The effect of therapeutic anticoagulation on overall survival (OS) in men receiving docetaxel chemotherapy for metastatic castration-resistant prostate cancer (mCRPC)

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Background: Anticoagulants have been postulated to possess antitumor activity, although clinical data supporting this claim are conflicting. We sought to examine the effect of therapeutic anticoagulation on OS in men with mCRPC receiving first-line docetaxel chemotherapy. Methods: We retrospectively reviewed the records of 247 consecutive mCRPC patients who received first-line docetaxel chemotherapy between 1/1/1998 and 1/1/2010. Information on anticoagulant use, type of anticoagulant administered, indication for anticoagulation, and duration of anticoagulation were captured. Univariate and multivariable Cox proportional hazards regression models were developed to investigate the effect of anticoagulant use on OS. Results: In all, 29/247 men (11.7%) received anticoagulation (LMW heparin: 17/247; warfarin: 12/247). The indication was DVT in 15/247, PE in 9/247, and both DVT and PE in 5/247 men. In univariate analysis, anticoagulant use was associated with improved OS (any anticoagulant, HR 0.61 [95%CI 0.40–0.94] P=0.024; LMW heparin, HR 0.58 [95%CI 0.34–0.99] P=0.048; warfarin, HR 0.82 [95%CI 0.55–1.28] P=0.23). Median OS was 20.9 mo (with any anticoagulant) versus 17.1 mo (with no anticoagulant). In multivariable analysis, anticoagulant use remained a significant predictor of OS after adjusting for other prognostic factors (Table). Conclusions: Anticoagulant use is an independent predictor of OS in men with mCRPC receiving docetaxel. This finding is surprising given that the occurrence of venous thrombosis might be expected to negatively influence OS. If validated, these data may provide the impetus to explore the antitumor potential of anticoagulants in prospective clinical trials. [Table: see text]

Repeated treatment with high dose cyclophosphamide for severe autoimmune diseases

High dose cyclophosphamide (HiCY) without stem cell rescue has been shown to induce remissions in patients with severe autoimmune disorders (SADS). However, up to 80% of these patients ultimately relapse. Here we review the outcomes of seven patients treated with two cycles and one patient treated with three cycles of HiCY. The diseases re-treated were scleroderma, multiple sclerosis, three patients with severe aplastic anemia (SAA), and three patients with myasthenia gravis (MG). All but two patients with SAA had received standard immunomodulatory therapy for their disease up front and had been refractory. All patients had complete hematologic recovery. Overall survival in this cohort was 100%. All patients relapsed after the initial cycle but event free survival thereafter was 93.3%. All are still in remission except two MG patients, one of whom relapsed after a severe GI infection requiring hospitalization, and the other relapsed 3 years after the second treatment and she did not respond to the third treatment. This shows that HiCY can be safely re-administered in patients with SAA and refractory SADS. The quality and duration of second remissions appears to be equal or superior to the first remission.

Predictors of hemoglobin response to eculizumab therapy in paroxysmal nocturnal hemoglobinuria

BACKGROUND

Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal, hematopoietic stem cell disorder that manifests with hemolytic anemia and bone marrow failure. Eculizumab has been shown to improve anemia, decrease intravascular hemolysis, and reduce the risk of thrombosis.

DESIGN AND METHODS

This is a retrospective, single-center study of patients treated with eculizumab and categorized according to response criteria. Complete response (CR) was defined as transfusion independence with normal hemoglobin for age/sex, absence of symptoms, and lactate dehydrogenase <1.5 times the upper limit of normal. A good partial response (GPR) was defined as decreased transfusions from pretreatment and lactate dehydrogenase <1.5 upper limit of normal without thrombosis. These patients did not achieve normal hemoglobins for age and sex. A suboptimal response was defined as unchanged transfusion needs and persistent of symptoms.

