BK virus-specific T cells for immunotherapy of progressive multifocal leukoencephalopathy: an open-label, single-cohort pilot study

Abstract

Background: Progressive multifocal leukoencephalopathy, a rare disease of the CNS caused by JC virus and occurring in immunosuppressed people, is typically fatal unless adaptive immunity is restored. JC virus is a member of the human polyomavirus family and is closely related to the BK virus. We hypothesised that use of partly HLA-matched donor-derived BK virus-specific T cells for immunotherapy in progressive multifocal leukoencephalopathy would be feasible and safe.

Methods: We did an open-label, single-cohort pilot study in patients (aged 18 years or older) with clinically definite progressive multifocal leukoencephalopathy and disease progression in the previous month at the National Institutes of Health (NIH) Clinical Center (Bethesda, MD, USA). Overlapping peptide libraries derived from large T antigen and major capsid protein VP1 of BK virus with high sequence homology to JC virus counterparts were used to generate polyomavirus-specific T cells cross-recognising JC virus antigens. Polyomavirus-specific T cells were manufactured from peripheral blood mononuclear cells of first-degree relative donors aged 18 years or older. These cells were administered to patients by intravenous infusion at 1 × 10⁶ polyomavirus-specific T cells per kg, followed by up to two additional infusions at 2 × 10⁶ polyomavirus-specific T cells per kg. The primary endpoints were feasibility (no manufacturing failure based on meeting release criteria, achieving adequate numbers of cell product for clinical use, and showing measurable antiviral activity) and safety in all patients. The safety monitoring period was 28 days after each infusion. Patients were followed up with serial MRI for up to 12 months after the final infusion. This trial is registered at ClinicalTrials.gov, NCT02694783.

Findings: Between April 7, 2016, and Oct 19, 2018, 26 patients were screened, of whom 12 were confirmed eligible and received treatment derived from 14 matched donors. All administered polyomavirus-specific T cells met the release criteria and recognised cognate antigens in vitro. 12 patients received at least one infusion, ten received at least two, and seven received a total of three infusions. The median on-study follow-up was 109·5 days (range 23-699). All infusions were tolerated well, and no serious treatment-related adverse events were observed. Seven patients survived progressive multifocal leukoencephalopathy for longer than 1 year after the first infusion, whereas five died of progressive multifocal leukoencephalopathy within 3 months.

Interpretation: We showed that generation of polyomavirus-specific T cells from healthy related donors is feasible, and these cells can be safely used as an infusion for adoptive immunotherapy of progressive multifocal leukoencephalopathy. Although not powered to assess efficacy, our data provide additional support for this strategy as a potential life-saving therapy for some patients.

Funding: Intramural Research Program of the National Institute of Neurological Disorders and Stroke of the NIH.

Figure 1.

Trial schema. Candidate patients and donors were screened for study eligibility contemporaneously. Selected donors underwent leukapheresis, and PyVST cultures were initiated either from cryopreserved peripheral blood mononuclear cells or freshly isolated cells. Final cell product was harvested at Day 14. Patients returned for baseline study visit and confirmation of eligibility criteria. First dose of PyVST was administered at 1x10⁶ cells/kg followed by 28-day safety monitoring period with scheduled testing at Days 3, 7, 14 and 28. Patients were eligible for up to 2 additional doses of PyVST of 2x10⁶ cells/kg, no less than 28 days from last infusion; each additional infusion was followed by 28-day safety monitoring as previously. Patients were followed for up to 1 year after last infusion with scheduled clinic visits and testing.

Figure 2.

CONSORT diagram.

Figure 3.

Characterization of clinical allogeneic PyVST products derived from matched healthy donors. Peripheral blood mononuclear cells from healthy related donors were isolated from the apheresis product, stimulated with BK virus LT and VP1 pepmixes and expanded in G-rex tissue culture containers for 14 days. Upon harvest, as part of the release criteria, the resulting PyVST were enumerated, analyzed for identity, cellular content, and viability. Additionally, antiviral potency was assessed, measured by cytokine release. A. Expansion of PyVST cells as measured by absolute number of viable nucleated cells (left panel) and fold expansion relative to day 0 from the initiation of the culture (right panel). B. Composition and viability of the final PyVST products was evaluated by flow cytometry and trypan blue exclusion (respectively) on harvest (day 14 from the culture initiation). C. Antiviral activity of the final PyVST products in the viable CD3⁺, CD4⁺, and CD8⁺ T cell compartments was measured by intracellular staining for TNF-α and IFN-γ upon 6hr restimulation with BK virus LT and/or VP1 pepmixes in presence of brefeldin A and monesin using flow cytometry (infused products only shown). Unrelated pepmix was used as negative control.

Figure 4.

Comparison of survivors and non-survivors. CSF JCV load at baseline (A) and longitudinally over course of the trial (B) in non-survivors (NS), survivors (S), and the 5 patients who underwent screening but died of PML within a few weeks of first visit, prior to receiving treatment with PyVST. C. Longitudinal MRI PML lesion burden over course of trial in non-survivors (NS) and survivors (S). D. Cell composition of the PyVST products received by survivors (S) and non-survivors (NS). E. Potency of PyVST received by survivors (S) and non-survivors (NS), measured as TNF-α and IFN-γ secretion upon stimulation with indicated pepmixes. F and G. Antiviral reactivity within CD4⁺ and CD8⁺ T cell compartments of PyVST products received by survivors (S) and non-survivors (NS).