T cell responses to SARS-CoV-2 infection and vaccination are elevated in B cell deficiency and reduce risk of severe COVID-19

Individuals with primary and pharmacologic B cell deficiencies have high rates of severe disease and mortality from coronavirus disease 2019 (COVID-19), but the immune responses and clinical outcomes after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and vaccination have yet to be fully defined. Here, we evaluate the cellular immune responses after both SARS-CoV-2 infection and vaccination in patients receiving the anti-CD20 therapy rituximab (RTX) and those with low B cell counts due to common variable immune deficiency (CVID) disease. Assessment of effector and memory CD4+ and CD8+ T cell responses to SARS-CoV-2 revealed elevated reactivity and proliferative capacity after both infection and vaccination in B cell-deficient individuals, particularly within the CD8+ T cell compartment, in comparison with healthy controls. Evaluation of clinical outcomes demonstrates that vaccination of RTX-treated individuals was associated with about 4.8-fold reduced odds of moderate or severe COVID-19 in the absence of vaccine-induced antibodies. Analysis of T cell differentiation demonstrates that RTX administration increases the relative frequency of naïve CD8+ T cells, potentially by depletion of CD8+CD20dim T cells, which are primarily of an effector memory or terminal effector memory (TEMRA) phenotype. However, this also leads to a reduction in preexisting antiviral T cell immunity. Collectively, these data indicate that individuals with B cell deficiencies have enhanced T cell immunity after both SARS-CoV-2 infection and vaccination that potentially accounts for reduced hospitalization and severe disease from subsequent SARS-CoV-2 infection.

Inflammatory vaginitis in women on long-term rituximab treatment for autoimmune disorders

Background

Consequences of long-term B cell depletion with rituximab are not well understood. We describe inflammatory vaginitis as a potential side effect of long-term rituximab treatment, distinct from previously described vulvovaginal pyoderma gangrenosum.

Methods

We performed a retrospective analysis of women treated with rituximab for more than 1 year to determine the prevalence and clinical characteristics of vaginitis cases. We conducted a case–control analysis with up to 3 controls for each vaginitis case.

Results

We identified sixteen inflammatory vaginitis cases. Women with vaginitis were age 23–68 (median 42), primarily being treated for ANCA-associated vasculitis (11/16; 69%). Most reported copious vaginal discharge (100%) and pain with sex (75%). All women with return of circulating B-cells to > 10 cells/mL had complete (5/9) or significant (4/9) improvement in symptoms. In case–control analysis there was no significant difference in length of B-cell depletion, immune parameters, creatinine levels, and history of neutropenia.

Conclusion

Inflammatory vaginitis is a potential side effect of prolonged continuous B cell depletion with rituximab. More studies are needed to characterize the incidence and etiology of vaginitis among women on long term rituximab therapy and establish a causal relationship.

Combination of Rituximab, Low-Dose Cyclophosphamide, and Prednisone for Primary Membranous Nephropathy: A Case Series With Extended Follow Up

RATIONALE & OBJECTIVE

B-cell depletion with rituximab has emerged as a first-line therapy for primary membranous nephropathy (MN). However, most patients do not achieve complete remission with rituximab monotherapy. In this case series, we report longer-term remission and relapse rates, anti-phospholipase A₂ receptor (PLA₂R) antibody levels, B-cell levels, and serious adverse events in patients with primary MN who received rituximab combined with an initial short course of low-dose oral cyclophosphamide and a course of rapidly tapered prednisone.

STUDY DESIGN

Single-center retrospective case series.

SETTING & PARTICIPANTS

60 consecutive patients with primary MN treated with the combination of rituximab, low-dose cyclophosphamide, and prednisone at the Vasculitis and Glomerulonephritis Center at the Massachusetts General Hospital.

