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Management goals and normalization concept for type 1 Gaucher disease : Results from a survey of expert physicians

Previously published guidelines for the diagnosis and management of primary immune thrombocytopenia (ITP) require updating largely due to the introduction of new classes of therapeutic agents, and a greater understanding of the disease pathophysiology. However, treatment-related decisions still remain principally dependent on clinical expertise or patient preference rather than high-quality clinical trial evidence. This consensus document aims to report on new data and provide consensus-based recommendations relating to diagnosis and treatment of ITP in adults, in children, and during pregnancy. The inclusion of summary tables within this document, supported by information tables in the online appendices, is intended to aid in clinical decision making.

Since 1968, a greater understanding of platelet biology and its regulation by thrombopoietin (TPO) has emerged. It is now recognized that immune thrombocytopenic purpura (ITP) is a disorder of reduced platelet production as well as increased platelet destruction. New therapies for ITP have emerged that have exploited this new pathophysiologic understanding. This article reviews the biology of TPO, the regulation of its circulating level in ITP, the platelet kinetic data supporting inappropriate platelet production in ITP, and the TPO mimetic agents available to treat ITP.

Purpose To assess efficacy and safety of single-agent bortezomib in previously untreated patients with multiple myeloma, investigate prevalence of baseline and treatment-emergent polyneuropathy, and identify molecular markers associated with response and neuropathy. Patients and Methods Patients received bortezomib 1.3 mg/m2 on days 1, 4, 8, and 11, for up to eight 21-day cycles. A subset of patients underwent neurophysiologic evaluation pre- and post-treatment. Bone marrow aspirates were performed at baseline for exploratory whole-genome analyses. Results Among 64 patients, 41% had partial response or better, including 9% complete/near-complete responses; median duration of response was 8.4 months. Response rates did not differ in the presence or absence of adverse cytogenetics. After median follow-up of 29 months, median time to progression was 17.3 months. Median overall survival had not been reached; estimated 1-year survival was 92%. Thirty-two patients successfully underwent optional stem-cell transplantation. Bortezomib treatment was generally well tolerated. At baseline, 20% of patients had sensory polyneuropathy. Sensory polyneuropathy developed during treatment in 64% of patients (grade 3 in 3%), but proved manageable and resolved in 85% within a median of 98 days. Neurologic examination, neurophysiologic testing, and measurements of epidermal nerve fiber densities in 35 patients confirmed pretreatment sensory neuropathy in 20% and new or worsening neuropathy in 63%. Pharmacogenomic analyses identified molecular markers of response and treatment-emergent neuropathy, which will require future study. Conclusion Single-agent bortezomib is effective in previously untreated myeloma. Baseline myeloma-associated neuropathy seems more common than previously reported, and bortezomib-associated neuropathy, although a common toxicity, is reversible in most patients.

Chronic immune thrombocytopenic purpura (ITP) is characterized by low platelet counts and mucocutaneous bleeding. In previous studies romiplostim (AMG531), a thrombopoiesis-stimulating protein, increased platelet counts in most patients with chronic ITP. This ongoing, long-term open-label, single-arm study investigated safety and efficacy in patients who completed a previous romiplostim study and had platelet counts less than 5 × 109/L. One hundred forty-two patients were treated for up to 156 weeks (mean, 69 weeks). Platelet responses (platelet count ≥ 50 × 109/L and double baseline) were observed in 87% of all patients and occurred on average 67% of the time in responding patients. In 77% of patients, the romiplostim dose remained within 2 μg/kg of their most frequent dose at least 90% of the time. Ninety patients (63%) received treatment by self-administration. Treatment-related serious adverse events were reported in 13 patients (9%). Bone marrow reticulin was observed in 8 patients; marrows were not routinely performed in this study, so the true incidence of this event cannot be determined. Severe bleeding events were reported in 12 patients (9%). Thrombotic events occurred in 7 patients (5%). In conclusion, romiplostim increased platelet counts in most patients for up to 156 weeks without tachyphylaxis and had an acceptable safety profile. (ClinicalTrials.gov Identifier NCT00116688).

Various agents to treat immune thrombocytopenic purpura (ITP) have been developed on the principle that stimulating the thrombopoietin (TPO) receptor would increase platelet production. First-generation agents--recombinant human thrombopoietin (rHuTPO) and pegylated recombinant human megakaryocyte growth and development factor (PEG rHuMGDF)--showed promise, but observations of antibody formation to PEG rHuMGDF led to the discontinuation of development of both agents. Second-generation agents--the TPO peptide mimetics, TPO non-peptide mimetics, and TPO agonist antibodies--have been developed to reduce or eliminate the problem of antigenicity. Clinical studies for some of these agents, such as AMG 531 (romiplosim, Nplate) and eltrombopag (Promacta), are demonstrating their relative safety and efficacy in increasing platelet counts in patients with ITP; AMG 531 and eltrombopag are in late-stage clinical development and are able to stimulate platelet production in patients with ITP. Some differences in safety profiles have been described and are undergoing further study. There are currently seven second-generation TPO receptor agonists that have been reported in the literature, representing the potential advantages--and continuing challenges--with this novel class of platelet-stimulating therapies for ITP and possibly thrombocytopenia in other disease states as well.

In bone marrow biopsies, stromal structural fibres are detected by reticulin and trichrome stains, routine stains performed on bone marrow biopsy specimens in diagnostic laboratories. Increased reticulin staining (reticulin fibrosis) is associated with many benign and malignant conditions while increased trichrome staining (collagen fibrosis) is particularly prominent in late stages of severe myeloproliferative diseases or following tumour metastasis to the bone marrow. Recent evidence has shown that the amount of bone marrow reticulin staining often exhibits no correlation to disease severity, while the presence of type 1 collagen, as detected by trichrome staining, is often associated with more severe disease and a poorer prognosis. It was originally thought that increases in bone marrow stromal fibres themselves contributed to the haematopoietic abnormalities seen in certain diseases, but recent studies suggest that these increases are a result of underlying cellular abnormalities rather than a cause. A growing body of evidence suggests that increased deposition of bone marrow stromal fibres is mediated by transforming growth factor-beta and other factors elaborated by megakaryocytes, but it is likely that other cells, cytokines and growth factors are also involved. This suggests new avenues for investigation into the pathogenesis of various disorders associated with increased bone marrow stromal fibres.