RESULTS

Thirty patients with PNH clones were treated with eculizumab and classified as complete responders (four patients), good partial responders (16), and suboptimal responders (10) over 863 patient-months of treatment. Complete responders had a decrease in red cell clone size, while good partial responders had an increase. Thirteen patients treated did not meet inclusion criteria for the clinical trials of eculizumab due to lack of transfusions or thrombocytopenia; eight had at least a GPR.

CONCLUSIONS

Eculizumab is efficacious in patients with PNH, but responses can vary and may depend on underlying marrow failure, underlying inflammatory conditions and red cell clone size following treatment. Normalization of hemoglobin with decrease in red cell clone size may predict CR.

Brief intensive therapy for older adults with newly diagnosed Burkitt or atypical Burkitt lymphoma/leukemia

Older patients with Burkitt lymphoma/leukemia (BL) have inferior outcomes. Because cyclophosphamide is highly active in BL and can be dose-escalated without stem-cell rescue, we designed a short, cyclophosphamide-intensive regimen without anthracyclines for patients aged ≥ 30 with untreated, non-HIV-associated BL/atypical BL. Two cycles involving cyclophosphamide 1500 mg/m(2), vincristine, rituximab, prednisone, methotrexate 3 g/m(2), and intrathecal cytarabine were delivered 2 weeks apart, followed by intensification with high-dose cyclophosphamide (50 mg/kg/day for 4 days) and rituximab. Of 21 patients, median age 53 (range, 34-75), 71% had stage IV, 95% were high-risk and 29% had performance status 3-4. Response occurred in all evaluable patients post-cycle 2 and in 76% post-intensification. Five non-relapse deaths occurred (four before intensification). The estimated 1-year and 3-year event-free survival was 52%; 1-year and 3-year overall survival was 57%. Seventeen (81%) received intensification (median 30 days to intensification). Brief, anthracycline-sparing, intensive cyclophosphamide (BASIC) therapy yields durable remissions in poorer-risk BL/atypical BL.

Abstract 5699: Mesenchymal stem cells (MSCs) as a selective delivery vehicle for a PSA-activated protoxin for advanced prostate cancer

Circulating bone marrow-derived Mesenchymal Stem Cells (MSCs) can differentiate into cells of the mesoderm lineage and have an innate tropism for tumor tissue in response to the inflammatory microenvironment present in malignant lesions. MSCs have been detected in the perivascular space of many tumors, including prostate. MSCs are inherently non-immunogenic, which prevents allogeneic MSCs from being rejected by host defense mechanisms. This immune-privileged status, together with their oncotropic properties, makes possible the infusion of allogeneic MSCs into patients for therapeutic purposes. PRX302 is a PSA-activated aerolysin-based protoxin that forms membrane pores and leads to necrosis by a proliferation-independent mechanism at low picomolar concentrations. Active PSA is bound to inhibitors, such as A2M, in the plasma, and therefore, is only present in an active form at sites of local and metastatic prostate cancer. Consequently, PRX302 will only be converted to a toxic form in the tumor microenvironment and thereby, limit off-target toxicity. Based upon this rationale we hypothesize that MSCs can be used as a cell-based targeting vehicle to selectively deliver therapeutic agents, such as PRX302, to primary and metastatic sites of prostate cancer, and thus spare host toxicity. We have demonstrated that fluorescently-labeled MSCs “home” to sites of prostate cancer in nude mice bearing castration-resistant CWR-22RH xenografts and a significant fraction are localized to the perivascular space. This co-localization with the tumor vasculature suggests that a MSC-delivered cytotoxin would have profound anti-tumor efficacy through effects on both cancer and endothelial cells. Furthermore, we have confirmed that MSCs and stromal cells derived from human prostate cancers (PrCSCs) in men older than 50 (&gt;10 tested), but not those isolated from normal prostates in men under 30 (&gt;7 tested), can differentiate into adipocytes, osteoblasts, and chondrocytes under the appropriate conditions. Furthermore, these PrCSCs are positive for CD90, CD73, CD105, and FAP, but do not express CD34, CD45, CD11b, CD19, or HLA-DR, which is consistent with the hMSC phenotype and suggests that MSCs migrate to cancerous prostates in the human as well. Importantly, PRX302 binds with low nanomolar affinity to GPI-anchor proteins, which are highly expressed on the surface of all mammalian cells. Using PIG-A-targeted zinc finger nucleases (ZFNs) to knockout GPI-anchor synthesis, we have demonstrated that GPI-anchor-deficient MSCs retain their tumor homing properties. Therefore, MSCs can be genetically modified to endogenously express PRX302 from the PIG-A locus as a ‘safe harbor’ and prevent self-sterilization due to protoxin secretion. The therapeutic efficacy and host toxicity of these PRX302-expressing MSCs will be evaluated against a series of human prostate cancer xenograft models.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5699. doi:1538-7445.AM2012-5699

