Partial or complete responses were noted in 81.5%, or 18 of 22 evaluable patients, including 10 (45.5%) who had complete remission. In the subset of nine patients who had failed both ibrutinib and venetoclax, that overall response rate was a “very impressive” 89% (eight of nine patients), said Dr. Siddiqi, including 67% complete remissions (six patients).
Undetectable minimal residual disease (MRD) was reported in 65% and 75% of patients, depending on the method used to evaluate it.
About two-thirds of the patients had responses by day 30 evaluation, and responses deepened over time in about one-quarter, according to Dr. Siddiqi. Of 12 patients with a response at 6 months, 10 (83%) were still in response at 9 months, and 8 patients have been in response for 12 months or longer, she reported.
Neurologic adverse events seen in the CLL/SLL patients in this study were associated with higher lymph node tumor burden, and increased levels of interleukin(IL)-16 or tumor necrosis factor (TNF), according to further analysis presented by Dr. Siddiqi.
That raises the possibility that IL-16 or TNF may be a “good predictive biomarker” for neurotoxicity, which seems to be driven at least in part by lymphadenopathy. “If there was a way that we could combine the CAR T-cell with something like a novel agent that can shrink the tumor burden quickly, then maybe we can have even less toxicities with these CAR T cells,” Dr. Siddiqi said.
Dr. Siddiqi reported disclosures related to Kite, TG Therapeutics, Celgene, Janssen, Seattle Genetics, AstraZeneca, PCYC, Juno Therapeutics, and BeiGene.
SOURCE: Siddiqi T et al. ASH 2019, Abstract 503.