Monoclonal antibody-associated progressive multifocal leucoencephalopathy in patients treated with rituximab, natalizumab, and efalizumab: a Review from the Research on Adverse Drug Events and Reports (RADAR) Project

To B or not to B cells-mediate a healthy start to life

Maternal immune responses during pregnancy are critical in programming the future health of a newborn. The maternal immune system is required to accommodate fetal immune tolerance as well as to provide a protective defence against infections for the immunocompromised mother and her baby during gestation and lactation. Natural immunity and antibody production by maternal B cells play a significant role in providing such immunoprotection. However, aberrations in the B cell compartment as a consequence of maternal autoimmunity can pose serious risks to both the mother and her baby. Despite their potential implication in shaping pregnancy outcomes, the role of B cells in human pregnancy has been poorly studied. This review focuses on the role of B cells and the implications of B cell depletion therapy in pregnancy. It highlights the evidence of an association between aberrant B cell compartment and obstetric conditions. It also alludes to the potential mechanisms that amplify these B cell aberrances and thereby contribute to exacerbation of some maternal autoimmune conditions and poor neonatal outcomes. Clinical and experimental evidence suggests strongly that maternal autoantibodies contribute directly to the pathologies of obstetric and neonatal conditions that have significant implications for the lifelong health of a newborn. The evidence for clinical benefit and safety of B cell depletion therapies in pregnancy is reviewed, and an argument is mounted for further clinical evaluation of B cell-targeted therapies in high-risk pregnancy, with an emphasis on improving neonatal outcomes and prevention of neonatal conditions such as congenital heart block and fetal/neonatal alloimmune thrombocytopenia.

Progressive multifocal leukoencephalopathy during treatment with rituximab and CHOP chemotherapy in a patient with a diffuse large B-cell lymphoma

A 74-year-old woman with a diffuse large B-cell lymphoma was treated with rituximab and CHOP chemotherapy. After three cycles of chemotherapy she developed progressive symptoms of motor imbalance, fatigue, weight loss and impaired cognitive function, which was interpreted as toxicity of the CHOP chemotherapy. The sixth cycle CHOP chemotherapy was withheld and three additional cycles of rituximab were given. Two weeks later, neurological symptoms appeared, including abducens nerve palsy of her left eye, ataxia and hemiparesis of her right body. MRI of the brain revealed two hyperintense lesions on T2-weighted and fluid-attenuated inversion recovery images without oedema or gadolinium enhancement. A PCR on John Cunningham (JC) virus DNA in cerebrospinal fluid was negative, but subsequent brain biopsy diagnosed progressive multifocal leukoencephalopathy (PML). She rapidly deteriorated and died. Awareness of PML during immunosuppressive therapy can be lifesaving, since only immune reconstitution can prevent mortality in these patients.

Disease-modifying therapy of pediatric multiple sclerosis

Multiple sclerosis (MS) is increasingly recognized in children and adolescents. Improved awareness, access to care, and subspecialty training in pediatric MS has allowed for better access to treatment. Children with MS present with an overwhelmingly relapsing form of the disease and have more frequent relapses than their adult counterparts during the early phases of disease. Cognitive deficits are prominent in pediatric MS, as opposed to locomotor disability. Beta interferons and glatiramer acetate are frequently used off-label drugs. Additional second-line therapies have occasionally been used in treatment failures. No randomized clinical trials have been performed to date in pediatric MS; however, recent legislation necessitates pediatric studies for new agents, which will allow for better defined pharmacokinetic, dosing, and efficacy data to guide the treating neurologist.

Polyomavirus JC infection inhibits differentiation of oligodendrocyte progenitor cells

Reactivation of the human polyomavirus JC (JCV) in the CNS results in a fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML). The lytic destruction of oligodendrocytes, which occurs at the terminal stage of the viral infection cycle, is considered a critical factor in the development of demyelination and the pathogenesis of PML. However, knowledge is limited about interaction of JCV with oligodendrocytes and its impact on the denudation of axons at the early stage of viral reactivation and prior to the destruction of the infected cells. We have developed an in vitro neuroprogenitor cell culture using human fetal brain that can be differentiated to the oligodendrocyte lineage to investigate interactions of JCV with its host cells. Results show that infection with JCV delays oligodendrocyte maturation as shown by reduced levels of oligodendrocytic markers, including myelin basic protein, proteolipid protein, and platelet-derived growth factor receptor-α. Furthermore, replication of JCV in these cells caused substantial dysregulation of several chemokines, including CCL5/RANTES, GRO, CXCL1/GROα, CXCL16, CXCL8/IL-8, CXCL5/ENA-78, and CXCL10/IP-10, all of which play a role in cell growth and differentiation.

Incidence of hypogammaglobulinemia in patients receiving rituximab and the use of intravenous immunoglobulin for recurrent infections

Rituximab targets normal B cells and tumor B cells. We used a unique data-mining tool to identify patients with lymphoma who were treated with rituximab and who had serial pre and post rituximab immunoglobulin concentrations evaluated. After treatment, 39% (69/179) of patients had low levels of immunoglobulin G. Recurrent sinopulmonary infections were seen in 6.6% (14/211). Intravenous immune globulin appeared to reduce the frequency of infection.

BACKGROUND

Rituximab has altered the treatment approach to B-cell malignancies and other diseases. Reports consider that rituximab had limited impact on serum immunoglobulins. However, anecdotes suggest that rituximab can cause symptomatic hypogammaglobulinemia. This retrospective study examined the relationship among rituximab, hypogammaglobulinemia, and treatment of symptomatic hypogammaglobulinemia with intravenous immune globulin (IVIG).

METHODS

Patients with serial quantitative serum immunoglobulin (SIgG) concentrations before and subsequent to rituximab administration at Memorial Sloan-Kettering Cancer Center were identified. Information regarding rituximab administration, SIgG concentrations, frequency of infection, and administration of IVIG were recorded.

