Alemtuzumab-induced thyroid eye disease successfully treated with a single low dose of rituximab.

Introduction: Secondary thyroid autoimmunity, especially Graves' disease (GD), frequently develops in patients with multiple sclerosis (MS) following alemtuzumab treatment (ALTZ; anti-CD52). Thyroid eye disease (TED) can also develop, and rituximab (RTX; anti-CD20) is a suitable treatment. Case presentation: A 37-year-old woman with MS developed steroid-resistant active moderate-to-severe TED 3 years after ALTZ, that successfully responded to a single 500 mg dose of i.v. RTX. Before RTX peripheral B-cells were low, and were totally depleted immediately after therapy. Follow-up analysis 4 years post ALTZ and 1 year post RTX showed persistent depletion of B cells, and reduction of T regulatory cells in both peripheral blood and thyroid tissue obtained at thyroidectomy. Conclusion: RTX therapy successfully inactivated TED in a patient with low B-cell count derived from previous ALTZ treatment. B-cell depletion in both thyroid and peripheral blood was still present 1 year after RTX, indicating a likely cumulative effect of both treatments.

The Changes in the Quantity of Lymphocyte Subpopulations during the Process of Sepsis.

Sepsis remains a global challenge, especially in low- and middle-income countries, where there is an urgent need for easily accessible and cost-effective biomarkers to predict the occurrence and prognosis of sepsis. Lymphocyte counts are easy to measure clinically, and a large body of animal and clinical research has shown that lymphocyte counts are closely related to the incidence and prognosis of sepsis. This review extensively collected experimental articles related to lymphocyte counts since the unification of the definition of sepsis. The article categorizes and discusses the relationship between absolute lymphocyte counts, intrinsic lymphocyte subsets, effector T-lymphocytes, B-lymphocytes, dendritic cells, and the incidence and prognosis of sepsis. The results indicate that comparisons of absolute lymphocyte counts alone are meaningless. However, in addition to absolute lymphocyte counts, innate lymphocyte subsets, effector T-cells, B-lymphocytes, and dendritic cells have shown certain research value in related studies.

Should complete B-cell depletion be maintained in patients treated long-term with rituximab for rheumatoid arthritis?

OBJECTIVE: To determine whether persistent complete B cell (BC) depletion was associated with a better clinical response in rheumatoid arthritis (RA) patients long-term treated with rituximab (RTX). METHODS: We conducted a retrospective study including RA patients admitted for a new infusion between 2019 and 2021. The primary end point was the comparison of the mean DAS28-CRP at each of the 4 last infusion visits between patients with persistent complete BC depletion (mean CD19 counts <18/µL at each of the last 4 visits) or without persistent complete BC depletion (mean CD19 counts of the last 4 visits ≥18/µL). Secondary endpoints included DAS28, pain/fatigue VAS, CRP, gammaglobulins and the frequency of self-reported RA flares. RESULTS: Of the 126 patients in maintenance therapy with RTX (exposure period: 76 ± 5 months, n 14 ± 7 infusions received), 43 (34%) had persistent complete BC depletion at each of the 4 last infusions. The mean DAS28-CRP calculated at each of the 4 last infusion visits did not significantly differ according to persistence or not of complete BC depletion. This result remained unchanged after adjusting for antibody status, number of previous therapies, number of RTX infusion and cumulative RTX dose. All secondary outcomes were also not significantly different between both groups. CONCLUSION: Maintaining complete BC depletion does not appear to be a therapeutic target to achieve in RA patients in long-term maintenance therapy with RTX. There is a limited benefit of monitoring CD19 in RA patients long term treated with RTX and having achieved low disease activity/remission.

Haematopoietic Stem Cell Transplantation for Chronic Granulomatous Disease.

Chronic granulomatous disease (CGD) is an inborn error of immunity due to defects in the transport or function of subunits of nicotinamide adenine dinucleotide phosphate oxidase, the enzyme that generates the phagocyte respiratory burst responsible for intracellular killing of engulfed micro-organisms. Patients present with infectious or inflammatory complications. Common bacterial pathogens include Staphylococcus aureus and Burkholderia cepacia complex. Fungal pathogens include Aspergillus species, particularly Aspergillus fumigatus. Inflammatory complications most commonly manifest as inflammatory bowel disease or lung disease. Granulomata are the distinguishing histological feature. Haematopoietic stem cell transplantation (HSCT) was first considered for CGD in the early 1970's. Since then, refinements in transplant technique, donor selection, conditioning regimens, and graft engineering have widened the option of HSCT to most patients with CGD. This review charts the progress made in HSCT for CGD.

