Montreal, April 18, 2023 - A team from CHU Sainte-Justine recently created cells to cure rare and resistant leukemias in children. Called ThINKK, these new cells provide hope for treating dozens of critically ill Canadian children, for whom traditional therapies do not work. Efforts are underway to make this treatment available in clinical trials as early as 2024, and the current preliminary results are exciting.

Obstacles and challenges of immunotherapy

Children with chemotherapy-resistant leukemia are typically treated with a combination of chemotherapy and immunotherapy. Aggressive chemotherapy is initially administered to reduce the number of cancer cells. Then, a bone marrow transplant is performed to use the donor's immune system to activate the "killer" cells (Natural Killers – NK) and to make the final assault on the cancer.

NK must be activated by immune sentinel cells in order to work as effectively as possible. However, these cells disappear after the transplant. While the presence of sentinel cells enhances the work of NK cells, it does pose another risk: that of also activating other immune cells that will attack the body of the young patient, with a risk of serious complications.

ThINKK cells: an innovation with encouraging results

Faced with this challenge, Dr. Michel Duval, Head of the Hematology-Oncology Department at CHU Sainte-Justine, decided to cultivate new cells from cord blood, which is collected after the birth of a child and sent to a dedicated bank at Héma-Québec. These cells are similar to sentinels, but they only activate the NK, the cancer killers. The results are astounding: "There is no more effective way to activate NK cells against leukemia than ours," proudly states Dr. Duval.

Preclinical cell trials show that this treatment is effective for several types of leukemia, including lymphoblastic leukemia, myeloid leukemia and neuroblastoma. For example, in the preclinical model of myeloid leukemia, 80% of cases were cured when ThINKK cells were administered. This therapy seems to work even for particularly severe cases: "We managed to destroy leukemia cells from a patient who had one of the most aggressive myeloid leukemias I’ve ever seen in my career," says Dr. Duval. Preclinical tests are also being carried out to confirm the potential for treating osteosarcoma.

Administration to patients starting in 2024

Plans are underway to obtain approval from Health Canada and the U.S. Food and Drug Administration to initiate a Phase 1 clinical trial in 2024. Already, with the support of valuable collaborators, a technology transfer has begun and a specialized plant in Edmonton is producing these novel cells. "I would like to thank all those involved this project, in particular the Fondation Charles-Bruneau and the CHU Sainte-Justine Research Centre, who believed in this project even in the most difficult moments. Thanks to their support and trust, the hope of a cure for the hundreds of Canadian children with these types of cancers is finally becoming a reality," says Dr. Duval.

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