Low-dose rituximab for the treatment of acute thrombotic thrombocytopenic purpura: report of four cases

Predictors of relapse and preventative strategies in immune thrombotic thrombocytopenic purpura

INTRODUCTION

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare autoimmune blood disorder, which presents with microangiopathic hemolytic anemia, thrombocytopenia, and microvascular thrombosis and is caused by severe deficiency of ADAMTS13. iTTP may result in both acute and chronic complications and is rapidly fatal without expedient treatment. Life-time risk of relapse is approximately 40%.

AREAS COVERED

A number of predictors of relapse has been described in the literature. The most well-studied predictor of relapse is persistent ADAMTS13 deficiency; however, it is not a perfect marker. Relapse can be prevented by treatment with immunosuppressive medications, with rituximab being the most studied.

EXPERT OPINION

Patients who recover from iTTP should be regularly assessed, including with ADAMTS13 activity testing. The optimal frequency of assessments has not been established, but every 3 months is recommended. Considering the potential for significant organ damage and mortality associated with iTTP relapse, patients in remission and with persistent ADAMTS13 activity of 10-20% should be prophylactically treated with immunosuppression. Additional markers to precisely identify patients at higher risk of relapse are needed.

The clinical efficacy of Rituximab administration in autoimmunity disorders, primary immunodeficiency diseases and malignancies

Rituximab (RTX), as a monoclonal antibody-based immunotherapeutic intervention targeting CD20 on B cells, has proven efficacy in the treatment of patients with some immune-mediated diseases. In the present review, we provided information on the immunobiological mechanisms of signaling for RTX and its clinical applications, according to the immune-pathophysiology involved in the microenvironment of multiple diseases. We highlighted combination therapy, dose schedules, and laboratory monitoring, as well as the associated common and rare side effects to avoid. We also discussed the efficacy and safety of RTX-based therapeutic strategies and whether RTX therapy can be used as a promising treatment regimen for autoimmune diseases, primary immunodeficiency diseases, and malignancies. Our review highlights and supports the importance of collaboration between basic medical researchers and clinical specialists when considering the use of RTX in the treatment of various immune-mediated disorders.

Comparison of low fixed dose versus standard-dose rituximab to treat thrombotic thrombocytopenic purpura in the acute phase and preemptively during remission

The standard dose of rituximab used in B-cell hematological malignancies, 375 mg/m² weekly, may be excessive for autoimmune conditions. Successful use of a low, fixed dose of 100-200 mg of rituximab, weekly for 4 weeks, has been reported in the literature in the treatment of autoimmune thrombotic thrombocytopenic purpura (aTTP). We retrospectively analyzed our rituximab data in aTTP over a 13-year-period for 39 patients, with the aim of comparing response and outcomes with a standard lymphoma-dose course versus a low fixed 100 mg-dose course. Compared to the standard dose (17 patients, 17 courses of 4 infusions), our patients who received a low dose (8 patients, 9 courses of 4 infusions) had a possibly lower baseline risk but did achieve a similar time to remission and number of plasma exchange procedures to remission. Preemptive low-dose courses for ADAMTS13 activity <50 % during remission (6 patients, 10 courses of 4 infusions) achieved a median peak ADAMTS13 activity of 99 %, in a median of 1 month, with no clinical relapses. Our results provide additional evidence for the efficacy of low-dose rituximab, with the benefit of much lower cost, less infusion time, and theoretically lower risk of toxicity.

Longitudinal assessments of plasma ADAMTS13 biomarkers predict recurrence of immune thrombotic thrombocytopenic purpura