FINDINGS

After treatment initiation, median follow-up was 38 (interquartile range [IQR], 25-62) months; 100% of patients achieved partial remission, defined as a urinary protein-creatinine ratio (UPCR) < 3 g/g and a 50% reduction from baseline, at a median of 3.4 months. By 2 years after treatment initiation, 83% achieved complete remission, defined as a UPCR < 0.3 g/g. The median time to complete remission was 12.4 months. Immunologic remission (defined by an anti-PLA₂R titer < 14 RU/mL) was achieved by 86% and 100% of anti-PLA₂R seropositive patients (n = 29) at 3 and 6 months, respectively, after treatment initiation. After 1 year, the median UPCR fell from 8.4 (IQR, 5.0-10.7) to 0.3 (IQR, 0.2-0.8) g/g (P < 0.001). No patient relapsed throughout the duration of B-cell depletion. Relapse occurred in 10% of patients at 2 years after the onset of B-cell reconstitution following the last rituximab dose. Over a combined follow-up time of 228 patient-years, 18 serious adverse events occurred. One death occurred unrelated to treatment or primary MN, and 1 patient progressed to kidney failure requiring kidney replacement therapy.

LIMITATIONS

Absence of a comparison group.

CONCLUSIONS

All patients with primary MN treated with combination therapy achieved partial remission and most achieved a durable complete remission with an acceptable safety profile.

Incidence, Clinical Features, and Outcomes of Late-Onset Neutropenia From Rituximab for Autoimmune Disease

OBJECTIVE

Late-onset neutropenia (LON) is an underrecognized complication of rituximab treatment. We undertook this study to describe its incidence, risk factors, clinical features, management, and recurrence.

METHODS

We conducted a single-center retrospective cohort study of 738 adult patients with autoimmune disease who were treated with rituximab to induce continuous B cell depletion. The primary outcome measure was LON, defined as an unexplained absolute neutrophil count of <1,000 cells/µl during B cell depletion. Secondary outcome measures included incidental diagnosis, fever, sepsis, filgrastim use, and recurrent LON. We assessed predictors of LON using Cox proportional hazards regression models. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

We identified 107 episodes of LON in 71 patients. The cumulative incidence at 1 year of B cell depletion therapy was 6.6% (95% CI 5.0-8.7). The incidence rate during the first year was higher compared to thereafter (7.2 cases per 100 person-years [95% CI 5.4-9.6] versus 1.5 cases per 100 person-years [95% CI 1.0-2.3]). Systemic lupus erythematosus and combination therapy with cyclophosphamide were each independently associated with an increased risk of LON (adjusted HR 2.96 [95% CI 1.10-8.01] and 1.98 [95% CI 1.06-3.71], respectively). LON was not observed in minimal change disease or focal segmental glomerulosclerosis. The majority of episodes (59.4%) were asymptomatic. Fever and sepsis complicated 31.3% and 8.5% of episodes, respectively. Most patients (69%) were treated with filgrastim. Rituximab rechallenge occurred in 87% of patients, of whom 21% developed recurrent LON.

CONCLUSION

LON is common and often incidental. Most cases are reversible and respond well to filgrastim. However, LON can be associated with serious infections and thus warrants vigilant monitoring.

Continuous B-cell depletion in frequently relapsing, steroid-dependent and steroid-resistant nephrotic syndrome

Background

Patients with frequently relapsing (FR), steroid-dependent (SD) and steroid-resistant (SR) nephrotic syndrome are a therapeutic challenge with limited treatment options. Here, we retrospectively analyze the efficacy and safety of rituximab-induced continuous B-cell depletion in these populations.

Methods

Patients were included if they were at least 18 years of age and had FR, SD or SR minimal change disease (MCD) or primary focal segmental glomerulosclerosis (FSGS) and were treated with a strategy of continuous B-cell depletion. Partial remission (PR) was defined as a urinary protein:creatinine ratio (UPCR) of ≤3.5 g/g and a 50% reduction in the UPCR from baseline. Complete remission (CR) was defined as a UPCR ≤0.3 g/g.

