Acute promyelocytic leukemia in a patient with multiple sclerosis following treatment with mitoxantrone

Synergistic and complete reversal of the multidrug resistance of mitoxantrone hydrochloride by three-in-one multifunctional lipid-sodium glycocholate nanocarriers based on simultaneous BCRP and Bcl-2 inhibition

Multidrug resistance (MDR) is a severe obstacle to successful chemotherapy due to its complicated nature that involves multiple mechanisms, such as drug efflux by transporters (P-glycoprotein and breast cancer resistance protein, BCRP) and anti-apoptotic defense (B-cell lymphoma, Bcl-2). To synergistically and completely reverse MDR by simultaneous inhibition of pump and non-pump cellular resistance, three-in-one multifunctional lipid-sodium glycocholate (GcNa) nanocarriers (TMLGNs) have been designed for controlled co-delivery of water-soluble cationic mitoxantrone hydrochloride (MTO), cyclosporine A (CsA – BCRP inhibitor), and GcNa (Bcl-2 inhibitor). GcNa and dextran sulfate were incorporated as anionic compounds to enhance the encapsulation efficiency of MTO (up to 97.8%±1.9%) and sustain the release of cationic MTO by electrostatic interaction. The results of a series of in vitro and in vivo investigations indicated that the TMLGNs were taken up by the resistant cancer cells by an endocytosis pathway that escaped the efflux induced by BCRP, and the simultaneous release of CsA with MTO further efficiently inhibited the efflux of the released MTO by BCRP; meanwhile GcNa induced the apoptosis process, and an associated synergistic antitumor activity and reversion of MDR were achieved because the reversal index was almost 1.0.

Nanostructured lipid-carrageenan hybrid carriers (NLCCs) for controlled delivery of mitoxantrone hydrochloride to enhance anticancer activity bypassing the BCRP-mediated efflux

Novel nanostructured lipid-carrageenan hybrid carriers (NLCCs) were exploited for controlled delivery of water soluble chemotherapeutic agent mitoxantrone hydrochloride (MTO) with high loading capacity, sustained release property, and potential for improving oral bioavailability and antitumor efficacy. By introducing the negative polymer of carrageenan, MTO was highly incorporated into NLCCs with encapsulation efficiency of 95.8% by electrostatic interaction. In vivo pharmacokinetics of MTO solution (MTO-Sol) and MTO-NLCCs in rats demonstrated that the apparent bioavailability of MTO-NLCCs was increased to approximate 3.5-fold compared to that of MTO-Sol. The cytotoxicity investigations by MTT method indicated that NLCCs could significantly enhanced the antitumor efficacy against resistant MCF-7/MX cells. The relative cellular association of MTO-NLCCs was 9.2-fold higher than that of MTO-Sol in breast cancer resistance protein (BCRP) over-expressing MCF-7/MX cells, implying that BCRP-mediated drug efflux was diminished by the introduction of NLCCs. The endocytosis inhibition study implied that the NLCCs entered the MCF-7/MX cells by clathrin-mediated endocytosis process, which can bypass the efflux of MTO mediated by BCRP. The new developed NLCCs provide an effective strategy for oral delivery of water-soluble MTO with improved encapsulation efficiency, oral bioavailability, and cytotoxicity against resistant breast cancer cells.

Fetal risks related to the treatment of multiple sclerosis during pregnancy and breastfeeding

In women with multiple sclerosis, pregnancy does not have a long-term adverse effect on lifetime disability; however, there is an increased risk of relapses during the postpartum. Therapies taken during pregnancy may have adverse effects on pregnancy outcome. The small number of pregnancies included in most studies, particularly those evaluating the risks related to the administration of immunomodulating drugs, do not allow firm conclusions to be drawn with regards to their safety. Therefore, until more information regarding safety is available, glatiramer acetate, mitoxantrone and interferon-beta should be discontinued before an anticipated pregnancy. By contrast, glucocorticoids can be used to treat acute relapses during pregnancy.

Results from the 5-year, phase IV RENEW (Registry to Evaluate Novantrone Effects in Worsening Multiple Sclerosis) study

Background

Registry to Evaluate Novantrone Effects in Worsening Multiple Sclerosis (RENEW) was a 5-year, phase IV study in which the safety of Mitoxantrone was monitored in a patient cohort from the United States (US). The objective of the study was to evaluate the long-term safety profile of Mitoxantrone in patients with secondary progressive multiple sclerosis (SPMS), progressive relapsing multiple sclerosis (PRMS), and worsening relapsing-remitting multiple sclerosis (RRMS).