Angiotensin II-Induced Memory γδ T Cells Sensitize Mice to a Mild Hypertensive Stimulus.

BACKGROUND: Memory T cells develop during an initial hypertensive episode, sensitizing mice to develop hypertension from further mild hypertensive challenges. We hypothesized that memory γδ T cells develop after a hypertensive challenge and sensitize mice to develop hypertension in response to a subsequent mild hypertensive challenge. METHODS: The first aim was to profile memory γδ T cells after a 14-day pressor dose angiotensin II (AngII) infusion (490 ng/kg/min, subcutaneously) in male mice. The second aim was to deplete γδ T cells during a second 14-day subpressor dose AngII challenge (140 ng/kg/min, subcutaneously) in mice pre-exposed to an initial pressor dose AngII challenge. The third aim was to transfer 2.5 × 105 live pre-activated or not γδ T cells from mice that had received a 14-day pressor dose AngII infusion or sham treatment, to naive recipient mice stimulated with a subpressor dose AngII infusion. RESULTS: Effector memory γδ T cells increased 5.2-fold in mesenteric vessels and perivascular adipose tissue, and 1.8-fold in mesenteric lymph nodes in pressor dose AngII-infused mice compared with sham-treated mice. Mice depleted of γδ T cells had 14 mm Hg lower systolic blood pressure (SBP) elevation than control mice from day 7 to 14 of subpressor dose AngII infusion. Adoptive transfer of γδ T cells from hypertensive mice induced an 18 mm Hg higher SBP elevation compared with a subpressor dose AngII infusion vs. γδ T cells transferred from sham-treated mice. CONCLUSIONS: Memory γδ T cells develop in response to hypertensive stimuli, and contribute to the pathogenesis of hypertension.

Absence of Tissue-Sparing Effects in Partial Proton FLASH Irradiation in Murine Intestine.

Ultra-high dose rate irradiation has been reported to protect normal tissues more than conventional dose rate irradiation. This tissue sparing has been termed the FLASH effect. We investigated the FLASH effect of proton irradiation on the intestine as well as the hypothesis that lymphocyte depletion is a cause of the FLASH effect. A 16 × 12 mm2 elliptical field with a dose rate of ~120 Gy/s was provided by a 228 MeV proton pencil beam. Partial abdominal irradiation was delivered to C57BL/6j and immunodeficient Rag1-/-/C57 mice. Proliferating crypt cells were counted at 2 days post exposure, and the thickness of the muscularis externa was measured at 280 days following irradiation. FLASH irradiation did not reduce the morbidity or mortality of conventional irradiation in either strain of mice; in fact, a tendency for worse survival in FLASH-irradiated mice was observed. There were no significant differences in lymphocyte numbers between FLASH and conventional-dose-rate mice. A similar number of proliferating crypt cells and a similar thickness of the muscularis externa following FLASH and conventional dose rate irradiation were observed. Partial abdominal FLASH proton irradiation at 120 Gy/s did not spare normal intestinal tissue, and no difference in lymphocyte depletion was observed. This study suggests that the effect of FLASH irradiation may depend on multiple factors, and in some cases dose rates of over 100 Gy/s do not induce a FLASH effect and can even result in worse outcomes.

Effects of syphilis infection among HIV-1-positive individuals on suppressive antiretroviral therapy.