Results

We identified 20 patients with MCD (n = 13) or FSGS (n = 7) who fulfilled the inclusion criteria. All patients had either SD (n = 12), SR (n = 7) or FR (n = 1) disease. Patients received a median of nine rituximab doses [interquartile range (IQR) 7.5, 11] and were treated for a median time of 28 months (IQR 23, 41). Prednisone was weaned from a median of 60 mg daily (IQR 40, 60) at rituximab initiation to 4.5 mg daily (IQR 0, 5.5) by 12 months. All patients achieved PR. CR occurred in 11 of 13 patients with FR or SD disease, but only 1 of 7 patients with SR disease (logrank P = 0.01). Four relapses occurred, all in patients with SR disease. Three serious infections occurred over 70.3 patient-years.

Conclusion

Continuous B-cell depletion is a therapeutic option in the management of complicated nephrotic syndrome. Additional studies are needed to clarify the utility of this strategy.

Continuous low volume delivery of intravenous treprostinil via a central venous catheter with a miniature pump in a conscious dog model

Purpose

Two animal studies were conducted to determine the feasibility of infusing treprostinil via a central venous catheter at an infusion rate of 0.1 mL/hour. Currently treprostinil is administered intravenously at infusion rates of approximately 1.0 to 2.0 mL/hour to patients with pulmonary arterial hypertension, which reflects standard clinical practice to ensure line patency with continuous intravenous administration via a central venous catheter.

Methods

In a pilot study three male beagle dogs were administered 50 ng/kg/min of treprostinil continuously at an infusion rate of 0.1 mL/hr via the MiniMed 407C infusion pump for 21 days. In a definitive study, six male beagle dogs were administered 50 ng/kg/min of treprostinil continuously at an infusion rate of 0.1 mL/hr via the MiniMed 407C infusion pump for 60 days. In both studies “no delivery” pump alarms were documented throughout the study in addition to pharmacokinetic data at specified time points.

Results

There were no documented occlusions in the 21-day pilot study. In the 60-day study one animal had a documented catheter occlusion after 16 days of therapy. Following re-implantation with a new catheter this animal did not have any additional occlusions for 40 days. No other animals in this study had any significant problems. In both studies, pharmacokinetic data were similar to that observed in previous animal studies evaluating treprostinil administration at the same dose and at higher infusion rates.

Conclusion

These animal data support the evaluation of administering treprostinil at a low infusion rate via the MiniMed 407C infusion pump in patients with pulmonary arterial hypertension.

Effect of Continuous B Cell Depletion With Rituximab on Pathogenic Autoantibodies and Total IgG Levels in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

OBJECTIVE

To evaluate the effect of rituximab on pathogenic autoantibodies and total Ig levels, and to identify serious adverse events in patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) treated with continuous B cell depletion.

METHODS

We conducted a retrospective analysis of 239 patients with AAV treated with rituximab-induced continuous B cell depletion. Two treatment cohorts were analyzed: an induction group (n = 52) and a maintenance group (n = 237). Changes in ANCA titers and total Ig levels over time were evaluated using mixed-effects models. Risk factors for serious infections during maintenance treatment were evaluated using Poisson regression.

RESULTS

During induction, IgG levels fell at a mean rate of 6% per month (95% confidence interval [95% CI] 4, 8%), while ANCA levels declined at a mean rate of 47% per month (95% CI 42, 52%) and 48% per month (95% CI 42, 54%) for patients with antimyeloperoxidase (anti-MPO) antibodies and those with anti-proteinase 3 (anti-PR3) antibodies, respectively. During maintenance treatment, with a median duration of 2.4 years (interquartile range 1.5, 4.0 years), IgG levels declined a mean of 0.6% per year (95% CI -0.2, 1.4%). New significant hypogammaglobulinemia (IgG level of <400 mg/dl) during maintenance treatment occurred in 4.6% of the patients, all of whom were in the lowest baseline IgG quartile. Serious infections during maintenance therapy occurred at a rate of 0.85 per 10 patient-years (95% CI 0.66, 1.1) and were independently associated with an IgG level of <400 mg/dl.

