Anti-CRLF2-R/TSLPR Chimeric Antigen Receptor T Cells (TSLPR-CART) in Participants With Recurrent or Refractory CRLF2-R/TSLPR-Overexpressing B-Cell Acute Lymphoblastic Leukemia (B-ALL)

Phase I Dose Escalation Study of Anti-CRLF2-R/TSLPR Chimeric Antigen Receptor T Cells (TSLPR-CART) in Participants With Recurrent or Refractory CRLF2-R/TSLPR-Overexpressing B-cell Acute Lymphoblastic Leukemia (B-ALL)

Background:

B-cell acute lymphoblastic leukemia (B-ALL) is a type of blood cancer. Some people with B-ALL have a gene mutation that makes the disease hard to treat. The mutation causes cancer cells to make too much of a protein called thymic stromal lymphopoietin receptor (TSLPR). Chimeric antigen receptor (CAR) T cell therapy is a treatment that takes immune cells (T cells) from a person s body and modifies them to attack specific proteins. Researchers want to test this treatment (TSLPR-CART) to find and kill cancer cells that produce too much TSLPR.

Objective:

To test TSLPR-CART in people with B-ALL.

Eligibility:

People aged 18 years and older with B-ALL that did not respond or returned after treatment. They must have TSLPR on their B-ALL.

Design:

Participants will be screened. They will have imaging scans and tests of their heart function. Samples will be taken from their bone marrow. They will have a lumbar puncture: A needle will be inserted into their back to collect a sample of the fluid around the spinal cord.

Participants will undergo leukapheresis: Blood will be taken from their body through a tube. The blood will pass through a machine that separates out the T cells. The remaining blood will be returned to the body through a different tube. The T cells will be used to create TSLPR-CART.

Participants will take drugs over 5 days to prepare their body for the therapy; then they will receive the modified cells through a tube inserted into a vein. Staying in the hospital during part of the treatment is expected and participants will be monitored locally to evaluate for side effects. Approximately 1 month after receiving TSLPR-CART, participants will undergo evaluations to see how the TSLPR-CART impacted their leukemia. Participants will have follow-up visits for 2 years either at NIH or at home....

Study Overview

• Status: Not yet recruiting
• Conditions: Acute Lymphoblastic Leukemia; B-All
• Intervention / Treatment: Drug: Cyclophosphamide; Drug: Fludarabine; Biological: TSLPR-CART

Detailed Description

Background:

• gPhiladelphia (Ph)-like h acute lymphoblastic leukemia (ALL) is a high-risk subgroup of B-ALL associated with high rates of chemotherapy resistance and relapse. Ph-like ALL is defined by an activated cytokine receptor and kinase signaling profile similar to that of Philadelphia chromosome-positive (Ph+) ALL yet lacking BCR-ABL1 rearrangement.
• Approximately half of childhood and adult Ph-like ALL cases have rearrangement in cytokine receptor like factor-2 (CRLF2), which encodes one subunit of the thymic stromal lymphopoietin receptor (TSLPR) and heterodimerizes with the interleukin-7 receptor alpha (IL7Ra) subunit. Its ligand, TSLP, is a cytokine that plays a critical role in regulation of the immune response and in the differentiation of hematopoietic cells. TSLP binding to the TSLPR in B-ALL induces constitutive Janus kinases and signal transducers and activators of transcription (JAK/STAT) pathway signaling.
• Most CRLF2-rearranged (CRLF2-R) Ph-like ALL cases can be readily identified by increased TSLPR surface expression by flow cytometric immunophenotyping, and specific CRLF2 rearrangements can then be confirmed by genetic testing. Given the prevalence of

CRLF2 rearrangements and the poor clinical outcomes of patients with Ph-like ALL, TSLPR is a promising target for new immunotherapies.

• Chimeric antigen receptor-expressing T cells (CAR) have proven highly successful in patients with cancer with dramatic responses in >70% of patients with relapsed/refractory B-ALL treated with CD19-redirected CAR T cells, resulting in Food and Drug Administration (FDA) approval of a CD19 CAR T-cell immunotherapy in children and young adults. A trial of CAR T cells targeting CD22 is currently ongoing at the NCI and has demonstrated comparable efficacy and toxicity results as the CD19 CAR.
• Emerging data have indicated that not all patients respond, and up to 50% of those who achieve remission will subsequently relapse. The most common cause of relapse is the target antigen loss, which is likely multi-factorial in etiology and for which this mechanism of escape is under active investigation. Novel targets are needed.
• This will be the first in human testing of anti-CRLF2-R/TSLPR CAR T cell (TSLPRCART) adoptive cell therapy.

