Shahrzad Afazel

Natalizumab therapy decreases surface expression of both VLA-heterodimer subunits on peripheral blood mononuclear cells

Natalizumab interferes with immune cell migration into the central nervous system via blocking the alpha-4 subunit of very-late activation antigen-4 (VLA-4). Occurrence of rare but serious progressive multifocal leukoencephalopathy during prolonged natalizumab therapy of multiple sclerosis (MS) calls for a more detailed understanding of potential coeffects. We longitudinally studied alpha-4 and beta-1 surface levels on blood cells from 18 MS patients by flow cytometry. Expectedly, detectability of natalizumab-blocked alpha-4 was diminished on all investigated cell subsets. In addition, we report a concurrent and significant decrease of beta-1 surface levels on T-cells, B-cells, natural killer cells, and natural killer T cells, but not on monocytes. Uncovering secondary effects of natalizumab is mandatory to increase safety in MS therapy.

Lymphocyte Subsets Show Different Response Patterns to In Vivo Bound Natalizumab—A Flow Cytometric Study on Patients with Multiple Sclerosis

Natalizumab is an effective monoclonal antibody therapy for the treatment of relapsing- remitting multiple sclerosis (RRMS) and interferes with immune cell migration into the central nervous system by blocking the α4 subunit of very-late activation antigen-4 (VLA-4). Although well tolerated and very effective, some patients still suffer from relapses in spite of natalizumab therapy or from unwanted side effects like progressive multifocal leukoencephalopathy (PML). In search of a routine-qualified biomarker on the effectiveness of natalizumab therapy we applied flow cytometry and analyzed natalizumab binding to α4 and α4 integrin surface levels on T-cells, B-cells, natural killer (NK) cells, and NKT cells from 26 RRMS patients under up to 72 weeks of therapy. Four-weekly infusions of natalizumab resulted in a significant and sustained increase of lymphocyte-bound natalizumab (p<0.001) which was paralleled by a significant decrease in detectability of the α4 integrin subunit on all lymphocyte subsets (p<0.001). We observed pronounced natalizumab accumulations on T and B cells at single measurements in all patients who reported clinical disease activity (n = 4). The natalizumab binding capacity of in vitro saturated lymphocytes collected during therapy was strongly diminished compared to treatment-naive cells indicating a therapy-induced reduction of α4. Summing up, this pilot study shows that flow cytometry is a useful method to monitor natalizumab binding to lymphocytes from RRMS patients under therapy. Investigating natalizumab binding provides an opportunity to evaluate the molecular level of effectiveness of natalizumab therapy in individual patients. In combination with natalizumab saturation experiments, it possibly even provides a means of studying the feasability of patient-tailored infusion intervals. A routine-qualified biomarker on the basis of individual natalizumab saturation on lymphocyte subsets might be an effective tool to improve treatment safety.

High interindividual variability in the CD4/CD8 T cell ratio and natalizumab concentration levels in the cerebrospinal fluid of patients with multiple sclerosis

Strongly decreased leucocyte counts and a reduced CD4/CD8 T cell ratio in the cerebrospinal fluid (CSF) of natalizumab (NZB)‐treated multiple sclerosis (MS) patients may have implications on central nervous (CNS) immune surveillance. With regard to NZB‐associated progressive multi‐focal leucoencephalopathy, we aimed at delineating a relationship between free NZB, cell‐bound NZB, adhesion molecule (AM) expression and the treatment‐associated shift in the CSF T cell ratio. Peripheral blood (PB) and CSF T cells from 15 NZB‐treated MS patients, and CSF T cells from 10 patients with non‐inflammatory neurological diseases and five newly diagnosed MS patients were studied. Intercellular adhesion molecule‐1 (ICAM‐1), leucocyte function antigen‐1 (LFA‐1), very late activation antigen‐4 (VLA‐4), NZB saturation levels, and T cell ratios were analysed by flow cytometry. NZB concentrations were measured by enzyme‐linked immunosorbent assay (ELISA). Lower NZB saturation levels (P < 0·02) and a higher surface expression of ICAM‐1 and LFA‐1 (P < 0·001) were observed on CSF CD8 T cells. CSF T cell ratios (0·3–2·1) and NZB concentrations (0·01–0·42 µg/ml) showed a pronounced interindividual variance. A correlation between free NZB, cell‐bound NZB or AM expression levels and the CSF T cell ratio was not found. Extremely low NZB concentrations and a normalized CSF T cell ratio were observed in one case. The differential NZB saturation and AM expression of CSF CD8 T cells may contribute to their relative enrichment in the CSF. The reduced CSF T cell ratio appeared sensitive to steady‐state NZB levels, as normalization occurred quickly. The latter may be important concerning a fast reconstitution of CNS immune surveillance.