CONCLUSION

B cell-targeted therapy causes a preferential decline in ANCA titers relative to total IgG levels. Despite prolonged maintenance therapy with rituximab, IgG levels remain essentially constant. Serious infections were rare.

Combination therapy with rituximab, low-dose cyclophosphamide, and prednisone for idiopathic membranous nephropathy: a case series

Background

Membranous nephropathy is a common cause of the nephrotic syndrome. Treatment with standard regimens fails to induce complete remission in most patients. We evaluated the efficacy of combination therapy with rituximab, low-dose, oral cyclophosphamide, and an accelerated prednisone taper (RCP) for the treatment of idiopathic membranous nephropathy.

Methods

We analyzed 15 consecutive patients with idiopathic membranous nephropathy treated with RCP at Massachusetts General Hospital. Seven patients (47%) received RCP as initial therapy, and the other eight patients (53%) received RCP for relapsing or refractory disease. All patients had at least 1 year of follow-up. The co-primary outcomes were attainment of partial and complete remission. Partial remission was defined as a urinary protein to creatinine ratio (UPCR) < 3 g/g and a 50% reduction from baseline. Complete remission was defined as a UPCR < 0.3 g/g. Secondary outcomes were serious adverse events and the change in proteinuria, serum creatinine, serum albumin, cholesterol, triglycerides, and immunoglobulin G levels after 1 year of treatment.

Results

Over a median follow-up time of 37 (IQR, 34–44) months, 100% of patients achieved partial remission and 93% of patients achieved complete remission at a median time of 2 and 13 months, respectively. After 1 year of treatment, median (IQR) UPCR declined from 8.2 (6.6–11.1) to 0.3 (0.2–0.7) g/g (P < 0.001). Three serious adverse events occurred over 51 patient years. No patients died or progressed to ESKD.

Conclusions

Treatment of idiopathic membranous nephropathy with RCP resulted in high rates of complete remission. Larger studies evaluating this regimen are warranted.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-017-0459-z) contains supplementary material, which is available to authorized users.

An evaluation of the pharmacokinetics of treprostinil diolamine in subjects with hepatic impairment

WHAT IS KNOWN AND OBJECTIVE

Treprostinil diolamine (oral treprostinil) is a prostacyclin analogue under evaluation for the treatment for pulmonary arterial hypertension (PAH). This study assessed the pharmacokinetics (PK) and safety of treprostinil following oral administration of a single sustained-release 1 mg dose in subjects with hepatic impairment.

METHODS

Four cohorts, including healthy volunteers, and subjects with mild, moderate and severe hepatic impairment were enrolled. Thirty subjects completed the study. Mean treprostinil clearance values (CL/F) decreased with the severity of hepatic impairment. The decrease in CL/F resulted in a marked increase in exposure levels of treprostinil. Relative to healthy subjects, mean area under the curve from time zero to 24 h after dosing interval (AUC0-24) values in subjects with mild, moderate and severe hepatic impairment increased by approximately 2·2-, 4·9- and 7·6-fold, respectively. The most frequent adverse events (AEs) exhibited in this study were similar to those seen with prostacyclin and its analogues and with AEs seen in other clinical studies with oral treprostinil (e.g. headache, diarrhoea and nausea). The overall incidence of all AEs and the specific events of headache and nausea increased with severity of hepatic impairment.

WHAT IS NEW AND CONCLUSION

Based on these results, dosage adjustments should be performed in subjects with hepatic impairment.

The effect of different meal compositions on the oral bioavailability of treprostinil diolamine in healthy volunteers

WHAT IS KNOWN

Treprostinil diolamine (oral treprostinil) is a prostacyclin analogue currently being evaluated for the treatment of pulmonary arterial hypertension as a sustained-release (SR) oral tablet. Previous data have demonstrated that the oral bioavailability of treprostinil was improved when taken with a meal containing at least 500 calories.