Objective:

-To assess the safety of administering escalating doses of autologous anti-CRLF2-R/TSLPR-CAR engineered T cells (TSLPR-CART) containing a truncated epidermal growth factor (tEGFR) suicide switch to determine a maximum tolerated dose (MTD) in participants with recurrent or refractory CRLF2/TSLPR-overexpressing B-cell acute lymphoblastic leukemia (ALL) following a cyclophosphamide/fludarabine lymphodepletion regimen.

Eligibility:

• Age >= 18 years
• Participants must have confirmed diagnosis of a B-cell ALL with TSLPR+ expression on flow cytometry who have relapsed or refractory disease after at least one standard chemotherapy regimen and one salvage regimen, with no alternative curative options.

Design:

• This is a first-in-human Phase I trial aimed to determine the safety of TSLPR-CART in participants with recurrent or refractory B-cell ALL.
• Participants will undergo apheresis and TSLPR-CART will be manufactured from the enriched T-cell product
• Participants will receive LD preparative regimen of fludarabine and cyclophosphamide followed by an infusion of TSLPR-CART.
• The MTD of autologous TSLPR-CAR T cells using a 3 + 3 dose escalation design will be determined.

Additional participants in an expansion cohort will be treated at an MTD dose to evaluate the rate of response to TSLPR-CAR T cells. Participants will be evaluated for toxicity, anti-tumor response, CAR expansion and persistence, and other biologic correlatives.

• Study Type: Interventional
• Enrollment (Estimated): 57
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: NCI Pediatric Leukemia, Lymphoma Transpl; Phone Number: (240) 760-6970; Email: ncilltct@mail.nih.gov
• Study Contact Backup: Name: Nirali N Shah, M.D.; Phone Number: (240) 760-6970; Email: shahnn@mail.nih.gov

Study Locations

• United States
  • Maryland
    • Bethesda, Maryland, United States, 20892
      • National Institutes of Health Clinical Center
      • Contact: National Cancer Institute Referral Office; Phone Number: 888-624-1937; Email: NCIMO_Referrals@mail.nih.gov

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

• INCLUSION CRITERIA:

  1. Documentation of pathologic confirmation of a diagnosis of B-Cell acute lymphoblastic leukemia (ALL).
  2. TSLPR+ expression must be detected on . 80% of the malignant cells by NSR device. Note: TSLPR+ expression does not need to be repeated by NSR device if there is a documentation of TSLPR surface expression by flow cytometry from a Clinical Laboratory Improvement Amendments (CLIA) approved laboratory.

  3. Participants must have a disease that is relapsed or refractory after initial systemic therapy and at least one salvage treatment, and must either be ineligible for, cannot access in a timely manner, or declined alternative curative options (including commercial CAR Tcell constructs*, and/or have relapsed after allogeneic HSCT).

     *Individuals that are CD19 positive will be considered for this study, However, these individuals should be ineligible for, unable to obtain in a timely manner, cannot access, unwilling to undergo, or have failed prior FDA approved CD19 CAR constructs.

  4. Participants must have measurable or evaluable disease at the screening, defined by any evidence of MRD or positron emission tomography (PET)-avid extramedullary disease
  5. Age >= 18 years
  6. Clinical performance status: Karnofsky >= 50%. Participants who are unable to walk because of paralysis, but who are upright in a wheelchair will be considered ambulatory for the purpose of calculating the performance score.

  7. Participants must have adequate organ and marrow function as defined below:

     • Leukocytes >= 750/mcL*
     • Platelets >= 50,000/mcL*
     • Total bilirubin <= 2 x upper limit of normal (ULN) (except in the case of participants with documented Gilbert fs disease > 3 X ULN)
     • Aspartate Aminotransferase (AST)/Alanine Aminotransferase (ALT) <= 5 X institutional ULN

     • Creatinine < 1.5X ULN OR Creatinine clearance >= 60 mL/min/1.73m^2 for participants with creatinine levels above max listed above

       • A participant will not be excluded because of pancytopenia >=Grade 3 if it is due to underlying bone marrow involvement by leukemia
  8. Cardiac function: left ventricular ejection fraction (LVEF) . 45% or fractional shortening >= 28%, and no clinically significant electrocardiogram (EKG) findings
  9. Pulmonary Function: Baseline oxygen saturation > 92% on room air at rest without oxygen supplementation

  10. Participants with the following central nervous system (CNS) status are eligible:

      • CNS 1, defined as absence of blasts in CSF on cytospin preparation, regardless of the number of WBCs;

      • CNS 2, defined as presence of < 5/mcL WBCs in CSF and cytospin positive for blasts, or > 5/mcL WBCs but negative by Steinherz/Bleyer algorithm:

        • CNS 2a: < 10/mcL red blood cells (RBCs); < 5/mcL WBCs and cytospin positive for blasts;
        • CNS 2b: >=10/mcL RBCs; < 5/mcL WBCs and cytospin positive for blasts;
        • CNS 2c: >=10/mcL RBCs; >= 5/mcL WBCs and cytospin positive for blasts but negative by Steinherz/Bleyer algorithm.