INTRODUCTION: Incident syphilis leads to changes in plasma HIV-1 RNA and CD4 + T-cell level in people with HIV (PWH) with viraemia. Its effect in PWH on suppressive antiretroviral therapy (ART) is less clear. METHODS: PWH on suppressive ART (plasma HIV-1 RNA < 50copies/mL) followed at the Queen Elizabeth Hospital, Hong Kong, China were regularly screened for syphilis. Their plasma HIV-1 RNA, CD4 + and CD8 + T-cell, and total lymphocyte levels before syphilis, during syphilis, and after successful treatment were compared. RESULTS: Between 2005 and 2020, 288 syphilis episodes from 180 individuals were identified; 287 episodes were related to male, with a median age of 41 at diagnosis; 221 (77%) were syphilis re-infection. The rates of plasma HIV-1 suppression were statistically unchanged across the time-points (97% pre-syphilis, 98% during syphilis, and 99% post-treatment). Total lymphocyte, CD4+ and CD8+ T-cell levels decreased during incident syphilis (p<0.01), and rebounded post-treatment (p<0.01). VDRL titre was associated with declines in CD4+ T-cell (p=0.045), CD8+ T-cell (p=0.004), and total lymphocyte levels (p=0.021). Pre-syphilis CD4/CD8 ratio was associated with increases in CD8+ T-cell (p=0.001) and total lymphocyte levels (p=0.046) during syphilis. Syphilis re-infection was associated with an increase in total lymphocyte level (p=0.037). In the multivariable analysis, only pre-syphilis CD4/CD8 ratio was independently associated with increases in CD8+ T-cell (p=0.014) and total lymphocyte levels (p=0.039) during syphilis. CONCLUSIONS: Among virally-suppressed PWH, total lymphocyte, CD4+, and CD8+ T-cell levels declined during incident syphilis but rebounded post-treatment. The status of plasma HIV suppression was unaffected by syphilis.

Effects of Reduced-Dose Anti-Human T-Lymphocyte Globulin on Overall and Donor-Specific T-Cell Repertoire Reconstitution in Sensitized Kidney Transplant Recipients.

Background: Pre-sensitized kidney transplant recipients have a higher risk for rejection following kidney transplantation and therefore receive lymphodepletional induction therapy with anti-human T-lymphocyte globulin (ATLG) whereas non-sensitized patients are induced in many centers with basiliximab. The time course of lymphocyte reconstitution with regard to the overall and donor-reactive T-cell receptor (TCR) specificity remains elusive. Methods/Design: Five kidney transplant recipients receiving a 1.5-mg/kg ATLG induction therapy over 7 days and five patients with 2 × 20 mg basiliximab induction therapy were longitudinally monitored. Peripheral mononuclear cells were sampled pre-transplant and within 1, 3, and 12 months after transplantation, and their overall and donor-reactive TCRs were determined by next-generation sequencing of the TCR beta CDR3 region. Overall TCR repertoire diversity, turnover, and donor specificity were assessed at all timepoints. Results: We observed an increase in the donor-reactive TCR repertoire after transplantation in patients, independent of lymphocyte counts or induction therapy. Donor-reactive CD4 T-cell frequency in the ATLG group increased from 1.14% + -0.63 to 2.03% + -1.09 and from 0.93% + -0.63 to 1.82% + -1.17 in the basiliximab group in the first month. Diversity measurements of the entire T-cell repertoire and repertoire turnover showed no statistical difference between the two induction therapies. The difference in mean clonality between groups was 0.03 and 0.07 pre-transplant in the CD4 and CD8 fractions, respectively, and was not different over time (CD4: F(1.45, 11.6) = 0.64 p = 0.496; CD8: F(3, 24) = 0.60 p = 0.620). The mean difference in R20, a metric for immune dominance, between groups was -0.006 in CD4 and 0.001 in CD8 T-cells and not statistically different between the groups and subsequent timepoints (CD4: F(3, 24) = 0.85 p = 0.479; CD8: F(1.19, 9.52) = 0.79 p = 0.418). Conclusion: Reduced-dose ATLG induction therapy led to an initial lymphodepletion followed by an increase in the percentage of donor-reactive T-cells after transplantation similar to basiliximab induction therapy. Furthermore, reduced-dose ATLG did not change the overall TCR repertoire in terms of a narrowed or skewed TCR repertoire after immune reconstitution, comparable to non-depletional induction therapy.

[Mechanisms of resistance and escape to CAR-T cells]. / Mécanismes de résistance et d'échappement aux cellules CAR-T.

