SAN DIEGO – A second-generation CD19-specific “armored” chimeric antigen receptor (CAR) T-cell construct was associated with high complete remission rates in diffuse large B-cell lymphoma (DLBCL) and indolent non-Hodgkin lymphoma (NHL) in a phase 1 trial.
The CAR T construct – labeled 1928z-41BBL – also induced “encouraging” complete remission rates in patients with chronic lymphocytic leukemia (CLL) with Richter’s transformation, reported, of Memorial Sloan Kettering Cancer Center (MSKCC), New York, and his colleagues.
“Interestingly and encouragingly, severe [cytokine release syndrome] was not seen and grade 3 neurotoxicity was observed in less than 10%, with no grade 4 neurotoxicity, so there appears to be a favorable side effect profile,” Dr. Park said at the annual meeting of the American Society of Hematology.
Just as armored cars are designed to protect their valuable contents from people with bad intent, armored CAR T cells are engineered to protect the modified T-cells from a hostile tumor microenvironment and simultaneously recruit non-modified T cells to the target to produce a more robust immune response against malignant cells.
MSKCC investigators had previously shown that in contrast to other CAR T-cell constructs, the 1928z-41BBL configuration, which consists of two signaling domains (CD28 and CD3zeta) and the 4-1BB ligand, hit the sweet spot between tumor-killing function and T-cell persistence ().
In the current study, they enrolled 35 adults with relapsed or refractory CD19-positive hematologic malignancies, 29 of whom eventually underwent CAR T-cell infusions. The treated population comprised 14 patients with CLL (4 of whom had Richter’s transformation), 9 with DLBCL, 5 with indolent NHL, and 1 with acute lymphoblastic leukemia.
The patients with CLL had received a median of 5.5 prior lines of therapy, including ibrutinib (Imbruvica) and venetoclax (Venclexta).
There were 15 complete remissions (CR), with CR rates of 78% in DLBCL, 20% in CLL, 67% in CLL with Richter’s transformation, 60% in patients with indolent NHL, as well as CR in the single patient with ALL.
There were eight partial remissions. One patient with CLL had stable disease, and four patients had disease progression (one patient each with DLBCL, CLL, CLL with Richter’s, and indolent NHL).
Dr. Park noted that T cells are being detected in peripheral blood more than 6 months after T-cell infusion.
There were no cases of severe cytokine release syndrome, defined as requiring vasopressors and/or mechanical ventilation for hypoxia, and just three cases of grade 3 neurotoxicity. There were no cases of grade 4 neurotoxicity, no deaths related to neurotoxicity, and no cases of cerebral edema – a serious complication that has been seen in earlier CAR T-cell studies.
Split or multiple infusions of CAR T cells or incorporation of the technique into earlier lines of therapy might generate higher response rates, Dr. Park said.
The study was supported by Juno Therapeutics. Dr. Park reported consulting for and research funding from Juno, and financial relationships with other companies.
SOURCE: Park JH et al. ASH 2018, Abstract 224.