease progression or relapse, whichever occurs first. Targeted AEs include and are limited to secondary malignancies, CRS, ICANS, prolonged cytopenia (defined as Grade 3 neutropenia or thrombocytopenia lasting more than 28 days after WS-CART-CS1 infusion), and SAEs or SUSARs that are not attributable to progressive disease or extraneous causes.
From leukapheresis through 24 months after WS-CART-CS1 infusion (approximately 24 months and 1 week)
Part A: Frequency of dose-limiting toxicities (DLTs)
Time Frame: From WS-CART-CS1 infusion through 28 days
DLTs are defined in the protocol.
From WS-CART-CS1 infusion through 28 days
Part B: Frequency and severity of treatment-emergent adverse events
Time Frame: From leukaphereis through 24 months after WS-CART-CS1 infusion (approximately 24 months and 1 week)
  • Graded by CTCAE v 5.0.
  • Adverse events will be tracked at the time of leukapheresis through 28 days post leukapheresis, to capture any AEs related to leukapheresis only.
  • Adverse events will then be collected beginning with lymphodepletion chemotherapy and continue through Day 100 post WS-CART-CS1 infusion or until initiation of another anticancer therapy, whichever occurs first.
  • After Day 100, only targeted AEs will be reported through 24 months after WS-CART-CS1 infusion or until disease progression or relapse, whichever occurs first. Targeted AEs include and are limited to secondary malignancies, CRS, ICANS, prolonged cytopenia (defined as Grade 3 neutropenia or thrombocytopenia lasting more than 28 days after WS-CART-CS1 infusion), and SAEs or SUSARs that are not attributable to progressive disease or extraneous causes.
From leukaphereis through 24 months after WS-CART-CS1 infusion (approximately 24 months and 1 week)

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Part A MTD and Part B: Disease-specific objective response rate (ORR)
Time Frame: Within 3 months of WS-CART-CS1 infusion
-Defined as stringent complete response (sCR), plus complete response (CR), plus very good partial response (VGPR), plus partial response (PR), plus minimal response (MR) in MM within 3 months of infusion using the International Myeloma Working Group (IMWG) response criteria in MM.
Within 3 months of WS-CART-CS1 infusion
Part A MTD and Part B: Minimal residual disease (MRD) negativity in the marrow
Time Frame: Week 12
-Based on next-generation flow (NGF), next-generation sequencing (NGS), or both
Week 12
Part A MTD and Part B: Progression-free survival (PFS)
Time Frame: From WS-CART-CS1 infusion through completion of follow-up (estimated to be 15 years)
-PFS is measured from Day 0 to time of relapse, progression or death, whichever occurs first.
From WS-CART-CS1 infusion through completion of follow-up (estimated to be 15 years)
Part A MTD and Part B: Overall survival (OS)
Time Frame: From WS-CART-CS1 infusion through completion of follow-up (estimated to be 15 years)
-OS is defined as the time from start of treatment (Day 0) to time of death.
From WS-CART-CS1 infusion through completion of follow-up (estimated to be 15 years)
Part A MTD and Part B: Duration of response (DoR)
Time Frame: -From response 24 months after WS-CART-CS1 infusion (estimated to be 24 months)
-DoR for subjects who respond to treatment is measured from the time measurement criteria are met for response (whichever is first recorded) until the first date that relapse or progression is objectively documented.
-From response 24 months after WS-CART-CS1 infusion (estimated to be 24 months)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Washington University School of Medicine

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Paula C. & Rodger O. Riney Blood Cancer Research

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Armin Ghobadi, M.D., Washington University School of Medicine

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
August 22, 2024

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
August 31, 2029

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
August 31, 2040

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 15, 2023

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 15, 2023

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
December 29, 2023

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 30, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 24, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 202404090

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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