RESULTS

Between December 1998 and April 2009, 211 patients with B-cell lymphoma treated with rituximab and with serial SIgG concentrations were identified. One hundred seventy-nine (85%) patients had normal SIgG before rituximab, 32 (15%) had low SIgG. After rituximab use, hypogammaglobulinemia was identified in 38.54% of patients with initially normal SIgG. The risk was greater in patients who received maintenance rituximab. Symptomatic hypogammaglobulinemia that prompted IVIG administration developed in 6.6% of patients.

CONCLUSIONS

In this data set, rituximab administration was associated with a high frequency of hypogammaglobulinemia, particularly symptomatic hypogammaglobulinemia, among patients who received multiple courses of rituximab. Baseline and periodic monitoring of SIgGs is appropriate in patients who receive rituximab.

Islet transplantation in type 1 diabetes: ongoing challenges, refined procedures, and long-term outcome

Remarkable progress has been made in islet transplantation over a span of 40 years. Once just an experimental curiosity in mice, this therapy has moved forward, and can now provide robust therapy for highly selected patients with type 1 diabetes (T1D), refractory to stabilization by other means. This progress could not have occurred without extensive dynamic international collaboration. Currently, 1,085 patients have undergone islet transplantation at 40 international sites since the Edmonton Protocol was reported in 2000 (752 allografts, 333 autografts), according to the Collaborative Islet Transplant Registry. The long-term results of islet transplantation in selected centers now match registry data of pancreas-alone transplantation, with 6 sites reporting five-year insulin independence rates ≥50%. Islet transplantation has been criticized for the use of multiple donor pancreas organs, but progress has also occurred in single-donor success, with 10 sites reporting increased single-donor engraftment. The next wave of innovative clinical trial interventions will address instant blood-mediated inflammatory reaction (IBMIR), apoptosis, and inflammation, and will translate into further marked improvements in single-donor success. Effective control of auto- and alloimmunity is the key to long-term islet function, and high-resolution cellular and antibody-based assays will add considerable precision to this process. Advances in immunosuppression, with new antibody-based targeting of costimulatory blockade and other T-B cellular signaling, will have further profound impact on the safety record of immunotherapy. Clinical trials will move forward shortly to test out new human stem cell derived islets, and in parallel trials will move forward, testing pig islets for compatibility in patients. Induction of immunological tolerance to self-islet antigens and to allografts is a difficult challenge, but potentially within our grasp.

Anti-integrin therapy for multiple sclerosis

Integrins are the foremost family of cell adhesion molecules that regulate immune cell trafficking in health and diseases. Integrin alpha4 mediates organ-specific migration of immune cells to the inflamed brain, thereby playing the critical role in the pathogenesis of multiple sclerosis. Anti-alpha4 integrin therapy aiming to block infiltration of autoreactive lymphocytes to the inflamed brain has been validated in several clinical trials for the treatment of multiple sclerosis. This paper provides readers with an overview of the molecular and structural bases of integrin activation as well as rationale for using anti-alpha4 integrin therapy for multiple sclerosis and then chronicles the rise and fall of this treatment strategy using natalizumab, a humanized anti-alpha4 integrin.

[Personalized medicine for rheumatoid arthritis : serological and clinical patient profiles to optimize B and T cell targeted therapy]

Nowadays B and T-cell directed biologics in addition to TNF inhibitors are established as effective and safe treatment options for rheumatoid arthritis. As shown by the approval of rituximab for the treatment of systemic vasculitis, these drugs can also be useful for the treatment of other systemic autoimmune diseases; however, to optimize therapeutic strategies, predictive factors for treatment response as well as a good characterized safety profile are essential. So far implementation of real personalized medicine is not feasible in the field of rheumatology, but first biomarkers have already been identified and provide promising results. In this context, it has been shown that a B-cell directed therapy with rituximab is more effective in seropositive patients with rheumatoid arthritis. In addition, characterization of the cytokine milieu as well as of circulating and tissue infiltrating B and T-cell subsets might be useful for prediction of treatment response in the near future.

JC virus detection and JC virus-specific immunity in natalizumab-treated multiple sclerosis patients

Background

The use of natalizumab in multiple sclerosis (MS) may favour JC virus reactivation; this phenomenon is usually asymptomatic but can, albeit rarely, evolve into frank progressive multifocal leucoencephalopathy (PML).

Methods

JCV-specific CD8+ T lymphocytes were evaluated by flow cytometry over a 24-month period in 24 natalizumab-treated MS patients in whom JCV DNA was or was not detected in blood using quantitative real-time polymerase chain reaction; all these cases were asymptomatic.

Results

Perforin- and grazymes-containing VP-1-specific CD8+ T lymphocytes were reduced whereas CD107a-expressing cells were increased in JCV positive patients, suggesting an active degranulation of these cells; naïve CD8+ T lymphocytes were also decreased whereas memory cells were increased in patients in whom JCV reactivation was observed.

Conclusion

The presence of a CD8+ T lymphocyte-mediated effector immune response offers a greater insight into reactivation of JCV and its clinical sequelae, and may help the monitoring of patients on natalizumab therapy.

Nail psoriasis: a review

Nail psoriasis is common, occurring in up to half of patients with psoriasis and in 90% of patients with psoriatic arthritis. Left untreated, it may progress to debilitating nail disease, which leads to significant functional impairment. The most common clinical signs of nail psoriasis are nail plate pitting and onycholysis. Other classical signs include oil drop discoloration, subungual hyperkeratosis, and splinter hemorrhages. The modified Nail Psoriasis Severity Index (mNAPSI) can be used to grade the severity of nail psoriasis, while the Nail Psoriasis Quality of Life Scale (NPQ10) is a questionnaire that evaluates the impact of nail psoriasis on the patient's functional status and quality of life. Treatment of nail psoriasis should be individualized according to the patient's preferences, severity of nail changes, and presence of skin and/or joint involvement. Both topical and intralesional therapies are safe and effective treatment modalities for nail disease, but are limited by poor adherence and pain, respectively. Systemic therapy such as oral retinoids may be considered for widespread nail disease causing significant morbidity. Among biologic agents, tumor necrosis factor-α inhibitors and T-cell-targeted therapies such as ustekinumab may be useful for refractory severe nail psoriasis.

