Pilot Study of T-APCs Following CAR T Cell Immunotherapy for CD19+ Leukemia

NCT ID: NCT03186118

Last Updated: 2025-06-17

Basic Information

• Recruitment Status: ACTIVE_NOT_RECRUITING
• Clinical Phase: PHASE1
• Total Enrollment: 30 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2017-08-04
• Study Completion Date: 2033-07-31

Brief Summary

Patients with relapsed or refractory CD 19+ leukemia who have achieved remission after CD19 CAR-T cell treatment sometimes relapse because the CD 19 CAR-T cells decrease in number over time. Study PLAT-03 will test whether administering T cell antigen presenting cells (T-APCs) at intervals following treatment with CAR-T cells improves CD 19 CAR-T cell persistence and reduces the incidence of leukemia relapse.

Detailed Description

This pilot study seeks to examine the feasibility and safety of administering T cell antigen presenting cells (T-APCs) designed to reactivate and numerically expand CD19-specific CAR T cells. The underlying hypothesis to be examined is that after remission is achieved with CAR T cell treatment, the duration, magnitude, and activation state of persisting memory CAR T cells impact on the potential for durable leukemia eradication. This is of particular relevance in two groups of patients we have identified: those who are predicted to lose persistence of their CAR T cells before Day 63, and those who have definitively lost persistence of CAR T cells prior to 6 months. By providing these patients with episodic exposure to T-APCs capable of activating CD19-specific CAR T cells for proliferation and redistribution to tissue beds where tumor cells of ALL seed, ideally over several months following remission induction, it is posited that the incidence of disease relapse will be diminished.

Conditions

CD 19+ Acute Leukemia

Study Design

• Allocation Method: NON_RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: NONE

Study Groups

Cohort A

Participants will receive CD19-targeting CAR T cells. Participants who have a total CD19 antigen load in bone marrow of \<15% will be assigned to Cohort A, to receive up to 6 T-APC treatments.

Group Type: EXPERIMENTAL

T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC)

Intervention Type: BIOLOGICAL

Autologous CD4 and CD8 T cells transduced to express a truncated CD19 (CD19t) Transgene

Cohort B

Participants will receive CD19-targeting CAR T cells. Participants for whom laboratory testing on Study Day 14 indicates they are at risk for early loss of CAR T cells will be assigned to Cohort B to receive up to 6 T-APC treatments. If laboratory testing prior to planned T-APC treatment indicates loss of CAR-T cells, participants may move to Cohort C.

Group Type: EXPERIMENTAL

T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC)

Intervention Type: BIOLOGICAL

Autologous CD4 and CD8 T cells transduced to express a truncated CD19 (CD19t) Transgene

Cohort C

Participants will receive CD19-targeting CAR T cells. Participants for whom laboratory testing shows loss of CAR T cells within 6 months will be assigned to Cohort C. They will receive another CAR T cell infusion followed by up to 6 T-APC treatments.

Group Type: EXPERIMENTAL

T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC)

Intervention Type: BIOLOGICAL

Autologous CD4 and CD8 T cells transduced to express a truncated CD19 (CD19t) Transgene

Cohort D

Participants will receive CD19-targeting CAR T cells. Participants who do not meet assignment rules for Cohorts A, B, or C will be followed after CAR T cell infusion in Cohort D.

Group Type: EXPERIMENTAL

T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC)

Intervention Type: BIOLOGICAL

Autologous CD4 and CD8 T cells transduced to express a truncated CD19 (CD19t) Transgene

Interventions

T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC)

Autologous CD4 and CD8 T cells transduced to express a truncated CD19 (CD19t) Transgene

Intervention Type: BIOLOGICAL

Other Intervention Names

CD19+ Chimeric Antigen Receptor T-cells (CAR-T cells)

Eligibility Criteria

Inclusion Criteria

• Diagnosis of recurrent or refractory CD19+ leukemia
• Adequate performance status
• Able to tolerate apheresis, including placement of temporary apheresis line if required
• Adequate renal, liver, cardiac, and respiratory function
• Adequate absolute lymphocyte count
• HIV negative; Hepatitis B and C negative within 3 months prior to enrollment.

Exclusion Criteria

• Evidence of active clinically significant CNS dysfunction
• Evidence of active malignancy other than CD19+ malignancy
• Evidence of active GVHD, or on immunosuppressive GVHD therapy within 4 weeks prior to enrollment

• Minimum Eligible Age: 1 Year
• Maximum Eligible Age: 30 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Seattle Children's Hospital

OTHER

Sponsor Role: lead

Responsible Party

Colleen Annesley

Medical Director, Seattle Children's Therapeutics

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Colleen Annesley, MD

Role: STUDY_CHAIR

Seattle Children's Hospital

Locations

Seattle Children's Hospital

Seattle, Washington, United States

Countries

United States

References

Annesley C, Seidel K, Wu Q, Summers C, Wayne AS, Pulsipher MA, Agrawal AK, Brown CT, Mgebroff S, Lindgren C, Rawlings-Rhea S, Huang W, Wilson AL, Jensen MC, Park JR, Gardner RA. Outcomes of PLAT-02 and PLAT-03: evaluating CD19 CAR T-cell therapy and CD19-expressing T-APC support in pediatric B-ALL. Blood. 2025 Aug 14;146(7):789-801. doi: 10.1182/blood.2025028359.

Reference Type: DERIVED

PMID: 40233328 (View on PubMed)

Other Identifiers

PLAT-03

Identifier Type: -

Identifier Source: org_study_id