CAR-T cells represent a new approach to anti-tumor cellular immunotherapy allowing to combine the recognition of tumor antigens on target cells and the activation, proliferation and cytotoxic capacity of T lymphocytes. Impressive clinical results have been obtained with CAR-T cells targeting the CD19 antigen in relapsing or refractory B cell malignant lymphomas or acute lymphoblastic leukemias, with complete response rates of 40 to 90%. However, 30 to 50% of responding patients in B malignancies will escape treatment secondarily, and the effectiveness of these approaches in solid tumors remains limited. Different mechanisms of primary resistance and/or escape to CAR-T cells have been described. This review aims to describe these mechanisms and explore potential ways for optimization. We will see that the initial response and its long-term persistence depends on several parameters: the functional characteristics of the CAR-T cells in vivo, the expression of targeted antigens on tumor cells, the development of a immunosuppressive microenvironment. Or of an immune response directed against the CAR molecule. In solid tumors in particular, the specificity of the antigen target and the "homing" of CAR-T cells in the tumor site are additional elements to consider. A better knowledge of mechanisms of resistance will help to improve the clinical outcomes by either modulating the construction and the production of CAR-T cells and/or to combine them with other immunotherapeutic approaches to better control the tumor microenvironment.

Rabbit Antithymocyte Globulin Induction in Heart Transplant Recipients at High Risk for Rejection.

Background: Induction with lymphocyte-depleting antibodies may improve allograft outcomes in heart transplant recipients who are at high immunologic risk for rejection. Methods: We conducted a single-center retrospective cohort study that compared outcomes between adult patients receiving rabbit antithymocyte globulin (rATG) induction vs no induction from 2011 through 2017. Key exclusion criteria were patients who did not receive tacrolimus and mycophenolate and patients who did not meet high immunologic risk criteria. Results: A total of 50 patients were included in the analysis. At 1 year, the composite primary outcome of ≥2R rejection as defined by the International Society for Heart and Lung Transplantation, any treated rejection, development of cardiac allograft vasculopathy, or graft loss was not different between groups (P=0.474). Serious infections were also similar between groups (P=0.963). In accordance with institutional guidelines, prednisone exposure was decreased in the rATG induction group at 1 month (24.04 mg ± 13.74 vs 35.18 mg ± 16.95; P=0.014). Conclusion: These results suggest that while rATG induction does not improve heart allograft outcomes, it may enable reducing early corticosteroid exposure in patients at high immunologic risk.

The Lymphocyte Depletion in Patients with Acute Ischemic Stroke Associated with Poor Neurologic Outcome.

PURPOSE: Inflammation plays an important role and is involved in all stages of acute ischemic stroke. One of these stages involves the recruitment of leukocytes from the peripheral circulation into the ischemic tissue. Lymphocytes as a subtype of leukocytes are important mediators and can become a predictor of neurological outcome. Several studies have been conducted regarding the correlation between differential lymphocyte counts and acute ischemic stroke. Most of these studies analyzed lymphocyte ratio to other leukocyte subtypes such as neutrophils and monocytes. This study specifically observed the role of lymphocytes as an indicator of the inflammatory response in patients with acute ischemic stroke. This study aimed to observe the correlation among risk factors, infarct location, leukocyte counts, lymphocyte value and neurologic output in acute ischemic stroke patients. PATIENTS AND METHODS: We observed and analyzed 193 patients' data from medical record which met the inclusion and exclusion criteria with a diagnosis of acute ischemic stroke at the Department of Neurology of Dr. Hasan Sadikin General Bandung. Data were then analysed using appropriate statistical tests. RESULTS: Most patients have more than one risk factor with a leukocyte count of less than 10,000 cell/mm3. Infarct was mostly located in subcortical area (basal ganglia), with moderate average NIHSS values at admission and at discharge. The number of lymphocytes decreased in the subject group with more than 10,000 cell/mm3 leukocytes. Subsequently, data were analyzed using Spearman's test and there was a correlation between NIHSS on admission and lymphocyte depletion. CONCLUSION: The lymphocyte depletion in patients with leukocytosis is a predictor of poor NIHSS.

Emerging Role of EGFR Mutations in Creating an Immune Suppressive Tumour Microenvironment.

