Interleukin-11 administration normalizes the platelet count in a hypersplenic cirrhotic patient

We report the successful administration of interleukin-11 (IL-11 or oprelvekin), a promoter of megakaryocyte maturation, to a 54-year-old male Jehovah's Witness with hepatic cirrhosis and hypersplenic thrombocytopenia requiring surgery for symptomatic interstitial cystitis. This observation suggests that oprelvekin might be crucial in the acute management of certain types of hypersplenic thrombocytopenias.

Effects of intravenous immunoglobulin on platelet count and antiplatelet antibody disposition in a rat model of immune thrombocytopenia

Experiments were conducted to investigate the effects of intravenous immunoglobulin (IVIG) in a rat model of immune thrombocytopenia (ITP). Rats were pretreated with 0 to 2 g/kg IVIG and then challenged with an antiplatelet antibody (7E3, 8 mg/kg). IVIG effects on 7E3-induced thrombocytopenia and on 7E3 pharmacokinetics were determined. IVIG pretreatment led to significant changes in the degree and time-course of 7E3-induced thrombocytopenia (P =.031). Nadir percent platelet counts were 121% to 279% greater in animals treated with IVIG (0.4-2 g/kg) than in animals receiving 7E3 alone. IVIG treatment also led to dose-dependent increases in 7E3 clearance (P <.001), with more than 2-fold increases in 7E3 clearance seen following the highest dose of IVIG. In vitro experiments showed that IVIG effects on platelet count are not likely due to anti-idiotypic inhibition of 7E3-platelet binding and that IVIG did not directly bind to 7E3. Consequently, IVIG-7E3 binding cannot explain the increase of 7E3 clearance following IVIG treatment. We propose that the observed increase in 7E3 clearance with IVIG therapy is due to saturation of the FcRn salvage receptor for IgG. The importance of the effect of IVIG on 7E3 clearance to the prevention of thrombocytopenia in these animals is unclear at present; nonetheless, these data provide experimental support for a new mechanism of IVIG action in ITP (ie, IVIG-mediated increases in antiplatelet antibody elimination). This model of ITP will be useful for further investigations of IVIG mechanism of action and for development of new therapies for ITP.

[Current recommendations for diagnosis and therapy of heparin-induced thrombocytopenia]

Thrombosis prophylaxis using heparins is mandatory in most trauma patients. However, heparins can induce heparin-induced thrombocytopenia (HIT), the most common and clinically important immune-mediated drug-dependent thrombocytopenia. Affected patients are at risk of developing new thromboembolic complications. HIT has to be considered if platelet counts decrease >50% between day 5-10 of heparin therapy that cannot be explained alternatively or if new thromboses occur in a sufficiently heparinised patient. Immediately changing the anticoagulant to danaparoid or lepirudin is most important. Proof of anti-platelet-factor-4/heparin antibodies secures the diagnosis, usually retrospectively. Diagnosis and therapy are demonstrated in a typical HIT patient. HIT usually occurs in the second week of heparin administration. Heparin-reexposure within 100 days can lead to HIT before day 5. For early recognition of HIT, platelet counts should be monitored regularly. Because of earlier discharge of patients to rehabilitation or outpatient care, the problem of HIT-diagnosis and therapy gains increasing relevance in these sectors.

Current agents for the treatment of patients with heparin-induced thrombocytopenia