The quinoline methanol antimalarial drug mefloquine is a structural analogue of the Cinchona alkaloids, quinine and quinidine. We have elucidated the single crystal X-ray diffraction structure of the complexes formed between racemic erythro mefloquine and ferriprotoporphyrin IX (Fe(III)PPIX) and show that alkoxide coordination is a key interaction in the solid-state. Mass spectrometry confirms the existence of coordination complexes of quinine, quinidine and mefloquine to Fe(III)PPIX in acetonitrile. The length of the iron(III)–O bond in the quinine and quinidine complexes as determined by Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy unequivocally confirms that coordination of the quinoline methanol compounds to Fe(III)PPIX occurs in non-aqueous aprotic solution via their benzylic alkoxide functional group. UV-visible spectrophotometric titrations of the low-spin bis-pyridyl-Fe(III)PPIX complex with each of the quinoline methanol compounds results in the displacement of a single pyridine molecule and subsequent formation of a six-coordinate pyridine–Fe(III)PPIX-drug complex. We propose that formation of the drug–Fe(III)PPIX coordination complexes is favoured in a non-aqueous environment, such as that found in lipid bodies or membranes in the malaria parasite, and that their existence may contribute to the mechanism of haemozoin inhibition or other toxicity effects that lead ultimately to parasite death. In either case, coordination is a key interaction to be considered in the design of novel antimalarial drug candidates.

Thrombocytopenia is a common problem in cancer patients. Aside from bleeding risk, thrombocytopenia limits chemotherapy dose and frequency. In evaluating thrombocytopenic cancer patients, it is important to assess for other causes of thrombocytopenia, including immune thrombocytopenia, coagulopathy, infection, drug reaction, post-transfusion purpura, and thrombotic microangiopathy. The incidence of chemotherapy-induced thrombocytopenia varies greatly depending on the treatment used; the highest rates of this condition are associated with gemcitabine- and platinum-based regimens. Each chemotherapy agent differs in how it causes thrombocytopenia: alkylating agents affect stem cells, cyclophosphamide affects later megakaryocyte progenitors, bortezomib prevents platelet release from megakaryocytes, and some treatments promote platelet apoptosis. Thrombopoietin is the main regulator of platelet production. In numerous studies, recombinant thrombopoietin raised the platelet count nadir, reduced the need for platelet transfusions, reduced the duration of thrombocytopenia, and allowed maintenance of chemotherapy dose intensity. Two thrombopoietin receptor agonists now available, romiplostim and eltrombopag, are potent stimulators of platelet production. Although few studies have been completed to demonstrate their ability to treat chemotherapy-induced thrombocytopenia, these agents may be useful in treating this condition in some situations. Chemotherapy dose reduction and platelet transfusions remain the major treatments for affected patients.

Thrombopoietin receptor agonists increase platelet (PLT) counts and are approved for the treatment of chronic immune thrombocytopenia (ITP). These agents may also be useful for the management of thrombocytopenia in patients requiring surgical procedures.We conducted a retrospective review of patients with thrombocytopenia (baseline PLT count,150 × 10(9) /L) who received romiplostim before planned operative procedures. We characterized patient demographics, dosing and duration of romiplostim use, success in achieving PLT counts high enough for surgery, and clinical outcomes.Eighteen patients underwent a total of 22 operative procedures, including three Jehovah's Witnesses who underwent five procedures. Etiologies of thrombocytopenia included mild ITP (not on romiplostim at baseline), liver disease, hematologic malignancy, and drug-related thrombocytopenia. Median PLT count at romiplostim initiation was 47 × 10(9) /L (range, 11 × 10(9) -120 × 10(9) /L). All patients experienced a PLT count increase over a median of 4 weeks; median PLT count at surgery was 144 × 10(9) /L (range, 28 × 10(9) -370 × 10(9) /L). PLT counts increase to more than 150 × 10(9) /L in four of five Jehovah's Witness patients by the time of surgery. There were no surgical delays or cancellations due to thrombocytopenia. Four bleeding events occurred; none were fatal and none occurred at a PLT count of fewer than 80 × 10(9) /L. No definitive thromboembolic events occurred.Romiplostim successfully increased preoperative PLT counts allowing operative interventions, was well tolerated, did not lead to any significant thromboembolic events, and avoided the need for transfusion. Romiplostim may be of clinical utility in the preoperative management of thrombocytopenic patients, especially those unable to receive or unresponsive to PLT transfusion.

Human exposure to bovine serum albumin (BSA) is very common and occurs through dietary and medicinal routes. Although great effort has been made to reduce exposure to BSA in pharmaceuticals to eliminate the threat of bovine spongiform encephalopathy, less attention has been given to assessing the human immune response after exposure to BSA. A sensitive quantitative radioimmunoassay was therefore developed to measure anti-BSA IgG antibodies in healthy subjects and in cancer patients participating in a randomized, placebo controlled clinical trial where they were exposed to BSA as an intrathoracic surgical sealant during pneumonectomy. Anti-BSA antibodies were detected in 55% of 60 healthy blood donors and 51% of 83 patients before lung cancer resection. The median antibody levels were the same in both cohorts; 0.086 microg/mL (range 0.016-19.5 microg/mL) for health blood donors and 0.062 microg/mL (range 0.009-44 microg/mL) for cancer patients. Six months after exposure of the cancer patients to BSA, the percentage of patients with anti-BSA antibody rose to 96% and the median antibody level rose to 19 microg/mL (range 0.009-258 microg/mL). Placebo-treated cancer patients showed no significant increase in the percentage of patients with anti-BSA antibody (41%) or the median antibody level (0.047 microg/mL; range 0.008-1.58) over 6 months. Western blot analysis confirmed the presence of anti-BSA antibody. Elevated levels of anti-BSA antibody were not associated with any detectable clinical events in either the healthy blood donors or the cancer patients.