Immune thrombotic thrombocytopenic purpura (iTTP) is primarily caused by immunoglobulin G (IgG)-type autoantibodies that bind and inhibit plasma ADAMTS13 activity and/or accelerate its clearance from circulation. Approximately 50% of patients with iTTP who achieve initial clinical response to therapy experience recurrence (ie, exacerbation and/or relapse); however, a reliable biomarker that predicts such an event is currently lacking. The present study determines the role of longitudinal assessments of plasma ADAMTS13 biomarkers in predicting iTTP exacerbation/recurrence. Eighty-three unique iTTP patients with 97 episodes from the University of Alabama at Birmingham Medical Center between April 2006 and June 2019 were enrolled. Plasma levels of ADAMTS13 activity, antigen, and anti-ADAMTS13 IgG on admission showed no significant value in predicting iTTP exacerbation or recurrence. However, persistently low plasma ADAMTS13 activity (<10 U/dL; hazard ratio [HR], 4.4; 95% confidence interval [CI], 1.6-12.5; P = .005) or high anti-ADAMTS13 IgG (HR, 3.1; 95% CI, 1.2-7.8; P = .016) 3 to 7 days after the initiation of therapeutic plasma exchange was associated with an increased risk for exacerbation or recurrence. Furthermore, low plasma ADAMTS13 activity (<10 IU/dL; HR, 4.8; 95% CI, 1.8-12.8; P = .002) and low ADAMTS13 antigen (<25th percentile; HR, 3.3; 95% CI, 1.3-8.2; P = .01) or high anti-ADAMTS13 IgG (>75th percentile; HR, 2.6; 95% CI, 1.0-6.5; P = .047) at clinical response or remission was also predictive of exacerbation or recurrence. Our results suggest the potential need for a more aggressive approach to achieve biochemical remission (ie, normalization of plasma ADAMTS13 activity, ADAMTS13 antigen, and anti-ADAMTS13 IgG) in patients with iTTP to prevent the disease recurrence.

When targeted therapies alleviate the burden of TPE: The example of immune-mediated TTP

Thrombotic thrombocytopenic purpura is a rare and severe disease that manifests as a thrombotic microangiopathy with severe thrombocytopenia and variable multiorgan failure. The disease relies on a severe deficiency in a disintegrin and metalloprotease with thrombospondin type-1 repeats, 13^th member (ADAMTS13), the von Willebrand factor (vWF) cleaving protease which can be either inherited (congenital TTP) or immune-mediated (iTTP). In iTTP, the therapeutic strategy has long relied on therapeutic plasma exchange alone which still represents the only way to deliver large amounts of ADAMTS13 without risking fluid overload. Yet, several therapeutic strategies have been developed in recent years and are about to transform the standard of care of iTTP. The immunosuppressive regimen now increasingly encompasses the administration of frontline rituximab to all patients. Moreover, the impressive results of the anti-vWF nanobody caplacizumab in phase 2 and 3 studies have recently prompted its approval by health authorities for the initial treatment of the disease. The increasing use of these highly effective targeted therapies should translate in a reduced need for therapeutic plasma exchange and an improvement in the prognosis of the disease. Nevertheless, and until the development of a recombinant ADAMTS13, this cornerstone therapy remains irreplaceable.

Rituximab as first-line treatment for acquired thrombotic thrombocytopenic purpura

Objective To investigate the efficacy and safety of rituximab (RTX) as first-line treatment of acquired thrombotic thrombocytopenic purpura (aTTP). Methods Twenty-five patients with acute aTTP and/or severe a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) deficiency were admitted to our centre from April 2009 to March 2015. Fourteen patients received RTX plus standard therapy (plasma exchange and corticosteroids) at acute episodes. Haemoglobin, platelet count, schistocytes, lactate dehydrogenase levels, ADAMTS13 activity and its inhibitors, and the ratio of B lymphocytes in the peripheral blood, were monitored. The number of plasma exchange (PEXs), total plasma volume, remission time, relapse ratio, and adverse effects were recorded. Results The median number of PEXs was 5 (2-17) sessions and median total plasma volume was 168.43 ml/kg (62.86-469.52 ml/kg). Patients achieved haematological remission at a median of 15 days (5-22 days), and the median time of immunological remission was 2 weeks (2-8 weeks) with a median follow-up of 13 months (3-61 months). ADAMTS13 activity significantly increased after 2 weeks. The B lymphocyte percentage in peripheral blood was reduced 1 week after the first dose of RTX infusion compared with before treatment (2.21% ± 5.23% vs 18.47% ± 7.34%, P = 0.000 [the result of statistical software]), and began to gradually increase 9 months later. Severe adverse effects and relapsing TTP were not observed during therapy and follow-up. However, one patient who had sustained immunological remission died of severe pneumonia 7 months later. Conclusion Although our study was limited by its small sample number and it was a non-controlled, clinical trial, it showed potential benefits of RTX therapy for acute aTTP. RTX may be administered as a first-line therapy for lowering patients' relapse rate in the long term. Randomized, controlled trials of RTX for aTTP are required.