Several counterintuitive treatment paradoxes complicate the management of immune heparin-induced thrombocytopenia (HIT). For example, simple discontinuation of heparin often fails to prevent subsequent HIT-associated thrombosis. Thus, current treatment guidelines recommend substituting heparin with a rapidly acting alternative anticoagulant (eg, danaparoid, lepirudin, or argatroban) even when HIT is suspected on the basis of thrombocytopenia alone ("isolated HIT"). Another paradox-coumarin (warfarin) anticoagulation-can lead to venous limb gangrene in a patient with HIT-associated deep-vein thrombosis. Thus, warfarin is not recommended during acute thrombocytopenia secondary to HIT. However, warfarin can be given as overlapping therapy with an alternative anticoagulant, provided that (1) initiation of warfarin is delayed until substantial platelet count recovery has occurred (to at least above 100 x 10(9)/L); (2) low initial doses of warfarin are used; (3) at least 5 days of overlapping therapy are given; and (4) the alternative agent is maintained until the platelet count has normalized. It has recently been recognized that HIT antibodies are transient and usually do not recur upon subsequent re-exposure to heparin. This leads to a further paradox-patients with previous HIT can be considered for a brief re-exposure to heparin under exceptional circumstances; for example, heart surgery requiring cardiopulmonary bypass, if HIT antibodies are no longer detectable using sensitive assays. For patients with acute or recent HIT who require urgent heart surgery, other approaches include use of alternative anticoagulants (eg, lepirudin or danaparoid) for cardiopulmonary bypass or antiplatelet agents (eg, tirofiban or epoprostenol) to permit intraoperative use of heparin.

Effect of anti-CD20 (rituximab) on resistant thrombocytopenia in autoimmune lymphoproliferative syndrome

Fas (CD95) plays an important role in apoptosis. Patients with defects in Fas have an autoimmune lymphoproliferative syndrome (ALPS) characterized by lymphadenopathy, autoimmune cytopenias and an increased incidence of lymphomas. There are approximately 70 known cases described worldwide. The autoimmune cytopenias are difficult to treat in this group. We describe a patient with a defect in the death domain of the FAS molecule who had autoimmune thrombocytopenia resistant to conventional therapy but which responded to a combination of rituximab and vincristine.

Antiphospholipid syndrome treated with prednisolone, cyclophosphamide and double-filtration plasmapheresis

A case of antiphospholipid syndrome (APS) is reported. A 48-year-old man visited our hospital because of proteinuria. He had suffered from thrombosis and had high titers of antibodies to beta2-glycoprotein I (abeta2GPI) and anticardiolipin antibodies (aCLIgG) and thrombocytopenia. We started anticoagulation therapy using warfarin combined with prednisolone. Although platelet count was improved, the titers of anti-beta2GPI and aCLIgG still remained high. Therefore, double-filtration plasmapheresis (DFPP) was carried out to remove the antibodies. After the treatment with DFPP, cyclophosphamide was administered. These therapies resulted in lower titers of abeta2GPI and aCLIgG and no more thrombosis occurred. A combination therapy using warfarin, prednisolone, cyclophosphamide and DFPP might be effective for the treatment of patients with APS.

The effects of pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) on platelet recovery in breast cancer patients undergoing autologous bone marrow transplantation

OBJECTIVE

To assess the safety and efficacy of pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) administered after autologous bone marrow transplantation (ABMT).

PATIENTS AND METHODS

Two randomized, double-blind, placebo-controlled studies were done. In the phase 1/2 study, 75 breast cancer patients underwent a bone marrow harvest and myeloablative STAMP V chemotherapy and were randomized to receive placebo or one of three doses of PEG-rHuMGDF. In the phase 3 study, 64 patients were randomized to receive placebo or the minimally effective dose of PEG-rHuMGDF. The study drug was administered daily starting on the day of bone marrow infusion until the platelet count was greater than or equal to 50 x 10(9)/L (without transfusion) or for a maximum of 28 days. All patients received 10 microg/kg/day filgrastim starting on day 2 until neutrophil count recovery.

RESULTS

PEG-rHuMGDF appeared to be safe and well tolerated. No significant differences were noted in mortality or disease progression rates. Antibodies to MGDF were not observed. In the phase 1/2 study, the time to platelet recovery to greater than or equal to 20 x 10(9)/L and platelet transfusion requirements were significantly reduced for patients treated with PEG-rHuMGDF compared with placebo (p < 0.05). In the phase 3 study, no significant differences in the kinetics of early thrombopoiesis or platelet transfusions after ABMT were observed.