Central venous catheters (CVCs) are commonly used in oncology patients. Up to 50% of CVCs are complicated by thrombosis within the catheter or the blood vessel. These thrombi are the result of local tissue damage, the catheter itself, and the thrombophilia of cancer. Frequent flushes with saline or heparin may reduce the frequency of catheter dysfunction but do not reduce the rate of deep venous thrombosis (DVT) in the catheterized blood vessel. Efforts to use prophylactic heparin or warfarin to reduce catheter-related DVT have not been rewarding.

Immunoglobulin A (IgA) deficiency may result in the development of anti-IgA antibodies. Such antibodies may result in anaphylaxis when patients receive standard blood products. Hemophilia A is a deficiency of clotting factor VIII that results in a significant coagulopathy and bleeding in the perioperative period unless precautions are taken. We present a case of successful management of combined hemophilia A and IgA deficiency in a patient undergoing repeated sternotomy for aortic valve replacement.

BACKGROUND: PLTs stored at 22 degrees C have the potential for bacterial contamination, a problem that could be reduced by 4 degrees C storage. Nevertheless, PLTs stored at 4 degrees C exhibit a significantly reduced life span. This study was performed to determine whether treatment of PLTs with thrombopoietin or cytochalasin B plus ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetic acid (EGTA)-AM could prevent exponential loss of PLTs stored at 4 degrees C. STUDY DESIGN AND METHODS: Autologous baboon PLTs were stored at 22 or 4 degrees C. The 4 degrees C stored PLTs were treated with 1.5 ng per mL thrombopoietin, with 1 micro mol per L cytochalasin B, and 80 micromol per L EGTA-AM (cyto-EGTA) or not treated and labeled with (111)In-oxine to study their in vivo recovery and life span. PLT function was assessed by correction of an aspirin-induced prolonged bleeding time. Aggregation responses and morphology were also assessed. RESULTS: PLTs stored at 22 degrees C had normal in vivo recovery and linear survival. PLTs stored at 4 degrees C, whether or not they were treated with thrombopoietin, had normal recovery and exponential survival. Aggregation of cyto-EGTA-treated PLTs was similar for PLTs stored at 4 degrees C and fresh PLTs, but decreased in PLTs stored at 22 degrees C for 5 days. The addition of cyto-EGTA to PLTs before 4 degrees C storage inhibited morphologic changes that occurred in PLTs stored at 22 degrees C and cold-induced PLT clumping, but did not prevent exponential disappearance of the PLTs. CONCLUSION: Addition of thrombopoietin or cyto-chalasin B and EGTA-AM to PLTs before 4 degrees C storage did not prevent exponential loss of PLTs.

Learning Objectives After completing this course, the reader will be able to: Describe the mechanism of thrombosis in CVCs. Explain the symptoms, signs, and sequelae of CVC thrombosis. Discuss the evidence supporting the prophylaxis of CVC thrombosis. Access and take the CME test online and receive one hour of AMA PRA category 1 credit at http://CME.TheOncologist.com Central venous catheters (CVCs), such as the tunneled catheters and the totally implanted ports, play a major role in general medicine and oncology. Aside from the complications (pneumothorax, hemorrhage) associated with their initial insertion, all of these CVCs are associated with the long-term risks of infection and thrombosis. Despite routine flushing with heparin or saline, 41% of CVCs result in thrombosis of the blood vessel, and this markedly increases the risk of infection. Only one-third of these clots are symptomatic. Within days of insertion, almost all CVCs are coated with a fibrin sheath, and within 30 days, most CVC-related thrombi arise. Aside from reducing the function of the catheter, these CVC-related thrombi can cause postphlebitic syndrome in 15%–30% of cases and pulmonary embolism in 11% (only half of which are symptomatic). Risk factors for CVC thrombosis include the type of malignancy, type of chemotherapy, type of CVC, and locations of insertion site and catheter tip, but not inherited thrombophilic risk factors. Efforts to reduce CVC thrombosis with systemic prophylactic anticoagulation with low-molecular-weight heparin have failed. Low-dose warfarin prophylaxis remains controversial; all studies are flawed, with older studies, but not newer ones, showing benefit. Currently, less than 10% of patients with CVCs receive any systemic prophylaxis. Although its general use cannot be recommended, low-dose warfarin may be a low-risk treatment in patients with good nutrition and adequate hepatic function. Clearly, additional studies are required to substantiate the prophylactic use of low-dose warfarin. Newer anticoagulant treatments, such as pentasaccharide and direct thrombin inhibitors, need to be explored to address this major medical problem.

Reports from uncontrolled studies suggest that linezolid is associated with rates of thrombocytopenia higher than those reported in clinical studies. We assessed the risk of thrombocytopenia in 686 patients with nosocomial pneumonia who received linezolid or vancomycin foror =5 days in 2 randomized, double-blind studies and for whom follow-up platelet counts had been measured. New-onset thrombocytopenia (platelet count of150x10(9) platelets/L) occurred in 19 (6.4%) of 295 linezolid recipients and 22 (7.7%) of 285 vancomycin recipients with baseline platelet counts ofor =150x10(9) platelets/L; severe thrombocytopenia (platelet count of50x10(9) platelets/L) occurred in only 1 patient in each group. Platelet counts decreased to less than the baseline level in 4 (6.6%) of 61 linezolid recipients and 5 (11.1%) of 45 vancomycin recipients who had baseline counts of150x10(9) platelets/L. No patient had a decrease to20x10(9) platelets/L. There were no statistically significant differences between groups in these or any other platelet assessments. Clinically significant thrombocytopenia was uncommon in our analysis, and linezolid was not associated with a greater risk of thrombocytopenia in seriously ill patients than was vancomycin.

