Multi-modular Chimeric Antigen Receptor T Cells tarGeting B7-H3 in Children, Teenage & Young Adult Sarcoma (MIGHTY)

August 3, 2026 updated by: University College, London

MIGHTY is a multicentre, open label, phase 1 clinical trial of an Advanced Therapy Investigational Medicinal Product (ATIMP) in children, teenagers and young adults aged 1-24 with relapsed or refractory (r/r) rhabdomyosarcoma (RMS), Ewing sarcoma (ES) or desmoplastic small round cell tumour (DSRCT).

The study will assess the feasibility of generating the ATIMP and administering hBRCA84D CAR T cells to patients with r/r RMS, ES or DSRCT.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

MIGHTY is a multicentre, open label, phase 1 clinical trial of an Advanced Therapy Investigational Medicinal Product (ATIMP) in children, teenagers and young adults aged 1-24 with relapsed or refractory (r/r) rhabdomyosarcoma (RMS), Ewing sarcoma (ES) or desmoplastic small round cell tumour (DSRCT).

The ATIMP for this study (hBRCA84D CAR T cells) are autologous T cells targeting B7-H3 in patients with r/r RMS, ES, or DSRCT.

Patients will undergo an unstimulated leucapheresis for the generation of the ATIMP which will take approximately 15 days to generate.

Patients will receive lymphodepleting (LD) chemotherapy with fludarabine administered over 4 days (Day -6 to Day -3) and cyclophosphamide administered over 2 days (Day -4 and Day-3).

Patients will be treated at one of three dose levels following LD chemotherapy as described above.

The study will evaluate the feasibility of generating the ATIMP, the safety of administering ATIMP, the tolerability of the ATIMP and how effectively the CAR T cells engraft, expand and persist following administration in patients with r/r RMS, ES or DSRCT.

Following infusion of the CAR T cells, patients will be monitored for between 2-4 weeks as an inpatient. Following discharge, patients will enter the interventional follow up phase and be followed up for 1 year. Patients will be seen at 6 weeks post infusion then 3 monthly until 1 year post CAR T cells infusion.

If patients relapse within the first-year post CAR T cell infusion, they will come off the interventional follow up and will be followed up annually until 15 years after the CAR T infusion.

After completing the 1-year interventional phase of the study, all patients, irrespective of whether they progressed or responded to treatment, will enter long term follow up until 15 years post CAR T infusion.

Study Type

Interventional

Enrollment (Estimated)

12

Phase

  • 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

  • Name: Karin Straathof

Study Contact Backup

Study Locations

      • London, United Kingdom
        • Recruiting
        • Great Ormond Street Hospital
        • Contact:
          • Olga Slater
      • London, United Kingdom
        • Recruiting
        • University College London Hospital
        • Contact:
          • Sandra Strauss

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

Ages Eligible for Study

  • Child
  • Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Age ≥ 1 and ≤ 24 years.
  2. Tissue diagnosis of RMS, ES or DSRCT
  3. Expression of B7-H3 in the tumour
  4. Relapsed or refractory disease after one or multiple lines of previous treatment.
  5. Measurable disease by cross sectional imaging. Patients with only bone marrow detectable disease (bone marrow aspirate or trephine) are NOT eligible for the study.
  6. At least 3 weeks or 5 half-lives, whichever is shorter, after treatment with agents on other early phase clinical trial.
  7. Performance status: Karnofsky (age ≥ 10 years) or Lansky (age < 10) score ≥ 50%.
  8. Creatinine ≤1.5 x Upper Limit of Normal (ULN) for age, if higher, an estimated (calculated) creatinine clearance must be ≥ 60 ml/min/1.73 m2.
  9. Left ventricular ejection fraction (LVEF) ≥ 50%
  10. Absolute lymphocyte count ≥ 0.25 x 109/L.
  11. Women of childbearing potential (WOCBP) must have a negative pregnancy test and agree to comply with the pregnancy reporting requirements of the protocol (if applicable).
  12. Written informed consent.

Exclusion Criteria:

  1. Patients with only bone marrow detectable disease in the absence of measurable disease by cross sectional imaging.
  2. Patients with active, inoperative central nervous system (CNS) disease including leptomeningeal disease.
  3. Active hepatitis B, C or HIV infection.
  4. Inability to tolerate leukapheresis.
  5. Clinically significant systemic illness or medical condition (e.g., significant cardiac, pulmonary, hepatic or other organ dysfunction), that in the judgement of the investigator is likely to interfere with assessment of safety or efficacy of the investigational regimen and its requirements.
  6. Any contraindication to lymphodepletion or to the use of Cyclophosphamide or Fludarabine as per the local SmPC.
  7. Any contraindication to the use of Anticoagulant Citrate Dextrose Solution.
  8. Known allergy to albumin, EDTA or DMSO.
  9. Primary immunodeficiency or history of autoimmune disease (e.g., Crohn's, rheumatoid arthritis, systemic lupus) requiring systemic immunosuppression /systemic disease modifying agents within the last 2 years.
  10. Prior treatment with investigational or approved gene therapy or cell therapy products.
  11. Life expectancy <3 months.
  12. Systemic corticosteroid therapy ≥ 0.05 mg/kg dexamethasone daily (or equivalent) at time of hBRCA84D CAR T cells infusion.
  13. Women who are pregnant or breastfeeding.
  14. Patients who have received any live vaccine in the six weeks prior to planned lymphodepletion

Exclusion criteria for the ATIMP infusion:

  1. Uncontrolled fungal, bacterial, viral, or other infection. Previously diagnosed infection for which the patient continues to receive antimicrobial therapy is permitted if responding to treatment and clinically stable at the time of scheduled hBRCA84D CAR T cell infusion.
  2. Systemic corticosteroid therapy ≥ 0.05 mg/kg dexamethasone daily (or equivalent) at time of hBRCA84D CAR T cell infusion.

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

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: hBRCA84D CAR T cells
Treatment with hBRCA84D CAR T cells
The hBRCA84D CAR T cells target B7-H3 positive cells.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Safety of administering the ATIMP
Time Frame: 28 days
Incidence of grade 3-5 toxicity causally related to the ATIMP, particularly severe cytokine release syndrome and severe neurotoxicity.
28 days
Number of therapeutic products generated and the number of ATIMPs infused after successful manufacture
Time Frame: 28 days
Feasibility of generation of the ATIMP as evaluated by the number of therapeutic products generated and the number of ATIMPs infused after successful manufacture.
28 days

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Progression Free Survival (PFS)
Time Frame: 1 year
Progression Free Survival (PFS) after the ATIMP intravenous administration
1 year
Time to Progression (TTP)
Time Frame: 1 year
Time to Progression (TTP) after the ATIMP intravenous administration
1 year
Overall survival
Time Frame: 1 year
Overall Survival after the ATIMP intravenous administration
1 year
Objective response rate
Time Frame: 1 year
Based on cross-sectional imaging after the ATIMP intravenous administration
1 year

Collaborators and Investigators

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

Sponsor

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)

July 23, 2025

Primary Completion (Estimated)

July 1, 2028

Study Completion (Estimated)

July 1, 2042

Study Registration Dates

First Submitted

August 3, 2026

First Submitted That Met QC Criteria

August 3, 2026

First Posted (Actual)

August 7, 2026

Study Record Updates

Last Update Posted (Actual)

August 7, 2026

Last Update Submitted That Met QC Criteria

August 3, 2026

Last Verified

August 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • UCL/150859

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

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.