The phase 1/2 TRANSCEND CLL 004 trial represents “the first pivotal multicenter trial to evaluate a CAR T-cell therapy in heavily pretreated patients with relapsed or refractory chronic lymphocytic leukemia or small lymphocytic lymphoma,” first author Tanya Siddiqi, MD, associate professor in the division of lymphoma, City of Hope National Medical Center, Duarte, Calif., said in a press statement in connection with her presentation at the annual meeting of the American Society of Clinical Oncology.
“The durable complete responses observed with liso-cel in the TRANSCEND CLL 004 trial are remarkable and represent a major step in bringing a personalized, T cell–based treatment approach delivered as a one-time infusion into clinical practice for a complex and historically incurable disease,” she said.
Real-world evidence shows that patients with CLL or SLL who have relapsed or are refractory to treatment with BTKi therapy can have progressively worse outcomes. Moreover, with few other treatment options, research shows that the median time from dual discontinuation of BTKi and venetoclax to subsequent treatment failure or death is just 5.6 months.
“We are seeing a subset of patients now who are progressing on BTK inhibitors and venetoclax, and there is a high, unmet medical need for new, more effective treatments in this patient population,” Dr. Siddiqi said.
With liso-cel showing efficacy in the treatment of large B-cell lymphoma and receiving approval from the Food and Drug Administration for the indication, the multicenter TRANSCEND CLL 004 trial was launched to investigate the therapy’s effects in r/r CLL/SLL.
In a safety set of 117 patients with r/r CLL or SLL who received at least two prior lines of therapy, including a BTKi, patients received a single target dose of either 50 (n=9) or 100 × 106 (n = 87) CAR-positive T cells.
The primary efficacy analysis set included 49 patients who were treated with the target dose of 100 x 106 CAR-positive viable T cells of liso-cel.
With a median on-study follow-up of 21.1 months, the primary endpoint of a complete response (CR) and complete response was achieved among 18.4% (n = 9; P = .0006).
Among patients achieving a complete response, no disease progression or deaths were reported, with a median duration of response that was not reached.
The undetectable minimal residual disease (MRD) rate was 63.3% in blood and 59.2% in bone marrow, which was associated with progression-free survival.
The overall response rate was 42.9%, which was not statistically significant, and the median duration of an objective response was 35.3 months (95% confidence interval, 11.01 to not reached).
The median time to first response was 1.2 months, and the median time to first complete response was 3.0 months.
The results were consistent in the broader safety set of 117 patients, including those who were heavily pretreated with a median of five prior lines of therapy (range, 2-12) and high-risk disease, with a CR rate of 18.4%.
In terms of safety, no new safety signals were observed, and the treatment’s safety profile was manageable, the authors noted.
Cytokine release syndrome (CRS), common with CAR T-cell therapy, occurred in 85% of patients; however, most cases were low grade; 9% of cases were grade 3, and there were no grade 4 or 5 cases.
Neurologic events occurred among 45%, including grade 3 in 17.9% and grade 4 in 0.9%, with no cases of grade 5.
For treatment of the CRS, 69.2% of patients received tocilizumab and/or corticosteroids for the cases of CRS and neurological events.
Of 51 deaths that occurred while on the study, 43 occurred following liso-cel infusion, including 5 caused by treatment-emergent adverse events occurring within 90 days of liso-cel infusion.
One death was determined to be related to liso-cel, involving macrophage activation syndrome–hemophagocytic lymphohistiocytosis.
“The safety profile was manageable, with low rates of grade 3 or higher CRS and neurotoxicity,” Dr. Siddiqi said.
She noted that, as encouraging as the results are, work should continue regarding further improving survival for patients.
“We need to look at this population more closely to see how we can make it even better for them,” she said in her talk.
For instance, “do we need to add maintenance, or do we need to do something else with CAR T therapy? Because one shot of CAR T is buying them a lot of time – 6 or 12 months of progression-free survival, but maybe we can make it even better.”
Dr. Siddiqi noted that she has “a lot of patients” who received CAR T-cell therapy who have not progressed or relapsed after as long as 4 years.
“I also have some patients who did relapse at 3 or 3 and 1/2 years, but everybody is so thankful for having that time of several years without any treatment; without the need for continuous therapy or continuous doctors’ visits. It is actually priceless,” she said.