CONCLUSIONS

PEG-rHuMGDF was not consistently efficacious in reducing the duration of severe thrombocytopenia. The maximum platelet counts for PEG-rHuMGDF-treated patients occurred a median of 2 weeks after the last dose of drug, suggesting that the biologic effects of this hematopoietic cytokine are delayed compared with other hematopoietic cytokines.

[Common variable immunodeficiency. Report of 2 cases]

We report two cases with common variable immunodeficiency. Both of them had gammaglobulin concentration lower than 300 mg/dL and evolved differently. The first one had three pneumonic episodes that responded satisfactorily to antibiotics. Today, this patient presents only two or three sinusitis clinical schemes per year, and has a good response to treatment. The second one has a bad evolution and presents hematological problems like thrombocytopenia and neutropenia. She also suffers lymphoid nodular hyperplasia in the intestinal tract and atrophy in the intestinal. These cases illustrate the wide clinical, immunological and genetic variety of the syndrome.

Preventing complications in heparin-induced thrombocytopenia. Alternative anticoagulants are improving patient outcomes

HIT is a common, potentially catastrophic syndrome. Awareness and early diagnosis allow effective therapeutic intervention. Ineffective strategies include stopping heparin only and starting warfarin early. Use of alternative anticoagulants is improving patient outcomes. Lepirudin, argatroban, and danaparoid each have advantages and disadvantages; treatment should be tailored to each patient.

Venous limb gangrene during overlapping therapy with warfarin and a direct thrombin inhibitor for immune heparin-induced thrombocytopenia

We report two patients with deep-vein thrombosis complicating immune heparin-induced thrombocytopenia who developed venous limb gangrene during overlapping therapy with a direct thrombin inhibitor (lepirudin or argatroban) and warfarin. In both patients, therapy with the direct thrombin inhibitor was interrupted during persisting severe athrombocytopenia while warfarin administration continued. Both patients exhibited the typical feature of a supratherapeutic international normalized ratio (INRs, 5.9 and 7.3) that has been linked previously with warfarin-associated venous limb gangrene. These data suggest that warfarin anticoagulation be postponed in patients with acute heparin-induced thrombocytopenia until substantial recovery of the platelet count has occurred.

Antithymocyte globulin for treatment of the bone marrow failure associated with myelodysplastic syndromes

BACKGROUND

Almost half of the deaths that result from myelodysplastic syndromes are due to cytopenia associated with bone marrow failure. Treatment is mostly supportive care.

OBJECTIVE

To determine whether treatment with antithymocyte globulin improves cytopenia and reverses dependence on red blood cell transfusions in patients with myelodysplastic syndromes.

DESIGN

Single-treatment, prospective study.

SETTING

Tertiary referral center.

PATIENTS

61 patients with myelodysplastic syndromes.

INTERVENTION

Antithymocyte globulin, 40 mg/kg of body weight, given daily for 4 days.

MEASUREMENTS

Evaluation of bone marrow, blood counts, transfusions, progression, and survival for a median of 30 months (range, 1 to 88 months).

RESULTS

Within 8 months of treatment, 21 of 61 patients (34%) no longer required red blood cell transfusions. This independence from transfusions was maintained in 17 responders (81%) for a median of 36 months (range, 3 to 72 months). Ten of 21 patients (47.5%) with severe thrombocytopenia had sustained platelet count increases, and 6 of 11 patients (55%) with severe neutropenia had sustained neutrophil counts of greater than 1 x 10(9) cells/L. Characteristics favorable for response were younger patient age (P = 0.005) and lower platelet counts (P = 0.038). One of the 21 responders (5%) and 22 of the 40 nonresponders (55%) died before the end of the study (P = 0.008). One of the 21 responders (5%) and 13 of the 40 nonresponders (33%) had disease progression (P = 0.086).

