Alemtuzumab-induced immune phenotype and repertoire changes: implications for secondary autoimmunity

Abstract

Alemtuzumab is a monoclonal antibody that causes rapid depletion of CD52-expressing immune cells. It has proven to be highly efficacious in active relapsing–remitting multiple sclerosis; however, the high risk of secondary autoimmune disorders has greatly complicated its use. Thus, deeper insight into the pathophysiology of secondary autoimmunity and potential biomarkers is urgently needed. The most critical time points in the decision-making process for alemtuzumab therapy are before or at Month 12, where the ability to identify secondary autoimmunity risk would be instrumental. Therefore, we investigated components of blood and CSF of up to 106 multiple sclerosis patients before and after alemtuzumab treatment focusing on those critical time points. Consistent with previous reports, deep flow cytometric immune-cell profiling (n = 30) demonstrated major effects on adaptive rather than innate immunity, which favoured regulatory immune cell subsets within the repopulation. The longitudinally studied CSF compartment (n = 18) mainly mirrored the immunological effects observed in the periphery. Alemtuzumab-induced changes including increased numbers of naïve CD4+ T cells and B cells as well as a clonal renewal of CD4+ T- and B-cell repertoires were partly reminiscent of haematopoietic stem cell transplantation; in contrast, thymopoiesis was reduced and clonal renewal of T-cell repertoires after alemtuzumab was incomplete. Stratification for secondary autoimmunity did not show clear immununological cellular or proteomic traits or signatures associated with secondary autoimmunity. However, a restricted T-cell repertoire with hyperexpanded T-cell clones at baseline, which persisted and demonstrated further expansion at Month 12 by homeostatic proliferation, identified patients developing secondary autoimmune disorders (n = 7 without secondary autoimmunity versus n = 5 with secondary autoimmunity). Those processes were followed by an expansion of memory B-cell clones irrespective of persistence, which we detected shortly after the diagnosis of secondary autoimmune disease. In conclusion, our data demonstrate that (i) peripheral immunological alterations following alemtuzumab are mirrored by longitudinal changes in the CSF; (ii) incomplete T-cell repertoire renewal and reduced thymopoiesis contribute to a proautoimmune state after alemtuzumab; (iii) proteomics and surface immunological phenotyping do not identify patients at risk for secondary autoimmune disorders; (iv) homeostatic proliferation with disparate dynamics of clonal T- and B-cell expansions are associated with secondary autoimmunity; and (v) hyperexpanded T-cell clones at baseline and Month 12 may be used as a biomarker for the risk of alemtuzumab-induced autoimmunity.

Specific Patterns of Immune Cell Dynamics May Explain the Early Onset and Prolonged Efficacy of Cladribine Tablets

“…The reported secondary autoimmunities reported for alemtuzumab include glomerulonephritis, immune thrombocytopenia, sarcoidosis, thyroid autoimmunity, and vitiligo. 38 As previously suggested, the less pronounced effects of cladribine on T cells, particularly during the first few months after treatment, may be key, alongside the described immune cell dynamics of specific B-cell subsets, for the protection from secondary autoimmunity with cladribine tablets. 24 A recent in-depth immune phenotyping study 38 provided further evidence of alemtuzumab-induced changes to lymphocytes and the underlying immunologic processes involved in secondary autoimmunity.…”

“…The reported secondary autoimmunities reported for alemtuzumab include glomerulonephritis, immune thrombocytopenia, sarcoidosis, thyroid autoimmunity, and vitiligo. 38 …”

“…As previously suggested, the less pronounced effects of cladribine on T cells, particularly during the first few months after treatment, may be key, alongside the described immune cell dynamics of specific B-cell subsets, for the protection from secondary autoimmunity with cladribine tablets. 24 A recent in-depth immune phenotyping study 38 provided further evidence of alemtuzumab-induced changes to lymphocytes and the underlying immunologic processes involved in secondary autoimmunity. Autoimmunity after treatment with alemtuzumab is associated with homeostatic proliferation of T cells, and it has been suggested that this occurs in the context of a defective thymus.…”

Learning multiple sclerosis immunopathogenesis from anti-CD20 therapy

“…Promising examples of immune signatures using deep immune phenotyping approaches have been carried forward recently: Immunophenotyping of blood by mass cytometry identified a memory T helper cell population that correlated with treatment response of dimethyl fumarate in MS patients ( 21 ). While high-dimensionality blood immune flow cytometry profiles following CD52-depletion with alemtuzumab did not correlate with the risk of secondary autoimmune, T cell receptor analysis exhibited hyperexpanded T cell clones prior to treatment in the group that developed secondary autoimmunity ( 7 ).…”

“…The advent of specific immune therapies, with now 20 FDA-approved therapies, represents a crucial part of the tremendous advancement the modality of this disease has made over the last 20 y. Alongside significantly changing the natural disease course and fate of individuals affected, a stunning gain of knowledge in the field was generated applying a novel paradigm exemplifying reverse translational medicine: learning immunopathogenesis via therapeutic intervention ( 2 ). Prominent examples include insights gained from leukocyte trafficking interference with natalizumab (preventing migration of leukocytes into the central nervous system (CNS) via VLA-4 neutralization) ( 3 , 4 ), cladribine (reduction of B and T cells) ( 5 ), alemtuzumab (depletion of CD52 + immune cells) ( 6 , 7 ), and rituximab/ocrelizumab/ofatumumab/ublituximab (depletion of CD20 + immune cells) ( 8 – 11 ). Using samples from different compartments (mainly peripheral blood, cerebrospinal fluid, and CNS tissue) helped to unravel mechanisms of relapsing and nonrelapsing MS biology.…”