Several types of tumours overexpress the Epidermal Growth Factor Receptor (EGFR) in either wild type or mutated form. These tumours are often highly aggressive and difficult to treat. The underlying mechanisms for this phenomenon have remained largely unresolved, but recent publications suggest two independent mechanisms that may contribute. According to one line of research, tumours that overexpress the EGFR grow autonomously and become "addicted" to growth factor signalling. Inhibition of this signal using EGFR inhibitors can, therefore, induce cell death in tumour cells and lead to tumour shrinkage. The other line of research, as highlighted by recent findings, suggests that the overexpression, specifically of mutant forms of the EGFR, may create an immune-suppressive and lymphocyte depleted microenvironment within tumours. Such a lymphocyte depleted microenvironment may explain the resistance of EGFR overexpressing cancers to tumour therapies, particularly to check-point inhibitor treatments. In this article, we discuss the recent data which support an immune modulatory effect of EGFR signalling and compare these published studies with the most recent data from The Cancer Genome Atlas (TCGA), in this way, dissecting possible underlying mechanisms. We thereby focus our study on how EGFR overexpression may lead to the local activation of TGFß, and hence to an immune suppressive environment. Consequently, we define a novel concept of how the mitogenic and immune modulatory effects of EGFR overexpression may contribute to tumour resistance to immunotherapy, and how EGFR specific inhibitors could be used best to enhance the efficacy of tumour therapy.

A tumor-immune interaction model for hepatocellular carcinoma based on measured lymphocyte counts in patients undergoing radiotherapy.

PURPOSE: The impact of radiation therapy on the immune system has recently gained attention particularly when delivered in combination with immunotherapy. However, it is unclear how different treatment fractionation regimens influence the interaction between the immune system and radiation. The goal of this work was to develop a mathematical model that quantifies both the immune stimulating as well as the immunosuppressive effects of radiotherapy and simulates the effects of different fractionation regimens based on patient data. METHODS AND MATERIALS: The framework describes the temporal evolution of tumor cells, lymphocytes, and inactivated dying tumor cells releasing antigens during radiation therapy, specifically modeling how recruited lymphocytes inhibit tumor progression. The parameters of the model were partly taken from the literature and in part extracted from blood samples (circulating lymphocytes: CLs) collected from hepatocellular carcinoma patients undergoing radiotherapy and their outcomes. The dose volume histograms to circulating lymphocytes were calculated with a probability-based model. RESULTS: Based on the fitted parameters, the model enabled a study into the depletion and recovery of CLs in patients as a function of fractionation regimen. Our results quantify the ability of short fractionation regimens to lead to shorter periods of lymphocyte depletion and predict faster recovery after the end of treatment. The model shows that treatment breaks between fractions can prolong the period of lymphocyte depletion and should be avoided. CONCLUSIONS: This study introduces a mathematical model for tumor-immune interactions using clinically extracted radiotherapy patient data, which can be applied to design trials aimed at minimizing lymphocyte depleting effects in radiation therapy.

Case Report: Complete Remission of C1q Nephropathy Treated With a Single Low-Dose Rituximab, a Reality or Coincidence?

C1q nephropathy is a glomerulopathy that is characterized by large amount of C1q deposits in the glomerular mesangium. It is a diagnosis of exclusion after ruling out systemic lupus erythematosus and membranoproliferative glomerulonephritis by systemic and serological examination. The pathogenesis of C1q nephropathy is unclear. In addition, there is very little generalizability in the treatment and prognosis for pediatric C1q nephropathy due to diversities in clinical manifestations and pathological types. Rituximab is a human/mouse chimeric monoclonal antibody against CD20, which is primarily used for treating lymphomas and, most recently, has been used to treat certain kidney diseases including C1q nephropathy. In this report, we used one quarter of the typical dose of rituximab for lymphoma treatment to achieve complete remission in a C1q nephropathy patient, significantly reducing deposition of immune complexes and glomerular damage. This case indicates that dosage reconsiderations may be necessary for rituximab in treatment of pediatric C1q nephropathy.

Time course of peripheral blood count recovery during induction chemotherapy for childhood acute lymphoblastic leukemia.

Introduction: Children with newly diagnosed acute lymphoblastic leukemia (ALL) present with low peripheral blood counts caused by bone marrow replacement. The recovery of counts during induction chemotherapy is not well described. Material and methods: Records for 63 children with ALL were reviewed. Peripheral hematology blood counts during five weeks of induction chemotherapy were extracted, and the time to partial recovery with safe counts and complete recovery with normal counts in the three cell lines determined. The number of red cell and platelet transfusions, the number of febrile episodes, and the number of days on intravenous antibiotics were counted. Results: Platelet recovery occurred early: median time to achieving counts >50/nL 14 days, to counts >100/nL 16 days. Neutrophil recovery was relatively slow: median time to counts >0.5/nL 18 days, to counts >1.0/nL 26 days. The time to partial recovery was shorter in high risk than in lower-risk treatment groups. Partial platelet recovery by day 15 indicated early recovery and lower morbidity. Complete platelet recovery day 15 was significantly associated with residual disease <0.1% after four weeks. Lymphocyte counts showed a marked decrease in first two weeks followed by a rise in the next three weeks; a count <0.35/nL on day 15 was associated with poor response. Conclusion: After starting chemotherapy for ALL, platelet recovery can be expected after two to three weeks while neutrophil recovery lasts three to five weeks. Platelet and lymphocyte counts after two weeks treatment may give an indication of residual disease after four weeks.

