Successful repeat therapy with rituximab for relapsed thrombotic thrombocytopenic purpura

Rituximab in autoimmune thrombotic thrombocytopenic purpura: A success story

Despite a significant improvement of thrombotic thrombocytopenic purpura (TTP) prognosis since the use of plasma exchange, morbidity and mortality remained significant because of poor response to standard treatment or exacerbations and relapses. Rituximab, a chimeric monoclonal antibody directed against the B-lymphocyte CD20 antigen, has shown a particular interest in this indication. Recent studies also reported strong evidence for its efficiency in the prevention of relapses. This review addresses these recent progresses and still opened questions in this topic: should rituximab be proposed in all patients at the acute phase? Should all patients benefit from a preemptive treatment? Is the infectious risk acceptable in this context?

Bortezomib for chronic relapsing thrombotic thrombocytopenic purpura: a case report

BACKGROUND

Acquired thrombotic thrombocytopenic purpura (TTP) is an autoimmune disorder characterized by a severe deficiency of ADAMTS13 activity. Although therapeutic plasma exchange (PLEX) is the standard of care, 30% to 50% patients develop exacerbation or relapse, requiring immunomodulatory agents. Of these agents, glucocorticoids, rituximab, and cyclosporine A are the most frequently used.

CASE REPORT

We report a case of chronic relapsing TTP in a patient who had eight relapses over a 14-year period. After her seventh relapse, the patient demonstrated only partial response to glucocorticoids, two courses of rituximab, and cyclophosphamide. The eighth relapse occurred 58 days after her last PLEX and subsequent to this she received a course of bortezomib (Velcade, Millennium Pharmaceuticals, Inc.). After treatment with bortezomib the patient demonstrated a complete response with a progressive increase in ADAMTS13 activity from less than 5% to 22% accompanied by undetectable inhibitor, and she has remained PLEX free for more than 169 days.

CONCLUSION

Bortezomib may serve as an adjunct treatment in patients with acquired TTP who exhibit an incomplete response or are refractory to conventional management.

Rituximab therapy for autoimmune haematological diseases

Autoimmune haematological diseases are characterized by the production of antibodies against blood proteins or cells, and comprise primary immune thrombocytopenia, autoimmune haemolytic anaemia, acquired haemophilia, and thrombotic thrombocytopenic purpura. Current treatments for these disorders include corticosteroids, cytotoxic drugs and splenectomy, which may be associated with significant systemic toxicity and/or morbility. B cells play a key role in both the development and perpetuation of autoimmunity, since they produce autoantibodies but also function as antigen-presenting cells, and release immunomodulatory cytokines. Rituximab, an anti-CD20 monoclonal antibody that specifically depletes B cells, may be an effective treatment strategy for patients with autoimmune disorders. This article reviews data of the literature, showing that patients with autoimmune haematological diseases can respond to rituximab irrespective of age and number or type of prior treatments. These data suggest that rituximab provides an effective and well-tolerated treatment option for these conditions.

Rituximab therapy to prevent relapse in chronic relapsing thrombotic thrombocytopenic purpura (TTP) in a child

Our patient first developed thrombotic thrombocytopenic purpura (TTP) at age 10 years with an initial platelet count of 10,000/microL. She achieved remission with plasmapheresis (PE), but suffered 2 relapses in the next 2 years, each approximately 1 year from PE, with ADAMTS13 levels of <5%. Early in her third remission, with vincristine (weekly x 4 doses) and prednisone (for 2 weeks) her ADAMTS13 increased to 99% in 24 weeks, but decreased to <4% in the next 38 weeks. After 4 weekly doses of rituximab (375 mg/m(2)), her ADAMTS13 level reached 101% in 9 weeks and has remained consistently above 97% on bimonthly monitoring for more than a year. She remains in continuous clinical and hematologic remission with an ADAMTS13 level of 108% at 60 weeks from rituximab therapy and 124 weeks from her second relapse. This case report suggests that monitoring ADAMTS13 level at regular intervals in recurrent TTP may help us identify patients at risk for further relapse; and such a relapse may be prevented, or at least delayed with timely rituximab therapy, thus reducing morbidity from relapsed TTP and its treatment.

Anti-CD20 monoclonal antibodies and their use in adult autoimmune hematological disorders

Autoimmune hematological disorders encompass a broad group of hematological conditions characterized by the loss of self-tolerance to a variety of antigens. Despite good response to first-line therapy in the majority of patients, relapses are common, necessitating new and safe therapeutic options. The anti-CD20 monoclonal antibody rituximab has led to substantial improvement in the treatment of malignant and immune-mediated disorders involving B cells. Although experience with rituximab in immune-mediated hematological disorders is rarely supported by randomized trials, there is now substantial experience with rituximab suggesting that anti-CD20 therapy is an effective and well-tolerated alternative to immunosuppressive therapy in these disorders. However, caution is needed based on recent reports describing-sometimes severe-rituximab-related complications.