Efficacy of a rituximab regimen based on B cell depletion in thrombotic thrombocytopenic purpura with suboptimal response to standard treatment: Results of a phase II, multicenter noncomparative study

The standard four-rituximab infusions treatment in acquired thrombotic thrombocytopenic purpura (TTP) remains empirical. Peripheral B cell depletion is correlated with the decrease in serum concentrations of anti-ADAMTS13 and associated with clinical response. To assess the efficacy of a rituximab regimen based on B cell depletion, 24 TTP patients were enrolled in this prospective multicentre single arm phase II study and then compared to patients from a previous study. Patients with a suboptimal response to a plasma exchange-based regimen received two infusions of rituximab 375 mg m^-2 within 4 days, and a third dose at day +15 of the first infusion if peripheral B cells were still detectable. Primary endpoint was the assessment of the time required to platelet count recovery from the first plasma exchange. Three patients died after the first rituximab administration. In the remaining patients, the B cell-driven treatment hastened remission and ADAMTS13 activity recovery as a result of rapid anti-ADAMTS13 depletion in a similar manner to the standard four-rituximab infusions schedule. The 1-year relapse-free survival was also comparable between both groups. A rituximab regimen based on B cell depletion is feasible and provides comparable results than with the four-rituximab infusions schedule. This regimen could represent a new standard in TTP. This trial was registered at www.clinicaltrials.gov (NCT00907751). Am. J. Hematol. 91:1246-1251, 2016. © 2016 Wiley Periodicals, Inc.

More about low-dose rituximab and plasma exchange as front-line therapy for patients with thrombotic thrombocytopenic purpura

INTRODUCTION

Thrombotic thrombocytopenic purpura (TTP) is characterized by a reduction in the von Willebrand cleavage protein ADAMTS-13, mainly as a consequence of autoimmunity. Plasma exchange (PEx) is standard, achieving complete remission (CR) in 77-83% of cases, but rates are variable depending on ADAMTS-13 activity and relapse is frequent in patients with <10%. Thus, an effective front-line immunosuppressive treatment is needed.

MATERIALS AND METHODS

We administered PEx daily until CR and rituximab 100 mg/dose/week for 4 consecutive weeks to 10 patients with a first TTP episode and 1 relapsed patient (8 females (72%) and 3 males (28%)). Median age was 34 years (15-46) and laboratory parameters at diagnosis were as follows: platelets 11 × 10(9)/l (range 7-27.4 × 10(9)/l), lactate dehydrogenase 1822 U/l (range 705-8220 U/l, normal 70-180 U/l), and haemoglobin 6 g/dl (range 4.2-11.8 g/dl). ADAMTS-13 activity was determined in eight patients and was <10% in all. ADAMTS-13 autoantibody titre was determined in seven patients and was >15 units/ml in all (ref: negative <12, undetermined 12-15, positive >15 units/ml); Shiga toxin was negative in all patients. The median number of PEx until CR was 7 (range 4-12); prednisone 1 mg/kg was administered to six patients.

RESULTS

The median follow-up was 22 months (range 4-49) and the estimated 2-year relapse-free survival was 89%; one HIV+ patient relapsed at 8 months follow-up. No complications related to PEx or rituximab were reported.

CONCLUSIONS

Our study suggests that low-dose rituximab and PEx are effective as front-line treatment for acute TTP; however, a prospective trial is needed to demonstrate whether low-dose rituximab is as effective as the conventional dose.

Long-term remission induced by low-dose rituximab for relapsed and refractory thrombotic thrombocytopenic purpura: A report of two cases

Thrombotic thrombocytopenic purpura (TTP) is acquired in the majority of cases. Traditional therapy consists of plasma exchange (PEX), as well as the administration of certain immunosuppressive agents including steroids. A standard dose of rituximab (RTX) at 375 mg/m² weekly for 4 consecutive weeks was recently demonstrated to have significant activity in patients with acquired TTP. To date, clinicians have limited experience using low-dose RTX. In the present study, 2 patients were treated with low-dose RTX at 100 mg weekly for 4 consecutive weeks as a salvage therapy following failure to respond to PEX and other immunosuppressive agents. Prior to RTX therapy, the patients had severely deficient ADAMTS13 activity and detectable anti-ADAMTS13 inhibitors. The patients achieved complete remission and presented long-term stabilization during follow-up. Repeated detection during follow-up demonstrated that the patients had 100% ADAMTS13 activity and undetectable anti-ADAMTS13 antibodies. Although further investigation in a prospective clinical trial is required, the use of low-dose RTX seems to be as effective as a standard dose for patients with relapsing or refractory acquired TTP.