[Central nervous system complications in patients undergoing cytotoxic chemotherapy and targeted therapies]

Anti-cancer treatments (cytotoxic chemotherapies, targeted therapies and hormonotherapies) are known to induce early and delayed neurological toxicities. Acute encephalopathies and posterior reversible encephalopathies are better known and described, physiopathological hypotheses are emerging. It is difficult to discriminate what drug is causing the symptoms in patients treated with multiple cytotoxic drugs. Methotrexate and ifosfamide are responsible for acute encephalopathies. L-asparaginase and methotrexate or targeted therapies may induce cerebrovascular complications. As life expectancy increases and more complex regimen including innovative targeted therapies are developed, new toxicity profiles can be expected. To be able to provide an early diagnosis, prevention, and treatment (when existing) of these pathologies remains a tremendous challenge that would allow a good quality of life with social and professional life after their cancer is cured.

PML-IRIS in a patient treated with brentuximab

A 38-year-old woman was diagnosed with cutaneous anaplastic T-cell lymphoma that proved refractory to methotrexate, bexarotene, denileukin diftitox, interferon γ-1b, interferon α-2b, vorinostat, and pralatrexate. She was therefore started on the newly approved monoclonal anti-CD30 antibody brentuximab vedotin. Treatment with brentuximab 1.8 mg/kg IV every 3 weeks quickly led to disappearance of her cutaneous tumors. The day after her second brentuximab infusion she developed word-finding difficulties and unsteady gait. Due to further neurologic deterioration, she was admitted to an outside hospital. Brain MRI revealed multifocal enhancing white matter lesions throughout bilateral cerebral hemispheres and posterior fossa (figure, A-C). Brain biopsy was performed 15 days after her last brentuximab dose to rule out metastases and she was diagnosed with progressive multifocal leukoencephalopathy (PML) (figure, J). The patient was discharged home with hospice care. Upon discharge, she was started on prednisone 50 mg daily to help treat her eczema. Her family brought her to our clinic for a second opinion.

Molecular biology, epidemiology, and pathogenesis of progressive multifocal leukoencephalopathy, the JC virus-induced demyelinating disease of the human brain

Progressive multifocal leukoencephalopathy (PML) is a debilitating and frequently fatal central nervous system (CNS) demyelinating disease caused by JC virus (JCV), for which there is currently no effective treatment. Lytic infection of oligodendrocytes in the brain leads to their eventual destruction and progressive demyelination, resulting in multiple foci of lesions in the white matter of the brain. Before the mid-1980s, PML was a relatively rare disease, reported to occur primarily in those with underlying neoplastic conditions affecting immune function and, more rarely, in allograft recipients receiving immunosuppressive drugs. However, with the onset of the AIDS pandemic, the incidence of PML has increased dramatically. Approximately 3 to 5% of HIV-infected individuals will develop PML, which is classified as an AIDS-defining illness. In addition, the recent advent of humanized monoclonal antibody therapy for the treatment of autoimmune inflammatory diseases such as multiple sclerosis (MS) and Crohn's disease has also led to an increased risk of PML as a side effect of immunotherapy. Thus, the study of JCV and the elucidation of the underlying causes of PML are important and active areas of research that may lead to new insights into immune function and host antiviral defense, as well as to potential new therapies.

Progressive multifocal leukoencephalopathy: why gray and white matter

Since it was first described in 1958, progressive multifocal leukoencephalopathy (PML), a demyelinating disease of the brain caused by the polyomavirus JC (JCV), has evolved tremendously. It was once considered a noninflammatory disease that affected exclusively oligodendrocytes and astrocytes in the white matter of immunosuppressed individuals and was almost always fatal. Today, we understand that PML can present during the course of an immune reconstitution inflammatory syndrome and that it affects a broader range of individuals, including patients with minimal immunosuppression and those who are treated with novel immunomodulatory medications. Furthermore, JCV-infected glial cells are frequently located at the gray matter-white matter junction or within the gray matter, causing demyelinating lesions within cortical areas. Finally, JCV variants can also infect neurons, leading to the recognition of two distinct clinical entities: JCV granule cell neuronopathy and JCV encephalopathy.

Suppressive effect of PARP-1 inhibitor on JC virus replication in vitro

The incidence of progressive multifocal leukoencephalopathy (PML) has increased due to the AIDS pandemic, hematological malignancies, and immunosuppressive therapies. Recently, the number of cases of monoclonal antibody-associated PML has increased in patients treated with immunomodulatory drugs such as natalizumab. However, no common consensus regarding PML therapy has been reached in clinical studies. In order to examine the suppression of JC virus (JCV) replication by 3-aminobenzamide (3-AB), a representative PARP-1 inhibitor, a DNA replication assay was carried out using the neuroblastoma cell line IMR-32 and IMR-adapted JCV. The suppression of JCV propagation by 3-AB was also examined using JCI cells, which are a carrier culture producing continuously high JCV titers. The results indicated that PARP-1 inhibitors, such as 3-aminobenzamide (3-AB), suppress JCV replication and propagation significantly in vitro, as judged by DNA replication assay, hemagglutination, and real-time PCR analysis. It has been also shown that 3-AB reduced PARP-1 activity in IMR-32 cells. According to the results of the MTT assay, the enzyme activity of 3-AB-treated cells was slightly lower than that of DMSO-treated cells. However, the significant suppression of JCV propagation is not related to the slight decrease in cell growth. To our knowledge, this is the first report that PARP-1 inhibitor suppresses the replication of JCV significantly in neuroblastoma cell lines via the reduction of PARP-1 activity. Thus, PARP-1 inhibitors also may be a novel therapeutic drug for PML.