CONCLUSIONS

Although this study was a nonrandomized, single-treatment study, 34% of patients treated with antithymocyte globulin became transfusion independent. Response was associated with a statistically significant longer survival and an almost significant decreased time to disease progression. Treatment with antithymocyte globulin did not seem to be detrimental because historical overall median survival times were similar to those of nonresponders.

Kasabach-merritt phenomenon: a retrospective study of treatment with vincristine

PURPOSE

Kasabach-Merritt phenomenon (KMP) is characterized by profound thrombocytopenia, microangiopathic hemolytic anemia, a consumptive coagulopathy, and an enlarging vascular lesion. The syndrome develops in infancy and is associated with a high morbidity and mortality rate. The purpose of this study was to assess the effectiveness of vincristine in the treatment of KMP.

METHODS

We retrospectively reviewed the clinical and laboratory data of 15 patients with KMP treated with vincristine at 9 institutions across the United States, South America, and Europe.

RESULTS

All 15 patients had profound thrombocytopenia and consumption of fibrinogen at presentation. Ten patients had biopsies of their lesions, and results included five (33.3%) kaposiform hemangioendotheliomas, three (20%) tufted angiomas, one lesion (6.7%) with features of both kaposiform hemangioendothelioma and tufted angioma, and one (6.7%) unclassified vascular tumor. All 15 patients had an increase in platelet count of at least 20,000 with an average response time of 4.0 weeks after initiation of vincristine therapy. Thirteen patients had an increase in fibrinogen level of 50 mg/dL with an average response time of 3.4 weeks. In 13 patients there was a significant decrease in the size of the vascular lesion. The average duration of treatment was 21.5 (+/-12.6) weeks. Four patients (26%) relapsed. All four were successfully treated with a second course of vincristine. Complications included one patient with abdominal pain, one patient with transient loss of deep tendon reflexes, and one patient with irritability.

CONCLUSION

Vincristine presents a safe and sometimes effective treatment option in the management of KMP.

[Clinical study of rhIL-11 for prevention and treatment of chemotherapy-induced thrombocytopenia]

BACKGROUND AND OBJECTIVE

Cancer chemotherapy can induce thrombocytopenia. It is necessory to develop drugs that can prevent and treat thrombocytopenia. The current study was designed to evaluate the efficacy and toxicity of rhIL-11 in prevention and treatment of chemotherapy-induced thrombocytopenia.

METHOD

A total of 109 cancer patients were involved randomly into AB or BA group and every patient received 2 cycles of chemotherapy. IL-11 was administered subcutaneously(50 micrograms/kg/d), beginning 24 hours after completion of chemotherapy for 14 consecutive days or continuing until platelet count was > 400 x 10(9)/L during cycle A. Patients did not received IL-11 during cycle B. Another 41 cases of cancer patients whose platelet were less than 50 x 10(9)/L after chemotherapy entered into open study group. IL-11 administration was the same as above.

RESULTS

Efficacy can be evaluated in 107 cases in controlled study group. Mean platelet count of cycle A was (246.49 +/- 88.64) x 10(9)/L and cycle B was (180.24 +/- 83.34) x 10(9)/L(P = 0.000). Grade III/IV thrombocytopenia in cycle A and cycle B were 7/107(6.5%) and 15/107(14%), respectively (P = 0.04). The minimum platelet counts were (136.46 +/- 74.64) x 10(9)/L and (107.77 +/- 61.33) x 10(9)/L, respectively (P = 0.000). The maximum platelet counts were (381.28 +/- 150.39) x 10(9)/L and (207.44 +/- 113.32) x 10(9)/L, respectively (P = 0.000). For open study group, 32 patients could be evaluated. The platelet count increased from(30.1875 +/- 12.13) x 10(9)/L to (226.25 +/- 163.91) x 10(9)/L after IL-11 administration. Major adverse effects were edema, dizziness, palpitation, etc.

