Research and Clinical Trials

CAR T-Cell Immunotherapy Clinical Trials for Leukemia and Lymphoma

Seattle Children’s doctors and researchers are leaders in developing investigational chimeric antigen receptor (CAR) T-cell immunotherapies for children, teens and young adults with relapsed or refractory leukemia and lymphoma.

T-cell immunotherapy is an experimental cancer treatment that stimulates the immune system to fight disease.

Read more about how T-cell immunotherapy for leukemia and lymphoma works.

Food and Drug Administration (FDA)–authorized trials at Seattle Children’s are testing T-cell therapy in children and young adults with relapsed or refractory acute leukemia or lymphoma who are not likely to survive with current treatments.

These trials are known as Pediatric Leukemia Adoptive Therapy (PLAT). These trials, developed by Seattle Children’s Therapeutics, are testing chimeric antigen receptor (CAR) T-cell immunotherapy.

Doctors hope that when T-cell therapy is fully tested:

It will work quickly, so treatment takes weeks, not years.
It will have milder side effects than other treatments, like chemotherapy.

What is the goal of the CAR T-cell therapy for leukemia clinical trials?

PLAT includes phase 1 and phase 2 trials. Phase 1 trials focus on finding out how much of a therapy to give, how to give it, how often to give it and when side effects occur. Phase 2 trials look at whether a therapy is safe and whether it works in people who have a certain disease.

Through the PLAT studies, researchers are working to answer these questions:

Is T-cell therapy safe to give to children and young adults with relapsed or refractory acute leukemia or lymphoma?
What is the largest dose that children and young adults can stand (the maximum tolerated dose)?
Does T-cell therapy work against leukemia and lymphoma?

What is the process of the CAR T-cell therapy for leukemia clinical trials?

PLAT-07, phase 1/2 (targets CD22)

PLAT-07 is a first-in-human phase 1/2 clinical trial. In PLAT-07, the CAR T cells are reprogrammed to recognize and target the CD22 protein expressed by most B-cell types of leukemia and lymphoma.

PLAT-07 opened for enrollment in September 2020 and is currently recruiting.

Learn more about this and other clinical trials at Seattle Children's.
Read more about the PLAT-07 study protocol at ClinicalTrials.gov.
For more information, call 206-987-2106 or send us an email.

PLAT-08, phase 1, (targets CD33)

PLAT-08 is a phase 1 clinical trial open to children and young adults up to age 28 with relapsed or refractory acute myeloid leukemia. In PLAT-08, the CAR T cells are reprogrammed to recognize and target the CD33 protein.

PLAT-08 opened for enrollment in November 2021 and is currently enrolling.

Learn more about this and other clinical trials at Seattle Children's.
Read more about the PLAT-08 study protocol at ClinicalTrials.gov.
For more information, call 206-987-2106 or send us an email.

Additional leukemia/lymphoma clinical trials include:

JCAR017: This is an industry-sponsored trial studying the CD19-targeting CAR T cell, lisocabtagene maraleucel, in pediatric patients with relapsed and/or refractory B-ALL. Lisocabtagene maraleucel is FDA approved for some types of adult non-Hodgkin lymphoma.
NMDP CD33 CAR: This is a collaboration with the National Marrow Donor Program studying a CD33-targeting CAR T cell in pediatric patients with relapsed and/or refractory AML.

What is the success rate of T-cell therapy for leukemia and lymphoma?

The clinical trials needed to answer that question are ongoing, but early results are very promising.

In April 2017, Seattle Children's published in the scientific journal Blood that 40 of 43 patients treated in the phase 1 PLAT-02 clinical trial achieved complete initial remission.

This 93% remission rate was confirmed by highly sensitive tests designed to detect tiny amounts of cancer cells.
The 40 patients who have achieved complete remission included children with very high tumor burdens, as well as children who were diagnosed with acute lymphoblastic leukemia (ALL) as infants. When they started the clinical trial, patients had less than a 20% chance of survival using current treatments.
Of the patients who achieved initial remission, about 50% remained in remission 1 year after therapy. Some are still in remission more than 5 years after therapy. For the patients whose cancer came back, researchers have found that either their reprogrammed T cells are no longer in their body or the cancer cells have changed so that the T cells cannot find and destroy them.

Relapse is a challenge in CAR T-cell trials across the country. Seattle Children’s researchers are dedicated to improving the therapy with the goal of long-term remission for all patients and – ultimately – a cure. Based on what they learned from previous trials, our research team developed new PLAT trials to test innovative ways to cut the relapse rate.

Are there side effects of CAR T-cell immunotherapy for leukemia and lymphoma?

After patients receive an infusion of their reprogrammed T cells, some can experience a side effect called cytokine release syndrome (CRS). This usually involves a fever and changes in blood pressure. Other patients can experience neurological side effects that typically involve temporary confusion or being overly tired (lethargy). In rare cases, these side effects could be more severe.

Read about efforts to limit these side effects.

Who can join the leukemia and lymphoma clinical trials?

These studies are for children and young adults who:

Have relapsed or refractory leukemia and lymphoma that has failed standard therapies. To be eligible, the leukemia has to be either pre-B acute lymphoblastic leukemia (ALL) or other CD19+ or CD22+ acute leukemia or CD33+ acute myeloid leukemia. For lymphoma, it needs to express CD22. It is not open to young people with other leukemias or other childhood cancers.
Researchers use many other factors to decide whether a patient can take part in a study (inclusion criteria) or cannot take part (exclusion criteria). The study team at Seattle Children’s can explain what these factors mean for you or your child.

Are there clinical trials for other childhood cancers?

Brain and central nervous system tumors: BrainChild-03 and -04 are phase 1 clinical trials testing CAR T-cell therapy in children and adolescents with recurrent or refractory brain or central nervous system (CNS) tumors that express the proteins HER2, EGFR, B7-H3 or IL13Ra2.
Solid tumors: STRIvE-01 is a phase 1 clinical trial testing CAR T-cell therapy in children and young adults with relapsed or refractory solid tumors that express the protein EGFR or B7H3. ENLIGHTen-01 is a phase 1 feasibility and safety study of fluorescein-specific (FITC-E2) CAR T cells in combination with parenterally administered folate-fluorescein (UB-TT170) for osteosarcoma.
See many of Seattle Children's open clinical trials on our Current Research Studies page.
Or search by diagnosis for many clinical trials available through Seattle Children's and our partners on ClinicalTrials.gov. Read our guide about searching for trials on ClinicalTrials.gov (PDF).