Treatment of Neuromyelitis Optica: Review and Recommendations

Neuromyelitis optica (NMO) is an autoimmune demyelinating disease preferentially targeting the optic nerves and spinal cord. Once regarded as a variant of multiple sclerosis (MS), NMO is now recognized to be a different disease with unique pathology and immunopathogenesis that does not respond to traditional MS immunomodulators such as interferons. Preventive therapy in NMO has focused on a range of immunosuppressive medications, none of which have been validated in a rigorous randomized trial. However, multiple retrospective and a few recent prospective studies have provided evidence for the use of six medications for the prevention of NMO exacerbations: azathioprine, rituximab, mycophenolate mofetil, prednisone, methotrexate and mitoxantrone. This review provides a comprehensive analysis of each of these medications in NMO and concludes with a set of recommended consensus practices.

Bag3-induced autophagy is associated with degradation of JCV oncoprotein, T-Ag

JC virus, JCV, is a human neurotropic polyomavirus whose replication in glial cells causes the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML). In addition, JCV possesses oncogenic activity and expression of its transforming protein, large T-antigen (T-Ag), in several experimental animals induces tumors of neural origin. Further, the presence of JCV DNA and T-Ag have been repeatedly observed in several human malignant tissues including primitive neuroectodermal tumors and glioblastomas. Earlier studies have demonstrated that Bag3, a member of the Bcl-2-associated athanogene (Bag) family of proteins, which is implicated in autophagy and apoptosis, is downregulated upon JCV infection of glial cells and that JCV T-Ag is responsible for suppressing the activity of the BAG3 promoter. Here, we investigated the possible impact of Bag3 on T-Ag expression in JCV-infected human primary glial cells as well as in cells derived from T-Ag-induced medulloblastoma in transgenic animals. Results from these studies revealed that overexpression of Bag3 drastically decreases the level of T-Ag expression by inducing the autophagic degradation of the viral protein. Interestingly, this event leads to the inhibition of JCV infection of glial cells, suggesting that the reduced levels of T-antigen seen upon the overexpression of Bag3 has a biological impact on the viral lytic cycle. Results from protein-protein interaction studies showed that T-Ag and Bag3 physically interact with each other through the zinc-finger of T-Ag and the proline rich domains of Bag3, and this interaction is important for the autophagic degradation of T-Ag. Our observations open a new avenue of research for better understanding of virus-host interaction by investigating the interplay between T-Ag and Bag3, and their impact on the development of JCV-associated diseases.

Assessing the safety of biologic agents in patients with rheumatoid arthritis

Biologic treatments--including five TNF-α inhibitors, the IL-1 receptor antagonist anakinra, the IL-6 receptor inhibitor tocilizumab, the selective inhibitor of T-cell co-stimulation abatacept and the B-cell-directed mAb rituximab--have provided effective therapeutic options for patients with RA with inadequate response to conventional DMARDs. However, the fact that these agents are immune modulators has raised safety concerns, prompting careful evaluation in clinical trials and intensive post-marketing surveillance. Serious infections may arise, and diagnosis may be delayed by an atypical spectrum of signs and symptoms. Patients may experience reactivation of latent tuberculosis, hepatitis B or C or opportunistic infections. RA is a risk factor for cancer, and biologic therapy may modestly increase the risk of lymphoma and some solid tumours beyond background. During biologic therapy, demyelinating disorders of the CNS have been noted, and pre-existing disease manifestations may be aggravated. Hepatic transaminase levels may increase, although these elevations are usually mild to moderate, transient and without clinical consequence. Hyperlipidaemia, which is responsive to lipid-lowering therapy, may develop, and patients with congestive heart failure may experience symptom exacerbation. Safe use of biologic agents requires thorough risk assessment of potential candidates for treatment and careful monitoring during and after therapy.

Autoimmune neuromuscular disorders

Autoimmune neuromuscular disorders affecting peripheral nerves, neuromuscular junction or muscle have a wide clinical spectrum with diverse pathogenetic mechanisms. Peripheral nervous system may be targeted in the context of complex immune reactions involving different cytokines, antigen-presenting cells, B cells and different types of T cells. Various immunomodulating and cytotoxic treatments block proliferation or activation of immune cells by different mechanisms attempting to control the response of the immune system and limit target organ injury. Most treatment protocols for autoimmune neuromuscular disorders are based on the use of corticosteroids, intravenous immunoglobulins and plasmapheresis, with cytotoxic agents mostly used as steroid-sparing medications. More recently, development of specific monoclonal antibodies targeting individual cell types allowed a different approach targeting specific immune pathways, but these new treatments are also associated with various adverse effects and their long-term efficacy is still unknown.

CNS infections in patients with cancer

PURPOSE OF REVIEW

This article provides a practical clinical approach to potential CNS infections in patients with cancer, discusses problematic presentations of posterior reversible encephalopathy syndrome and immune reconstitution inflammatory syndrome, and includes specific testing and treatment recommendations for bacterial meningitis, invasive fungal infections, and opportunistic viral infections.

RECENT FINDINGS

The major deficits predisposing patients with cancer to CNS infection are neutropenia, barrier disruption, B-lymphocyte or immunoglobulin deficiency, and impaired T lymphocyte-mediated immunity. Evolving patterns of drug resistance and prophylactic antimicrobial regimens have altered the timing and range of organisms causing infections. Increasingly intensive immunosuppression has made new groups of patients vulnerable to infections such as progressive multifocal leukoencephalopathy. New MRI sequences offer the potential to diagnose such infections earlier, at a stage when they are more treatable.

SUMMARY

Despite improved prophylactic and therapeutic antibiotic regimens, CNS infections remain an important source of morbidity and mortality among several cancer patient groups, particularly those patients undergoing craniotomy and those with hematologic malignancies receiving either hematopoietic cell transplantation or other intensive chemotherapy regimens.

Immune surveillance in the central nervous system

The CNS, which consists of the brain and spinal cord, is continuously monitored by resident microglia and blood-borne immune cells such as macrophages, dendritic cells and T cells to detect for damaging agents that would disrupt homeostasis and optimal functioning of these vital organs. Further, the CNS must balance between vigilantly detecting for potentially harmful factors and resolving any immunological responses that in themselves can create damage if left unabated. We discuss the physiological roles of the immune sentinels that patrol the CNS, the molecular markers that underlie their surveillance duties, and the consequences of interrupting their functions following injury and infection by viruses such as JC virus, human immunodeficiency virus, herpes simplex virus and West Nile virus.

