Pediatric and Young Adult Leukemia Adoptive Therapy (PLAT)-03: A Pilot Feasibility and Safety Study of CD19t T-Antigen Presenting Cells (T-APCs) Following CAR T Cell Immunotherapy for CD19+ Leukemia
Sponsor study identifier
interventional
30
1 country
1
Study Start
August 4, 2017
Actual (reported)Primary Completion
September 13, 2021
Actual (reported)Study Completion
July 2033
EstimatedPlanned date reported by the registry; this milestone is not confirmed as achieved.
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.
Registry-reported information. Elapsed time and enrollment totals alone do not measure study progress or recruitment pace.
July 2033
EstimatedPlanned date reported by the registry; this milestone is not confirmed as achieved.
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Dates and qualifiers reported by the registry. Estimated dates do not confirm that a milestone has occurred.
June 12, 2017
Actual (reported)June 14, 2017
Actual (reported)August 4, 2017
Actual (reported)September 13, 2021
Actual (reported)July 2033
EstimatedPlanned date reported by the registry; this milestone is not confirmed as achieved.
The adverse events associated with one or multiple CD19t T-APC product infusions will be assessed.
Type, frequency, severity, and duration of adverse events will be summarized
up to 6 months
Determine the feasibility of deriving and administering a CD19t T-APC product
Proportion of products successfully manufactured and infused
28 days
Quantification of changes in the number of CAR T cells in peripheral blood before and after receiving CD19t T-APCs
6 months
Duration of B cell aplasia in CD19t T-APC treated patients
up to 5 years
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.
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.
Autologous CD4 and CD8 T cells transduced to express a truncated CD19 (CD19t) Transgene
Registry-reported names are shown in full. Names without a link have not yet been matched to a Syfrah profile.
Seattle Children's Hospital
Seattle, Washington, 98105, United States
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.
Colleen Annesley, MD
Seattle Children's Hospital
First Submitted
June 12, 2017
First Posted
June 14, 2017
Study Start
August 4, 2017
Actual (reported)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.
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.
Contact the study team to confirm eligibility.
Primary Completion
September 13, 2021
Actual (reported)Study Completion
July 2033
EstimatedPlanned date reported by the registry; this milestone is not confirmed as achieved.
Last Updated
June 5, 2026
Record last verified: 2026-06
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Source: ClinicalTrials.gov.
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