OBJECTIVE

As twice-daily intake of a high-fat, high-calorie meal may be undesirable or not feasible for some patients, this open-label, randomized, crossover study evaluated the effect of different meal compositions [a 500-calorie well-balanced meal (WB500), a 250-calorie well-balanced meal (WB250), a 250-calorie high-fat meal (HF250) and a 250-calorie well-balanced liquid meal (Ensure®)] on the relative bioavailability of oral treprostinil.

METHODS

Thirty-two healthy volunteers were administered a single 1-mg SR tablet of oral treprostinil immediately following each study meal. Each dose of oral treprostinil was separated by a 7-day washout period. Serial plasma samples were obtained over a 36-h postdose. Safety was assessed in all patients who received study drug.

RESULTS AND DISCUSSION

Treprostinil plasma exposure (Cmax and AUC0-inf) decreased only slightly, 5-15% with decreasing caloric and increasing fat content. Headache was the most commonly reported prostacyclin-related adverse event (three reports).

WHAT IS NEW AND CONCLUSION

Overall, there were no clinically significant differences in the relative bioavailability of oral treprostinil when administered immediately after meals containing 250-500 calories and 30-50% fat. These data support the administration of oral treprostinil with a meal containing as few as 250 calories and 30-50% fat, which is significant for ensuring patient convenience and compliance, particularly as consistency with regard to meals may impact oral treprostinil pharmacokinetics.

Fibroblast growth factor 23, high-sensitivity cardiac troponin, and left ventricular hypertrophy in CKD

BACKGROUND

Detectable levels of cardiac troponins are common in individuals with chronic kidney disease (CKD), even in the absence of symptomatic cardiovascular disease. Abnormal cardiac troponin values are associated with coronary artery disease and left ventricular hypertrophy (LVH) and predict poor clinical outcomes. Elevated levels of fibroblast growth factor 23 (FGF-23) contribute to LVH in CKD. We investigated the association of FGF-23 and hs-cTnI (high-sensitivity cardiac troponin I) and hs-cTnT (high-sensitivity cardiac troponin T) levels in CKD and examined the role of LVH in this association.

STUDY DESIGN

Cross-sectional observational study.

SETTING & PARTICIPANTS

153 stable outpatients with non-dialysis-dependent CKD.

PREDICTOR

The primary predictor was FGF-23 level.

OUTCOMES

hs-cTnI, hs-cTnT.

MEASUREMENTS

FGF-23, hs-cTnI, hs-cTnT; left ventricular mass index (LVMI) assessed by echocardiography; coronary artery calcification (CAC) measured by computed tomography. LVMI and CAC were evaluated as potential mediators of the effect of FGF-23 on hs-cTnI/T.

RESULTS

Mean age was 64 ± 12 (SD) years, mean estimated glomerular filtration rate was 34 ± 11 mL/min/1.73 m(2), median FGF-23 level was 120 (25th-75th percentile, 79-223) reference unit (RU)/mL, median hs-cTnI level was 6.5 (25th-75th percentile, 3.5-14.5) pg/mL, and median hs-cTnT level was 16.8 (25th-75th percentile, 11.1-33.9) pg/mL. cTnI and cTnT concentrations were higher than the 99th percentile of a healthy population in 42% and 61% of patients, respectively. In unadjusted and multivariable-adjusted analyses, hs-cTnI/T levels were associated significantly with FGF-23 levels. Adjusting for LVMI, but not CAC, weakened the association of FGF-23 and hs-cTnI/T levels.

LIMITATIONS

Vitamin D levels were not measured. The prevalence of coronary artery disease may have been underestimated because it was ascertained by self-report.

CONCLUSIONS

Minimally elevated cTnI and cTnT levels, detectable by high-sensitivity assays, are associated with elevated FGF-23 levels in stable outpatients with CKD. FGF-23-associated LVH may contribute to detectable hs-cTnI/T levels observed in non-dialysis-dependent patients with CKD.