Combined costimulatory and leukocyte functional antigen-1 blockade prevents transplant rejection mediated by heterologous immune memory alloresponses

BACKGROUND

Recent evidence suggests that alloreactive memory T cells are generated by the process of heterologous immunity, whereby memory T cells arising in response to pathogen infection crossreact with donor antigens. Because of their diminished requirements for costimulation during recall, these pathogen-elicited allocrossreactive memory T cells are of particular clinical importance, especially given the emergence of costimulatory blockade as a transplant immunosuppression strategy.

METHODS

We used an established model of heterologous immunity involving sequential infection of a naïve C57BL/6 recipient with lymphocytic choriomeningitis virus and vaccinia virus, followed by combined skin and bone marrow transplant from a BALB/c donor.

RESULTS

We demonstrate that coupling the integrin antagonist anti-leukocyte functional antigen (LFA)-1 with costimulatory blockade could surmount the barrier posed by heterologous immunity in a fully allogeneic murine transplant system. The combined costimulatory and integrin blockade regimen suppressed proliferation of alloreactive memory T cells and attenuated their cytokine effector responses. This combined blockade regimen also promoted the retention of FoxP³⁺ Tregs in draining lymph nodes. Finally, we show that in an in vitro mixed lymphocyte reaction system using human T cells, the combination of belatacept and anti-LFA-1 was able to suppress cytokine production by alloreactive memory T cells that was resistant to belatacept alone.

CONCLUSIONS

As an antagonist against human LFA-1 exists and has been used clinically to treat psoriasis, these findings have significant translational potential for future clinical transplant trials.

Tolerogenic therapies in transplantation

Since the concept of immunologic tolerance was discovered in the 1940s, the pursuit of tolerance induction in human transplantation has led to a rapid development of pharmacologic and biologic agents. Short-term graft survival remains an all-time high, but successful withdrawal of immunosuppression to achieve operational tolerance rarely occurs outside of liver transplantation. Collaborative efforts through the NIH sponsored Immune Tolerance Network and the European Commission sponsored Reprogramming the Immune System for Establishment of Tolerance consortia have afforded researchers opportunity to evaluate the safety and efficacy of tolerogenic strategies, investigate mechanisms of tolerance, and identify molecular and genetic markers that distinguish the tolerance phenotype. In this article, we review traditional and novel approaches to inducing tolerance for organ transplantation, with an emphasis on their translation into clinical trials.

Antibodies against human BLyS and APRIL attenuate EAE development in marmoset monkeys

B lymphocyte stimulator (BLyS, also indicated as BAFF (B-cell activating factor) and CD257), and A Proliferation Inducing Ligand (APRIL, CD256) are two members of the TNF superfamily with a central role in B cell survival. Antibodies against these factors have potential therapeutic relevance in autoimmune inflammatory disorders with a proven pathogenic contribution of B cells, such as multiple sclerosis (MS). In the current study we performed a multi-parameter efficacy comparison of monoclonal antibodies against human anti-BLyS and anti-APRIL in a common marmoset (Callithrix jacchus) model of experimental autoimmune encephalomyelitis (EAE). A MS-like disease was induced by immunization with recombinant human myelin/oligodendrocyte glycoprotein (rhMOG) in complete Freund’s adjuvant. The results show that the anti-BLyS and anti-APRIL antibody cause significant depletion of circulating CD20+ B cells, but a small subset of CD20 + CD40^high B cells was not depleted. Induction of CD20+ B cell depletion from lymph nodes was only observed in the anti-BLyS treated monkeys. Both antibodies had a significant inhibitory effect on disease development, but all monkeys developed clinically evident EAE. Anti-BLyS treated monkeys were sacrificed with the same clinical signs as saline-treated monkeys, but nevertheless displayed significantly reduced spinal cord demyelination. This effect was not observed in the anti-APRIL treated monkeys. The two antibodies had a different effect on T cell subset activation and the profiles of ex vivo released cytokines. In conclusion, treatment with anti-BLyS and anti-APRIL delays the development of neurological disease in a relevant preclinical model of MS. The two mAbs achieve this effect via different mechanisms.

Leukocyte function-associated antigen-1/intercellular adhesion molecule-1 interaction induces a novel genetic signature resulting in T-cells refractory to transforming growth factor-β signaling

The immunesuppressive cytokine TGF-β plays crucial regulatory roles in the induction and maintenance of immunologic tolerance and prevention of immunopathologies. However, it remains unclear how circulating T-cells can escape from the quiescent state maintained by TGF-β. Here, we report that the T-cell integrin leukocyte function-associated antigen-1 (LFA-1) interaction with its ligand intercellular adhesion molecule-1 (ICAM-1) induces a genetic signature associated with reduced TGF-β responsiveness via up-regulation of SKI, E3 ubiquitin-protein ligase SMURF2, and SMAD7 (mothers against decapentaplegic homolog 7) genes and proteins. We confirmed that the expression of these TGF-β inhibitory molecules was dependent on STAT3 and/or JNK activation. Increased expression of SMAD7 and SMURF2 in LFA-1/ICAM-1 cross-linked T-cells resulted in impaired TGF-β-mediated phosphorylation of SMAD2 and suppression of IL-2 secretion. Expression of SKI caused resistance to TGF-β-mediated suppression of IL-2, but SMAD2 phosphorylation was unaffected. Blocking LFA-1 by neutralizing antibody or specific knockdown of TGF-β inhibitory molecules by siRNA substantially restored LFA-1/ICAM-1-mediated alteration in TGF-β signaling. LFA-1/ICAM-1-stimulated human and mouse T-cells were refractory to TGF-β-mediated induction of FOXP3(+) (forkhead box P3) and RORγt(+) (retinoic acid-related orphan nuclear receptor γt) Th17 differentiation. These mechanistic data suggest an important role for LFA-1/ICAM-1 interactions in immunoregulation concurrent with lymphocyte migration that may have implications at the level of local inflammatory response and for anti-LFA-1-based therapies.