Adaptive Immune Responses in a Multiple Sclerosis Patient with Acute Varicella-Zoster Virus Reactivation during Treatment with Fingolimod

Fingolimod, an oral sphingosine 1-phosphate (S1P) receptor modulator, is approved for the treatment of relapsing forms of multiple sclerosis (MS). The interference with S1P signaling leads to retention particularly of chemokine receptor-7 (CCR7) expressing T cells in lymph nodes. The immunological basis of varicella zoster virus (VZV) infections during fingolimod treatment is unclear. Here, we studied the dynamics of systemic and intrathecal immune responses associated with symptomatic VZV reactivation including cessation of fingolimod and initiation of antiviral therapy. Key features in peripheral blood were an about two-fold increase of VZV-specific IgG at diagnosis of VZV reactivation as compared to the previous months, a relative enrichment of effector CD4+ T cells (36% versus mean 12% in controls), and an accelerated reconstitution of absolute lymphocytes counts including a normalized CD4+/CD8+ ratio and reappearance of CCR7+ T cells. In cerebrospinal fluid (CSF) the lymphocytic pleocytosis and CD4+/CD8+ ratios at diagnosis of reactivation and after nine days of fingolimod discontinuation remained unchanged. During this time CCR7+ T cells were not observed in CSF. Further research into fingolimod-associated VZV reactivation and immune reconstitution is mandatory to prevent morbidity and mortality associated with this potentially life-threatening condition.

From natalizumab to fingolimod in eight weeks - Immunological, clinical, and radiological data in quest of the optimal switch.

Natalizumab (NZB) discontinuation during a treatment change is associated with recurrence of disease activity in a significant proportion of multiple sclerosis (MS) patients. The immunological basis why disease reactivation occurs in selected patients is unresolved. In search of a prognostic biomarker for a safe and effective transition from NZB to fingolimod, we monitored five parameters related to pharmacokinetic and pharmacodynamic effects of the two drugs in 12 MS patients until six months on fingolimod. Clearance of free and cell-bound NZB, re-expression of alpha-4, and fingolimod-mediated changes on CD8+ and CD4+ T cell subsets showed pronounced interindividual variability. Higher frequencies of memory CD8+ T cells after six months on fingolimod were the sole association with disease reactivation. None of the investigated parameters thus had potential as prognostic biomarker for the outcome of the switch. Our findings rather support the thesis of broad interindividual differences in the immunopathogenesis of MS.

Clinical decision rules for the use of liquor diagnostics in hospitalized neurology patients reduced costs without affecting clinical outcomes.

OBJECTIVES Excessive use of laboratory diagnostics has been common. This study aimed to evaluate whether clinical decision rules for the use of liquor diagnostics would enable cost containment without affecting medical care. METHODS This was a single-center, retrospective, cost-minimization study based on the records of all 16,319 patients hospitalized and discharged at a Neurology Clinic in Austria between 2004 and 2006. Cost of liquor diagnostics, discharge diagnosis, duration of hospital stay, and mortality were compared along the line before, during, and after implementation of decision rules in mid-2005. RESULTS There were no significant changes in patient characteristics over time, not in the diagnoses at discharge, nor in the percentage of patients undergoing liquor diagnostics. The average number of tests per patient significantly decreased. Standard tests largely replaced serological tests for infections, regardless of diagnosis. Annual costs for liquor diagnostics decreased by 32.9 percent. Overall, the duration of hospital stay and mortality significantly decreased as well; however, differences were not significant for any single diagnosis-related group. CONCLUSIONS Diagnostic algorithms may allow cost containment without affecting medical care.