Efficacy and Safety of Rituximab for Refractory and Relapsing Thrombotic Thrombocytopenic Purpura: A Cohort of 10 Cases

OBJECTIVE

Idiopathic thrombotic thrombocytopenic purpura (TTP) is a life-threatening disorder mediated by autoantibodies directed against ADAMTS13. This provides a rationale for the use of rituximab in this disorder. We report our experience and the outcome of 10 cases of TTP (9 refractory and 1 relapsing) successfully treated with rituximab in combination with plasma exchange (PE) and other immunosuppressive treatments.

METHODS

The diagnosis of TTP was based on clinical criteria and supported by severe deficiency of ADAMTS13 activity and presence of inhibitors in seven cases. Rituximab was started after a median of 18.6 sessions of PE (range: 5–35) at the dose of 375 mg/m²/week for 4–8 weeks.

RESULTS

Complete remission was achieved in all patients after a median time of 14.4 days of the first dose (range: 6–30). After a median follow-up of 30 months (range: 8–78), eight patients were still in remission and two developed multiple relapses, treated again with the same therapy, and achieved complete responses; they are alive, and in complete remission after a follow-up of 12 and 16 months.

CONCLUSION

Rituximab appears to be a safe and effective therapy for refractory and relapsing TTP. However, longer follow-up is recommended to assess relapse and detect possible long-term side effects of this therapy.

Rituximab versus azathioprine for maintenance in ANCA-associated vasculitis

BACKGROUND

The combination of cyclophosphamide and glucocorticoids leads to remission in most patients with antineutrophil cytoplasm antibody (ANCA)-associated vasculitides. However, even when patients receive maintenance treatment with azathioprine or methotrexate, the relapse rate remains high. Rituximab may help to maintain remission.

METHODS

Patients with newly diagnosed or relapsing granulomatosis with polyangiitis, microscopic polyangiitis, or renal-limited ANCA-associated vasculitis in complete remission after a cyclophosphamide-glucocorticoid regimen were randomly assigned to receive either 500 mg of rituximab on days 0 and 14 and at months 6, 12, and 18 after study entry or daily azathioprine until month 22. The primary end point at month 28 was the rate of major relapse (the reappearance of disease activity or worsening, with a Birmingham Vasculitis Activity Score >0, and involvement of one or more major organs, disease-related life-threatening events, or both).

RESULTS

The 115 enrolled patients (87 with granulomatosis with polyangiitis, 23 with microscopic polyangiitis, and 5 with renal-limited ANCA-associated vasculitis) received azathioprine (58 patients) or rituximab (57 patients). At month 28, major relapse had occurred in 17 patients in the azathioprine group (29%) and in 3 patients in the rituximab group (5%) (hazard ratio for relapse, 6.61; 95% confidence interval, 1.56 to 27.96; P=0.002). The frequencies of severe adverse events were similar in the two groups. Twenty-five patients in each group (P=0.92) had severe adverse events; there were 44 events in the azathioprine group and 45 in the rituximab group. Eight patients in the azathioprine group and 11 in the rituximab group had severe infections, and cancer developed in 2 patients in the azathioprine group and 1 in the rituximab group. Two patients in the azathioprine group died (1 from sepsis and 1 from pancreatic cancer).

CONCLUSIONS

More patients with ANCA-associated vasculitides had sustained remission at month 28 with rituximab than with azathioprine. (Funded by the French Ministry of Health; MAINRITSAN ClinicalTrials.gov number, NCT00748644; EudraCT number, 2008-002846-51.).

Low-dose rituximab in the treatment of acquired haemophilia

OBJECTIVE AND IMPORTANCE

Acquired haemophilia is a rare hemorrhagic disease caused by inhibitory autoantibodies against coagulation factor VIII. Rituximab has become a popular choice for immunosuppressive therapy in acquired haemophilia, almost with the same schedule of 375 mg/m(2) per week for 4-6 doses. While the effect of low-dose rituximab has seldom been reported.

CLINICAL PRESENTATION

We report a patient, aged 88 years, who developed acquired haemophilia with severe hemorrhage and elevation of carbohydrate antigen 125 (CA125), but in the absence of a detectable cause.

INTERVENTION

We prescribed a low-dose rituximab alone (100 mg per week for a total of four infusions) for the patient, different from the conventional usage, but received a similar effect. In addition, the patient was diagnosed with immune thrombocytopenia 22 months after rituximab, while FVIII activity and activated partial thromboplastin time remained within the normal range. After four infusions of low-dose rituximab, the platelet count recovered.

CONCLUSION

At a follow-up of 34 months, the patient remains in remission without further treatment, suggesting low-dose rituximab seems to be a safe and effective regimen for the elderly patients with acquired haemophilia.