BACKGROUND Bortezomib, a boronic acid dipeptide, is a novel proteasome inhibitor that has been shown in preclinical and phase 1 studies to have antimyeloma activity. METHODS In this multicenter, open-label, nonrandomized, phase 2 trial, we enrolled 202 patients with relapsed myeloma that was refractory to the therapy they had received most recently. Patients received 1.3 mg of bortezomib per square meter of body-surface area twice weekly for 2 weeks, followed by 1 week without treatment, for up to eight cycles (24 weeks). In patients with a suboptimal response, oral dexamethasone (20 mg daily, on the day of and the day after bortezomib administration) was added to the regimen. The response was evaluated according to the criteria ofthe European Group for Blood and Marrow Transplantation and confirmed by an independent review committee. RESULTS Of 193 patients who could be evaluated, 92 percent had been treated with three or more ofthe major classes of agents for myeloma, and in 91 percent, the myeloma was refractory to the therapy received most recently. The rate of response to bortezomib was 35 percent, and those with a response included 7 patients in whom myeloma protein became undetectable and 12 in whom myeloma protein was detectable only by immuno-fixation. The median overall survival was 16 months, with a median duration of response of 12 months. Grade 3 adverse events included thrombocytopenia (in 28 percent of patients), fatigue (in 12 percent), peripheral neuropathy (in 12 percent), and neutropenia (in 11 percent). Grade 4 events occurred in 14 percent of patients. CONCLUSIONS Bortezomib, a member of a new class of anticancer drugs, is active in patients with relapsed multiple myeloma that is refractory to conventional chemotherapy.

Background PLTs for transfusion lose viability during storage in blood banking. This loss of viability is accelerated at 37 degrees C, as is the risk of bacterial contamination, and has led to the selection of 22 degrees C as the routine storage temperature. Because PLTs contain an intact apoptotic mechanism, we sought to determine whether PLTs undergo apoptosis during storage and whether storage at 37 degrees C accelerated this process. Study design and methods PLT-rich plasma from PLT concentrates was stored at 37 or 22 degrees C in small aliquots or whole bags, with and without cell-permeable caspase inhibitors. Number of PLTs, pH, LDH level, and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium activity were analyzed over time. PLT lysates were prepared and tested for the presence and activation of apoptotic proteins by enzyme assay and Western blotting. Results PLT viability was greatly reduced after 1 to 2 days of storage at 37 degrees C; however, signs of apoptosis were evident by 3 hours after temperature shift. In temperature-stressed PLTs only, a gradual rise in caspase-3 activity was detected that correlated with the appearance of the 17- to 20-kDa cleavage products of caspase-3. Gelsolin, a caspase-3 substrate, underwent cleavage within the same time frame. Bcl-xL and caspase-2 also declined significantly; caspase-9 activity rose. Specific caspase inhibitors could prevent caspase activation but did not improve PLT cellular viability at 37 degrees C. Conclusions PLTs contain apoptotic proteins that are activated during PLT storage at 37 degrees C and may account for the rapid decline in PLT cellular viability. Although ineffective here, inhibition of PLT apoptosis may improve PLT cellular viability.

This observational study aimed to assess real-world treatment patterns and clinical outcomes for patients with chronic immune thrombocytopenia (ITP) currently being treated with eltrombopag or romiplostim after switching from corticosteroids, rituximab, or the alternate thrombopoietin receptor agonist (TPO-RA). The study examined the rationale for switching to TPO-RA therapy using aided responses. Dosing patterns were also analyzed before and after switching. Treatment outcomes were assessed through platelet counts at multiple time points including treatment initiation and after switching at the last office visit. A total of 280 patients were enrolled whose active therapy for ITP was replaced with either eltrombopag (n = 130) or romiplostim (n = 150). Efficacy-related issues (desired platelet count not achieved and/or lack of response to prior therapy) were the main drivers for therapy switching among all patients (54 % for eltrombopag vs. 57 % for romiplostim). Platelet counts at the last office visit showed improvement compared with counts at the initiation of either eltrombopag or romiplostim treatment. No significant differences were noted when comparing clinical outcomes between the eltrombopag and romiplostim treatment cohorts. Our results suggest that switching to the other TPO-RA may be beneficial if there is inadequate response to treatment with the initial TPO-RA.

Stimulation of platelet production by thrombopoietin-receptor agonists (TPO-RAs) is an effective second-line treatment in immune thrombocytopenia (ITP). This 28-day phase 2 study assigned subjects with ITP of ≥3 months to once-daily oral avatrombopag (2.5, 5, 10, or 20 mg), an investigational nonpeptide TPO-RA active in humans, or placebo; subjects completing randomized treatment could enroll in a 24-week extension study. Of 64 randomized subjects, 13% (avatrombopag 2.5 mg), 53% (5 mg), 50% (10 mg), and 80% (20 mg), vs 0% for placebo, achieved a platelet count (PC) response of ≥50 × 10(9)/L with ≥20 × 10(9)/L increase above baseline at day 28. Fifty-three subjects (83%) entered the extension: 52% and 76% had a durable (PC response at ≥75% of their platelet assessments over the last 14 weeks) and overall (stable response or response at any ≥2 consecutive visits) response, respectively. All subjects experienced ≥1 adverse event (AE) (most commonly fatigue, headache, and epistaxis); 19% (n = 12) reported ≥1 serious AE; 10 (16%) withdrew due to an AE (5 due to increased PC). Avatrombopag was active and generally well tolerated, with PC response rates and AE incidence comparable with other TPO-RAs. These studies were registered at www.clinicaltrials.gov as #NCT00441090 and #NCT00625443.

Under influence of hematopoietic growth factors, particularly thrombopoietin (TPO), hematopoietic stem cells in the bone marrow go through a process of commitment, proliferation, differentiation, and maturation and become mature megakaryocytes. At this critical point, terminally differentiated megakaryocytes face a new fate: ending the old life as mature megakaryocytes by induction of apoptosis and beginning a new life as platelets by fragmentation of the large megakaryocyte cytoplasm. These events are as important as megakaryocyte commitment, proliferation, differentiation, and maturation, but the molecular mechanisms regulating these events are not well established. Although TPO drives megakaryocyte proliferation and differentiation and protects hematopoietic progenitor cells from death, it does not appear to promote platelet release from terminally differentiated megakaryocytes. Although mature megakaryocyte apoptosis is temporally associated with platelet formation, premature megakaryocyte death directly causes thrombocytopenia in cancer therapy and in diseases such as mvelodysplastic syndromes and human immunodeficiency virus infection. Also, genetic studies have shown that accumulation of megakaryocytes in bone marrow is not necessarily sufficient to produce platelets. All of these findings suggest that platelet release from megakaryocytes is an important and regulated aspect of platelet production, in which megakaryocyte apoptosis may also play a role. This review summarizes recent research progress on megakaryocyte apoptosis and platelet release.