[Membranous glomerulonephritis : An example of individualized medicine in nephrology]. / Membranöse Glomerulonephritis : Ein Beispiel für individualisierte Medizin in der Nephrologie.

BACKGROUND: Membranous glomerulonephritis (MGN) is the most frequent cause of a nephrotic syndrome in adults. It is an autoimmune disease caused by binding of autoantibodies to endogenous proteins expressed on glomerular podocytes. Antibody binding and activation of inflammatory mediators result in the onset of proteinuria. Recently, two endogenous podocytic target antigens in MGN have been characterized and their clinical role is a main focus of research in nephrology. OBJECTIVE: The discovery that antibodies against phospholipase A2 receptor 1 (PLA2R1) and thrombospondin type 1 domain containing 7A (THSD7A) mediate the pathogenesis of MGN leads to the question of what clinical role these antibodies have in patients with MGN. MATERIAL AND METHODS: Evidence published in recent years on the role of the described antigens is analyzed and critically discussed. The clinical conclusions derived for patients with MGN are presented. RESULTS: Antibodies against PLA2R1 are detectable in approximately 80% of patients with MGN, while 2-3% of patients have antibodies against THSD7A. Serum analyses of antibodies and immunohistological staining in kidney biopsies enable an almost 100% certain diagnosis of PLA2R1 and THSD7A-mediated MGN. Serum levels of PLA2R1 antibodies are predictors for the response to therapy, determine the prognosis and allow an exact individualized monitoring of treatment. The THSD7A antibodies are associated with an increased prevalence of malignant tumors and play a pathogenetic role in the genesis of this secondary form of MGN. CONCLUSION: The characterization of the antibodies responsible for the development of MGN is an example of precision medicine in nephrology and the foundation for the development of new, curative treatments.

Clinical pharmacology of alemtuzumab, an anti-CD52 immunomodulator, in multiple sclerosis.

Alemtuzumab, a humanized anti-CD52 monoclonal antibody, is approved for treatment of relapsing multiple sclerosis (MS). In the Phase II/III trials, patients received 12 or 24 mg/day of alemtuzumab in two treatment courses (5 days for course 1 and 3 days for course 2), 12 months apart. Serum concentrations of alemtuzumab peaked on the last day of dosing in each course and mostly fell below the limit of quantitation by day 30. Alemtuzumab rapidly depleted circulating T and B lymphocytes, with the lowest observed values occurring within days. Lymphocytes repopulated over time, with B cell recovery usually complete within 6 months. T lymphocytes recovered more slowly and generally did not return to baseline by 12 months post-treatment. Approximately 40 and 80% of patients had total lymphocyte counts, reaching the lower limit of normal by 6 and 12 months after each course, respectively. The clearance of alemtuzumab is dependent on circulating lymphocyte count. A majority of treated patients tested positive for anti-alemtuzumab antibodies, including inhibitory antibodies, during the 2-year studies, and a higher proportion of patients tested positive in course 2 than in course 1. The presence of anti-alemtuzumab antibody appeared to be associated with slower clearance of alemtuzumab from the circulation but had no impact on the pharmacodynamics. No effects of age, race or gender on the pharmacokinetics or pharmacodynamics were observed. Together, the pharmacokinetics, pharmacodynamics and immunogenicity results support the continued development and use of alemtuzumab for the treatment of MS, and probably explain its sustained effects beyond the dosing interval.

Pharmacokinetics and pharmacodynamics of the cytolytic anti-CD38 human monoclonal antibody TAK-079 in monkey - model assisted preparation for the first in human trial.

