CD 19+ Acute LeukemiaPhase 1NCT03186118
Pilot Study of T-APCs Following CAR T Cell Immunotherapy for CD19+ Leukemia
A Phase 1 study testing T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC) in people with CD 19+ Acute Leukemia, run by Seattle Children's Hospital at 1 site in United States.
Trial 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. Read more about this study
- Who is it for?
- Ages 1 year to 30 years
- Conditions the study is for
- CD 19+ Acute Leukemia
- What is being tested?
- T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC)
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 30 participants
- Where
- 1 siteUnited States
- Study dates
- 4 Aug 2017to Jul 2033
- Phase
- Phase 1
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 1 year to 30 years
- All sexes
- No healthy volunteers
- Child, Adult
Who may be able to join
- 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.
Who cannot join
- 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
Trial locations and contacts
1 site in 1 country.
United States1 site
Seattle Children's Hospital
Seattle, Washington, 98105
About this study
Official title: 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
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.
Read the 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
- Being tested
- T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC)
- Keywords
- pediatric, young adult, acute lymphoblastic leukemia, CD 19, leukemia, chimeric antigen receptor, T cell
- Medical subject headings
- Precursor Cell Lymphoblastic Leukemia-Lymphoma, Leukemia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC)Biological
Also called CD19+ Chimeric Antigen Receptor T-cells (CAR-T cells)
Autologous CD4 and CD8 T cells transduced to express a truncated CD19 (CD19t) Transgene
| Study group | Role | What they receive |
|---|---|---|
| Cohort A | Experimental | 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. Receives: Biological: T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC) |
| Cohort B | Experimental | 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. Receives: Biological: T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC) |
| Cohort C | Experimental | 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. Receives: Biological: T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC) |
| Cohort D | Experimental | 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. Receives: Biological: T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC) |
What is being measured
The primary outcome is the main question the study is designed to answer.
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
Measured: up to 6 months
Determine the feasibility of deriving and administering a CD19t T-APC product
Proportion of products successfully manufactured and infused
Measured: 28 days
Secondary outcomes (2)
Quantification of changes in the number of CAR T cells in peripheral blood before and after receiving CD19t T-APCs
Multiparameter Flow Cytometry (MPF) from peripheral blood as a measure of magnitude and presence of CAR T cells before and after a dose of T-APCs
Measured: 6 months
Duration of B cell aplasia in CD19t T-APC treated patients
MPF from peripheral blood as a measure of B cell aplasia
Measured: up to 5 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted14 Jun 2017
- Study start4 Aug 2017
- Primary completion13 Sep 2021
- Study completionJul 2033 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for CD 19+ Acute LeukemiaStudies of the same condition, open and under way.
- More trials run by Seattle Children's HospitalThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 1
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Model description
- Subjects are assessed during the parent study for total CD 19 load in bone marrow. Participants meeting eligibility criteria are transitioned into one of 3 arms in PLAT-03.
- Masking
- None (open label)
- Enrolment
- 30 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Seattle Children's Hospital
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Colleen Annesley, Seattle Children's Hospital
- Investigators
- Colleen Annesley, MD, Study chair, Seattle Children's Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03186118
- Sponsor's protocol ID
- PLAT-03
- Status last verified
- Jun 2026
- First submitted
- 12 Jun 2017
- Last updated
- 5 Jun 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Publications
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.
PubMed 40233328
Study at a glance
From the registry record, last updated by the sponsor on 5 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- 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
- ClinicalTrials.gov ID
- NCT03186118
- Acronym / sponsor ID
- PLAT-03
- Conditions
- CD 19+ Acute Leukemia
- Keywords
- pediatric, young adult, acute lymphoblastic leukemia, CD 19, leukemia, chimeric antigen receptor, T cell
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 30 participants (estimated)
- Lead sponsor
- Seattle Children's HospitalUniversity, hospital or other
- Study start
- 4 Aug 2017 (actual)
- Primary completion
- 13 Sep 2021 (actual)
- Study completion
- Jul 2033 (estimated)
- First posted
- 14 Jun 2017 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 4
- Model description
- Subjects are assessed during the parent study for total CD 19 load in bone marrow. Participants meeting eligibility criteria are transitioned into one of 3 arms in PLAT-03.
| Arm | Type | Receives |
|---|---|---|
| Cohort A | Experimental | Biological: T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC)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. |
| Cohort B | Experimental | Biological: T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC)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. |
| Cohort C | Experimental | Biological: T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC)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. |
| Cohort D | Experimental | Biological: T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC)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. |
Who may qualify
- Ages
- 1 year to 30 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult
Key inclusion criteria (6 listed)
- 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
Key exclusion criteria (3 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC)Also: CD19+ Chimeric Antigen Receptor T-cells (CAR-T cells)Autologous CD4 and CD8 T cells transduced to express a truncated CD19 (CD19t) Transgene | Biological | Cohort A, Cohort B, Cohort C, Cohort D |
Primary outcome
The adverse events associated with one or multiple CD19t T-APC product infusions will be assessed.
Time frame: up to 6 months
Type, frequency, severity, and duration of adverse events will be summarized
Determine the feasibility of deriving and administering a CD19t T-APC product
Time frame: 28 days
Proportion of products successfully manufactured and infused
2 secondary outcomes
Quantification of changes in the number of CAR T cells in peripheral blood before and after receiving CD19t T-APCs
Time frame: 6 months
Duration of B cell aplasia in CD19t T-APC treated patients
Time frame: up to 5 years
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 5 Jun 2026.
- Derived from this study: PubMed 40233328Annesley 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.
Related trials for CD 19+ Acute Leukemia
Enrolling by invitationPhase 1/2
This is a Phase I/II Interventional, Open-label Treatment Study Designed to Evaluate the Safety and Efficacy of Anti CD 19/22 CAR- T Cells Immunotherapy for Adults With Relapsed or Refractory Acute Lymphoblastic Leukemia/Lymphoma.
Acute Lymphobkastic Leukemia, B Cell Lymphoma
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Colleen Annesley, MD study chair
Seattle Children's Hospital
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing T-cell Antigen Presenting Cells expressing truncated CD19 (T-APC) in people with CD 19+ Acute Leukemia, run by Seattle Children's Hospital at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 5 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
The adverse events associated with one or multiple CD19t T-APC product infusions will be assessed. (time frame: up to 6 months). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT03186118, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 5 Jun 2026.