CONCLUSION

rhIL-11 can reduce thrombocytopenia induced by chemotherapy and is a safe and effective drug for treatment of thrombocytopenia.

Increased levels of platelet-associated immunoglobulin G in a patient with mixed connective tissue disease

We report the case of a 71-year-old Japanese woman with mixed connective tissue disease and increased levels of platelet-associated immunoglobulin G. After administration of oral prednisolone, platelet-associated immunoglobulin G levels decreased with a simultaneous increase in the number of platelets, suggesting that the thrombocytopenia observed in this patient was mediated by immune mechanisms. This is the first reported case of increased platelet-associated immunoglobulin G levels in a patient with mixed connective tissue disease.

[Experimental and clinical results with the thrombin inhibitor Argatroban]

Argatroban is the smallest anticoagulant molecule of direct thrombin inhibitors. The main attributes of this synthetic drug are its rapid onset of anti-thrombin action, the rapid reversibility of its anticoagulant effect, potent inhibition of clot-bound thrombin, the absence of antibody formation and no need for dosage adjustment in patients with renal impairment. It is eliminated by hepatic metabolism. These properties make argatroban a predictable anticoagulant with intravenous use in a routine clinical setting. Argatroban is approved in the US and Canada for both prophylaxis and treatment of thrombosis in patients with heparin-induced throm-bocytopenia (HIT) and in the US as an antithrombotic agent during percutaneous coronary interventions in patients with HIT or a history of HIT. Preliminary reports document the feasibility of using argatroban for anticoagulation during hemodialysis and as adjunct to thrombolysis for treatment of myocardial infarction. Current recommendations for argatroban monitoring are to use the aPTT (activated partial thromboplastin time) for low doses and the ACT (activated clotting time) for high doses. The specific inhibition of thrombin can be measured with the ECT (ecarin clotting time).

[Hirudins in the treatment of heparin-induced thrombocytopenia and in thrombosis prophylaxis]

Approved indications for the recombinant hirudins lepirudin (Refludan(R)) und desirudin (Revasc(R)) are therapy of heparin-induced thrombocytopenia (HIT) and thrombosis prophylaxis following knee or hip replacement surgery. Kidney function dependent pharmacokinetics and their capability of inducing antibodies directed against hirudin are characteristic of this class of drugs. However, close dose-monitoring allows safe and effective use of both compounds. While lepirudin is used widely, besides danaparoid, for treatment of HIT, desirudin has not yet been widely accepted for thrombosis prophylaxis following knee or hip replacement surgery.

Antithrombotic drugs for the treatment of heparin-induced thrombocytopenia

Because patients with heparin-induced thrombocytopenia (HIT) have an extremely high frequency of developing thrombosis, treatment options other than heparin are essential. Prophylaxis against thrombosis should also be considered. The current American College of Chest Physicians guidelines for the treatment of acute heparin-induced thrombocytopenia and thrombosis syndrome (HITTS) include the use of danaparoid, lepirudin or argatroban, alone or in combination with warfarin. For documented clinical thrombosis associated with HIT, patients should be treated with a direct thrombin inhibitor at therapeutic activated partial thromboplastin time for 7 to 10 days. Warfarin should not be used during the acute phase of HIT, unless a thrombin inhibitor is being used simultaneously. Conversion to warfarin can be done when the acute phase of HIT has passed. Due to the high likelihood of cross-reactivity, the use of low molecular weight heparins in patients with HIT is not recommended. For prophylactic treatment of HIT patients, despite a lack of other indications for anticoagulation, a direct thrombin inhibitor can be initiated with a low level of anticoagulation until the thrombocytopenia resolves. This regimen is continued until laboratory evidence is provided that the HIT antibody is no longer detectable. HIT patients, in addition to needing anticoagulation to treat thrombosis, can require anticoagulation for non HIT-related events, such as for the treatment of myocardial infarction, unstable angina and long-term anticoagulation for heart valves or atrial fibrillation. For these situations, and if immediate anticoagulation is needed, the use of a direct thrombin inhibitor with switch-over to warfarin is a useful option. However, optimal dosing regimens have not been established in all cases.