Challenges for synthesising data in a network of registries for systemic psoriasis therapies

BACKGROUND

Large disease registries are the preferred method to assess long-term treatment safety. If psoriasis registries collaborate in a network, their power to assess safety is increased.

OBJECTIVE

To identify heterogeneity in psoriasis registries and methodological challenges for synthesising the data they provide.

METHODS

We surveyed the registries in PSONET and identified and addressed the challenges to collaborative analysis for the network in several round table meetings.

RESULTS

Eight out of 10 registries had a prospective comparator cohort with similar disease characteristics but not on biologics. Registries differed in the coding and validation or follow-up of adverse events and in the way they sampled their population. Fifteen challenges to registries collaborating were identified in the areas of operational governance, structural conduct, bias and analysis.

CONCLUSIONS

Participation in PSONET, a network of psoriasis registries, helps identify and solve common issues, enhancing the individual registries, and provides larger sets of more powerful safety data in a diverse population. Challenges to interpreting data collectively include heterogeneity in sampling, variable penetration of biologics and compatibility of different datasets.

Successful immune tolerance induction to enzyme replacement therapy in CRIM-negative infantile Pompe disease

PURPOSE

Infantile Pompe disease resulting from a deficiency of lysosomal acid α-glucosidase (GAA) requires enzyme replacement therapy (ERT) with recombinant human GAA (rhGAA). Cross-reactive immunologic material negative (CRIM-negative) Pompe patients develop high-titer antibody to the rhGAA and do poorly. We describe successful tolerance induction in CRIM-negative patients.

METHODS

Two CRIM-negative patients with preexisting anti-GAA antibodies were treated therapeutically with rituximab, methotrexate, and gammaglobulins. Two additional CRIM-negative patients were treated prophylactically with a short course of rituximab and methotrexate, in parallel with initiating rhGAA.

RESULTS

In both patients treated therapeutically, anti-rhGAA was eliminated after 3 and 19 months. All four patients are immune tolerant to rhGAA, off immune therapy, showing B-cell recovery while continuing to receive ERT at ages 36 and 56 months (therapeutic) and 18 and 35 months (prophylactic). All patients show clinical response to ERT, in stark contrast to the rapid deterioration of their nontolerized CRIM-negative counterparts.

CONCLUSION

The combination of rituximab with methotrexate ± intravenous gammaglobulins (IVIG) is an option for tolerance induction of CRIM-negative Pompe to ERT when instituted in the naïve setting or following antibody development. It should be considered in other conditions in which antibody response to the therapeutic protein elicits robust antibody response that interferes with product efficacy.

T cell homing to epithelial barriers in allergic disease

Allergic inflammation develops in tissues that have large epithelial surface areas that are exposed to the environment, such as the lung, skin and gut. In the steady state, antigen-experienced memory T cells patrol these peripheral tissues to facilitate swift immune responses against invading pathogens. In at least two allergy-prone organs, the skin and the gut, memory T cells are programmed during the initial antigen priming to express trafficking receptors that enable them to preferentially home to these organs. In this review we propose that tissue-specific memory and inflammation-specific T cell trafficking facilitates the development of allergic disease in these organs. We thus review recent advances in our understanding of tissue-specific T cell trafficking and how regulation of T cell trafficking by the chemokine system contributes to allergic inflammation in mouse models and in human allergic diseases of the skin, lung and gut. Inflammation- and tissue-specific T lymphocyte trafficking pathways are currently being targeted as new treatments for non-allergic inflammatory diseases and may yield effective new therapeutics for allergic diseases.

I-domain-antigen conjugate (IDAC) for delivering antigenic peptides to APC: synthesis, characterization, and in vivo EAE suppression

The objectives of this work are to characterize the identity of I-domain-antigen conjugate (IDAC) and to evaluate the in vivo efficacy of IDAC in suppressing experimental autoimmune encephalomyelitis (EAE) in mouse model. The hypothesis is that the I-domain delivers PLP(139-151) peptides to antigen-presenting cells (APC) and alters the immune system by simultaneously binding to ICAM-1 and MHC-II, blocking immunological synapse formation. IDAC was synthesized by derivatizing the lysine residues with maleimide groups followed by conjugation with PLP-Cys-OH peptide. Conjugation with PLP peptide does not alter the secondary structure of the protein as determined by CD. IDAC suppresses the progression of EAE, while I-domain and GMB-I-domain could only delay the onset of EAE. As a positive control, Ac-PLP-BPI-NH(2)-2 can effectively suppress the progress of EAE. The number of conjugation sites and the sites of conjugations in IDAC were determined using tryptic digest followed by LC-MS analysis. In conclusion, conjugation of I-domain with an antigenic peptide (PLP) resulted in an active molecule to suppress EAE in vivo.

Heterogeneity within T Cell Memory: Implications for Transplant Tolerance

Adaptive immunity in both mouse and man results in the generation of immunological memory. Memory T cells are both friend and foe to transplant recipients, as they are intimately involved and in many cases absolutely required for the maintenance of protective immunity in the face immunosuppression, yet from the evidence presented herein they clearly constitute a formidable barrier for the successful implementation of tolerance induction strategies in transplantation. This review describes the experimental evidence demonstrating the increased resistance of memory T cells to many distinct tolerance induction strategies, and outlines recent advances in our knowledge of the ways in which alloreactive memory T cells arise in previously untransplanted individuals. Understanding the impact of alloreactive memory T cell specificity, frequency, and quality might allow for better donor selection in order to minimize the donor-reactive memory T cell barrier in an individual transplant recipient, thus allowing stratification of relative risk of alloreactive memory T cell mediated rejection, and conversely increase the likelihood of successful establishment of tolerance. However, further research into the molecular and cellular pathways involved in alloreactive memory T cell-mediated rejection is required in order to design new strategies to overcome the memory T cell barrier, without critically impairing protective immunity.