Thrombotic thrombocytopenic purpura in childhood

Thrombotic thrombocytopenic purpura (TTP) is a rare disease, especially in childhood, and has a high mortality rate in the absence of appropriate treatment. It is characterised by microangiopathic haemolytic anaemia and consumptive thrombocytopenia. TTP may be difficult to distinguish from haemolytic uraemic syndrome (HUS) because of similar clinical manifestations and laboratory findings. In the past, TTP and HUS have often been considered to represent variable expressions of a single entity. Our increased understanding of the pathogenesis of TTP has in turn resulted in significant improvements in its treatment and outcomes. Several immunomodulating agents are currently being used with variable outcomes.

Sustained response with rituximab in patients with thrombotic thrombocytopenic purpura: a report of 13 cases and review of the literature

Idiopathic thrombotic thrombocytopenic purpura (TTP) is a life-threatening disease mediated by autoantibodies directed against ADAMTS-13. A number of small series and case reports have shown promising results with rituximab in refractory or relapsed TTP. In this report, we present 13 patients with TTP treated with rituximab. Twelve of the 13 patients (92%) achieved complete response; no subsequent relapses occurred with median follow-up of 24 months (range, 13-84 months). The addition of rituximab to standard therapy appears to be effective in sustaining long-term remission in TTP. However, the optimal dosing and timing of rituximab warrant further investigation. Am. J. Hematol., 2009. (c) 2009 Wiley-Liss, Inc.

The contribution of endothelial activation and injury to end-organ toxicity following allogeneic hematopoietic stem cell transplantation

Over the last 25 years, allogeneic hematopoietic stem cell transplantation (HSCT) has been used increasingly as a curative treatment option for patients with hematologic and neoplastic diseases. Despite major advances in transplant immunology and improvements in supportive and critical care medicine, HSCT is still plagued by several life-threatening complications. As such, the establishment of effective therapeutic options for these complications will be crucial as increasing numbers of high-risk transplants are performed each year. This brief review will discuss the contribution of vascular endothelial cell activation and injury to inflammation and end-organ toxicity that occurs following allogeneic HSCT, and will highlight translational research efforts that have paved the way to the development of novel strategies to treat and prevent disease. Finally, we will discuss in detail the clinical manifestations and challenges encompassed by the syndrome of thrombotic microangiopathy following HSCT.

New treatment options for immune-mediated hematological disorders

In recent years, there has been a tremendous increase in the number of clinical studies with monoclonal antibodies and small molecules in the treatment of hematological malignancies. Clinical observations have shown that some of these molecules may also aid in the treatment of immune-mediated hematological disorders. Moreover, immunotherapy has become an important treatment cornerstone in other, non-hematological, auto-immune diseases. This paper reviews the current state of the use of these new molecules in the treatment of the most frequently encountered immune-mediated hematological disorders: auto-immune hemolytic anemia (AIHA), idiopathic thrombocytopenic purpura (ITP), and thrombotic thrombocytopenic purpura (TTP).

Von Willebrand factor, ADAMTS13, and thrombotic thrombocytopenic purpura

Discoveries during the past decade have revolutionized our understanding of idiopathic thrombotic thrombocytopenic purpura (TTP). Most cases in adults are caused by acquired autoantibodies that inhibit ADAMTS13, a metalloprotease that cleaves von Willebrand factor within nascent platelet-rich thrombi to prevent hemolysis, thrombocytopenia, and tissue infarction. Although approximately 80% of patients respond to plasma exchange, which removes autoantibody and replenishes ADAMTS13, one third to one half of survivors develop refractory or relapsing disease. Intensive immunosuppressive therapy with rituximab appears to be effective as salvage therapy, and ongoing clinical trials should determine whether adjuvant rituximab with plasma exchange also is beneficial at first diagnosis. A major unanswered question is whether plasma exchange is effective for the subset of patients with idiopathic TTP who do not have severe ADAMTS13 deficiency.

The potential utility of B cell-directed biologic therapy in autoimmune diseases

Increasing awareness of the importance of aberrant B cell regulation in autoimmunity has driven the clinical development of novel B cell-directed biologic therapies with the potential to treat a range of autoimmune disorders. The first of these drugs-rituximab, a chimeric monoclonal antibody against the B cell-specific surface marker CD20-was recently approved for treating rheumatoid arthritis in patients with an inadequate response to other biologic therapies. The aim of this review is to discuss the potential use of rituximab in the management of other autoimmune disorders. Results from early phase clinical trials indicate that rituximab may provide clinical benefit in systemic lupus erythematosus, Sjögren's syndrome, vasculitis, and thrombocytopenic purpura. Numerous case reports and several small pilot studies have also been published reporting the use of rituximab in conditions such as myositis, antiphospholipid syndrome, Still's disease, and multiple sclerosis. In general, the results from these preliminary studies encourage further testing of rituximab therapy in formalized clinical trials. Based on results published to date, it is concluded that rituximab, together with other B cell-directed therapies currently under clinical development, is likely to provide an important new treatment option for a number of these difficult-to-treat autoimmune disorders.