Thrombopoietin: from theory to reality

Much is now known about the physiology of platelets and their role in primary hemostasis; however, until recently far less was understood about their immediate precursors, marrow megakaryocytes (MKs). With the cloning and characterization of thrombopoietin (TPO), the principle regulator of the growth and development of MKs, research has been rapid and broad-based. In several laboratories TPO was cloned based on it's binding to the product of the proto-oncogene c-mpl, at the time an orphan cytokine receptor, and was subsequently found to affect nearly all aspects of thrombopoiesis. Many of the molecular pathways that mediate TPO action have been explored. Like all other members of the hematopoietic cytokine receptor family upon hormone binding members of the JAK family of kinases are activated, which, in turn, phosphorylate the TPO receptor, generating docking sites for second messengers that affect multiple signaling pathways. Ultimately, cellular proliferative and anti-apoptotic mechanisms are initiated, increasing MK numbers, and a process termed endomitosis (EnM) begins, generating large, highly polyploid cells. The net result is the expansion of cells that give rise to mature platelets, a process that can be accentuated by the therapeutic administration of the hormone to thrombocytopenic patients.

Direct antithrombin agents ameliorate disseminated intravascular coagulation in suspected heparin-induced thrombocytopenia thrombosis syndrome

This is a case series of 5 patients who were treated with the direct antithrombin agents (lepirudin or argatroban) for known or suspected heparin-induced thrombocytopenia thrombosis syndrome (HITTs). Coincidentally all had evidence of disseminated intravascular coagulation (DIC). The DIC parameters improved with treatment and each patient was successfully discharged from the hospital. These observations provide evidence that the direct antithrombin inhibitors, lepirudin and argatroban, can improve DIC. Moreover the presence of DIC in a patient with suspected HlTTs should not mitigate against the use of these agents.

Thrombopoietin as a drug: biologic expectations, clinical realities, and future directions

After the cloning of thrombopoietin (c-mpl ligand, Tpo) in 1994, 2 recombinant thrombopoietic growth factors, full-length glycosylated recombinant human Tpo (reHuTPO) and polyethylene glycol conjugated megakaryocyte growth and development factor (PEG-reHuMGDF), have been studied in humans in a variety of clinical settings. Both thrombopoietins are generally well tolerated if administered intravenously (IV). The c-mpl ligands produce a dose-related enhancement of platelet levels, reduce nonmyeloablative chemotherapy-induced mild thrombocytopenia, and mobilize hematopoietic progenitors. On September 11, 1998, the development of PEG-reHuMGDF was suspended in the U.S., due to formation of the neutralizing anti-Tpo antibody. Those neutralizing antibodies lead to thrombocytopenia and pancytopenia in some patients receiving subcutaneous (SC) PEG-reHuMGDF. Japanese investigators indicate that the probability of antibody formation against PEG-reHuMGDF is low when the drug is administered IV instead of SC. reHuTPO has a more favorable safety profile from the point of antibody production. The c-mpl ligands can improve apheresis yields when administered to normal platelet donors. Preliminary data about the use of PEG-reHuMGDF in myelodysplasia, aplastic anemia, and immune thrombocytopenic purpura are promising. Tpo is usually not effective in myeloablative thrombocytopenia when bone marrow hematopoietic progenitors are not present. The major obstacle for the thrombopoietins is their delayed action for managing clinical thrombocytopenia. This review will focus on the biologic basis, current clinical experience, and future directions for the use of thrombopoietic molecules as drugs. The identification of a safe, effective, and potent pharmacologic platelet growth factor could significantly improve the management of thrombocytopenia-induced bleeding.