Fibroblast growth factor 23 and left ventricular hypertrophy in chronic kidney disease

BACKGROUND

Fibroblast growth factor 23 (FGF-23) is a phosphorus-regulating hormone. In chronic kidney disease (CKD), circulating FGF-23 levels are markedly elevated and independently associated with mortality. Left ventricular hypertrophy and coronary artery calcification are potent risk factors for mortality in CKD, and FGFs have been implicated in the pathogenesis of both myocardial hypertrophy and atherosclerosis. We conducted a cross-sectional study to test the hypothesis that elevated FGF-23 concentrations are associated with left ventricular hypertrophy and coronary artery calcification in patients with CKD.

METHODS AND RESULTS

In this study, 162 subjects with CKD underwent echocardiograms and computed tomography scans to assess left ventricular mass index and coronary artery calcification; echocardiograms also were obtained in 58 subjects without CKD. In multivariable-adjusted regression analyses in the overall sample, increased log FGF-23 concentrations were independently associated with increased left ventricular mass index (5% increase per 1-SD increase in log FGF-23; P=0.01) and risk of left ventricular hypertrophy (odds ratio per 1-SD increase in log FGF-23, 2.1; 95% confidence interval, 1.03 to 4.2). These associations strengthened in analyses restricted to the CKD subjects (11% increase in left ventricular mass index per 1-SD increase in log FGF-23; P=0.01; odds ratio of left ventricular hypertrophy per 1-SD increase in log FGF-23, 2.3; 95% confidence interval, 1.2 to 4.2). Although the highest tertile of FGF-23 was associated with a 2.4-fold increased risk of coronary artery calcification > or =100 versus <100 U compared with the lowest tertile (95% confidence interval, 1.1 to 5.5), the association was no longer significant after multivariable adjustment.

CONCLUSIONS

FGF-23 is independently associated with left ventricular mass index and left ventricular hypertrophy in patients with CKD. Whether increased FGF-23 is a marker or a potential mechanism of myocardial hypertrophy in CKD requires further study.

Fibroblast growth factor 23 and left ventricular hypertrophy in chronic kidney disease

BACKGROUND

Fibroblast growth factor 23 (FGF-23) is a phosphorus-regulating hormone. In chronic kidney disease (CKD), circulating FGF-23 levels are markedly elevated and independently associated with mortality. Left ventricular hypertrophy and coronary artery calcification are potent risk factors for mortality in CKD, and FGFs have been implicated in the pathogenesis of both myocardial hypertrophy and atherosclerosis. We conducted a cross-sectional study to test the hypothesis that elevated FGF-23 concentrations are associated with left ventricular hypertrophy and coronary artery calcification in patients with CKD.

METHODS AND RESULTS

In this study, 162 subjects with CKD underwent echocardiograms and computed tomography scans to assess left ventricular mass index and coronary artery calcification; echocardiograms also were obtained in 58 subjects without CKD. In multivariable-adjusted regression analyses in the overall sample, increased log FGF-23 concentrations were independently associated with increased left ventricular mass index (5% increase per 1-SD increase in log FGF-23; P=0.01) and risk of left ventricular hypertrophy (odds ratio per 1-SD increase in log FGF-23, 2.1; 95% confidence interval, 1.03 to 4.2). These associations strengthened in analyses restricted to the CKD subjects (11% increase in left ventricular mass index per 1-SD increase in log FGF-23; P=0.01; odds ratio of left ventricular hypertrophy per 1-SD increase in log FGF-23, 2.3; 95% confidence interval, 1.2 to 4.2). Although the highest tertile of FGF-23 was associated with a 2.4-fold increased risk of coronary artery calcification > or =100 versus <100 U compared with the lowest tertile (95% confidence interval, 1.1 to 5.5), the association was no longer significant after multivariable adjustment.

CONCLUSIONS

FGF-23 is independently associated with left ventricular mass index and left ventricular hypertrophy in patients with CKD. Whether increased FGF-23 is a marker or a potential mechanism of myocardial hypertrophy in CKD requires further study.