The small population of PIG-A mutant cells in myelodysplastic syndromes do not arise from multipotent hematopoietic stem cells

BACKGROUND

Patients with paroxysmal nocturnal hemoglobinuria harbor clonal glycosylphosphatidylinositol-anchor deficient cells arising from a multipotent hematopoietic stem cell acquiring a PIG-A mutation. Many patients with aplastic anemia and myelodysplastic syndromes also harbor small populations of glycosylphosphatidylinositol-anchor deficient cells. Patients with aplastic anemia often evolve into paroxysmal nocturnal hemoglobinuria; however, myelodysplastic syndromes seldom evolve into paroxysmal nocturnal hemoglobinuria. Here, we investigate the origin and clonality of small glycosylphosphatidylinositol-anchor deficient cell populations in aplastic anemia and myelodysplastic syndromes.

DESIGN AND METHODS

We used peripheral blood flow cytometry to identify glycosylphosphatidylinositol-anchor deficient blood cells, a proaerolysin-resistant colony forming cell assay to select glycosylphosphatidylinositol-anchor deficient progenitor cells, a novel T-lymphocyte enrichment culture assay with proaerolysin selection to expand glycosylphosphatidylinositol-anchor deficient T lymphocytes, and PIG-A gene sequencing assays to identify and analyze PIG-A mutations in patients with aplastic anemia and myelodysplastic syndromes.

RESULTS

Twelve of 15 aplastic anemia patients were found to harbor a small population of glycosylphosphatidylinositol-anchor deficient granulocytes; 11 of them were found to harbor a small population of glycosylphosphatidylinositol-anchor deficient erythrocytes, 10 patients were detected to harbor glycosylphosphatidylinositol-anchor deficient T lymphocytes, and 3 of them were detected only after T-lymphocyte enrichment in proaerolysin selection. PIG-A mutation analyses on 3 patients showed that all of them harbored a matching PIG-A mutation between CFU-GM and enriched T lymphocytes. Two of 26 myelodysplastic syndromes were found to harbor small populations of glycosylphosphatidylinositol-anchor deficient granulocytes and erythrocytes transiently. Bone marrow derived CD34(+) cells from 4 patients grew proaerolysin-resistant colony forming cells bearing PIG-A mutations. No glycosylphosphatidylinositol-anchor deficient T lymphocytes were detected in myelodysplastic syndrome patients.

CONCLUSIONS

In contrast to aplastic anemia and paroxysmal nocturnal hemoglobinuria, where PIG-A mutations arise from multipotent hematopoietic stem cells, glycosylphosphatidylinositol-anchor deficient cells in myelodysplastic syndromes appear to arise from more committed progenitors.

Treatment of relapsing-remitting multiple sclerosis with high-dose cyclophosphamide induction followed by glatiramer acetate maintenance

BACKGROUND

Previous studies have described stabilization of aggressive multiple sclerosis (MS) with one-time induction therapy with high-dose cyclophosphamide (HiCy). The long-term benefit of this stabilization followed by conventional therapy has not been explored.

