ORLANDO – KTE-X19, an anti-CD19 chimeric antigen receptor (CAR) T-cell therapy, demonstrated unprecedented efficacy in the ZUMA-2 trial, according to an investigator involved in the study.
KTE-X19 produced a 93% overall response rate in patients with relapsed/refractory mantle cell lymphoma (MCL). This is the highest reported response rate in patients who have failed treatment with a Bruton’s tyrosine kinase (BTK) inhibitor, said Michael L. Wang, MD, of the University of Texas MD Anderson Cancer Center in Houston.
Dr. Wang presented results from ZUMA-2 at the annual meeting of the American Society of Hematology.
“Patients with relapsed/refractory MCL have very poor outcomes,” Dr. Wang noted. “In patients who progress after BTK inhibition therapy, the overall response rate is only between 25% and 42%, and the overall survival is only between 6 and 10 months. Few patients proceed to allogeneic transplantation.”
The phase 2was designed to test KTE-X19 in these patients. KTE-X19 is an anti-CD19 CAR T-cell therapy containing a CD3-zeta T-cell activation domain and a CD28 signaling domain. KTE-X19 is distinct from axicabtagene ciloleucel (KTE-C19) because the manufacturing process for KTE-X19 removes circulating tumor cells.
The trial enrolled 74 patients, and 68 of them received KTE-X19. Manufacturing failed for three patients, two patients died of progressive disease before they could receive KTE-X19, and one patient was found to be ineligible for treatment.
The 68 patients had a median age of 65 years (range, 38-79 years), and 84% were men. A majority of patients (85%) had stage IV disease and classical (59%) or blastoid (25%) morphology. Most patients (69%) had a Ki-67 proliferation index of 50% or greater, and most (56%) were intermediate- or high-risk according to the Mantle Cell Lymphoma International Prognostic Index (MIPI).
Patients had received a median of three prior therapies (range, one to five). All had been treated with a BTK inhibitor, with 85% receiving ibrutinib, 24% receiving acalabrutinib, and 9% receiving both. Most patients (68%) were refractory to BTK inhibition, and 32% relapsed on or after BTK inhibitor therapy.