Anti-CD19 CAR-T cells are effective in severe idiopathic Lambert-Eaton myasthenic syndrome

Abstract

Lambert-Eaton myasthenic syndrome (LEMS) is an autoantibody-mediated disease of the neuromuscular junction characterized by muscular weakness. Autoantibodies to presynaptic P/Q-type voltage-gated calcium channels (VGCCs) induce defective neuromuscular function. In severe cases, current immunosuppressive and immunomodulatory treatment strategies are often insufficient. First reports show beneficial effects of anti-CD19 chimeric antigen receptor (CAR)-T cell therapy in patients with autoantibody-mediated myasthenia gravis. We report a patient with isolated idiopathic LEMS treated with autologous anti-CD19-CAR-T cells. In this patient, CAR-T infusion leads to expansion of predominantly CD4⁺ CAR-T cells with a terminally differentiated effector memory cells re-expressing CD45RA (TEMRA)-like phenotype indicating cytotoxic capabilities and subsequent B cell depletion. VGCC antibody titers decrease, resulting in a clinical improvement of LEMS symptoms, e.g., 8-fold increase in walking distance. The patient does not show relevant side effects except for cytokine release syndrome grade 2 and intermittent neutropenia suggesting that anti-CD19 CAR-T cell therapy may be a treatment option in patients with LEMS.

Keywords: B cell autoimmunity; CAR-T cells; CD19; Lambert-Eaton myasthenic syndrome; P/Q-type; VGCC; autoantibody; chimeric antigen receptor; myasthenia gravis; neuroimmunological disorder.

Graphical abstract

Figure 1

Patient history and disease course of severe LEMS (A) As a key electrophysiological finding in LEMS, compound muscle action potential shows a significant increase after exercise (increment). (B) Schematic timeline including disease course, antibody detection, treatment approaches, and CAR-T cell infusion (KYV-101).

Figure 2

CAR-T cell expansion and B cell depletion after anti-CD19 CAR-T cell infusion (A) Schematic presentation of second-generation KYV-101 CAR construct containing a fully human CD19-binding domain (scFv), CD8α hinge and transmembrane domains, a CD28 costimulatory, and a CD3ζ chain domain. (B) Left: CAR-T cell expansion shows a peak on day 7 after CAR-T cell infusion. Brown: total CAR-T cells, yellow: CD4⁺ CAR-T cells, green: CD8⁺ CAR-T cells. Right: total lymphocyte count. (C) Fluorescence-activated cell sorting pseudocolor dot plots of vital CD3⁺ CAR⁺ T cells (CAR+) at several time points between day 5 and day 20 after CAR-T cell infusion. 100% stacked bar graphs indicate ratio between CD4⁺ (yellow) and CD8⁺ (green) CAR⁺ T cells. (D) Percentage ratio of CD25⁺ cells among CD4⁺ CAR⁺ T cells. (E) Percentage ratio of CD25⁺ cells among CD8⁺ CAR⁺ T cells. (F) B cell count showing B cell depletion from day 1 to day 37 following CAR-T cell infusion and subsequent repopulation. Day 0, time point of CAR-T cell infusion; scFv, single-chain fragment variable; TM, transmembrane. Green areas in (B) and (F) represent reference normal values.

Figure 3

CD4⁺ CD19 CAR-T cells show a Th1-like and a high-effector TEMRA-like phenotype (A) Flow cytometric analysis of patient’s isolated mononuclear cells. Anti-CD19-CAR⁺ CD3⁺ T cells (CAR-T cells) were subdivided into CD4⁺ and CD8⁺ T cells and analyzed for CXCR3 expression. The graph shows mean fluorescence intensity (MFI) for total CAR-T cells, as well as CD4⁺ and CD8⁺ CAR-T cells from day 1 to day 29 after CAR-T infusion. (B) Exemplary pseudocolor dot plot illustrating differentiation of CAR-T cells into central memory (CD45RA⁻CCR7⁺), effector memory (CD45RA⁻CCR7⁻), naive (CD45RA⁺CCR7⁺), and terminally differentiated effector cells re-expressing CD45RA (TEMRA, CD45RA⁺CCR7⁻). (C) Bar graphs show distribution of T cell subtypes as gated in (B) from day 1–20 after CAR-T cell infusion for CD8⁺ CAR⁺ T cells, CD4⁺ CAR⁺ T cells. (D) Bar graphs show the distribution of T cell subtypes as gated in (B) from day 1 to day 20 after CAR-T cell infusion for CD4⁺ CAR⁻ T cells. Day 0, time point of CAR-T cell infusion. TEMRA, terminal-differentiated effector memory cells re-expressing CD45RA.

Figure 4

LEMS symptoms improve upon anti-CD19 CAR-T cell treatment (A–H) Time course of QMG score (A), Besinger score (B), and MG-ADL score (C). Higher scores indicate more severe disease activity. Time course of walking distance with support walker (D), leg-holding time (E), and arm-holding time (F). VGCC antibody (G) and TPO antibody (H) levels before and after CAR-T cell infusion. Day 0, time point of CAR-T cell infusion. QMG, quantitative myasthenia gravis; MG-ADL, myasthenia gravis activities of daily living; VGCC, voltage-gated calcium channel; Abs, antibodies; TPO, thyroid peroxidase. Green areas in (G) and (H) represent reference normal values.