Serial flow cytometric analyses of blood and cerebrospinal fluid in natalizumab‐associated progressive multifocal leukencephalopathy with an excellent outcome

We report on a 43-year-old male patient. The first diagnosis of multiple sclerosis (MS) was assessed at the age of 30 years. Disease progression under firstline treatment with interferon beta 1-a (44 lg) indicated escalation therapy with natalizumab in June 2007. Henceforward, the patient was free from clinical disease activity and remained stable on an Expanded Disability Status Scale of 4. With detection of John Cunningham virus antibodies in the serum in 2011 and treatment duration of more than 2 years, the risk of suffering progressive multifocal leukencephalopathy (PML) increased with further treatment. Because of the excellent clinical response, this risk was accepted with the consent of the patient after detailed information was given to him. An increase in gait disturbance in February 2013 was the reason for an unscheduled admission to the Department of Neurology, Christian-DopplerKlinik, Salzburg, Austria. Magnetic resonance imaging (MRI) showed an atypical lesion in the cerebellum (Fig. 1). Detection of John Cunningham virus DNA in the cerebrospinal fluid (CSF) by polymerase chain reaction led to the diagnosis of natalizumabassociated PML. Immune phenotyping showed the typical inversed CD4/CD8 T-cell ratio in the CSF reflective of natalizumab effects behind the blood– brain barrier (Fig. 2). We carried out serial plasma exchanges (PLEX) to accelerate immune reconstitution, and monitored natalizumab desaturation of lymphocytes by flow

Routine-taugliche durchflusszytometrische Methode zur Identifikation von Multiple Sklerose PatientInnen mit einer nicht ausreichenden Therapieeffizienz unter einer Natalizumab-Therapie

Zusammenfassung Einleitung: Neutralisierende Antikörper gegen Natalizumab (NAB) kommen in 9% der mit Natalizumab behandelten Multiple Sklerose (MS) PatientInnen vor. Dies ist assoziiert mit einer verminderten Wirksamkeit von Natalizumab und in der Folge muss bei PatientInnen mit persistierenden NAB die Behandlung mit Natalizumab beendet werden. Ziel: Da hohe Titer an NAB stark mit persistierenden NAB assoziiert sind, haben wir untersucht, ob die durchflusszytometrische Bestimmung der Sättigung des Alpha-4-Integrins mit Natalizumab das Potenzial hat, PatientInnen mit NAB früher zu identifizieren. Methoden: Zellgebundenes Natalizumab und Natalizumab-Sättigung des Alpha-4 Integrins auf T-Zellen wurden mittels Durchflusszytometrie unter Verwendung eines monoklonalen anti-human IgG4 Antikörpers nachgewiesen. Mononukleäre Zellen wurden aus venösem Blut angereichert und bei PatientInnen mit NAB (n=4) 9 Monate lang alle 4 Wochen unmittelbar vor der nächsten Infusion und bei PatientInnen ohne NAB vor Beginn der Therapie und nach 1 (n=15), 2 (n=14), 3 (n=9), 6 (n=7) und 9 Monate (n=3) auf gebundenes Natalizumab untersucht. Der Natalizumab-Sättigungsgrad (in%) der T-Zellen wurde durch das ins Verhältnis Setzen von der mittleren Fluoreszenzintensität (MFI) von in vivo gebundenem Natalizumab mit der MFI von mit in vitro mit Natalizumab gesättigten Immunzellen bestimmt. Die Bestimmung der NAB aus dem Serum wurde mittels ELISA durchgeführt. Ergebnisse: Bei PatientInnen ohne NAB betrug die mittlere Natalizumab-Sättigung von T-Zellen über einen Zeitraum von 9 Monaten durchschnittlich 75% (95%iges Konfidenzintervall: 72–78%). Bei 2 der 4 PatientInnen mit NAB erreichte die Natalizumab-Sättigung der T-Zellen nach der ersten Infusion ca. 50% und fiel auf die Höhe des Ausgangsniveaus (Natalizumab-Sättigung vor Beginn der Therapie) nach der zweiten Infusion zurück. Im ELISA wurden niedrige NAB-Titer nach der ersten Infusion gemessen und die anschließende Entwicklung von anhaltend hoch titrigen NAB führte nach ca. 6 Monaten zum Abbruch der Therapie mit Natalizumab. Bei den zwei anderen PatientInnen betrug der Natalizumab-Sättigungsgrad der T-Zellen 74% und 68% nach der ersten Infusion, und ging danach vorübergehend auf das Ausgangsniveau zurück. Bei beiden PatintInnen erholten sich die Natalizumab-Sättigungen nach ca. 6 Monaten wieder. NAB wurden nach 2 bzw. 3 Monaten nachgewiesen und waren nach ca. 5 bis 6 Monaten wieder verschwunden. Schlussfolgerungen: Die Überwachung der Natalizumab-Sättigung auf T-Zellen ist eine schnelle und zuverlässige Methode, um PatientInnen zu identifizieren, bei denen aufgrund von NAB Natalizumab nur vermindert wirken kann. Beides, hoch- und niedrig titrige NAB, reduzieren gleichermaßen effektiv die zelluläre Natalizumab-Sättigung. Interessanterweise zeigte die mittels Durchflusszytometrie gemessene Natalizumab-Sättigung, dass dieses Verfahren sehr empfindlich ist, da die NAB anscheinend länger wirksam sind, als die Nachweisgrenze des ELISA vermuten lässt.

