Approach to management of thrombotic thrombocytopenic purpura at university of cincinnati

Best practices and recommendations for drug regimens and plasma exchange for immune thrombotic thrombocytopenic purpura

INTRODUCTION

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening thrombotic microangiopathy characterized by microangiopathic hemolytic anemia, thrombocytopenia, and organ injury. TTP pathophysiology is based on a severe ADAMTS13 deficiency, and is a medical emergency with fatal outcome if appropriate treatment is not initiated promptly.

AREAS COVERED

Authors will review the best options currently available to minimize mortality, prevent relapses, and obtain the best clinical response in patients with immune TTP (iTTP). Available bibliography about iTTP treatment has been searched in Library's MEDLINE/PubMed database from January 1990 until April 2021.

EXPERT OPINION

The generalized use of plasma exchange marked a paradigm in the management of iTTP. In recent years, strenuous efforts have been done for a better understanding of the pathophysiology of this disease, improve diagnosis, optimize treatment, reduce mortality, and prevent recurrences. The administration of front-line rituximab and, more recently, the availability of caplacizumab, the first targeted therapy for iTTP, have been steps toward a further reduction in early mortality and for the prevention of relapses.

Thrombotic Thrombocytopenic Purpura: Pathophysiology, Diagnosis, and Management

Thrombotic thrombocytopenic purpura (TTP) is a rare thrombotic microangiopathy characterized by microangiopathic hemolytic anemia, severe thrombocytopenia, and ischemic end organ injury due to microvascular platelet-rich thrombi. TTP results from a severe deficiency of the specific von Willebrand factor (VWF)-cleaving protease, ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 repeats, member 13). ADAMTS13 deficiency is most commonly acquired due to anti-ADAMTS13 autoantibodies. It can also be inherited in the congenital form as a result of biallelic mutations in the ADAMTS13 gene. In adults, the condition is most often immune-mediated (iTTP) whereas congenital TTP (cTTP) is often detected in childhood or during pregnancy. iTTP occurs more often in women and is potentially lethal without prompt recognition and treatment. Front-line therapy includes daily plasma exchange with fresh frozen plasma replacement and immunosuppression with corticosteroids. Immunosuppression targeting ADAMTS13 autoantibodies with the humanized anti-CD20 monoclonal antibody rituximab is frequently added to the initial therapy. If available, anti-VWF therapy with caplacizumab is also added to the front-line setting. While it is hypothesized that refractory TTP will be less common in the era of caplacizumab, in relapsed or refractory cases cyclosporine A, N-acetylcysteine, bortezomib, cyclophosphamide, vincristine, or splenectomy can be considered. Novel agents, such as recombinant ADAMTS13, are also currently under investigation and show promise for the treatment of TTP. Long-term follow-up after the acute episode is critical to monitor for relapse and to diagnose and manage chronic sequelae of this disease.

Comparison of the Long-Term Remission of Rituximab and Conventional Treatment for Acquired Thrombotic Thrombocytopenic Purpura: A Systematic Review and Meta-Analysis

The current systematic review and meta-analysis aimed to summarize the results of all available studies to compare the efficacies of rituximab and conventional treatment for acquired thrombotic thrombocytopenic purpura (TTP). Three investigators independently searched studies in the MEDLINE and EMBASE databases published before December 11, 2018. To be included in the meta-analysis, studies needed to be randomized-controlled or cohort studies comparing the efficacies of rituximab and conventional therapy for TTP treatment. The effect estimates and 95% confidence intervals (CIs) from each study were collected, and Mantel-Haenszel methods were used to pool the data. A total of 570 patients from 9 eligible studies were included in the meta-analysis (280 patients in the rituximab arm and 290 in the conventional treatment arm). Patients receiving rituximab in an acute phase to induce disease remission had a significantly lower relapse rate than those given conventional treatment (odds ratio [OR]: 0.40, 95% CI: 0.19-0.85, P = .02, I² = 43%). Similarly, the relapse rate in the rituximab group for preemptive therapy to prevent clinical relapse was also significantly lower than in the control group (OR: 0.09, 95% CI: 0.04-0.24, P < .00001, I² = 11%). Furthermore, the conventional treatment group had a significantly higher mortality rate than the rituximab group during the follow-up (OR: 0.41, 95% CI: 0.18-0.91, P = .03, I² = 0%). Rituximab offered high efficacy for the prevention of relapses and lower mortality rate in cases of acquired TTP.

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.

[Clinical study on Rituximab in the treatment of idiopathic thrombotic thrombocytopenic purpura]

目的

观察利妥昔单抗（RTX）在特发性血栓性血小板减少性紫癜(ITTP)治疗中的价值。

方法

17例ITTP患者中9例采用RTX＋血浆置换＋糖皮质激素治疗（RTX组），8例采用血浆置换+糖皮质激素±免疫抑制剂（对照组）。RTX用法为375 mg/m²每周1次连续4次。监测患者血常规、LDH、ADAMTS13活性及抑制物、外周血B淋巴细胞百分比。观察两组患者的血浆置换次数/总量、缓解时间、复发率及不良反应发生情况。

结果

RTX组、对照组血浆置换次数中位数分别为5(2~8)、6(4~9）次，血浆置换总量中位数分别为9.6(4.0~15.4)、11.2(7.5~14.6)L。RTX组、对照组达到血液学缓解中位时间分别为15(5~20)d、22(7~36)d，达到免疫学缓解中位时间分别为2(2~8)、2(2~4）周。两组患者ADAMTS13活性均在2周后显著回升。RTX组随访期内无复发，对照组4例患者复发。RTX给药前及治疗后1周患者外周血B淋巴细胞百分比差异有统计学意义[(18.39±7.15)％对(2.19±5.11)%，P<0.001], 9个月后逐渐回升，治疗中未观察到RTX相关严重不良反应，但该组1例患者持续免疫学缓解7个月后死于肺部感染。

结论

RTX联合血浆置换和糖皮质激素治疗ITTP，能快速获得血液学甚至免疫学缓解，降低复发率，不良反应少，但需注意防治感染。