Drug-induced PML: a global agenda for a global challenge

The occurrence of severe adverse events such as progressive multifocal leukoencephalopathy (PML) has the potential to limit the benefits of highly efficacious medicines being developed to fulfill unmet clinical needs across therapeutic areas. Following an Expert meeting in London in July 2011 (http://www.ema.europa.eu/docs/en_GB/document_library/Report/2011/09/WC500111562.pdf), a research agenda, highlighting methodological, clinical, and communication elements, to mitigate the risk and improve the management of drug-induced PML has been agreed upon.

Medications in patients treated with therapeutic plasma exchange: prescription dosage, timing, and drug overdose

Therapeutic plasma exchange (TPE) is an extracorporeal process commonly used in clinical medicine for the treatment of a variety of neurological, renal, hematological, dermatological, and other diseases. Inherent to the procedure, patients' plasma removal may lead to the extraction of drugs they are concurrently receiving. This review discusses the published literature assessing TPE's influence on different drug classes' disposition and, when applicable, sets forth management recommendations in cases where the drugs are used at the usual doses and in cases of drug overdose.

Fatal PML associated with efalizumab therapy: insights into integrin αLβ2 in JC virus control

OBJECTIVES

Progressive multifocal leukoencephalopathy (PML) has become much more common with monoclonal antibody treatment for multiple sclerosis and other immune-mediated disorders.

METHODS

We report 2 patients with severe psoriasis and fatal PML treated for ≥3 years with efalizumab, a neutralizing antibody to αLβ2-leukointegrin (LFA-1). In one patient, we conducted serial studies of peripheral blood and CSF including analyses of leukocyte phenotypes, migration ex vivo, and CDR3 spectratypes with controls coming from HIV-infected patients with PML. Extensive pathologic and histologic analysis was done on autopsy CNS tissue of both patients.

RESULTS

Both patients developed progressive cognitive and motor deficits, and JC virus was identified in CSF. Despite treatment including plasma exchange (PE) and signs of immune reconstitution, both died of PML 2 and 6 months after disease onset. Neuropathologic examination confirmed PML. Efalizumab treatment was associated with reduced transendothelial migration by peripheral T cells in vitro. As expression levels of LFA-1 on peripheral T cells gradually rose after PE, in vitro migration increased. Peripheral and CSF T-cell spectratyping showed CD8+ T-cell clonal expansion but blunted activation, which was restored after PE.

CONCLUSIONS

From these data we propose that inhibition of peripheral and intrathecal T-cell activation and suppression of CNS effector-phase migration both characterize efalizumab-associated PML. LFA-1 may be a crucial factor in homeostatic JC virus control.

Cost-effectiveness of adding rituximab to fludarabine and cyclophosphamide for the treatment of previously untreated chronic lymphocytic leukemia

A recent phase III trial demonstrated improved progression-free survival (PFS) and overall survival (OS) associated with adding rituximab to fludarabine and cyclophosphamide (R-FC) compared to FC in treatment of previously untreated chronic lymphocytic leukemia (CLL). A cost-effectiveness analysis of R-FC over FC was performed from a US third-party payer perspective over a lifetime horizon in the base case. One-way, two-way and probabilistic sensitivity analyses were conducted to assess the robustness of the results. A secondary analysis was performed by also considering a societal perspective. R-FC was associated with an incremental 1.15 quality-adjusted life-years (QALYs) compared to FC and resulted in an incremental cost-effectiveness ratio of $23 530 per QALY in the base case and $31 513 per QALY considering a societal perspective. Results were most sensitive to time horizon, discount rate and unit drug cost for rituximab. Within the limitations of modeling long-term outcomes, R-FC is cost-effective for previously untreated CLL.

Risk stratification for progressive multifocal leukoencephalopathy in patients treated with natalizumab

Natalizumab is a highly effective immunomodulator in the treatment of multiple sclerosis (MS). Treatment with natalizumab has been associated with progressive multifocal leukoencephalopathy (PML), an infection of the central nervous system (CNS) caused by a pathogenic form of the normally benign JC virus (JCV). We searched PubMed and used current data from the natalizumab global safety database to assess risk factors and quantify the risk of PML. Natalizumab treatment duration and prior use of immunosuppressive therapies are established risk factors for development of PML in natalizumab-treated patients. With the development of a reliable and validated assay for detection of antibodies in patients with MS directed against JCV, it is now possible to identify persons who are carriers of JCV. The availability of this assay provides an additional option for risk stratification of PML in patients using or considering natalizumab therapy. Recommendations for clinical management of patients with MS and use of natalizumab are provided based on the presence of these three risk factors. The identification of risk factors that increase the likelihood of PML in natalizumab-treated patients can facilitate benefit-risk discussions between health care professionals and patients. Continued research and data collection will further develop our understanding of PML and the mechanisms by which these risk factors contribute to its development.

Obinutuzumab for the treatment of lymphoproliferative disorders

INTRODUCTION

Targeted therapy against CD20 with the mAb rituximab has led to significant improvements in survival for patients with B-cell non-Hodgkin's lymphoma (NHL). Despite these improvements, many patients relapse and/or become refractory after rituximab-containing therapies and thus better therapies are required for NHL.

AREAS COVERED

Obinutuzumab is a novel, humanized, anti-CD20 mAb currently being investigated in Phase III studies in comparison to rituximab. An overview of obinutuzumab, its mechanisms of action and the results of pre-clinical and Phase I/II studies are presented.

EXPERT OPINION

Pre-clinical studies suggest that obinutuzumab is a more potent anti-CD20 mAb than Rituximab at inducing antibody-dependent cellular cytotoxicity (ADCC) and direct cell death (DCD). Obinutuzumab is safe and effective in CD20 + NHL and further study is warranted. Results of ongoing Phase III clinical trials comparing Obinutuzumab to Rituximab in different disease settings and with different chemotherapy regimens are eagerly awaited.

