Genetically reprogrammed T cells, which have been making waves in adult acute lymphocytic leukemia (ALL), have also shown promise in pediatric ALL patients, according to early results from the Pediatric Leukemia Adoptive Therapy-02 (PLAT-02) trial. The findings were presented by Michael C. Jensen, MD, director of Ben Towne Center for Childhood Cancer Research at Seattle Children’s Research Institute at the American Association for Cancer Research meeting.
In the PLAT-02 trial, researchers from the Seattle’s Children’s Hospital, led by principal investigator Rebecca Gardner, MD, administered reengineered chimeric antigen receptor (CAR) T cells to 22 pediatric patients with ALL who had either relapsed after a bone marrow transplantation or who were unable to achieve remission to proceed with a bone marrow transplantation – a patient group that has a 10 to 20 percent chance of survival with standard treatment.
Using highly sensitive tests to detect minute amounts of cancer cells, Dr. Gardner and colleagues confirmed that 20 of the 22 patients (91%) treated thus far in the clinical trial achieved complete remission.
“Some of our earliest treated patients are now one year post-therapy and are still in remission,” Dr. Gardner said. “These patients have remained in remission without further chemotherapy or other treatments. This gives us hope that, eventually, we will be able to use this therapy in patients who are newly diagnosed, reducing the need for toxic therapies and bone marrow transplant.”
The first phase of this trial was designed to investigate the safety of cancer immunotherapy. The second phase of the trial is slated to begin in late 2015 and will allow more patients to be treated.
“This study is helping direct us toward more targeted therapies for pediatric ALL, with the ultimate goal of more efficacy and less long-term toxicity,” Dr. Gardner told ASH Clinical News. Because of the limited follow-up, the long-term durability of the responses has not yet been demonstrated, but investigators are encouraged by the results. “As we learn more about the use of CD19 CAR therapy in pediatric ALL, I am hopeful that we can make this available sooner in the course of treatment, and hopefully move it into front-line therapy.”
Jensen MC. Advancing CAR T cell immunotherapy in pediatric oncology. Presented at the American Association for Cancer Research Annual Meeting, April 21, 2015.