  11. Contraception:

      • Women of child-bearing potential (WOCBP) must agree to use a highly effective contraception (hormonal, intrauterine device [IUD], surgical sterilization, abstinence) at the study entry and up to 12 months after the last dose of combined chemotherapy. Note: WOCBP is defined as any individual who has experienced menarche and who has not undergone successful surgical sterilization or who is not postmenopausal.
      • Men able to father a child must agree to use an effective method of contraception (barrier, surgical sterilization, abstinence) at the study entry and for 4 months after the last dose of study drugs. We also will recommend men ask their partners to be on highly effective birth control (hormonal, IUD, surgical sterilization). Men able to father a child must not freeze or donate sperm within the same period.
  12. Nursing participants must be willing to discontinue nursing from study treatment initiation through 1 month after the last dose of the study drug(s).
  13. Ability and willingness of participant or Legally Authorized Representative (LAR) to coenroll on 15-C-0028: Follow-up Evaluation for Gene-Therapy Related Delayed Adverse Events after Participation in Pediatric Oncology Branch Clinical Trials.

  14. Participant or LAR must understand and sign a written informed consent.

      EXCLUSION CRITERIA:

  1. Recurrent or refractory leukemia limited to isolated testicular or isolated CNS disease
  2. CNS 3 disease including participants with radiologically detected active CNS lymphoma, or participants who have cranial nerve palsy from active CNS leukemia. Note: Chronic complications of prior CNS disease are not exclusionary in the absence of active disease (e.g., blindness from prior ocular CNS disease or persistent cranial nerve palsy)
  3. Hyperleukocytosis (>=50,000 blasts/mcL)
  4. Positive serum or urine beta-human chorionic gonadotropin (beta-HCG) pregnancy test performed in WOCBP at screening.

  5. Washout criteria (time prior to apheresis or prior to start of LD if apheresis is not done on this protocol):

     ====

     Therapy: Systemic chemotherapy, antineoplastic investigational agents, or antibody-based therapies, any investigational therapy

     Washout*: >= 2 weeks

     Exceptions: 6 weeks for clofarabine or nitrosoureas No washout for prior intrathecal chemotherapy, steroid therapy, hydroxyurea (no dose increases within prior 2 weeks) or ALL maintenance type chemotherapy (vincristine, 6- mercaptopurine, oral methotrexate, or a tyrosine kinase for participants with Ph+ or Ph-like ALL) provided there is recovery from any acute toxic effects

     ====

     Therapy: Radiation therapy

     Washout*: >= 3 weeks

     Exceptions: No time restriction with radiation therapy if the volume of bone marrow treated is less than 10% and the participant has measurable/evaluable disease outside the radiation window.

     ====

     Therapy: History of allogeneic HSCT

     Washout*: >=100 days since HSCT; >=30 days since completion of immunosuppression; >=6 weeks since donor lymphocyte infusion (DLI)

     ====

     Therapy: History of prior CAR therapy or other adoptive cell therapies

     Washout*: > 30 days post infusion

     • Time between prior therapy and apheresis or prior to start of LD if apheresis is not done on this protocol
  6. Human immunodeficiency virus (HIV) infection, as measured by seropositivity for HIV antibody
  7. Hepatitis B virus (HBV) infection, as measured by positivity for hepatitis B surface antigen (HbsAg)
  8. Hepatitis C virus (HCV) infection, as measured by seropositivity for hepatitis C
  9. Active second malignancy with the exception of in situ carcinoma of the cervix, unless the tumor was treated with curative intent at least two years previously and participant is in remission
  10. History of severe, immediate hypersensitivity reactions attributed to compounds of similar chemical or biologic composition to any agents used in study or in the manufacturing of the cells
  11. Evidence of active graft-versus- host disease (GVHD)
  12. Uncontrolled, symptomatic, intercurrent illness or social situations as evaluated by medical history, physical exam, and laboratory evaluations that would limit compliance with study requirements or would pose an unacceptable risk to the participant

