GPC3 CAR T Cells With IL-15 and IL-21 for Recurrent ATRT and CNS Rhabdoid Tumors (RADIANT)

Conditions

• Atypical Teratoid Rhabdoid Tumor
• Central Nervous System Rhabdoid Tumor

Eligibility Criteria

Sex

ALL

Age

1 Year - 21 Years

Healthy Volunteers

Not accepted

Interventions

• 21.15.GPC3-CAR T Cells — BIOLOGICAL
  Autologous T cells genetically engineered using retroviral vectors encoding a GPC3-specific CAR and IL-15 and IL-21 cytokines. The product also includes an inducible caspase-9 safety switch allowing pharmacologic elimination of the CAR T cells in the event of severe toxicity.

Study Details

This study is being conducted in patients with GPC3-positive brain tumors that have recurred or have not responded to standard therapy. Atypical teratoid rhabdoid tumors (ATRT) are aggressive tumors with poor outcomes and limited treatment options, particularly in young children. There is a need for new therapies that can improve outcomes while minimizing toxicity. This study evaluates a new experimental treatment using genetically engineered T cells (RADIANT-T cells) that target glypican-3 (GPC3), a protein expressed on tumor cells. These T cells are modified to express a chimeric antigen receptor (CAR) targeting GPC3, along with IL-15 and IL-21 to enhance their persistence and activity. The cells also include an inducible safety mechanism (iCasp9) that allows them to be eliminated if necessary. The purpose of this study is to determine the highest safe dose of RADIANT-T cells, evaluate their safety and side effects, assess how long they persist in the body, and determine whether they show anti-tumor activity in patients with GPC3-positive brain tumors.

Key Dates

Start date

Sep 1, 2026

Status verified

Apr 2026

Primary completion

Oct 31, 2029

Completion

Oct 31, 2044

Study Design

Enrollment

21 participants (estimated)

Allocation

NA

Intervention model

SINGLE_GROUP

Primary purpose

TREATMENT

Arms

• Experimental: Treatment with 21.15.GPC3-CAR T Cell Therapy (RADIANT CAR T Cells)
  Participants will receive autologous 21.15.GPC3-CAR T cells administered intratumorally into the tumor resection cavity and/or intracerebroventricularly via an Ommaya reservoir. CAR T cells are genetically engineered using retroviral vectors encoding a GPC3-specific chimeric antigen receptor and cytokines IL-15 and IL-21. The following dose levels of CAR T cells will be evaluated: * DL0: 1 × 10⁷ CAR T cells * DL1: 3 × 10⁷ CAR T cells * DL2: 5 × 10⁷ CAR T cells * DL3: 1 × 10⁸ CAR T cells If dose de-escalation from DL1 is required, patients will be treated at DL0. Further de-escalation may use half-log reductions if needed. Dose escalation will occur only after safety evaluation of prior cohorts.

Primary Outcome Measure

Number of Participants with Dose-Limiting Toxicity [ Time Frame: 4 weeks after CAR T-cell administration ]

Central Contacts

• David Steffin, MD
  (832) 824-4233
  [email protected]
• Ramy Sweiden
  [email protected]

Locations (1)

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