Before receiving the immunotherapy, patients underwent a procedure known as lymphodepletion. This preparatory chemotherapy regimen clears out the patient’s existing immune cells, essentially "making room" for the newly infused therapeutic CAR-T cells to expand, multiply, and begin their search-and-destroy mission against the cancer.
The results among the evaluable patients were striking. Of the 11 patients who could be fully assessed following the treatment at the target dose, the overall response rate reached 91%. This means that nearly every patient in that group saw a significant reduction in their cancer burden or showed no remaining signs of the disease. Specifically, eight out of those 11 patients (72.7%) achieved a complete remission.
"These response and remission rates—ranging from 70%-90% of patients—are much higher than we would expect from standard-of-care for this cancer type, which typically leads to remission in only 20%-40% of patients," said Armin Ghobadi, MD, the study’s first and corresponding author. Ghobadi is a professor of medicine and the clinical director of the Center for Gene and Cellular Immunotherapy at WashU Medicine. "These responses are remarkable because the patients in this trial had run out of options. They had very aggressive cancers return after several lines of therapy, including several who relapsed after an earlier stem cell transplant."
Perhaps most importantly, the therapy allowed several patients to stabilize long enough to undergo a stem cell transplant. At the time of the study’s data cutoff, six patients who moved on to a transplant remained in remission, with no evidence of disease, six to 12 months after the procedure. This "bridge-to-transplant" capability is vital, as many patients with aggressive leukemia are often too sick or have too high a disease burden to survive the transplant process without first achieving a state of remission.
Safety and Side Effect Management
While the efficacy of WU-CART-007 was high, the researchers also closely monitored the side effects common to CAR-T cell therapies. The most frequent adverse event was cytokine release syndrome (CRS), which occurred in 88.5% of the patients. CRS is a systemic inflammatory response triggered when the infused CAR-T cells become highly active and release a flood of cytokines into the bloodstream.
Most cases of CRS in the trial were classified as mild or moderate, though approximately 19% of patients experienced more severe symptoms. These symptoms can include high fevers, low blood pressure, and respiratory issues, but they were generally manageable with existing medical protocols. A smaller subset of patients experienced rarer side effects, including neurotoxicity syndrome and low-grade graft-versus-host disease (GvHD). Two patients in the study passed away due to complications from their cancer or treatment-related infections, underscoring the high-risk nature of both the disease and the intensive therapeutic interventions required to treat it.
Off-the-shelf cell therapy
One of the most significant technological breakthroughs of the WU-CART-007 therapy is its "universal" or "off-the-shelf" nature. Most currently approved CAR-T therapies are autologous, meaning they are manufactured using a patient’s own blood cells. This requires a logistical odyssey: cells must be collected from the patient, shipped to a central manufacturing facility, genetically engineered over several weeks, and then shipped back to the hospital for infusion. For patients with rapidly progressing T-cell leukemia, this three-to-six-week wait time can be a death sentence.