Methods

Overall, 509 patients (395 SPMS, 81 worsening RRMS, 33 PRMS) were enrolled and treated at 46 multiple sclerosis (MS) treatment centers located in the US. Patients received Mitoxantrone in accordance with the package insert every 3 months. During the treatment phase, patients received laboratory workups and cardiac monitoring every 3 months and then annually for a total of 5 years.

Results

Five hundred and nine subjects were enrolled in this trial and received at least one infusion of Mitoxantrone. Overall, 172 (33.8%) completed the 5-year trial (i.e., participated for 5 years ± 3 months [treatment + follow-up]); 337 (66.2%) did not complete the 5-year trial. Annual follow-up data were available for 250 of 509 enrolled patients. Left ventricular ejection fraction reduction under 50% was reported in 27 (5.3%) patients during the treatment phase (n = 509) and 14 (5.6%) patients during the annual follow-up phase (n = 250). Signs and symptoms of congestive heart failure were observed in 10 (2.0%) patients (six during treatment phase and four during the annual follow-up phase). Post-hoc analyses of the risk for cardiotoxicity outcomes revealed that cumulative dose exposure is the primary risk factor associated with the risk of cardiac toxicity with Mitoxantrone. Therapy-related leukemia was reported in three (0.6%) patients who received total cumulative Mitoxantrone doses of 73.5 mg/m², 107.3 mg/m², and 97.1 mg/m² respectively. During the treatment phase, persistent amenorrhea developed in 22% (28/128) of women with regular menses and 51% (25/49) of women with irregular menses at baseline. During the annual follow-up phase, persistent amenorrhea developed in 5% (4/73) of women with regular menses at baseline.

Conclusion

RENEW results are consistent with the known safety profile of Mitoxantrone, and provide additional long-term safety data for Mitoxantrone in MS patients.

Spectroscopic investigations of the molecular interaction of anticancer drug mitoxantrone with non-ionic surfactant micelles

Objectives

The aim of this study was to investigate the interaction of the anticancer drug mitoxantrone with non-ionic micelles, as simple model systems of biological membranes.

Methods

UV-VIS absorption spectroscopy was used to quantify the drug–surfactant micelle interactions in terms of the binding constant and the micelle–water partition coefficient of the drug.

Key findings

Interaction of mitoxantrone with non-ionic micelles reduces the dimerization process of mitoxantrone, the drug molecules being encapsulated into micelles as monomer. The strength of the interaction between mitoxantrone and non-ionic micelles is higher at pH 10 than at pH 7.4, and depends on the surfactant in the order Tween 80 > Tween 20 > Triton X-100. The higher partition coefficient at pH 10 compared to pH 7.4 suggests that at basic pH the deprotonated mitoxantrone is incorporated more efficiently into the hydrophobic medium of non-ionic micelles compared to physiological pH, when the protonated drug is predominant.

Conclusions

These results on simple model systems miming the drug–membrane interactions contribute to the elucidation of the behaviour of the drug in vivo, as well as the possible utilization of surfactant micelles as drug carriers.

Acute myeloid leukemia developing in patients with autoimmune diseases

Therapy-related acute myeloid leukemia is an unfortunate complication of cancer treatment, particularly for patients with highly curable primary malignancies and favorable life expectancy. The risk of developing therapy-related acute myeloid leukemia also applies to patients with non-malignant conditions, such as autoimmune diseases treated with cytotoxic and/or immunosuppressive agents. There is considerable evidence to suggest that there is an increased occurrence of hematologic malignancies in patients with autoimmune diseases compared to the general population, with a further increase in risk after exposure to cytotoxic therapies. Unfortunately, studies have failed to reveal a clear correlation between leukemia development and exposure to individual agents used for the treatment of autoimmune diseases. Given the dismal outcome of secondary acute myeloid leukemia and the wide range of available agents for treatment of autoimmune diseases, an increased awareness of this risk and further investigation into the pathogenetic mechanisms of acute leukemia in autoimmune disease patients are warranted. This article will review the data available on the development of acute myeloid leukemia in patients with autoimmune diseases. Possible leukemogeneic mechanisms in these patients, as well as evidence supporting the association of their primary immunosuppressive status and their exposure to specific therapies, will also be reviewed. This review also supports the idea that it may be misleading to label leukemias that develop in patients with autoimmune diseases who are exposed to cytotoxic agents as 'therapy-related leukemias'. A better understanding of the molecular defects in autoimmune disease patients who develop acute leukemia will lead to a better understanding of the association between these two diseases entities.