JC virus intranuclear inclusions associated with PML-NBs: analysis by electron microscopy and structured illumination microscopy

Progressive multifocal leukoencephalopathy is a fatal demyelinating disorder caused by JC virus infection. JC virus was recently found to target promyelocytic leukemia nuclear bodies (PML-NBs), punctuate domains in the nuclei. Thus, the virus progenies cluster in dots as intranuclear inclusions (ie, as dot-shaped inclusions). In the present study, both the viral major and minor capsid proteins were expressed from polycistronic expression vectors with a powerful promoter, and formation into virus-like particles (VLPs) was examined by electron microscopy. When the upstream regulatory sequence including the agnogene (nt 275 to 490) was present, capsid protein expression was suppressed, but numerous VLPs were efficiently formed with restricted accumulation to PML-NBs. VLPs were uniform, and the cells were severely degraded. In contrast, when the 5' terminus of the agnogene (nt 275 to 409; 135 bp) was deleted, capsid protein expression was markedly enhanced, but VLPs were more randomly produced in the nucleus outside of PML-NBs. VLPs were pleomorphic, and cell degradation was minimal. JC virus association with PML-NBs was confirmed in human brain tissues by structured illumination microscopy. PML-NBs were shaped in spherical shells, with viral capsid proteins circumscribing the surface. These findings indicate that PML-NBs are intranuclear locations for pathogenic JC virus proliferation. Either the agnogene or its product likely supports efficient progeny production at PML-NBs, leading to subsequent degeneration of host glial cells.

Monoclonal antibodies and recombinant immunoglobulins for the treatment of multiple sclerosis

Multiple sclerosis (MS) is an inflammatory and degenerative disease leading to demyelination and axonal damage in the CNS. Autoimmunity plays a central role in MS pathogenesis. Per definition, monoclonal antibodies are recombinant biological compounds with a well defined target, thus carrying the promise of targeting pathogenic cells or molecules with high specificity, avoiding undesired off-target effects. Natalizumab was the first monoclonal antibody to be approved for the treatment of MS. Several other monoclonal antibodies are in development and have demonstrated promising efficacy in phase II studies. They can be categorized according to their mode of action into compounds targeting (i) leukocyte migration into the CNS (natalizumab); (ii) cytolytic antibodies (rituximab, ocrelizumab, ofatumumab, alemtuzumab); or (iii) antibodies and recombinant proteins targeting cytokines and chemokines and their receptors (daclizumab, ustekinumab, atacicept, tabalumab [Ly-2127399], secukinumab [AIN457]). In this review, we discuss the specific molecular targets, clinical efficacy and safety of these compounds and discuss criteria to anticipate the position of monoclonal antibodies in the diversifying armamentarium of MS therapy in the coming years.

Integrin antagonists prevent costimulatory blockade-resistant transplant rejection by CD8(+) memory T cells

The success of belatacept in late-stage clinical trials inaugurates the arrival of a new class of immunosuppressants based on costimulatory blockade, an immunosuppression strategy that disrupts essential signals required for alloreactive T-cell activation. Despite having improved renal function, kidney transplant recipients treated with belatacept experienced increased rates of acute rejection. This finding has renewed focus on costimulatory blockade-resistant rejection and specifically the role of alloreactive memory T cells in mediating this resistance. To study the mechanisms of costimulatory blockade-resistant rejection and enhance the clinical efficacy of costimulatory blockade, we developed an experimental transplant system that models a donor-specific memory CD8(+) T-cell response. After confirming that graft-specific memory T cells mediate costimulatory blockade-resistant rejection, we characterized the role of integrins in this rejection. The resistance of memory T cells to costimulatory blockade was abrogated when costimulatory blockade was coupled with either anti-VLA-4 or anti-LFA-1. Mechanistic studies revealed that in the presence of costimulatory blockade, anti-VLA-4 impaired T-cell trafficking to the graft but not memory T-cell recall effector function, whereas anti-LFA-1 attenuated both trafficking and memory recall effector function. As antagonists against these integrins are clinically approved, these findings may have significant translational potential for future clinical transplant trials.

Treatment of myasthenia gravis based on its immunopathogenesis

The prognosis of myasthenia gravis (MG) has improved dramatically due to advances in critical-care medicine and symptomatic treatments. Its immunopathogenesis is fundamentally a T-cell-dependent autoimmune process resulting from loss of tolerance toward self-antigens in the thymus. Thymectomy is based on this immunological background. For MG patients who are inadequately controlled with sufficient symptomatic treatment or fail to achieve remission after thymectomy, remission is usually achieved through the addition of other immunotherapies. These immunotherapies can be classified into two groups: rapid induction and long-term maintenance. Rapid induction therapy includes intravenous immunoglobulin (IVIg) and plasma exchange (PE). These produce improvement within a few days after initiation, and so are useful for acute exacerbation including myasthenic crisis or in the perioperative period. High-dose prednisone has been more universally preferred for remission induction, but it acts more slowly than IVIg and PE, commonly only after a delay of several weeks. Slow tapering of steroids after a high-dose pulse offers a method of maintaining the state of remission. However, because of significant side effects, other immunosuppressants (ISs) are frequently added as "steroid-sparing agents". The currently available ISs exert their immunosuppressive effects by three mechanisms: 1) blocking the synthesis of DNA and RNA, 2) inhibiting T-cell activation and 3) depleting the B-cell population. In addition, newer drugs including antisense molecule, tumor necrosis factor alpha receptor blocker and complement inhibitors are currently under investigation to confirm their effectiveness. Until now, the treatment of MG has been based primarily on experience rather than gold-standard evidence from randomized controlled trials. It is hoped that well-organized studies and newer experimental trials will lead to improved treatments.

The advent of monoclonal antibodies in the treatment of chronic autoimmune diseases

Monoclonal antibodies, first introduced in cancer therapy and to prevent allograft rejection, represent new pharmacological tools for the treatment of autoimmune diseases. With the knowledge of immunological movements in autoimmunity, it is now possible to target each single step of the immune process, from the activation of T lymphocytes in lymph nodes to the formation of the immunological synapse, and to T cell differentiation and cytokine production. However, this approach is still not devoid of adverse effects. In fact, even if monoclonal antibodies exert selective immunomodulation by targeting only cells expressing a specific antigen, a widespread perturbation of the immune system is induced, leading to a predisposition for infections and infestations and to the occurrence of tumours.