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: 1; TSLPR-CART at escalating doses	Drug: Cyclophosphamide; Cyclophosphamide will be diluted in an appropriate solution and infused over one hour. The dose will be based on the patient s body weight, at 500 mg/m^2/dose after fludarabine infusion on days -3 and -2.; Drug: Fludarabine; Fludarabine is administered as an IV infusion in an appropriate solution over 30 minutes on days -5 through -2. To prevent undue toxicity the dose will be based on BSA (30 mg/m^2/dose).; Biological: TSLPR-CART; TSLPR CAR transduced T cells on D0 after lymphodepleting preparative regimen
Experimental: 2; TSLPR-CART at MTD or highest dose administered	Drug: Cyclophosphamide; Cyclophosphamide will be diluted in an appropriate solution and infused over one hour. The dose will be based on the patient s body weight, at 500 mg/m^2/dose after fludarabine infusion on days -3 and -2.; Drug: Fludarabine; Fludarabine is administered as an IV infusion in an appropriate solution over 30 minutes on days -5 through -2. To prevent undue toxicity the dose will be based on BSA (30 mg/m^2/dose).; Biological: TSLPR-CART; TSLPR CAR transduced T cells on D0 after lymphodepleting preparative regimen

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
To assess the safety of administering escalating doses of TSLPR-CART containing a tEGFR suicide switch to determine an MTD	Safety analyses will consist of tabulations of grades of toxicity by type of toxicity	28 days post cell infusion

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Efficacy of TSLPR-CART	The BOR will be assessed at end of study, based upon the disease assessments recorded during the study visits, and reported by dose level with a separate evaluation in the 12 participants per category treated at the MTD, in terms of confirmed CR/PR, unconfirmed CR/PR, SD, or PD. The rate of relapse from CR prior to end of study will also be summarized by dose level only for the participants who achieve confirmed CR during the study. The overall objective response rate (CR + PR) will be summarized by dose level. The DOR will be summarized for those participants who achieve objective response (CR + PR). In participants who have a confirmed response, DOR will be calculated from the first date of documented response until PD. Unconfirmed CR or PR is defined as the first documentation of response	2 years post cell infusion
1-year and 2-year OS (overall survival)	OS will be determined as the time from the start of the preparative regimen until death.	2 years post cell infusion

Collaborators and Investigators

• Sponsor: National Cancer Institute (NCI)
• Investigators: Principal Investigator: Nirali N Shah, M.D., National Cancer Institute (NCI)

Publications and helpful links

Helpful Links

• NIH Clinical Center Detailed Web Page

Study record dates

Study Major Dates

• Study Start (Estimated): June 10, 2026
• Primary Completion (Estimated): June 30, 2030
• Study Completion (Estimated): June 30, 2032

Study Registration Dates

• First Submitted: May 6, 2026
• First Submitted That Met QC Criteria: May 6, 2026
• First Posted (Actual): May 7, 2026

Study Record Updates

• Last Update Posted (Actual): June 5, 2026
• Last Update Submitted That Met QC Criteria: June 4, 2026
• Last Verified: May 4, 2026

More Information

Terms related to this study

• Keywords: Acute Lymphoblastic Leukemia; Adoptive Immunotherapy; B-All; CRLF2-R/TSLPR Expressing Tumor
• Additional Relevant MeSH Terms: Neoplasms; Immune System Diseases; Neoplasms by Histologic Type; Hematologic Diseases; Lymphatic Diseases; Lymphoproliferative Disorders; Immunoproliferative Disorders; Leukemia, Lymphoid; Leukemia; Hemic and Lymphatic Diseases; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Organic Chemicals; Hydrocarbons; Phosphoramide Mustards; Nitrogen Mustard Compounds; Mustard Compounds; Hydrocarbons, Halogenated; Phosphoramides; Organophosphorus Compounds; Cyclophosphamide; fludarabine
• Other Study ID Numbers: 10001555; 001555-C

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: This study will comply with the NIH Data Management and Sharing (DMS) Policy, which applies to all new and ongoing NIH-funded research in the IRP, as of January 25, 2023, that is associated with a ZIA, with a clinical protocol that undergoes scientific review and/or will involve genomic data sharing.
• IPD Sharing Time Frame: Data will be made available as soon as possible or at the time of associated publication. Data not published in a manuscript will be shared via public source once the data set completes QC.
• IPD Sharing Access Criteria: Clinical data will be made available upon request and with the permission of the study PI. Genomic data are made available via dbGAP through requests to the data custodians.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No