All complete responders with FL were still in remission at a median follow-up of 24 months, but the median duration of response was 10.2 months for patients with tFL.
Alexandre V. Hirayama, MD, of the Fred Hutchinson Cancer Research Center in Seattle, and colleagues reported these results in Blood.
The trial enrolled 21 adults with relapsed/refractory CD19+ B-cell malignancies, including 8 patients with FL and 13 with tFL. At baseline, the FL/tFL patients had a median age of 56 years (range, 51-62), and 67% were male. Most patients (n = 19) had stage III/IV disease, 17 had extranodal disease, 8 had bulky disease, and 6 had bone marrow involvement. The patients had received a median of 5 prior therapies (range, 2-8), and 13 had received a transplant.
In this study, patients received a lymphodepleting regimen of cyclophosphamide and fludarabine, followed by 2 x 106 CD19 CAR T cells/kg. Five patients (one with FL and four with tFL) also received bridging chemotherapy between leukapheresis and lymphodepletion.
Grade 1-2 cytokine release syndrome occurred in 50% of FL patients and 39% of tFL patients (P = .35). Grade 1-2 neurotoxicity occurred in 50% and 23%, respectively (P = .67). There were no cases of grade 3 or higher cytokine release syndrome or neurotoxicity.
Most FL patients (7 of 8; 88%) achieved a complete response (CR) to treatment, and all of these patients were still in CR at a median follow-up of 24 months (range, 5-37 months). One FL patient received a transplant while in CR.
Six of 13 tFL patients (46%) achieved a CR. At a median follow-up of 38 months (range, 3-39 months), the median duration of response was 10.2 months. The median progression-free survival was 11.2 months in patients who achieved a CR and 1.4 months in all tFL patients.
The researchers noted that peak CAR T-cell counts and the duration of CAR T-cell detection were similar between FL and tFL patients. However, tFL patients had higher serum interleukin-8 concentrations and higher lactate dehydrogenase levels before treatment.
Past research suggested that IL-8 mediates the recruitment of tumor-associated neutrophils, promotes diffuse large B-cell lymphoma progression, and can contribute to local immune suppression. Other studies have linked elevated lactate dehydrogenase to aggressive disease and a more immunosuppressive tumor microenvironment.
“Although these data raise the possibility that differences in the tumor microenvironment may, in part, contribute to differences in outcomes after CAR T-cell immunotherapy in FL and tFL patients, additional studies are required,” the researchers wrote.
This research was supported by the National Institutes of Health, the Life Science Discovery Fund, the Bezos family, the University of British Columbia Clinician Investigator Program, the Fred Hutchinson Cancer Research Center’s Immunotherapy Integrated Research Center, and Juno Therapeutics/Celgene.
The researchers disclosed relationships with Celgene, Juno Therapeutics, Lyell Immunopharma, Adaptive Biotechnologies, Nohla, Kite Pharma, Gilead, Genentech, Novartis, Eureka Therapeutics, Nektar Therapeutics, Caribou Biosciences, Precision Biosciences, Aptevo, Humanigen, and Allogene.
SOURCE: Hirayama AV et al. Blood. 2019 Jun 26. doi: 10.1182/blood.2019000905