OBJECTIVE

The objective of this study was to evaluate the safety and clinical outcomes following treatment of relapsing-remitting MS with HiCy induction therapy followed by glatiramer acetate maintenance.

METHODS

A retrospective review of a closely followed population of thirty two MS patients treated with HiCy (200mg/kg intravenous infusion over 4 days) followed by maintenance with glatiramer acetate was performed.

RESULTS

Annualized relapse rate was reduced from 1.37 in the 2 years prior to treatment to 0.27 over a mean post-treatment follow-up period of 14 months (range 0.5-33.8). The projected probability of relapse-free survival at 2 years was 0.64 (95% CI 0.37-0.82). The projected probability of Expanded Disability Status Scale (EDSS) progression-free survival at 2 years was 0.77 (95% CI 0.43-0.92). The mean number of gadolinium-enhanced lesions was reduced from 0.86 (SD 1.6) at baseline to 0 at 12 months and 0.08 (SD 0.28) at 15-24 months. A total of 55% of patients had no evidence of disease activity in follow-up. Infectious complications occurred in 47% with no long-term morbidity and no deaths.

CONCLUSIONS

Induction therapy with HiCy followed by long-term maintenance with glatiramer acetate is well tolerated in patients with MS, and appears to be efficacious in reducing the risk of relapse, disability progression, and new MRI lesions.

Natural history of paroxysmal nocturnal hemoglobinuria clones in patients presenting as aplastic anemia

OBJECTIVE

 To investigate the natural history of paroxysmal nocturnal hemoglobinuria (PNH) clones in patients with acquired aplastic anemia (AA).

PATIENTS AND METHODS

 Twenty-seven patients with AA and a detectable PNH clone were monitored for a median of 5.7 years (range 1.5-11.5 years). Twenty-two patients received high-dose cyclophosphamide (HiCy) therapy. The erythrocyte and granulocyte PNH clone sizes were measured using flow cytometry and analyzed via CellQuest software. PE-conjugated anti-glycophorin A, anti-CD15, FITC-conjugated anti-CD59, and FLAER staining were used to define glycosylphosphatidylinositol-AP-deficient cells.

RESULTS

We found a linear relationship between PNH clone size and the development of intravascular hemolysis, assessed by lactate dehydrogenase (LDH) values (Pearson correlation coefficient = 0.80, P < 0.001 for erythrocyte PNH clones; and Pearson correlation coefficient = 0.73, P < 0.0001 for granulocyte PNH clones). An erythrocyte PNH size of 3-5% and granulocyte PNH size of 23% were the thresholds to predict hemolysis as measured by an elevated LDH (receiver operating characteristic analyses with AUC = 0.96 for erythrocyte PNH clone sizes and AUC = 0.88 for granulocyte PNH clone sizes). Patients with small (≤15%) initial PNH clone sizes were less likely to develop an elevated LDH (mean ± SD: 236.9 ± 109.9 vs. 423.1 ± 248.8; P = 0.02). Over time, the PNH clone sizes remained stable in 25.9% of patients; 48.1% experienced a rise in the PNH clone size; and 25.9% experienced a decrease.

CONCLUSION

The risk of developing clinically significant PNH after HiCy therapy appears to be low in AA patients with PNH clones, especially for those with small initial PNH clones and for those who respond to HiCy therapy.

Clinical management of aplastic anemia

Acquired aplastic anemia is a potentially fatal bone marrow failure disorder that is characterized by pancytopenia and a hypocellular bone marrow. Hematopoietic stem-cell transplantation or bone marrow transplantation (BMT) is the treatment of choice for young patients who have a matched sibling donor. Immunosuppression with either anti-thymocyte globulin and cyclosporine or high-dose cyclophosphamide is an effective therapy for patients who are not suitable BMT candidates owing to age or lack of a suitable donor. Results of BMT from unrelated and mismatched donors are improving, but presently this treatment option is best reserved for those patients who do not respond, relapse or develop secondary clonal disorders following immunosuppressive therapy. Efforts are currently underway to both improve immunosuppressive regimens and to expand the application of BMT.