We are studying the fully human, IgG1λ cytolytic monoclonal antibody TAK-079, which binds CD38. CD38 is expressed on plasma and natural killer (NK) cells constitutively and upregulated on subsets of B and T lymphocytes upon activation. TAK-079 cross-reacts with CD38 expressed by cynomolgus monkeys and depletes subsets of NK, B, and T cells. Therefore, safety and function of TAK-079 was evaluated in this species, prior to clinical development, using bioanalytical, and flow cytometry assays. We pooled the data from eight studies in healthy monkeys (dose range 0.03-100 mg/kg) and developed mathematical models that describe the pharmacokinetics and the exposure-effect relationship for NK cells, B cells, and T cells. NK cell depletion was identified as the most sensitive pharmacodynamic effect of TAK-079. It was adequately described with a turnover model (C50  = 27.5 µg/mL on depletion rate) and complete depletion was achieved with an IV dose of 0.3 mg/kg. Intermediate effects on T-cell counts were described with a direct response model (C50  = 11.9 µg/mL) and on B-cell counts with a 4-transit-compartment model (C50  = 19.8 µg/mL on depletion rate). Our analyses substantiate the observation that NK, B and T cells are cleared by TAK-079 at different rates and required different time spans to replete the blood compartment. The models were used to simulate pharmacokinetic and cell depletion profiles in humans after applying a straightforward scaling approach for monoclonal antibodies in preparation for the first-in-human clinical trial.

Relapse of nephrotic syndrome during post-rituximab peripheral blood B-lymphocyte depletion.

BACKGROUND: Rituximab is effective against complicated childhood steroid-dependent nephrotic syndrome (SDNS). Peripheral blood B-lymphocyte (B-cell) depletion is strongly correlated with persistent remission, relapse rarely occurring during B-cell depletion; however, we have encountered several such patients. METHODS: We retrospectively analyzed the characteristics and clinical course of 82 patients with SDNS treated with rituximab from January 2007 to December 2012 in our institution. RESULTS: Six of 82 patients (7.3%) had relapses during B-cell depletion after receiving rituximab (relapsed group). The remaining 76 patients did not have relapses during B-cell depletion (non-relapsed group). The median time to initial relapse during B-cell depletion was 85 days after receiving rituximab, which is significantly shorter than in the non-relapsed group (410 days, p = 0.0003). The median annual numbers of relapses after receiving rituximab were 2.5 and 0.9 in the relapsed and non-relapsed groups, respectively (p < 0.0001). Five patients in the relapsed group also had a total of 10 relapses after B-cell recovery; their median time from B-cell recovery to initial relapse was significantly shorter than in the non-relapsed group (31 vs. 161 days, p = 0.014). Number of relapses before rituximab, history of steroid resistance, onset age, previous treatment, time to ceasing steroids after rituximab, and duration of B-cell depletion did not differ between the two groups. CONCLUSION: Relapse during B-cell depletion after receiving rituximab suggests that various pathophysiological mechanisms play a part in childhood nephrotic syndrome.

Rare Control of SIVmac239 Infection in a Vaccinated Rhesus Macaque.

Effector memory T cell (TEM) responses display potent antiviral properties and have been linked to stringent control of simian immunodeficiency virus (SIV) replication. Since recurrent antigen stimulation drives the differentiation of CD8+ T cells toward the TEM phenotype, in this study we incorporated a persistent herpesviral vector into a heterologous prime/boost/boost vaccine approach to maximize the induction of TEM responses. This new regimen resulted in CD8+ TEM-biased responses in four rhesus macaques, three of which controlled viral replication to <1,000 viral RNA copies/ml of plasma for more than 6 months after infection with SIVmac239. Over the course of this study, we made a series of interesting observations in one of these successful controller animals. Indeed, in vivo elimination of CD8αß+ T cells using a new CD8ß-depleting antibody did not abrogate virologic control in this monkey. Only after its CD8α+ lymphocytes were depleted did SIV rebound, suggesting that CD8αα+ but not CD8αß+ cells were controlling viral replication. By 2 weeks postinfection (PI), the only SIV sequences that could be detected in this animal harbored a small in-frame deletion in nef affecting six amino acids. Deep sequencing of the SIVmac239 challenge stock revealed no evidence of this polymorphism. However, sequencing of the rebound virus following CD8α depletion at week 38.4 PI again revealed only the six-amino acid deletion in nef. While any role for immunological pressure on the selection of this deleted variant remains uncertain, our data provide anecdotal evidence that control of SIV replication can be maintained without an intact CD8αß+ T cell compartment.