A routine-qualified flow cytometric method for the identification of multiple sclerosis patients with a reduced therapeutic effectiveness of natalizumab

Abstract Background: Natalizumab-neutralizing antibodies (NABs) occur in 9% of natalizumab-treated multiple sclerosis (MS) patients. Loss of clinical and biological efficacy in patients with persisting NABs requires termination of natalizumab treatment. Because high-titer NABs are strongly associated with persistence of NABs, we investigated if determination of natalizumab saturation levels of α-4 integrins by flow cytometry has the potential to identify patients early with NABs. Methods: Cell-bound natalizumab and natalizumab saturation of α-4 integrins on T cells were detected by flow cytometry using a monoclonal anti-human IgG4 antibody. Peripheral blood mononuclear cells were enriched from venous blood collected at the start (baseline) and every 4 weeks immediately before subsequent infusions until up to 9 months from natalizumab-treated patients with NABs (n=4) and at the start and after 1 (n=15), 2 (n=14), 3 (n=9), 6 (n=7), and 9 months (n=3) from natalizumab-treated patients without NABs. Natalizumab saturation levels (in %) of T cells were determined by relating median fluorescence intensities (MFIs) of in vivo bound natalizumab to MFIs after in vitro incubation with saturating amounts of natalizumab. Determination of serum NABs was performed by ELISA. Results: In patients without NABs, the median natalizumab saturation level of T cells over 9 months was 75% (confidence interval of 95%: 72–78%). In two of the four patients with NABs, the natalizumab saturation level of T cells only reached approximately 50% after the first infusion and further declined to baseline levels with the second infusion. Low-titer NABs were measured after the first infusion and development of persistent high-titer NABs led to termination of natalizumab treatment after 6 months. In another two patients, the natalizumab saturation level of T cells was 74% and 68% after the first infusion, temporarily decreased to approximately baseline levels and re-increased after approximately 6 months. Transient NABs were detected after 2 and 3 months, which resolved after 5 and 6 months. Conclusions: Monitoring the natalizumab saturation level on T cells is a fast and reliable method to identify patients with a reduced treatment effect due to NABs. Both high- and low-titer NABs were equally effective in reducing cellular natalizumab saturation levels. We were able to show that monitoring the natalizumab saturation levels by flow cytometry, is a sensitive method for detecting a prolonged NAB-mediated reduced treatment effect because NABs are apparently effective longer than suggested by the detection limit of ELISA.

Flow cytometry and drug-monitoring of natalizumab saturation of immune cells in multiple sclerosis1)

Abstract Background: Natalizumab (Tysabri) is a blocking antibody specific to the α-4 integrin subunit and can be detected on the surface of immune cells by flow cytometry. We investigated if the determination of natalizumab saturation of immune cells has the potential to act as a biomarker for treatment effectiveness in multiple sclerosis (MS). Methods: Natalizumab saturation of immune cells from 11 patients was measured before the start of treatment and after 4, 8, and 12 weeks of natalizumab therapy on T cells (CD3+) and T cell subsets [naive (CD45RA+/memory (CD45R0+) CD4+ and CD8+] by flow cytometry. Results: At weeks 4, 8, and 12 the average (n=9) natalizumab saturation of T cells approximated 80%. One patient with natalizumab neutralizing antibodies (NABs) and another patient with irregular infusion intervals were identified by abnormalities in the natalizumab saturation of cells. Different α-4 expression levels of T cell subpopulations were irrelevant to measuring cellular natalizumab saturation. Conclusions: We showed that monitoring natalizumab saturation of T cells by flow cytometry is a useful and routine-qualified method to identify patients with a reduced treatment effect due to NABs or irregular infusion intervals. Further studies to determine a cut-off value for suboptimal natalizumab saturation of immune cells will also show the potential of this parameter concerning more individualized treatment schedules. Considering the risk of opportunistic infections it is very important to increase the safety of this highly effective MS therapy.