Many patients receiving dose-intensive chemotherapy acquire thrombocytopenia and need platelet transfusions. A study was conducted to determine whether platelets harvested from healthy donors treated with thrombopoietin could provide larger increases in platelet counts and thereby delay time to next platelet transfusion compared to routinely available platelets given to thrombocytopenic patients. Community platelet donors received either 1 or 3 microg/kg pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) or placebo and then donated platelets 10 to 15 days later. One hundred sixty-six of these platelet concentrates were then transfused to 120 patients with platelets counts 25 x 10(9)/L or lower. Pretransfusion platelet counts (11 x 10(9)/L) were similar for recipients of placebo-derived and PEG-rHuMGDF-derived platelets. Early after transfusion, the median platelet count increment was higher in patients receiving PEG-rHuMGDF-derived platelets: 19 (range, -12-66) x 10(9)/L, 41 (range, 5-133) x 10(9)/L, and 82 (range, -4-188) x 10(9)/L for placebo-, 1-microg/kg-, and 3-micro/kg-derived platelets, respectively. This difference was maintained 18 to 24 hours after transfusion. Transfusion-free intervals were 1.72, 2.64, and 3.80 days for the recipients of the placebo-, 1-microg/kg-, and 3-micro/kg-derived platelets, respectively. The rate of transfusion-related adverse events was not different in recipients of placebo-derived and PEG-rHuMGDF-derived platelets. Therefore, when transfused into patients with thrombocytopenia, platelets collected from healthy donors undergoing thrombopoietin therapy were safe and resulted in significantly greater platelet count increments and longer transfusion-free intervals than platelets obtained from donors treated with placebo.

Market introduction of savory snacks containing olestra offered an opportunity to evaluate the safety of olestra in a free-living population and thereby compare the outcome to the previously established safety profile determined in clinical trials in which subjects were required to eat predetermined amounts at prescribed intervals. Therefore, a multifaceted postmarketing surveillance program was designed to evaluate consumer experience and safety of olestra in the marketplace. Customer comments were solicited through toll-free telephone numbers. Collected data were evaluated by both internal and external medical experts. About 10% of toll-free telephone calls reported health effects, most of which were gastrointestinal (GI) in nature. Clinical studies were designed and conducted to determine potential GI effects under the range of consumption patterns reported by toll-free calls. Health effects reported were those found commonly in the general population and analyses of the data found no biological reason to conclude that serious or meaningful health effects were the result of olestra consumption.

SummaryAlthough heparin is widely used as an antithrombotic agent, its multiple mechanisms of action are not fully defined. Recent work has suggested that tissue factor pathway inhibitor (TFPI) may contribute to the antithrombotic activity of heparin by inhibiting the extrinsic pathway of coagulation. We have investigated the effect of heparin on TFPI and have found that when unfractionated heparin is given by continuous intravenous infusion to hospitalized inpatients, TFPI levels increase 2.3-fold and remain high as long as heparin is continued, but return to baseline levels soon after the infusion is stopped. In contrast, therapeutic doses of the low molecular weight heparin, dalteparin, resulted in significantly less TFPI induction. Given the increasing number of studies establishing the clinical efficacy of low molecular weight heparins as antithrombotic agents, these results suggest that TFPI may not be a major contributor to the antithrombotic effect of heparin.

Darbepoetin alfa is a novel erythropoiesis stimulating protein (NESP), which stimulates erythropoiesis by the same mechanism as recombinant human erythropoietin (rHuEPO). NESP has been shown to be safe and efficacious in patients with chronic renal failure. NESP is biochemically distinct from rHuEPO, due to its increased sialic acid content. NESP has an approximately 3-fold greater half-life. rHuEPO has been shown to be safe and effective for the treatment of chemotherapy-induced anaemia. This study assessed the safety and efficacy of NESP administered once per week, under the supervision of a physician, to patients with solid tumours who were receiving multicycle chemotherapy for up to 12 weeks. Three dose cohorts are presented in this sequential, unblinded and dose-escalating study. Thirteen to 59 patients received NESP (0.5, 1.5 or 2.25 mcg kg−1wk−1) in each cohort. Patients were monitored for adverse events, including antibody formation to NESP and for effects on haemoglobin. NESP appeared to be well tolerated. Adverse events were similar across all cohorts and were consistent with the population being studied. No antibody formation was detected over the 16-week study period and follow-up. A dose–response relationship was evident for NESP and multiple measures of efficacy, including proportion of patients responding to NESP and the mean change in haemoglobin by week 4 and end of treatment for NESP 0.5, 1.5 and 2.25 mcg kg−1wk−1cohorts (mean change in haemoglobin at end of treatment was 1.24, 1.73 and 2.15 g dl−1respectively). Controlled studies of this agent at higher doses and less frequent schedules of administration are ongoing. © 2001 Cance Cancer Research Campaign

Clinical signs suggestive of immune thrombocytopenia (ITP) include bruising, petechiae, nose bleeds, genitourinary (GU) bleeding, gum bleeding, gastrointestinal (GI) bleeding, and gynecologic bleeding [1]. Clinical experience and adverse events in clinical trials reveal other ITP-associated symptoms such as arthritis, abdominal pain, sleep disturbances, headache, and fatigue. Asking patients about such symptoms supplements the platelet count in assessing disease status and impact, and thus helps in the design of a patient-specific management plan. A short practice patterns survey was administered to healthcare providers attending ITP Continuing Medical Education (CME) activities to assess the questions they ask patients in monitoring visits. A high percentage of respondents routinely ask about signs of bleeding and associated symptoms but not as frequently about health-related quality of life (HRQOL). Only 39% of respondents ask about difficulty with sleep. A short standardized questionnaire may be a useful tool to help healthcare providers gather information about their patients with ITP.

