Drug-Induced Progressive Multifocal Leukoencephalopathy (PML): A Systematic Review and Meta-Analysis

INTRODUCTION

Progressive multifocal leukoencephalopathy (PML) was first described among patients affected by hematological or solid tumors. Following the human immunodeficiency virus (HIV) epidemic, people living with HIV have represented most cases for more than a decade. With the diffusion of highly active antiretroviral therapy, this group progressively decreased in favor of patients undergoing treatment with targeted therapy/immunomodulators. In this systematic review and meta-analysis, the objective was to assess which drugs are most frequently related to PML development, and report the incidence of drug-induced PML through a meta-analytic approach.

METHODS

The electronic databases MEDLINE, EMBASE, ClinicalTrials.gov, Web of Science and the Canadian Agency for Drugs and Technologies in Health Database (CADTH) were searched up to May 10, 2022. Articles that reported the risk of PML development after treatment with immunomodulatory drugs, including patients of both sexes under the age of 80 years, affected by any pathology except HIV, primary immunodeficiencies or malignancies, were included in the review. The incidence of drug-induced PML was calculated based on PML cases and total number of patients observed per 100 persons and the observation time. Random-effect metanalyses were conducted for each drug reporting pooled incidence with 95% confidence intervals (CI) and median (interquartile range [IQR]) of the observation time. Heterogeneity was measured by I2 statistics. Publication bias was examined through funnel plots and Egger's test.

RESULTS

A total of 103 studies were included in the systematic review. In our analysis, we found no includible study reporting cases of PML during the course of treatment with ocrelizumab, vedolizumab, abrilumab, ontamalimab, teriflunomide, daclizumab, inebilizumab, basiliximab, tacrolimus, belimumab, infliximab, firategrast, disulone, azathioprine or danazole. Dalfampridine, glatiramer acetate, dimethyl fumarate and fingolimod show a relatively safe profile, although some cases of PML have been reported. The meta-analysis showed an incidence of PML cases among patients undergoing rituximab treatment for multiple sclerosis (MS) of 0.01 cases/100 persons (95% CI - 0.08 to 0.09; I2 = 20.4%; p = 0.25) for a median observation period of 23.5 months (IQR 22.1-42.1). Treatment of MS with natalizumab carried a PML risk of 0.33 cases/100 persons (95% CI 0.29-0.37; I2 = 50%; p = 0.003) for a median observation period of 44.1 months (IQR 28.4-60) and a mean number of doses of 36.3 (standard deviation [SD] ± 20.7). When comparing data about patients treated with standard interval dosing (SID) and extended interval dosing (EID), the latter appears to carry a smaller risk of PML, that is, 0.08 cases/100 persons (95% CI 0.0-0.15) for EID versus 0.3 cases/100 persons (95% CI 0.25-0.34) for SID.

CONCLUSIONS

A higher risk of drug-related PML in patients whose immune system is not additionally depressed by means of neoplasms, HIV or concomitant medications is found in the neurological field. This risk is higher in MS treatment, and specifically during long-term natalizumab therapy. While this drug is still routinely prescribed in this field, considering the efficacy in reducing MS relapses, in other areas it could play a smaller role, and be gradually replaced by other safer and more recently approved agents.

Identification of patients with relapsing multiple sclerosis eligible for high-efficacy therapies

Relapsing multiple sclerosis (RMS) presents a highly variable clinical evolution among patients, and its management should be personalized. Although there is no cure at present, effective disease-modifying therapies (DMTs) are available. Selection of the most appropriate DMT for each patient is influenced by several clinical, radiological and demographic aspects as well as personal preferences that, at times, are not covered in the regulatory criteria. This may be a source of difficulty, especially in certain situations where so-called 'high-efficacy DMTs' (usually considered second-line) could be of greater benefit to the patient. In this narrative review, we discuss evidence and experience, and propose a pragmatic guidance on decision-making with respect to the indication and management of high-efficacy DMT in adult patients with RMS based on expert opinion.

Aggressive multiple sclerosis (2): Treatment

The natural history of multiple sclerosis (MS) is highly heterogeneous. A subgroup of patients has what might be termed aggressive MS. These patients may have frequent, severe relapses with incomplete recovery and are at risk of developing greater and permanent disability at the earlier stages of the disease. Their therapeutic window of opportunity may be narrow, and while it is generally considered that they will benefit from starting early with a highly efficacious treatment, a unified definition of aggressive MS does not exist and data on its treatment are largely lacking. Based on discussions at an international focused workshop sponsored by the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS), we review our current knowledge about treatment of individuals with aggressive MS. We analyse the available evidence, identify gaps in knowledge and suggest future research needed to fill those gaps. A companion paper details the difficulties in developing a consensus about what defines aggressive MS.

Do clinical trials for new disease modifying treatments include real world patients with multiple sclerosis?

We often see that clinical and demographic characteristics of real-world studies (RWS) do not differ from patients included in randomized controlled trials (RCT).

OBJECTIVE

to compare clinical and demographic aspects of patients included in RCT and RWS that evaluated new disease modifying treatment in multiple sclerosis (MS).

METHODS

a systematic non-language-restricted literature search of RCT and RWS that evaluated new disease modifying treatments (natalizumab, alemtuzumab, ocrelizumab, fingolimod, teriflunomide, dimethyl fumarate and cladribine) from January 2005 to January 2019. Demographic and clinical data were extracted, described and compared.

RESULTS

18 RCT and 73 RWS were included. We found no differences in clinical and demographic aspects between RCT and RWS except in the frequency of naïve patients included in RCT vs. RWS 65.6% (95%CI 52-74) vs. 36.4% (95%CI 21-46), respectively, (p = 0.013) at study entry, as well as for the inclusion of patients that used previous treatment 34.4% (95%CI 22-41) vs. 63.6% (95%CI 53-74) in RCT and RWS, respectively,(p = 0.007) at study entry.

CONCLUSION

We did not observe significant differences in most clinical and demographic aspects of included patients in RCT and RWS. Studies that include the full spectrum of MS patients followed in clinical practice are needed.

Vitamin D Supplementation in Central Nervous System Demyelinating Disease-Enough Is Enough

The exact cause of multiple sclerosis (MS) remains elusive. Various factors, however, have been identified that increase an individual's risk of developing this central nervous system (CNS) demyelinating disease and are associated with an acceleration in disease severity. Besides genetic determinants, environmental factors are now established that influence MS, which is of enormous interest, as some of these contributing factors are relatively easy to change. In this regard, a low vitamin D status is associated with an elevated relapse frequency and worsened disease course in patients with MS. The most important question, however, is whether this association is causal or related. That supplementing vitamin D in MS is of direct therapeutic benefit, is still a matter of debate. In this manuscript, we first review the potentially immune modulating mechanisms of vitamin D, followed by a summary of current and ongoing clinical trials intended to assess whether vitamin D supplementation positively influences the outcome of MS. Furthermore, we provide emerging evidence that excessive vitamin D treatment via the T cell-stimulating effect of secondary hypercalcemia, could have negative effects in CNS demyelinating disease. This jointly merges into the balancing concept of a therapeutic window of vitamin D in MS.

Update on monitoring and adverse effects of approved second-generation disease-modifying therapies in relapsing forms of multiple sclerosis

PURPOSE OF REVIEW

There has been a considerable increase in the number of disease-modifying therapies (DMTs) in recent years. It appears that the number of approved DMTs is going to continue to increase in the coming years. The growing number of DMTs has provided a challenge to the clinician to tailor their therapeutic recommendations based on patients' needs and preferences. To choose between these DMTs, knowledge of side-effect profiles is imperative.

RECENT FINDINGS

Alemtuzumab, a humanized recombinant monoclonal antibody, was recently approved for the management of relapsing forms of multiple sclerosis. Its use seems to be limited by significant adverse effects and regular monitoring requirement. In 2014, the first case of progressive multifocal leukoencephalopathy (PML) was diagnosed in a patient with relapsing remitting multiple sclerosis who received extended dimethyl fumarate without any significant confounding factors. Among patients receiving fingolimod after previous natalizumab treatment, there have been 17 suspected cases of PML. There have also been three confirmed cases of PML in individuals who received fingolimod without previous natalizumab treatment.

SUMMARY

In this review, we outline the potential adverse effects and recommended laboratory studies as part of the monitoring strategy following initiation of various DMTs.

Clinical and radiological control of highly active relapsing-remitting multiple sclerosis with first-line natalizumab

A 33-year-old man with gait instability, weakness of the left lower extremity, decreased visual acuity in the left eye, and urgency and urine incontinence was diagnosed of relapsing-remitting multiple sclerosis. He was treated with natalizumab (300 mg intravenously every 4 weeks) as first-line therapy, which reached at 6 months a favorable clinical evolution and dramatic radiological improvement (T2-weighted lesion load decreased by 50% and no gadolinium-enhancing T1 lesions) sustained over the course of 8 years. This clinical case shows the efficacy of natalizumab in a real-world setting and, particularly, the sustained effect of this drug in the long term as demonstrated by persistent radiological improvement. Natalizumab can be considered as the treatment of choice in relapsing-remitting multiple sclerosis forms presenting with two relapses and gadolinium-enhancing (Gd+) lesions.

Intractable and highly active relapsing multiple sclerosis - role of alemtuzumab

Alemtuzumab is a humanized recombinant monoclonal antibody that was recently approved by the US Food and Drug Administration and the European Medicines Agency for the management of relapsing forms of multiple sclerosis (MS). It has been utilized for the management of chronic lymphocytic leukemia, bone marrow and renal transplantation, or graft versus host disease. Because of its immunomodulatory properties, it was brought into clinical development in MS. One Phase II (CAMMS223) and two Phase III clinical trials (CARE-MSI and -II) have evaluated the safety and efficacy of alemtuzumab in patients with relapsing-remitting MS. Even though its efficacy profile and long-lasting effect have attracted much interest among physicians and patients, it has significant potential adverse effects that may limit its use to patients with active disease. Here, we review the history of drug development of alemtuzumab. Furthermore, we outline the postulated mechanisms of action, clinical evidence, and safety of alemtuzumab for its use as a disease-modifying agent in active and highly active MS.