Long-term safety profile of mitoxantrone in a French cohort of 802 multiple sclerosis patients: a 5-year prospective study

Background: From 2001, a French multicentre study was conducted prospectively in a large cohort of MS patients and annually updated up to at least 5 years after initiation of MITOX therapy. Objective: To determine long-term safety profile of mitoxantrone (MITOX) in multiple sclerosis (MS).

Methods: Eight hundred and two patients from 12 MS centres (308 relapsing–remitting, 352 secondary progressive and 142 primary progressive) received MITOX monthly for 6 months (87%) or every 3 months (13%). Patients underwent clinical and haematologic evaluations before every MITOX infusion and every 6–12 months up to 5 years after MITOX start. Echocardiograms were performed at the start and end of MITOX and up to 5 years after.

Results: The cohort was followed for 5354 patient-years (mean). One out of 802 patients (0.1%) presented with acute congestive heart failure and 39 out of 794 patients (4.9%) presented with asymptomatic left ventricular ejection fraction reduction under 50% (persistent in 11 patients (28%), transient in 27 patients (69%), on the last scan at year 5 in 1 patient). Two cases of therapy-related leukaemia (0.25%) were detected 20 months after MITOX start (one death and one with 8 years confirmed remission). Of the 317 women treated before the age of 45, 17.3% developed a persistent age-dependant amenorrhea. Conclusion: This large cohort with at least 5 years of follow-up provided good insights into the long-term safety profile of MITOX in MS.

Revision of the risk of secondary leukaemia after mitoxantrone in multiple sclerosis populations is required

The objective in this paper is to compare the cumulative incidence and incidence density of therapy-related acute myeloid leukaemia in two cohorts of patients with multiple sclerosis treated with mitoxantrone, and with previously reported data in the literature. Six new cases of acute myeloid leukaemia were observed by prospectively following two Spanish series of 142 and 88 patients with worsening relapsing multiple sclerosis and secondary-progressive disease treated with mitoxantrone. A literature review shows 32 further cases of acute myeloid leukaemia reported, 65.6% of which are therapy-related acute promyelocytic leukaemia. Five cases in the cohorts fulfilled the diagnostic criteria for acute promyelocytic leukaemia, and one patient was diagnosed with pre-B-acute lymphoblastic leukaemia. Acute myeloid leukaemia latency after mitoxantrone discontinuation was 1 to 45 months. The accumulated incidence and incidence density was 2.82% and 0.62%, respectively, in the Valencian cohort, and 2.27% and 0.44% in the Catalonian cohort. In the only seven previously reported series, the accumulated incidence varied from 0.15% to 0.80%. The real incidence of acute myeloid leukaemia after mitoxantrone therapy in the multiple sclerosis population could be higher as evidenced by the growing number of cases reported. Haematological monitoring should continue for at least 5 years after the last dose of mitoxantrone. These data stress the necessity of re-evaluating this risk.

Mitoxantrone-Associated Acute Myelogenous Leukemia in a Patient with High-Risk Adenocarcinoma of the Prostate: A Case Report and Brief Review

BACKGROUND

Mitoxantrone, a topoisomerase II-targeted drug, is used to treat several conditions and is a Food and Drug Administration approved chemotherapeutic agent for the treatment of advanced carcinoma of the prostate.

CASE REPORT

A 64-year-old male with high-risk prostate cancer was treated with adjuvant mitoxantrone (12 mg/meter2) every 3 weeks for 6 cycles. Approximately 10 months after finishing therapy, he was diagnosed with an inv [16] Acute Myelogenous Leukemia (AML). Despite aggressive treatment and support, the patient had a rapidly fatal clinical course.

CONCLUSION

Despite its regular use in this setting, this is the first reported case of treatment-associated AML after mitoxantrone in prostate cancer.

Acute promyelocytic leukemic involvement of the optic nerves following mitoxantrone treatment for multiple sclerosis

Mitoxantrone, the first immunosuppressant to receive FDA approval for treatment of worsening relapsing-remitting, secondary progressive, and progressive-relapsing multiple sclerosis (MS) is a DNA topoisomerase II inhibitor that has been associated with the development of acute promyelocytic myelogenous leukemia (APML). Central nervous system APML is a rare site of extramedullary involvement following mitoxantrone therapy. We report a patient with history of multiple sclerosis who developed bilateral optic nerve involvement as the primary manifestation of APML relapse following mitoxantrone treatment.

