Read how cancer immunotherapy is already helping patients like Greta.
Promising preliminary results underscore validity of immunotherapy’s ability to cure cancer.
Dr. Michael Jensen announced promising preliminary results of Seattle Children’s cancer immunotherapy clinical trial at the American Association for Cancer Research Annual Meeting in April 2015. Twenty of the 22 patients who were treated with genetically reprogrammed T cells to fight relapsed acute lymphoblastic leukemia (ALL) had achieved complete remission at the time of Jensen’s announcement. The trial, known as Pediatric Leukemia Adoptive Therapy-02 (PLAT-02), continues to enroll patients.
The 91% remission rate in PLAT-02 mirrors results from other research groups around the country that are studying cancer immunotherapy. Their collective success underscores the likelihood that this approach will revolutionize the treatment of cancer.
In T-cell therapy, T cells are taken from the child’s own blood and reprogrammed in the laboratory so they can recognize cancer cells. After the reprogrammed T cells are grown into billions of cells, they are infused back into the patient where they seek out and destroy cancer cells without harming normal, healthy cells.
PLAT-02’s unique features
“Some of our earliest treated patients are now nearly two years post-therapy and still in remission,” says Dr. Rebecca Gardner, Seattle Children’s oncologist and the lead investigator of the trial. “That they’ve remained in remission without further chemotherapy or other treatments gives us hope that, eventually, we will be able to use this therapy in patients who are newly diagnosed, thus reducing the need for toxic therapies and bone marrow transplants.”
The PLAT-02 trial is only open to children and young adults who have relapsed or refractory ALL or other CD19 positive acute leukemia. Several infants with ALL participated in the study – a feature that distinguishes Seattle Children’s trial from the others around the country that had an age cutoff of 3 years old. The short-to-nonexistent wait list at Seattle Children’s attracted patients from around the country.
“Our ability to enroll patients soon after validating that they are eligible is important,” notes Gardner. “Some of these sick children just won’t make it if they have to wait three months to enroll.”
The team plans to publish a paper on the results of PLAT-02 in spring 2016, and is already laying the groundwork for two new trials studying how to maintain remission or regain it in case of relapse.
“Not all of the patients who went into remission have stayed in remission,” notes Gardner. “Of those who have relapsed, about half of them recur because their T cells went away and their leukemia comes back. The other half recurs with a CD19 negative leukemia, so it’s as if their leukemia cells figured out how to escape the T cells.”
PLAT-03 is aimed at enhancing the life span of the modified T cells and is expected to open in summer of 2016.
PLAT-04 will enroll a group of patients whose leukemia recurred with CD19 negative leukemia that can escape detection from the re-engineered T cells. A re-engineered T cell that will target CD19 and CD22 leukemia will be studied so that even if the cancer becomes CD19 negative, the T cells can still find the cancer cells. PLAT-04 is expected to open in 2017.
The 91% remission rate … underscores the likelihood that this approach will revolutionize the treatment of cancer.