Essential thrombocythaemia (ET) is a relatively common myeloproliferative disorder characterized by an elevated platelet count. As thrombopoietin (TPO) and the TPO receptor (c-mpl) regulate platelet production in normal physiology, their role in ET was investigated. A well-characterized cohort of 23 ET patients was evaluated and followed for 3 years. The TPO levels in these ET patients (189 +/- 131 pg/ml) were the same as in normal subjects (179 +/- 112 pg/ml) and TPO was not produced by ET platelets. There were 5.6 +/- 5.5 TPO binding sites/ET platelet vs. 56 +/- 17 TPO binding sites/normal platelet and this was associated in ET patients with normal-sized platelet c-mpl protein and mRNA, but a 10-fold reduction in platelet c-mpl mRNA. The K(d) for the TPO receptor on ET platelets was 66 +/- 30 pmol/l vs. 163 +/- 31 pmol/l on normal platelets, but the c-mpl cDNA had a normal nucleic acid sequence. The decreased number of ET platelet TPO receptors resulted in a fourfold decrease in the platelet-dependent TPO clearance (0.30 +/- 0.14 ml/h/10(9) ET platelets vs. 1.24 +/- 0.38 ml/h/10(9) normal platelets) at a time when the platelet count in ET patients was 2.7-fold above normal. The fourfold decrease in the TPO clearance, elevated platelet mass and resulting normal total TPO clearance explain the normal TPO levels. These results also suggest that the thrombocytosis in ET may be attributed to an alteration of the normal feedback interaction between TPO and its receptor and not as a result of any defect in the structure of TPO or c-mpl.

The thrombopoietin receptor, c-mpl, is a crucial element not only in thrombopoietin (TPO)-initiated signaling pathways but also in the regulation of the circulating amount of TPO. We have identified a new c-mpl isoform, called c-mpl-del, that lacks 72 bp (24 amino acids) in the extracellular region of c-mpl and arises as a consequence of alternative RNA splicing between exons 8 and 9. c-mpl-del is expressed along with c-mpl-wt in blood mononuclear cells, CD34+cells, megakaryocytes, and platelets prepared from either normal donors or ET patients, although its relative expression appears to increase with megakaryocyte differentiation. The c-mpl-del-transfected cells expressed greater amounts of c-mpl-del RNA and protein than the comparable c-mpl-wt-transfected cells, however flow cytometry analysis could not detect any c-mpl receptor on the surface of the c-mpl-del-transfected cells. Further evidence for the absence of surface c-mpl-del was that in contrast to cells transfected with c-mpl-wt, those transfected with c-mpl-del did not grow in response to TPO, failed to undergo tyrosine phosphorylation of TPO-specific signal molecules, and did not bind125I-rHuTPO. Taken together, these results demonstrate that c-mpl-del, a naturally occurring variant of c-mpl, fails to be incorporated into the cell membrane but might serve as a mechanism to decrease the overall expression of functional c-mpl late in megakaryocyte differentiation.

Since the purification of thrombopoietin 6 years ago, c-Mpl ligands such as recombinant human thrombopoietin (rhTPO) and pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) have undergone extensive clinical investigation. Both recombinant forms have been shown to reduce the thrombocytopenia associated with nonmyeloablative chemotherapy. Several areas of research have been identified for further clinical development of c-Mpl ligands. One future direction is to continue to explore the intravenous route of administration of rhTPO and PEG-rHuMGDF, as well as fusion proteins of interleukin-3-thrombopoietin and thrombopoietin peptide mimetics, which may be as potent as thrombopoietin, but may lack antigenicity. Another focus would be on the use of these molecules in treating non-chemotherapy-induced thrombocytopenia associated with myelodysplastic syndrome (MDS), idiopathic thrombocytopenic purpura (ITP), human immunodeficiency virus (HIV)-related ITP, and liver disease. Additionally, c-Mpl ligands may have a role in improving apheresis yields when administered to normal platelet donors. Considerable data demonstrate the effectiveness of PEG-rHuMGDF in raising the platelet yields in apheresis donors. In the past few years, investigation into the use of thrombopoietin for ex vivo expansion of pluripotent stem cells has been extensive. Last, thrombopoietin may serve as a radioprotectant by preventing radiation-induced apoptosis of pluripotent stem cells. In the coming years, the clinical role of rhTPO, PEG-rHuMGDF, and related molecules such as the thrombopoietin peptide mimetics will probably be established for both chemotherapeutic and nonchemotherapeutic indications.

Thromboembolic disease affects about 15% of cancer patients and presents a challenge to the oncologist for both prophylaxis and treatment. Although long known to be associated with malignancy, the underlying biochemical mechanisms are poorly understood. Both low-dose warfarin and low molecular weight heparin are effective strategies for prophylaxis of venous thromboembolism, including those involving venous access devices. Current treatment options for venous thromboembolism include heparin (unfractionated and low molecular weight), warfarin, and internal vena cava filters. The appropriate use of these therapeutic options in cancer patients is reviewed herein. There is suggestive evidence that heparin may be superior to warfarin in the long-term treatment of venous thromboembolism. Whether anticoagulants might also improve cancer survival rates independent of their effect on thromboembolism deserves further investigation.

Thrombopoietin (TPO) is the primary regulator of platelet production and acts through binding its receptor, c-mpl, found on megakaryocyte progenitor cells, megakaryocytes and platelets. Circulating levels of TPO are regulated primarily by the clearance of TPO after it binds to c-mpl receptors on circulating platelets. In this study the interaction of TPO with the platelet c-mpl receptor has been analysed under physiological conditions using radiochemical and pharmacokinetic approaches. 125I-rHuTPO was prepared using a novel method of gentle iodination that preserved its biological activity and used to demonstrate that platelets, but not endothelial cells, have a single class of binding sites (56 +/- 17 binding sites/platelet) with high affinity (Kd = 163 +/- 31 pM). Cross-linking experiments confirmed that TPO, but not erythropoietin (EPO), specifically associated with the 95 kD platelet c-mpl receptor. Upon addition of TPO to platelets, 80% of the TPO binding sites were internalized within an hour and were not recycled. TPO that was not bound by platelets was stable for up to 6 d in both platelet-poor and platelet-rich plasma. Using unlabelled recombinant human TPO (rHuTPO), standard pharmacokinetic analysis demonstrated that platelets have an average TPO clearance of 1.24 +/- 0.38 ml/h/109 platelets and that TPO clearance was reduced by low temperature but not by a number of drugs or metabolic inhibitors. The maximal amount of TPO removed by platelets in vitro was identical to that predicted by the total number of TPO binding sites. These results provide a biochemical and pharmacokinetic basis for the clinical use of TPO and for understanding possible disorders of platelet production.

It has been suggested that circulating levels of thrombopoietin (TPO) are determined primarily by platelet and megakaryocyte clearance of TPO and not by changes in hepatic TPO production. The experimental evidence accumulated so far to support this hypothesis is incomplete. We have therefore developed a new model of non-immune thrombocytopenia in the rat and used it to assess the relationship of TPO (c-mpl ligand) to the platelet mass. 14 d following the administration of busulphan, the platelet count reached a nadir of

Since the discovery of thrombopoietin four years ago there has been much interest in the clinical use of this growth factor and its impact on platelet transfusions. Two recombinant thrombopoietin molecules are currently under intense clinical investigation. One is a full-length, glycosylated thrombopoietin (rHuTPO) and the other is a non-glycosylated, truncated thrombopoietin coupled to polyethylene glycol (PEG-rHuMGDF). Both bind to the thrombopoietin receptor, c-mpl, and stimulate megakaryocyte growth and platelet production in vitro and in vivo. In early clinical studies these "Mpl ligands" have been effective in reducing thrombocytopenia after non-myeloablative but not after myeloablative chemotherapy. In transfusion medicine, they may serve to increase the yield of stem cell harvests, expand progenitor cells ex vivo and stimulate platelet apheresis donors. Their impact on platelet usage is still unclear but may be less than initially estimated.

Platelet transfusions are increasingly being used to treat thrombocytopenic conditions ranging from aplastic anemia to that caused by cancer chemotherapy. Although historically whole-blood transfusions were the primary source of platelets for transfusion, random donor platelet concentrates and single-donor apheresis platelets are currently the only products used. The use of these products in the United States varies widely for different medical conditions; for example, surgical patients receive random donor platelet concentrates much more commonly than single-donor apheresis products, while the opposite is true for hematology/oncology patients. The past decade has seen a great change in the type of platelet product prescribed. Whereas random donor platelet concentrates were mostly used in the past, over 60% of the platelets transfused are now obtained from donors by apheresis. A crucial variable in the ability to collect platelets by apheresis is the donor platelet count. With the recent availability of thrombopoietin, there has been considerable interest in using this hematopoietic growth factor to stimulate platelet production in donors. Preliminary studies with the administration to platelet donors of one of the thrombopoietic growth factors, PEG-rHuMGDF, have demonstrated a marked increase in the apheresis yield and no side effects. The PEG-rHuMGDF-mobilized platelets were effective upon transfusion. Whether stimulation of platelet production in donors with thrombopoietic growth factors will become a widely accepted method will depend largely on the safety of this approach for the donor as well as on a number of lesser issues which concern the recipient and blood center.

Emerging issues in stimulating apheresis platelet donors with platelet growth factors, the relative costs of apheresis and random donor platelet concentrates, optimal platelet transfusion dose, and leucoreduction of platelet products have caused renewed debate regarding apheresis products vs. random, pooled concentrates. The future role of apheresis products in platelet transfusion therapy will in large part be determined by costs, which are increasingly recognized to be influenced by donor platelet count, apheresis yield, and platelet transfusion dose.

Background Many novel molecular and pharmacological modalities have been proposed for the treatment of accelerated vascular diseases. Yet the fundamental question remains of whether the vessel wall can be treated once only or whether single-dose therapy simply delays the inevitable processes that lead to intimal hyperplasia. Since platelet adhesion and aggregation are critical events in vascular healing, we sought to determine whether the injured blood vessel would retain its myointimal potential after reversal of even prolonged periods of thrombocytopenia. Methods and Results A novel nonimmune method sustained thrombocytopenia and suppressed postinjury neointimal hyperplasia by 88%. Infusion of fresh platelets, even 14 days after initial denuding injury, restored the full neointimal hyperplastic potential. Platelet depletion presumably removed factors chemotactic for vascular smooth muscle cells but had no effect on the overexpression of the platelet-derived growth factor receptor-β (PDGFR-β) subunit after vascular injury. In native vessels, 26.5±2.5% of medial smooth muscle cells expressed PDGFR-β. In all animals, medial PDGFR-β expression doubled 2 weeks after endothelial denudation and was evident in up to 74.5±2.5% of the cells forming the neointima. Conclusions Thus, though the hyperplastic potential of the injured blood vessel can be delayed with removal of growth stimuli, it is not lost forever, and if the media is not made quiescent, neointimal hyperplasia is simply delayed rather than prevented. These results may have a profound effect on our understanding and treatment of accelerated proliferative vascular diseases.

The Mpl ligands are a family of closely related hematopoietic growth factors that bind to the thrombopoietin receptor, c-Mpl. In addition to the endogenous Mpl ligand, thrombopoietin, two recombinant Mpl ligands, recombinant thrombopoietin and pegylated megakaryocyte growth and development factor (PEG-MGDF) are under investigation. Endogenous thrombopoietin regulates most of the normal production of platelets but also is essential for the normal development of other lineages. When recombinant thrombopoietin or PEG-MGDF is administered to normal animals or humans, there is a dose-dependent increase in the platelet count but no effect on leukocytes or erythrocytes. When administered following chemotherapy in animal models or humans, Mpl ligands reduce the duration and sometimes the degree of thrombocytopenia. The Mpl ligands also may be effective in reducing the thrombocytopenia of patients with HIV infection, liver disease, myelodysplasia, or after plateletpheresis.

Febrile neutropenia, a common side effect of myelosuppressive chemotherapy in patients with cancer, can result in prolonged hospitalization and broad-spectrum antibiotic use, often prompting treatment delays or dose reductions of drug regimens. Prophylactic use of myeloid growth factors (mainly the colony-stimulating factors filgrastim and pegfilgrastim) in patients of heightened risk can reduce the severity and duration of febrile neutropenia. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Myeloid Growth Factors provide recommendations on the use of these agents mainly in the oncology setting based on clinical evidence and expert consensus. This version includes revisions surrounding the issue of timing of pegfilgrastim administration. It also includes new sections on tbo-filgrastim, a recently approved agent that is biologically similar to filgrastim, and the role of myeloid growth factors in the hematopoietic cell transplant setting.

Thrombopoietin (TPO) is the major physiological regulator of platelet production. TPO binds the TPO receptor, activates JAK and STAT pathways, thus stimulating megakaryocyte growth and platelet production. There is no “sensor” of the platelet count; rather TPO is produced in the liver at a constant rate and cleared by TPO receptors on platelets. TPO levels are inversely proportional to the rate of platelet production. Early recombinant TPO molecules were potent stimulators of platelet production and increased platelets in patients with immune thrombocytopenia, chemotherapy-induced thrombocytopenia, myelodysplastic syndromes and platelet apheresis donors. Neutralizing antibodies formed against one recombinant protein and ended their development. A second generation of TPO receptor agonists, romiplostim and eltrombopag, has been developed. Romiplostim is an IgG heavy chain into which four TPO agonist peptides have been inserted. Eltrombopag is an oral small molecule. These activate the TPO receptor by different mechanisms to increase megakaryocyte growth and platelet production. After administration of either to healthy volunteers, there is a delay of 5 days before the platelet count rises and subsequently reaches a peak after 12–14 days. Both have been highly effective in treating ITP and hepatitis C thrombocytopenia. Studies in a wide variety of other thrombocytopenic conditions are underway.

Thrombopoietin (TPO) is the major regulator of megakaryopoiesis. Measurement of serum TPO levels may help distinguish between various causes of thrombocytopenia and predict treatment response to TPO receptor agonists. Serum TPO levels from 118 healthy volunteers and 88 patients with abnormal platelet counts were measured using a quantitative ELISA assay. The mean (range) TPO level in healthy volunteers was 39 (7-99) pg/mL. TPO values were correlated with the patient's diagnosis, platelet count, and response to TPO receptor agonists. 88 patients with history of consumptive thrombocytopenia (39) or hypoproliferative thrombocytopenia (49) were analyzed. Median (interquartile range) TPO level for consumptive thrombocytopenia patients was 63 (48-98) pg/mL with a corresponding median (interquartile range) platelet count of 73 (28-146) × 10(9) /L. In contrast, hypoproliferative thrombocytopenia patients had platelet counts [59 (30-117) × 10(9) /L] comparable with consumptive thrombocytopenia patients, but significantly higher serum TPO levels [706 (358-1546) pg/mL, P0.0001]. Analysis of 21 ITP patients treated with TPO receptor agonists demonstrated that a TPO level95 pg/mL was associated with lack of clinical response (P0.002). TPO levels may have diagnostic utility in discriminating between patients with hypoproliferative and consumptive thrombocytopenia. Elevated TPO levels in ITP patients may predict a poor clinical response to treatment with TPO receptor agonists.

We evaluated clinical and safety outcomes in adult patients with type 1 Gaucher disease receiving miglustat in clinical practice settings. An observational, retrospective cohort study was conducted in centers across the EU and the USA. Medical chart data were collected from consecutive patients between the 20th November 2002 and 31st December 2008. A total of 115 patients were included; 34 (30%) were enzyme replacement therapy-naive ('naive') and 81 (70%) were enzyme pretreated ('pretreated'). Median (range) miglustat exposures in these groups were 15.1 (0.6-52.9)months and 15.2 (0.3-62.1)months, respectively. Low numbers of patients were anemic (10/101) or thrombocytopenic (21/101) at initiation of miglustat therapy. The median (range) hemoglobin concentration at miglustat initiation was 12.8 (10.2-16.4)g/dl in naive patients and 13.6 (7.3-17.4)g/dl in pretreated patients; median (range) changes in hemoglobin were 0.3 (-2.5-3.6) and -0.3 (-4-4.6)g/dl, respectively. The median (range) platelet counts at miglustat initiation were 101 (37-730)×10(9)/l in naive patients and 173 (43-382)×10(9)/l in pretreated patients; median (range) changes in platelet count were 8 (-77-145)×10(9)/l and -10 (-144-434)×10(9)/l, respectively. Plasma chitotriosidase was substantially reduced in naive but not in pretreated patients. Organ volumes were not routinely monitored. Forty-nine (43%) patients discontinued miglustat; most due to gastrointestinal manifestations and some due to tremor. Overall, hemoglobin and platelet counts tended to increase in naive patients treated with miglustat, and to remain stable or decrease slightly in pretreated patients. The profile of safety and tolerability observed with miglustat in the current study is similar to previous studies.

In order to probe structure-activity relationships of association with ferriprotoporphyrin IX (logK) and inhibition of β-hematin formation, a series of 4-aminoquinolines with varying substituents at the 7-position (X) have been synthesized. These have been further elaborated by introduction of two different R groups on the 4-amino nitrogen atom in the form of methyl (R=Me) and ethylamine (R=EtNH2) side chains. Data for a previously investigated series containing an N,N-diethyl-ethylamine side chain were also compared with the findings of this study. Experimentally, logK values for the simple 4-aminoquinoline series (R=H) were found to correlate with the hydrophobicity constant (π) of the group X. The logK values for the series with R=Me and EtNH2 were found to correlate with those of the series with R=H. The log of the 50% β-hematin inhibitory activity (logBHIA50) was found to correlate with logK and either meta (σm) or para (σp) Hammett constants for the series with R=Me and EtNH2, but not the simple series with R=H. To further improve predictability, correlations with ab initio electrostatic parameters, namely Mulliken and CHelpG charges were investigated. The best correlations were found with CHelpG charges which indicated that logK values can be predicted from the charges on atom H-8 and the group X in the quinolinium species computed in vacuum, while logBHIA50 values can be predicted from the CHelpG charges on C-7, C-8 and N-1 for the neutral species in vacuum. These correlations indicate that association and inhibition of β-hematin formation are separately determined. They also suggest that electron withdrawing groups at the 7-position, but not necessarily hydrophobic groups are required for hemozoin inhibition. The upshot is that the correlations imply that considerably more hydrophilic hemozoin inhibitors are feasible.