Molecular analysis of t(15;17) genomic breakpoints in secondary acute promyelocytic leukemia arising after treatment of multiple sclerosis

Therapy-related acute promyelocytic leukemia (t-APL) with t(15;17) translocation is a well-recognized complication of cancer treatment with agents targeting topoisomerase II. However, cases are emerging after mitoxantrone therapy for multiple sclerosis (MS). Analysis of 12 cases of mitoxantrone-related t-APL in MS patients revealed an altered distribution of chromosome 15 breakpoints versus de novo APL, biased toward disruption within PML intron 6 (11 of 12, 92% vs 622 of 1022, 61%: P = .035). Despite this intron spanning approximately 1 kb, breakpoints in 5 mitoxantrone-treated patients fell within an 8-bp region (1482-9) corresponding to the "hotspot" previously reported in t-APL, complicating mitoxantrone-containing breast cancer therapy. Another shared breakpoint was identified within the approximately 17-kb RARA intron 2 involving 2 t-APL cases arising after mitoxantrone treatment for MS and breast cancer, respectively. Analysis of PML and RARA genomic breakpoints in functional assays in 4 cases, including the shared RARA intron 2 breakpoint at 14 446-49, confirmed each to be preferential sites of topoisomerase IIalpha-mediated DNA cleavage in the presence of mitoxantrone. This study further supports the presence of preferential sites of DNA damage induced by mitoxantrone in PML and RARA genes that may underlie the propensity to develop this subtype of leukemia after exposure to this agent.

Acute promyelocytic leukemia after mitoxantrone therapy for multiple sclerosis

Mitoxantrone is a DNA-topoisomerase 2 inhibitor used as a single agent for treatment of relapsing-remitting or progressive multiple sclerosis (MS). We present here two patients treated with mitoxantrone for MS who subsequently developed acute promyelocytic leukemia (APL). These constitute, to our knowledge, the eighth and ninth reports of APL in patients treated with mitoxantrone for MS. Topoisomerase 2 inhibitors are associated with therapy-related acute myeloid leukemia (t-AML) with 11q23 abnormalities, but therapy-related APL (t-APL) is less common, and documentation of nine cases of t-APL after mitoxantrone therapy for MS suggests a specific association.

Compared benefit of approved and experimental immunosuppressive therapeutic approaches in multiple sclerosis

An important amount has been learnt about the mechanisms of action, efficacy and long-term toxicities of mitoxantrone. Importantly, recent observations strongly suggest that early administration of potent immunosuppressants (mitoxantrone and alemtuzumab) is definitely more effective than approved immunomodulators to delay or even reverse disability progression. Given the cardiotoxicity of mitoxantrone, restricting exposure to the drug to 2 or 3 years, the benefits and risks of immunosuppressants previously used as off-label treatments (cyclophosphamide and cladribine) have been revisited, and the potential efficacy in multiple sclerosis of recent immunosuppressants used in other autoimmune diseases, organ transplantation and cancer therapy has received increasing attention. Those immunosuppressants comprise monoclonal antibodies targeting B cells, lymphocytes and monocytes, IL-2 receptor and alpha4 integrin, as well as new molecules (pixantrone and isoxazole derivatives) and a new generation of immunosuppressants (fingolimod), which modulate lymphocyte re-circulation. This review addresses the most recent data concerning the efficacy and safety of mitoxantrone and of new experimental therapies that are presently in progress.

Management of worsening multiple sclerosis with mitoxantrone: a review

BACKGROUND

Mitoxantrone, an intravenously administered immunosuppressant that inhibits T-cell, B-cell, and macrophage proliferation, is indicated for reducing neurologic disability and relapse frequency in patients with secondary progressive multiple sclerosis (SPMS), progressive relapsing MS, or worsening relapsing-remitting MS (RRMS).

OBJECTIVE

This article reviews the pathogenesis and natural history of MS and examines the available treatment options for patients with RRMS, worsening RRMS, or SPMS, with a focus on mitoxantrone.

METHODS

MEDLINE (1966-present) and the Cochrane Central Register of Controlled Trials (1994-present) were searched for relevant randomized, blinded, controlled clinical trials using the terms mitoxantrone, Novantrone, and multiple sclerosis.

RESULTS

Five randomized, blinded, controlled trials and an ongoing open-label Phase IV safety study were identified and included in this review. In one randomized, double-blind trial (N=25), patients with RRMS who received mitoxantrone 8 mg/m2 monthly had significantly reduced relapse rates at 1 year compared with those who received placebo (P=0.014). In a 2-year, randomized, partially blinded trial (N=51), patients with active RRMS who received mitoxantrone 8 mg/m2 monthly had significantly fewer relapses compared with those who received placebo (P<0.001), and significantly fewer patients had confirmed progression of disability (1-point increase in Expanded Disability Status Scale [EDSS] score) (P=0.02). In a randomized, double-blind trial (N=49), patients with relapsing SPMS who received mitoxantrone 12 mg/m2 monthly for 3 months followed by 12 mg/m2 g3mo for up to 32 months had significant improvements in EDSS scores compared with those who received methylprednisolone 1 g IV monthly for 3 months followed by 1 g IV g3mo (P=0.002 at 1 year, P=0.045 at 2 years) and significant reductions in the number of gadolinium-enhancing lesions on magnetic resonance imaging (MRI) (P=0.002 at 1 and 2 years, P=0.03 at 3 years). In a randomized, partially blinded Phase II trial in 42 patients with active RRMS or SPMS, patients who received mitoxantrone 20 mg IV monthly and methylprednisolone 1 g IV monthly had significantly fewer new gadolinium-enhancing lesions on MRI (P<0.001) and significantly fewer relapses (P<0.01) at 6 months compared with those who received methylprednisolone alone. In a pivotal Phase III trial (N=194), patients with worsening RRMS or SPMS who received mitoxantrone 12 mg/m2 g3mo for 2 years had significantly fewer relapses (P<0.001) and significantly less deterioration in disability, as measured by change in EDSS score (P=0.019), compared with those who received placebo. In a nonrandomized subgroup of patients from this study (n=110), those who received mitoxantrone 12 mg/m2 g3mo had a significant reduction in the number of T2-weighted MRI lesions at 24 months (P=0.027). The most common adverse events in these studies included nausea and/or vomiting (18%-85%), alopecia (33%-61%), amenorrhea (8%-53%), urinary tract infections (6%-32%), and upper respiratory tract infections (4%-53%). Leukopenia was reported in 10% to 19% of patients. Use of mitoxantrone can lead to serious adverse effects, particularly cardiotoxicity, myelosuppression, and, rarely, leukemia. Long-term use of mitoxantrone may compromise left ventricular function. Limited cardiotoxicity was reported in the clinical studies; in the pivotal clinical trial, 2 patients who received mitoxantrone 12 mg/m2 had decreases in left ventricular ejection fraction to <50% of baseline.

CONCLUSIONS

In the available clinical trials, mitoxantrone provided effective treatment for worsening RRMS or SPMS. When mitoxantrone is used as recommended, the risks of substantial myelosuppressive and cardiotoxic effects can be reduced by careful patient selection, drug administration, and monitoring. The lifetime cumulative dose should be strictly limited to 140 mg/m2, or 2 to 3 years of therapy.

Bioreductive activation of mitoxantrone by NADPH cytochrome P450 reductase. Implications for increasing its ability to inhibit the growth of sensitive and multidrug resistant leukaemia HL60 cells

The aim of this study was to examine the role of reductive activation of mitoxantrone (MX) by human liver NADPH cytochrome P450 reductase (CPR) in increasing its ability to inhibit the growth of human promyelocytic sensitive leukaemia HL60 cell line as well as its MDR sublines exhibiting two different phenotypes of MDR related to the overexpression of P-glycoprotein (HL60/VINC) or MRP1 (HL60/DOX). Our assays showed that the reduction of MX by exogenously added CPR in the presence of low NADPH concentration had no effect in increasing its ability to inhibit the growth of sensitive and MDR tumour cells. In contrast, an important increase in antiproliferative activity of MX after its reductive activation by CPR at high NADPH concentration was observed against HL60/VINC as well as HL60/DOX cells.

Étude observationnelle de la mitoxantrone dans les formes rémittentes actives de sclérose en plaques: suivi à long terme d’une cohorte de 100 patients consécutifs

INTRODUCTION

On the basis of the French and British (FB) MS Trial, Mitoxantrone (MITOX) was approved by the AFSAPPS in October 2003 in patients with aggressive multiple sclerosis (MS), given as induction therapy monthly for 6 months (ELSEP). We report an observational study of 100 aggressive relapsing remitting (RR) MS patients treated by induction therapy with MITOX and followed up to 5 years.