High-dose cyclophosphamide and rituximab without stem cell transplant: a feasibility study for low grade B-cell, transformed and mantle cell lymphomas

Relapse after autologous stem cell transplant for low grade B-cell lymphoma is common secondary to ineffective conditioning and/or tumor autograft contamination. We investigated high-dose cyclophosphamide and rituximab without stem cell rescue as first-line or salvage therapy in lymphomas. After establishing safety, accrual was increased to evaluate event-free survival (EFS). Eighty-one adults received rituximab (375 mg/m(2) days 1, 4, 8, 11, 45, 52), cyclophosphamide (50 mg/kg days 15-18), and pegfilgrastim (day 20). Forty-two patients had low grade B-cell lymphoma [grade I/II follicular (69%), transformed lymphoma (17%), other (15%)]: 45% were treated without measurable disease. Thirty-nine patients had mantle cell lymphoma: 82% were treated without measurable disease. All achieved hematopoietic recovery; 46% required brief hospitalizations. The 5-year EFS and overall survival (OS) for patients with low grade B-cell and transformed lymphoma were 40% and 72%, respectively. The 5-year EFS and OS for patients with MCL were 39% and 62%, respectively. This low-toxicity therapeutic approach obviates the need for stem cell products and establishes a platform for future therapies.

Paroxysmal nocturnal hemoglobinuria from bench to bedside

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematologic disease that presents with protean manifestations. Clinical and laboratory investigation over the past 25 years has uncovered most of the basic science underpinnings of PNH and has led to the development of a highly effective targeted therapy. PNH originates from a multipotent hematopoietic stem cell (HSC) that acquires a somatic mutation in a gene called phosphatidylinositol glycan anchor biosynthesis, class A (PIG-A). The PIG-A gene is required for the first step in glycosylphosphatidylinositol (GPI) anchor biosynthesis. Failure to synthesize GPI anchors leads to an absence of all proteins that utilize GPI to attach to the plasma membrane. Two GPI-anchor proteins, CD55 and CD59, are complement regulatory proteins; their absence on the surface of PNH cells leads to complement-mediated hemolysis. The release of free hemoglobin leads to scavenging of nitric oxide and contributes to many clinical manifestations, including esophageal spasm, fatigue, and possibly thrombosis. Aerolysin is a pore-forming toxin that binds GPI-anchored proteins and kills normal cells, but not PNH cells. A fluorescinated aerolysin variant (FLAER) binds GPI-anchor and serves as a novel reagent diagnosing PNH. Eculizumab, a humanized monoclonal antibody against C5, is the first effective drug therapy for PNH.

High-dose cyclophosphamide without stem cell rescue in 207 patients with aplastic anemia and other autoimmune diseases

High-dose cyclophosphamide has long been used as an anticancer agent, a conditioning regimen for hematopoietic stem cell transplantation, and a potent immunosuppressive agent in autoimmune diseases including aplastic anemia. High-dose cyclophosphamide is highly toxic to lymphocytes but spares hematopoietic stem cells because of their abundant levels of aldehyde dehydrogenase, the major mechanism of cyclophosphamide inactivation. High-dose cyclophosphamide therapy induces durable remissions in most patients with acquired aplastic anemia. Moreover, high-dose cyclophosphamide without hematopoietic stem cell rescue has shown activity in a variety of other severe autoimmune diseases. Here we review the history of cyclophosphamide as it applies to aplastic anemia and other autoimmune diseases. We include historical data from early patients treated for aplastic anemia as well as data from 140 patients from an observational retrospective study in a single tertiary care hospital. This latter component was designed to assess the safety and efficacy of high-dose cyclophosphamide therapy without stem cell rescue in patients with refractory autoimmune diseases. We analyzed the 140 patients with severe, progressive autoimmune diseases treated. All patients discussed here received cyclophosphamide, 50 mg/kg per day for 4 consecutive days. