Real-world clinical course of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) in Japan

Multicenter, randomized, double-blind, placebo-controlled phase 3 study of mogamulizumab with open-label extension study in a minimum number of patients with human T-cell leukemia virus type-1-associated myelopathy

Human T-cell leukemia virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic neurodegenerative disease. This multicenter, randomized phase 3 study evaluated the efficacy and safety of 0.3 mg/kg intravenous mogamulizumab, a monoclonal antibody targeting-CC chemokine receptor 4, every 12 weeks in HAM/TSP patients. This study comprised a 24-week double-blind, placebo-controlled period, 24-week open-label period, and extension treatment period. The primary endpoint was the proportion of patients with a ≥ 1-grade improvement in the Osame motor disability score (OMDS). Secondary endpoints were changes in HTLV-1 proviral load, 10-m timed walk, cerebrospinal fluid (CSF) neopterin levels, and safety. The exploratory endpoint was CSF chemokine C-X-C motif ligand 10 (CXCL10) levels. Thirty-four and 33 patients were randomized to mogamulizumab and placebo arms, respectively. At the end of the double-blind period, no significant difference was found in the OMDS improvement rate or other secondary efficacy endpoints assessing motor activities. However, the mogamulizumab arm showed a significant decrease in HTLV-1 proviral load (- 59.39 ± 29.91% vs. placebo 2.32 ± 36.31%) and CSF neopterin (p < 0.001)/CXCL10 levels (p = 0.004). The baseline OMDS pattern and the 60-80% HTLV-1 proviral load reduction were sustained through the open-label and extension treatment periods. Although a higher incidence of rash (69.2%) was reported, the safety profile was similar compared with a previous phase 1/2a study. We found no significant difference in clinical benefit; however, mogamulizumab may provide long-term clinical benefit by preventing disease progression, as CSF neopterin/CXCL10 levels are associated with long-term prognosis in HAM/TSP.Clinical Trial Registration Number: NCT03191526 (registered date: 6-June-2017).

HTLV-1-Associated Myelopathy (HAM) Incidence in Asymptomatic Carriers and Intermediate Syndrome (IS) Patients

Several studies suggest that HTLV-1 infection may be associated with a wider spectrum of neurological and clinical manifestations that do not meet diagnostic criteria for HAM. These conditions may later progress to HAM or constitute an intermediate clinical form: intermediate syndrome (IS), a mid-point between asymptomatic HTLV-1 carriers and those with full myelopathy. Thus, we determined the incidence of HAM cases in the HTLV-1-asymptomatic and IS patients, and the clinical/laboratory associated markers. A total of 204 HTLV-1-positive patients were included in this study, divided into two groups: Group 1, including 145 asymptomatic HTLV-1 subjects (ASY), and Group 2, including 59 patients with inflammatory clinical symptoms in more than three systems and a high proviral load (PVL). During a 60-month follow-up time, with the age ranging from 47 to 79 years, ten patients of the fifty-nine initially diagnosed as IS developed HAM (iHAM), and two patients of the initial 145 ASY developed HAM directly. Women were more prevalent in all groups. For the iHAM patients, the age ranged from 20 to 72 years, with a mean of 53 (±15 SD). Older age was associated with the development of HAM, higher PVL and IS; however, there was no any specific symptom or clinical sign, that was associated with risk for iHAM. In conclusion, IS cases could be an early phase of development of HAM. These findings show the presence of higher incidence probabilities in our cohort than previously reported.

Mycophenolate mofetil for the long-term treatment of HTLV-1 associated myelopathy: A case report

Human T-cell leukemia virus type 1 (HTLV-1) can cause HTLV-1 Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP). Current treatment options for HAM/TSP are limited. We present a woman with rapidly-progressive HAM/TSP with significant, sustained clinical improvement following initiation of mycophenolate mofetil (MMA). Peripheral blood mononuclear cells from the patient, her asymptomatic carrier husband and eight healthy controls were isolated. Frequencies of T-cell populations upon exposure to low and high MMA concentrations and differences in proliferation were analyzed using flow cytometry and a CSFE-proliferation assay. Characterization of T-cell function and proliferation showed higher levels of GranzymeB in HTLV-1+ donors. The improvement and stability of symptoms in this patient with HAM/TSP following MMA initiation requires further study as a potential treatment for HAM/TSP.

HTLV-1-associated myelopathy in Spain

BACKGROUND

HTLV-1 infection is a neglected disease. Over 10 million people are infected worldwide, with hot spots of high endemicity across all continents. Roughly 5% of HTLV-1 carriers develop HTLV-1-associated myelopathy (HAM), a progressive subacute neurological disabling disease.

METHODS

We report the main features of patients diagnosed with HAM up to date in Spain, a non-endemic country with a relatively high migrant flow from Latin America and Equatorial Africa, where HTLV-1 is endemic.

RESULTS

A total of 451 cases of HTLV-1 had been recorded in Spain until the end of year 2022. HAM had been diagnosed in 58 (12.9%). The current incidence is of 2-3 new cases per year. Women represent 76%. Mean age at diagnosis is 49 years-old. Nearly 60% are Latin Americans. Although sexual transmission is the most likely route of HTLV-1 acquisition, up to 6 individuals had been infected following solid organ transplantation. Rapid onset myelopathy developed in all but one of these transplant recipients from three HTLV-1-positive donors. HTLV-1 subtype 1a transcontinental was the only variant recognized in HAM patients. HTLV-1 proviral load was significantly greater in HAM patients than in asymptomatic HTLV-1 carriers (677 vs 104 HTLV-1 DNA copies/104 PBMC; p = 0.012). Symptom relief medications and physiotherapy have been the only treatment providing some benefit to HAM patients. Neither significant clinical nor virological efficacy was noticed using antiretrovirals in at least 9 HAM patients. Two thirds of HAM patients ended up in a wheelchair and with urinary/fecal sphincter incontinence.

CONCLUSION

HAM is the most frequent clinical manifestation of HTLV-1 infection in Spain, a non-endemic country. Middle aged women migrants from Latin America are the most frequently affected. Two thirds end up in a wheelchair despite using antiretroviral therapy.

EZH1/2 dual inhibitors suppress HTLV-1-infected cell proliferation and hyperimmune response in HTLV-1-associated myelopathy

Background

Human T-cell leukemia virus type 1 (HTLV-1) causes HTLV-1-associated myelopathy (HAM), adult T-cell leukemia/lymphoma (ATL), HTLV-1-associated uveitis, and pulmonary diseases. Although both HAM and ATL show proliferation of infected cells, their pathogeneses are quite different. In particular, the pathogenesis of HAM is characterized by hyperimmune responses to HTLV-1-infected cells. Recently, we demonstrated the overexpression of histone methyltransferase EZH2 in ATL cells and the cytotoxic effects of EZH2 inhibitors and EZH1/2 dual inhibitors on these cells. However, these phenomena have never been studied in HAM. Furthermore, what effect these agents have on the hyperimmune response seen in HAM is completely unknown.

Methods

In this study, we investigated histone methyltransferase expression levels in infected cell populations (CD4⁺ and CD4⁺CCR4⁺ cells) from patients with HAM using microarray and RT-qPCR analyses. Next, using an assay system that utilizes the spontaneous proliferation characteristic of peripheral blood mononuclear cells derived from patients with HAM (HAM-PBMCs), we investigated the effects of EZH2 selective inhibitors (GSK126 and tazemetostat) and EZH1/2 dual inhibitors (OR-S1 and valemetostat, also known as DS-3201), particularly on cell proliferation rate, cytokine production, and HTLV-1 proviral load. We also examined the effect of EZH1/2 inhibitors on the proliferation of HTLV-1-infected cell lines (HCT-4 and HCT-5) derived from patients with HAM.

Results

We found elevated expression of EZH2 in CD4⁺ and CD4⁺CCR4⁺ cells from patients with HAM. EZH2 selective inhibitors and EZH1/2 inhibitors significantly inhibited spontaneous proliferation of HAM-PBMC in a concentration-dependent manner. The effect was greater with EZH1/2 inhibitors. EZH1/2 inhibitors also reduced the frequencies of Ki67⁺ CD4⁺ T cells and Ki67⁺ CD8⁺ T cells. Furthermore, they reduced HTLV-1 proviral loads and increased IL-10 levels in culture supernatants but did not alter IFN-γ and TNF-α levels. These agents also caused a concentration-dependent inhibition of the proliferation of HTLV-1-infected cell lines derived from patients with HAM and increased annexin-V(+)7-aminoactinomycin D(-) early apoptotic cells.

Conclusion

This study showed that EZH1/2 inhibitors suppress HTLV-1-infected cell proliferation through apoptosis and the hyperimmune response in HAM. This indicates that EZH1/2 inhibitors may be effective in treating HAM.

Imaging Spectrum of HTLV-1–Related Neurologic Disease

Purpose of Review

Human T-cell lymphotropic virus type 1 (HTLV-1)–associated myelopathy (HAM) is a well-recognized neurologic complication of HTLV-1. Beyond HAM, several other neurologic manifestations are increasingly recognized, including acute myelopathy, encephalopathy, and myositis. The clinical and imaging features of these presentations are less well understood and potentially underdiagnosed. In this study, we summarize the imaging features of HTLV-1–related neurologic disease, providing both a pictorial review and pooled series of the less well-recognized presentations.

Recent Findings

35 cases of acute/subacute HAM and 12 cases of HTLV-1–related encephalopathy were found. In subacute HAM, cervical and upper thoracic longitudinally extensive tranverse myelitis was noted, while in HTLV-1–related encephalopathy, confluent lesions in the frontoparietal white matter and along the corticospinal tracts were the most prevalent finding.

Summary

There are varied clinical and imaging presentations of HTLV-1–related neurologic disease. Recognition of these features aids early diagnosis where therapy may have the greatest benefit.

Effect of HTLV-1 Infection on the Clinical Course of Patients with Rheumatoid Arthritis

Human T-cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The effects of HTLV-1 on health are not fully elucidated. Epidemiological studies have shown that the prevalence of HTLV-1 infection is high in patients with rheumatic diseases. The prevalence of comorbidities, such as Sjögren’s syndrome and rheumatoid arthritis (RA), is higher in patients with HAM/TSP than the in general population. Studies have shown the effects of HTLV-1-infection on the clinical course of RA. Major questions on the association between HTLV-1 infection and RA: (1) Is it possible that HTLV-1 infection causes RA? (2) Do patients with RA who are infected with HTLV-1 have different clinical features? (3) Are immunosuppressants associated with an increased prevalence of HAM/TSP or ATL in RA patients with HTLV-1 infection? Is ATL an immunosuppressive therapy-associated lymphoproliferative disorder? No large-scale studies have investigated the incidence of ATL in patients with RA. However, several studies have reported the development of ATL in patients with RA who have HTLV-1 infection. This review aimed to shed light on the association between HTLV-1 infection and RA and summarize the unmet medical needs of RA patients with HTLV-1 infection.

Transient Viral Activation in Human T Cell Leukemia Virus Type 1-Infected Macaques Treated With Pomalidomide

Human T cell leukemia virus type 1 (HTLV-1) persists in the host despite a vigorous immune response that includes cytotoxic T cells (CTL) and natural killer (NK) cells, suggesting the virus has developed effective mechanisms to counteract host immune surveillance. We recently showed that in vitro treatment of HTLV-1-infected cells with the drug pomalidomide (Pom) increases surface expression of MHC-I, ICAM-1, and B7-2, and significantly increases the susceptibility of HTLV-1-infected cells to NK and CTL killing, which is dependent on viral orf-I expression. We reasoned that by restoring cell surface expression of these molecules, Pom treatment has the potential to reduce virus burden by rendering infected cells susceptible to NK and CTL killing. We used the rhesus macaque model to determine if Pom treatment of infected individuals activates the host immune system and allows recognition and clearance of HTLV-1-infected cells. We administered Pom (0.2 mg/kg) orally to four HTLV-1-infected macaques over a 24 day period and collected blood, urine, and bone marrow samples throughout the study. Pom treatment caused immune activation in all four animals and a marked increase in proliferating CD4⁺, CD8⁺, and NK cells as measured by Ki-67⁺ cells. Activation markers HLA-DR, CD11b, and CD69 also increased during treatment. While we detected an increased frequency of cells with a memory CD8⁺ phenotype, we also found an increased frequency of cells with a Treg-like phenotype. Concomitant with immune activation, the frequency of detection of viral DNA and the HTLV-1-specific humoral response increased as well. In 3 of 4 animals, Pom treatment resulted in increased antibodies to HTLV-1 antigens as measured by western blot and p24Gag ELISA. Consistent with Pom inducing immune and HTLV-1 activation, we measured elevated leukotrienes LTB4 and LTE4 in the urine of all animals. Despite an increase in plasma LTB4, no significant changes in plasma cytokine/chemokine levels were detected. In all cases, however, cellular populations, LTB4, and LTE4 decreased to baseline or lower levels 2 weeks after cessation of treatment. These results indicated that Pom treatment induces a transient HTLV-1-specific immune activation in infected individuals, but also suggest Pom may not be effective as a single-agent therapeutic.

Clinical and Public Health Implications of Human T-Lymphotropic Virus Type 1 Infection

Human T-lymphotropic virus type 1 (HTLV-1) is estimated to affect 5 to 10 million people globally and can cause severe and potentially fatal disease, including adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The burden of HTLV-1 infection appears to be geographically concentrated, with high prevalence in discrete regions and populations. While most high-income countries have introduced HTLV-1 screening of blood donations, few other public health measures have been implemented to prevent infection or its consequences. Recent advocacy from concerned researchers, clinicians, and community members has emphasized the potential for improved prevention and management of HTLV-1 infection. Despite all that has been learned in the 4 decades following the discovery of HTLV-1, gaps in knowledge across clinical and public health aspects persist, impeding optimal control and prevention, as well as the development of policies and guidelines. Awareness of HTLV-1 among health care providers, communities, and affected individuals remains limited, even in countries of endemicity. This review provides a comprehensive overview on HTLV-1 epidemiology and on clinical and public health and highlights key areas for further research and collaboration to advance the health of people with and at risk of HTLV-1 infection.

Efficacy of Corticosteroid Therapy for HTLV-1-Associated Myelopathy: A Randomized Controlled Trial (HAMLET-P)

Corticosteroids are most commonly used to treat HTLV-1-associated myelopathy (HAM); however, their clinical efficacy has not been tested in randomized clinical trials. This randomized controlled trial included 8 and 30 HAM patients with rapidly and slowly progressing walking disabilities, respectively. Rapid progressors were assigned (1:1) to receive or not receive a 3-day course of intravenous methylprednisolone in addition to oral prednisolone therapy. Meanwhile, slow progressors were assigned (1:1) to receive oral prednisolone or placebo. The primary outcomes were a composite of ≥1-grade improvement in the Osame Motor Disability Score or ≥30% improvement in the 10 m walking time (10 mWT) at week 2 for rapid progressors and changes from baseline in 10 mWT at week 24 for slow progressors. In the rapid progressor trial, all four patients with but only one of four without intravenous methylprednisolone achieved the primary outcome (p = 0.14). In the slow progressor trial, the median changes in 10 mWT were −13.8% (95% CI: −20.1–−7.1; p < 0.001) and −6.0% (95% CI: −12.8–1.3; p = 0.10) with prednisolone and placebo, respectively (p for between-group difference = 0.12). Whereas statistical significance was not reached for the primary endpoints, the overall data indicated the benefit of corticosteroid therapy. (Registration number: UMIN000023798, UMIN000024085)

NMOSD-like and longitudinal extensive HTLV1-associated myelitis are extremes that flank an overlooked continuum

Background

HTLV1-associated myelitis (HAM) is a slowly progressive myelopathy in which spinal cord MRI demonstrates no lesion or atrophy.

Objective

We examined the overlap between NMOSD features and HTLV1 infection.

Methods

We included all HTLV1-infected patients recruited in French West Indies (FWI) or referred from different centers, and suffering from at least one NMOSD feature. Literature connecting HTLV1-infection and NMOSD was reviewed.

Results

We included six NMOSD-like HAM with acute onset, seronegative against AQP4 and MOG-Abs. All displayed extensive longitudinal myelitis, and the optic nerve was involved in three. We gathered 39 cases of NMOSD-like HAM patients from the literature. Atypical signs of HAM were relapses (15.4%), sensory level (50%), upper limb symptoms (35.9%), optic neuritis (10.2%). Typical lesions involved lateral funiculi and featured a double rope sign (56.3%).

Conclusion

We propose that acute onset of NMOSD-like HAM could be more frequent than expected and should be evoked in high-risk patients. Extensive but often transient cord lesions could be the hallmark of an excessive inflammation of the funiculi targeted by HTLV1 infection. Although usually minor, a few HAM cases demonstrate specific MRI lesions, and the most severe cases may mimic NMOSD attacks.

Immunopathogenesis and Cellular Interactions in Human T-Cell Leukemia Virus Type 1 Associated Myelopathy/Tropical Spastic Paraparesis

HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) is a neuropathological disorder in 1–3% of individuals infected with Human T-lymphotropic virus 1 (HTLV-1). This condition is characterized by progressive spastic lower limb weakness and paralysis, lower back pain, bladder incontinence, and mild sensory disturbances resembling spinal forms of multiple sclerosis. This disease also causes chronic disability and is therefore associated with high health burden in areas where HTLV-1 infection is endemic. Despite various efforts in understanding the virus and discovery of novel diagnostic markers, and cellular and viral interactions, HAM/TSP management is still unsatisfactory and mainly focused on symptomatic alleviation, and it hasn’t been explained why only a minority of the virus carriers develop HAM/TSP. This comprehensive review focuses on host and viral factors in association with immunopathology of the disease in hope of providing new insights for drug therapies or other forms of intervention.

An update on human T-cell leukemia virus type I (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) focusing on clinical and laboratory biomarkers

Human T-cell leukemia virus type I (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a rare inflammatory disease causing unremitting and progressive neurological disorders, such as spastic paraparesis, neurogenic bladder, and sensory disturbance of the lower extremities. Although there is no cure, immune-modulating agents such as corticosteroids are most widely used to slow disease progression. Biomarkers for the clinical assessment of HAM/TSP should be identified because the prediction of functional prognosis and the assessment of treatment efficacy are challenging due to the slowly progressive nature of the disease. The lack of surrogate biomarkers also hampers clinical trials of new drugs. This review summarizes biomarker candidates for the clinical assessment of patients with HAM/TSP. Most of the reported biomarker candidates are associated with viral components or inflammatory mediators because immune dysregulation provoked by HTLV-1 infection is thought to cause chronic inflammation and damage the spinal cord of patients with HAM/TSP. Although information on the diagnostic accuracy of most of the reported biomarkers is insufficient, several molecules, including inflammatory mediators such as CXCL10 and neopterin in the cerebrospinal fluid, have been suggested as potential biomarkers of functional prognosis and treatment response. Several clinical trials for HAM/TSP are currently underway, and we expect that these studies will provide not only evidence pertaining to treatment, but also novel findings regarding the utility of biomarkers in this disease. The establishment of clinical biomarkers will improve patient care and promote the development of therapies for HAM/TSP.

Hospital admissions in individuals with HTLV-1 infection in Spain

OBJECTIVE

To examine the clinical burden and disease spectrum, as well as time trends for human T-cell leukemia virus type 1 (HTLV-1) and HTLV type 2 (HTLV-2) hospital admissions.

DESIGN

Retrospective, observational study using the Spanish National Hospital Discharge Database.

METHODS

Information for the diagnostic codes HTLV-1 and HTLV-2 using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) was retrieved from the national public registry since 1997--2015.

RESULTS

From a total of 66 462 136 nationwide hospital admissions recorded during the study period, 135 included HTLV diagnosis, being HTLV-1 in 115 (85.2%) and HTLV-2 in 20 (14.8%). The overall hospital admission rate because of HTLV was 2.03 per million, without significant yearly changes. First admissions represented 104 (77%) whereas 31 (23%) were re-admissions. The median in-hospital stay for HTLV patients was 9 days. In-hospital death occurred in 11 (8.1%). The median age of individuals with HTLV admission was 48 years and 60 (44.4%) were women. HTLV was recorded as the main diagnosis in 20%. The most frequent clinical conditions recorded alongside HTLV diagnosis were myelopathy (61; 45.2%), leukemia/lymphoma (30; 22.2%), solid organ transplantation (14; 10.4%) and child delivery (7; 5.2%).

CONCLUSION

The rate of HTLV diagnosis in hospitalized patients in Spain is low, roughly of two per million admissions. Despite continuous large immigrant flows from HTLV-1 endemic areas, no significant rising in hospitalizations because of HTLV-1 associated illnesses were noticed during the last two decades. Classical clinical complications of HTLV-1 infection, such as myelopathy and lymphoma account for more than two-thirds of cases.

Management of HAM/TSP: Systematic Review and Consensus-based Recommendations 2019

Purpose of Review

To provide an evidence-based approach to the use of therapies that are prescribed to improve the natural history of HTLV-1–associated myelopathy/tropical spastic paraparesis (HAM/TSP)—a rare disease.

Recent Findings

All 41 articles on the clinical outcome of disease-modifying therapy for HAM/TSP were included in a systematic review by members of the International Retrovirology Association; we report here the consensus assessment and recommendations. The quality of available evidence is low, based for the most part on observational studies, with only 1 double-masked placebo-controlled randomized trial.

Summary

There is evidence to support the use of both high-dose pulsed methyl prednisolone for induction and low-dose (5 mg) oral prednisolone as maintenance therapy for progressive disease. There is no evidence to support the use of antiretroviral therapy. There is insufficient evidence to support the use of interferon-α as a first-line therapy.

HTLV-1 Infection and Rheumatic Diseases

Some major research and clinical questions about human T-cell leukemia virus type 1 (HTLV-1) infection and rheumatic diseases remain: (1) Does HTLV-1 infection cause rheumatic diseases? (2) Do patients with rheumatic diseases display different responses to treatment with anti-rheumatic agents when they are HTLV-1 carriers? (3) Is adult T-cell leukemia/lymphoma (ATL) or HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) more prevalent in HTLV-1 carriers with rheumatic diseases who are treated with anti-rheumatic agents? These questions are important because increasing numbers of patients with rheumatic diseases are currently receiving treatment with aggressive medicines such as immunosuppressants and biologics. Studies on HTLV-1 gene-transgenic mice have shown manifestations resembling rheumatic diseases. Epidemiological studies have shown a high incidence of HTLV-1 infection in patients with rheumatic diseases including rheumatoid arthritis (RA), Sjogren’s syndrome, and polymyositis. HTLV-1-positive and HTLV-1-negative patients with RA have displayed similar immunological features including the seroprevalence of anti-citrullinated peptide antibodies. Conversely, attenuated effectiveness of tumor necrosis factor inhibitors for HTLV-1-positive patients with RA in Japan has been reported. Therefore, although no direct evidence has shown that HTLV-1 infection alone causes rheumatic diseases, HTLV-1 may affect the inflammation of RA. Although the incidence of ATL or HAM/TSP among patients with rheumatic diseases has not been investigated in large-scale studies, ATL or HAM/TSP has developed among HTLV-1-positive patients with rheumatic diseases. HTLV-1 infection may affect the clinical course of patients with rheumatic diseases, particularly after receiving anti-rheumatic agents. Because studies on these issues are limited, further investigation with large sample sizes is necessary.