A high percentage of chronic lymphocytic leukemia patients saw their tumors shrink after an infusion of experimental CAR T-cell immunotherapy.
Chronic lymphocytic leukemia (CLL) is a type of cancer that starts from lymphocytes in the bone marrow. In a small, early phase trial, a high percentage of patients who had exhausted most traditional treatments for chronic lymphocytic leukemia saw their tumors shrink or even disappear after an infusion of a highly targeted, experimental CAR T-cell immunotherapy developed at Seattle's Fred Hutchinson Cancer Research Center. Fred Hutch researchers presented their findings at the American Society of Hematology Annual Meeting and Exposition in San Diego.
‘Chronic lymphocytic leukemia patients who had exhausted most traditional treatments saw their tumors shrink or even disappear after an infusion of a highly targeted, experimental CAR T-cell immunotherapy.’
Almost all of the 24 patients in the study had cancer that had
advanced despite treatment with a newly approved drug called ibrutinib -
an ominous indicator for patient survival. Most patients also had
chromosomal markers in their leukemia cells that put them at high risk -
"predictors of a bad response to most standard therapies," said Dr.
Cameron Turtle, a hematologist/oncologist in the Clinical Research
Division at Fred Hutch who co-leads the trial with colleagues Drs. David
Maloney and Stanley Riddell.Turtle's presentation will focus on the results in a subgroup of patients who received the CAR T-cell infusion using preferred chemotherapy and CAR T-cell doses that evolved from recent trial data. Fourteen of the 19 restaged patients experienced a partial or complete regression of the disease in their lymph nodes. Of the 17 who had leukemia in their marrow when they enrolled in the trial, 15 saw the marrow become cancer-free after receiving CAR T-cells.
"These are all heavily pretreated patients who've gone through many previous therapies," Turtle said. "It's very pleasing to see patients with refractory disease respond like this."
Participants with the highest number of CAR T-cells in their blood after infusion were the most likely to have their disease disappear from bone marrow after CAR T-cell infusion. Side effects included high fevers, due to activation of CAR T-cells, and neurologic symptoms. Although one patient died from severe toxicity, the side effects experienced by other patients in the study were temporary.
Turtle and his colleagues identified certain biomarkers in patients' blood the day after infusion that were associated with the later development of the most severe toxicities. The researchers hope these biomarkers could eventually lead to tests to predict and mitigate the most serious side effects.
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CD19 CAR T-cell studies at Fred Hutch are unique because the researchers engineer specific subsets of cells from the patient and formulate the cell product to be uniform. By creating CAR T-cells with a defined composition of T cell subsets, the researchers can improve the link between the dose of cells a patient receives and what they experience afterward - not just benefits, but also potential side effects.
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Source-Eurekalert