METHODS

One hundred patients with aggressive RR MS received an induction therapy with MITOX 20 mg monthly combined with methylprednisolone 1 g for 6 months. MRI data within 12 months before and 6 months after MITOX induction were collected (mean cumulative dose 65 mg/m2). Clinical evaluation was performed every 6 months and data (relapses and EDSS scores) were prospectively recorded in the EDMUS Database. After MITOX, a maintenance therapy was given to 57 patients (MITOX every 3 months: 21; Interferon beta: 13; Azathioprine: 14; Methotrexate: 7; Glatiramer acetate: 2). The mean follow-up period was of 3.8 years.

RESULTS

Patients were treated at a mean age of 27 +/- 9 years after 5 +/- 3 years of MS duration. Within the 12 months preceding MITOX onset, the annual relapse rate (ARR) was 3.2, the mean EDSS increased by 2.2 +/- 1 points (to a score of 4 at M0), 87 patients worsened by 1 point EDSS or more and 85 percent of patients had Gd enhancing lesions on MRI. During the 12 months following MITOX onset, the inflammatory activity of the disease dropped dramatically with a reduction of the ARR by 91 percent whereas 76 percent of patients were free of new relapse and MRI activity was reduced by 89 percent. In addition, the mean EDSS decreased by 1.2 points (p<10-6) and 60 percent of patients improved by 1 point EDSS or more. At a longer term, the reduction of the ARR was confirmed (0.28-0.37 up to 5 years) and the median time to the first relapse was 2.8 years. A significant improvement of disability was maintained until 4 years and got back to the initial level at year 5. The ARR was significantly lower (0.09) for patients treated with MITOX every 3 months as maintenance therapy than for patients treated by other disease modifying therapies (0.33-0.39) or not (0.43) after the induction. Three patients presented an asymptomatic decrease of the left ventricular ejection fraction under 50 percent, reversible in one case.

CONCLUSION

MITOX as induction therapy monthly for 6 months was safe and had a rapid and strong impact on the inflammatory process and on the evolution of disability. The drug might be a good candidate as induction therapy followed by a maintenance therapy in patients with aggressive MS.

Leucémies aiguës chez deux patients atteints de sclérose en plaques et traités par mitoxantrone

INTRODUCTION

Mitoxantrone (Mx) is used as a second-line treatment in multiple sclerosis. Since 1998, eight cases of acute leukemia (AL) have been described. We report two new cases of myeloid AL that occurred during treatment with Mx.

OBSERVATIONS

The first case concerned a women who was treated with Mx for 3 months. In spite of a very low total dose (58.32 mg), she developed promyelocytic AL. The second patient died of myeloid AL, 27 months after the last injection of Mx.

DISCUSSION

All the reported cases of AL occurring after Mx respond to the criteria of leukemia induced by anti-topoisomerases II. Epidemiological data and those from animal experiments suggest that Mx has direct role in the occurrence of leukemia.

CONCLUSION

It must be remembered that even if the risk of Mx-induced leukemia is low, blood cell counts must be closely monitored for at least five years after the last injection of this treatment.

Multiple sclerosis – novel insights and new therapeutic strategies

PURPOSE OF REVIEW

This review focuses on novel aspects of the pathogenesis and advances in the therapy of multiple sclerosis (MS).

RECENT FINDINGS

Recent observations suggest that early lesion development in MS may start in some forms with oligodendrocyte death and that inflammation appears as a secondary phenomenon only. The lack of sufficient remyelination in MS may be the result of a disturbed function of basic helix-loop-helix transcription factors. Clinically the identification of patients with a clinically isolated syndrome at high risk to develop clinically definite MS remains difficult; the predictive value of serum antibodies against myelin proteins remains controversial. The role of neutralizing antibodies in interferon therapy is discussed. New therapeutic approaches in MS are emerging.

SUMMARY

The existing view on the pathogenesis of MS is still changing. The original assumption that cell-mediated demyelination is the key event in lesion development dictating clinical disability is critically reviewed and alternative pathways have been suggested. Oligodendrocyte death, axonal loss, the role of CD8 T lymphocytes, T regulatory cells, and B lymphocytes have come into the focus of newly evolving concepts in MS pathogenesis. A deepened understanding of the immunopathogenesis of this disease translates into innovative therapeutic approaches, such as blockade of alpha4 integrins by a humanized monoclonal antibody. In various animal models cell-replacement strategies yield promising results; however, turning these findings into an effective therapy in MS patients has a long way to go.