CD22-directed CAR T-cell therapy induces complete remissions in CD19-directed CAR-refractory large B-cell lymphoma

Abstract

The prognosis of patients with large B-cell lymphoma (LBCL) that progresses after treatment with chimeric antigen receptor (CAR) T-cell therapy targeting CD19 (CAR19) is poor. We report on the first 3 consecutive patients with autologous CAR19-refractory LBCL who were treated with a single infusion of autologous 1 × 106 CAR+ T cells per kilogram targeting CD22 (CAR22) as part of a phase 1 dose-escalation study. CAR22 therapy was relatively well tolerated, without any observed nonhematologic adverse events higher than grade 2. After infusion, all 3 patients achieved complete remission, with all responses continuing at the time of last follow-up (mean, 7.8 months; range, 6-9.3). Circulating CAR22 cells demonstrated robust expansion (peak range, 85.4-350 cells per microliter), and persisted beyond 3 months in all patients with continued radiographic responses and corresponding decreases in circulating tumor DNA beyond 6 months after infusion. Further accrual at a higher dose level in this phase 1 dose-escalation study is ongoing and will explore the role of this therapy in patients in whom prior CAR T-cell therapies have failed. This trial is registered on clinicaltrials.gov as #NCT04088890.

Conflict of interest statement

Conflict-of-interest disclosure: P.S. has received research support from Kite Pharma-Gilead. A.R.R. has received research support from Pharmacyclics/AbbVie, served on 1-time ad hoc scientific advisory boards of Nohla Therapeutics and Kaleido, and was an expert witness for the U.S. Department of Justice. His brother works for Johnson & Johnson. C.L.M. has consulted for Lyell, Neoimmune Tech, Nektar, and Apricity; has received royalties from NIH and Juno Therapeutics for CD22-CAR; holds equity in Lyell and Apricity; and has received research support from Lyell. D.B.M. has consulted for Kite Pharma-Gilead, Juno Therapeutics-Celgene, Novartis, Janssen, and Pharmacyclics and has received research support from Kite Pharma-Gilead, Allogene, Pharmacyclics, Miltenyi Biotec, and Adaptive Biotechnologies. S.S. has consulted for Janssen. C.M., A.J., and I.K. are full-time employees of Adaptive Biotechnologies. S.A.F. has consulted for Lonza PerMed, Gradalis, Obsidian, and Samsara BioCapital; L.M. has received research support from Adaptive Biotechnologies and Servier Laboratories and has consulted for Amgen and Pfizer. The remaining authors declare no competing financial interests.

© 2021 by The American Society of Hematology.

Figures

Graphical abstract

Figure 1.

Protocol schema and assessment of target antigen expression CAR22 therapy. (A) Overview of the trial design, including enrollment, manufacturing of autologous CD22-directed CAR T cells, administration of the therapy, and follow-up monitoring. Patients had safety assessments performed and blood samples drawn at each arrow after infusion, for assessment of correlative biomarkers, and underwent clinical and radiographic response assessment at each blue arrow. The green arrow indicates the time period during which CAR-FACS, RT-PCR, and cytokines were collected at all specified time points. (B) Gating strategy and (C) flow cytometry histograms of CD19 and CD22 expression for each patient before CAR22 therapy. After CAR19 therapy, P1 demonstrated preserved CD19 expression, whereas P2 had heterogeneous and downregulated CD19 expression. In all 3 patients, CD22 expression was preserved at high levels. (D) Serial biopsy specimens of P3 showing CD19 downregulation after CAR19 therapy, then complete loss of CD19 expression after CAR20.19 therapy. Original IHC image magnification ×40. Anti-CD19 antibody clone BT51E (murine monoclonal, Leica #PA0843). Anti-CD22 antibody clone FPC1 (murine monoclonal, Leica #PA0249). CAR19, anti-CD19 CAR T-cell therapy; CAR20.19, anti-CD19, anti-CD20 tandem CAR T-cell therapy; CAR-FACS, high dimensional flow cytometry immunophenotyping of peripheral blood, including identification of CAR+ cells; DLT, dose-limiting toxicity; FSC-A, forward scatter area; IHC, immunohistochemistry; MNC, mononuclear cell; PET-CT, composite positron emission tomographic-computed tomographic imaging; qRT-PCR, quantitative reverse transcriptase-polymerase chain reaction for identification of CAR transgene copies in peripheral blood; SAE, severe adverse event; SSC-A, side scatter area.

Figure 2.

CAR22 cells expand and persist in vivo and induce complete clinical responses associated with reductions in ctDNA. (A) Maximum-intensity projections (MIPs) and PET-CT composite cross-sectional imaging for primary index lesions at specified assessment time points after infusion of CAR22 therapy. Two-dimensional MIP images are shown on the left of each panel, with blue arrows indicating index lesions shown in the cross-sectional imaging to the right. Response classifications at each time point are according to Lugano criteria. (B) Swimmer plot demonstrating late conversion of PR to CR in P1 and P2, as well as durability compared with prior CAR19 responses of P1 and P3. (C) ctDNA levels were consistently reduced after CAR22 therapy. CAR+ T-cell expansion and persistence as measured by flow cytometry (D) and quantitative PCR (E) measurements in all patients. CD8+ T cells were the predominant subset expanding in vivo, and CAR+ cells remained detectable in circulation up to 6 months. APH, apheresis; D28, day 28 after infusion; M3, day 90 after infusion; M6, day 180 after infusion; M9, day 270 after infusion; PD, progressive disease; PRE, preinfusion/baseline assessment; Pre-LD, pre-lymphodepletion chemotherapy; SD, stable disease.