Seattle Children’s doctors and researchers are leading efforts to better treat leukemia in children and young adults by boosting the immune system with immunotherapy.

Immunotherapy is a new cancer treatment that stimulates the immune system to better fight disease. It is also known as targeted therapy or biotherapy. Our research studies include Phase 1 and Phase 2 clinical trials. These trials are paving the way for other steps that may turn immunotherapy into a standard treatment for childhood leukemia, and someday even a cure.

A trial at Seattle Children’s is testing T-cell therapy in children and young adults with relapsed or refractory acute lymphoblastic leukemia (ALL) who are not likely to survive with current treatments. This trial is known as Pediatric Leukemia Adoptive Therapy (PLAT-02).

Doctors hope that when this new therapy is fully tested:

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

Is T-cell therapy effective?

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

In June 2016, Seattle Children's announced that 39 of 42 patients treated in the Phase 1 PLAT-02 clinical trial achieved complete remission.

  • This 93% remission rate was confirmed by highly sensitive tests designed to detect minute amounts of cancer cells.
  • The 39 patients who have achieved complete remission included children with very high tumor burdens as well as children who were diagnosed with ALL as infants. Patients treated in the trial had less than a 20% chance of survival upon enrollment using current treatments.
  • Another key finding from Phase 1 is that of the patients who achieved initial remission, about 50% are still in remission 1 year after therapy. Some are still in remission more than 2 years after therapy. For the patients who relapsed, researchers have found that their reprogrammed T cells are no longer present or the cancer has evolved to circumvent the T cells.
  • Phase 2 of the PLAT-02 trial aims to enroll 70 patients and began June 2016.

Dr. Rebecca Gardner, lead investigator for the trial, presented the Phase 1 results at the American Society for Clinical Oncology (ASCO) Annual Meeting on June 5, 2016. Read more.

  • T cells are white blood cells in the immune system that fight infection. In T-cell therapy, T cells are taken from the child’s own blood. Using laboratory techniques, we reprogram the T cells to recognize cancer cells, and we grow the reprogrammed T cells into billions of cells. When returned to the child’s body, the T cells seek out and destroy cancer cells without harming normal, healthy cells.

    Our doctors hope T-cell therapy will transform care for some childhood cancers, making treatment more effective, in less time, with milder side effects. We develop clinical trials of novel therapies like this so we can continue to provide the highest level of care for each child.

    Discover a World Without Childhood Cancer

    Watch Dr. Michael Jensen describe this new immunotherapy treatment for childhood cancer.

What is the goal of the study?

PLAT-02 is a Phase 1 and Phase 2 trial. 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 ALL?
  • What is the largest dose that children and young adults can stand (the maximum tolerated dose)?
  • Does T-cell therapy work against ALL?

Also, these clinical studies are meant to show that T cells taken from patients can be changed in the same way that T cells were changed in laboratory studies earlier.

Who can join the study?

The PLAT study is for children and young adults who:

  • Have relapsed or refractory acute lymphoblastic leukemia (ALL) or other CD19+ acute leukemia – not other leukemias or other childhood cancers
  • Are ages 1 to 26 years old

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.

Do you have trials for other childhood cancers?

We are currently enrolling patients in a Phase 1 clinical trial testing T-cell therapy in children and adolescents with recurrent or refractory neuroblastoma.

Who is leading the trials?

Dr. Rebecca Gardner is leading the PLAT study. She is a doctor in the Cancer and Blood Disorders Center at Seattle Children’s Hospital, and an investigator in the Ben Towne Center for Childhood Cancer Research at Seattle Children’s Research Institute.

PLAT-02 uses a method developed by Dr. Michael Jensen of the Ben Towne Center for Childhood Cancer Research.

Contact Us

For more information, please call 206-987-2106 or send us an email.

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New Cure. New Hope.

Strong Against Cancer logo Through our Strong Against Cancer initiative, we’re leading the fight against childhood cancer with new immunotherapy treatments. Learn how you can get involved.