Effect of Ocrelizumab on B- and T-Cell Receptor Repertoire Diversity in Patients With Relapsing Multiple Sclerosis From the Randomized Phase III OPERA Trial

BACKGROUND AND OBJECTIVES

The B cell-depleting anti-CD20 antibody ocrelizumab (OCR) effectively reduces MS disease activity and slows disability progression. Given the role of B cells as antigen-presenting cells, the primary goal of this study was to evaluate the effect of OCR on the T-cell receptor repertoire diversity.

METHODS

To examine whether OCR substantially alters the molecular diversity of the T-cell receptor repertoire, deep immune repertoire sequencing (RepSeq) of CD4⁺ and CD8⁺ T-cell receptor β-chain variable regions was performed on longitudinal blood samples. The IgM and IgG heavy chain variable region repertoire was also analyzed to characterize the residual B-cell repertoire under OCR treatment.

RESULTS

Peripheral blood samples for RepSeq were obtained from 8 patients with relapsing MS enrolled in the OPERA I trial over a period of up to 39 months. Four patients each were treated with OCR or interferon β1-a during the double-blind period of OPERA I. All patients received OCR during the open-label extension. The diversity of the CD4⁺/CD8⁺ T-cell repertoires remained unaffected in OCR-treated patients. The expected OCR-associated B-cell depletion was mirrored by reduced B-cell receptor diversity in peripheral blood and a shift in immunoglobulin gene usage. Despite deep B-cell depletion, longitudinal persistence of clonally related B-cells was observed.

DISCUSSION

Our data illustrate that the diversity of CD4⁺/CD8⁺ T-cell receptor repertoires remained unaltered in OCR-treated patients with relapsing MS. Persistence of a highly diverse T-cell repertoire suggests that aspects of adaptive immunity remain intact despite extended anti-CD20 therapy.

TRIAL REGISTRATION INFORMATION

This is a substudy (BE29353) of the OPERA I (WA21092; NCT01247324) trial. Date of registration, November 23, 2010; first patient enrollment, August 31, 2011.

Soluble TACI and soluble BCMA as biomarkers in primary central nervous system lymphoma

Background

B-cell survival is regulated through interactions of B-cell-activating factor and a proliferation-inducing ligand with their receptors transmembrane activator and CAML interactor (TACI) and B-cell maturation antigen (BCMA). We evaluated the diagnostic potential of soluble TACI (sTACI) and soluble BCMA (sBCMA) in CSF and serum as biomarkers in primary CNS lymphoma (PCNSL).

Methods

CSF (n = 176) and serum samples (n = 105) from patients with clinically or radiologically suspected PCNSL as well as from control patients were collected prospectively. Levels of sTACI and sBCMA were analyzed by enzyme-linked immunosorbent assay. Additionally, in patients with PCNSL, CSF was analyzed during disease course (time of diagnosis, n = 26; relapse, n = 10; remission, n = 14), and in 2 patients long-term longitudinal analysis was performed.

Results

Soluble TACI and sBCMA are significantly increased in patients with PCNSL (sTACI, median: 445 pg/mL; sBCMA, median: 760 pg/mL) compared with control patients (sTACI, median: 0 pg/mL; sBCMA, median: 290 pg/mL). At a cutoff value of 68.4 pg/mL, sTACI shows high sensitivity (87.9%) and specificity (88.3%) for the diagnosis of active PCNSL. Soluble BCMA is less sensitive (72.7%) and specific (71.8%) (cutoff: 460 pg/mL). When both markers are combined, specificity increases, however, at the cost of a lower sensitivity. In serum, both sTACI and sBCMA are not increased in PCNSL patients. Both soluble receptors correlate with clinical course and therapy response.

Conclusions

Our results suggest that sTACI and sBCMA in the CSF are promising new biomarkers for diagnosis and therapy monitoring in PCNSL. However, our findings need to be validated in an independent cohort.

The immunoregulator soluble TACI is released by ADAM10 and reflects B cell activation in autoimmunity

BAFF and a proliferation-inducing ligand (APRIL), which control B cell homeostasis, are therapeutic targets in autoimmune diseases. TACI-Fc (atacicept), a soluble fusion protein containing the extracellular domain of the BAFF-APRIL receptor TACI, was applied in clinical trials. However, disease activity in multiple sclerosis unexpectedly increased, whereas in systemic lupus erythematosus, atacicept was beneficial. In this study, we show that an endogenous soluble TACI (sTACI) exists in vivo. TACI proteolysis involved shedding by a disintegrin and metalloproteinase 10 releasing sTACI from activated B cells. The membrane-bound stub was subsequently cleaved by γ-secretase reducing ligand-independent signaling of the remaining C-terminal fragment. The shed ectodomain assembled ligand independently in a homotypic way. It functioned as a decoy receptor inhibiting BAFF- and APRIL-mediated B cell survival and NF-κB activation. We determined sTACI levels in autoimmune diseases with established hyperactivation of the BAFF-APRIL system. sTACI levels were elevated both in the cerebrospinal fluid of the brain-restricted autoimmune disease multiple sclerosis correlating with intrathecal IgG production, as well as in the serum of the systemic autoimmune disease systemic lupus erythematosus correlating with disease activity. Together, we show that TACI is sequentially processed by a disintegrin and metalloproteinase 10 and γ-secretase. The released sTACI is an immunoregulator that shares decoy functions with atacicept. It reflects systemic and compartmentalized B cell accumulation and activation.

Beta-blockade and brachial artery hemodynamics in hypertension

The effect of systemic adrenergic blockade on hypertensive brachial arteries was studied in humans with pulsed Doppler flowmetry. Blockade of beta-receptors by the nonselective beta-blocking agent propranolol did not modify the brachial artery diameter, whereas pindolol increased this parameter for the same degree of blood pressure reduction. The beta1-selective blocking agents atenolol and bisoprolol caused similar decreases in blood pressure and a reduction in the diameters of the brachial artery and abdominal aorta, respectively. The combination of alpha- and beta-blockade produced a rapid drop in blood pressure but did not change the brachial arterial diameter. Thus, following beta-blockade, the arterial diameter increased, did not change, or even decreased despite an adequate blood pressure reduction. It is suggested that beta-blockade in some instances resets the pressure-diameter curve and therefore has a direct action on the arterial wall independent of the mechanical effect of blood pressure reduction.

An indirect approach for the study of the elastic modulus of the brachial artery in patients with essential hypertension

An indirect approach for the study of the changes in the incremental circumferential modulus (E) of the brachial artery after arteriolar vasodilatation was undertaken in patients with sustained essential hypertension. The product of E and the thickness (h) of the arterial wall was evaluated by means of the Moens-Korteweg equation using determinations of brachioradial pulse wave velocity and brachial artery diameter with pulsed Doppler methods. In three homogeneous groups of patients with hypertension the Eh product was studied after vasodilatation caused either by nitrendipine, a calcium entry blocking agent, or by medroxalol, an alpha and beta blocking agent, or by isosorbid dinitrate. The three drugs caused similar reductions in blood pressure and increases in arterial diameter and hence decreases in wall thickness. Variance analysis for multigroups indicated that the decrease in Eh after vasodilatation was significant for nitrendipine but not for medroxalol and isosorbid dinitrate. Covariance analysis showed that for any level in Eh product the decrease in Eh was higher for nitrendipine than for isosorbid dinitrate and medroxalol. Since the three drugs had comparable mechanical and geometrical effects, the study provided evidence that, in men with essential hypertension, the smooth muscle tone of the brachial artery was significantly more sensitive to calcium inhibition than to autonomic blockade, causing a more important decrease in elastic modulus.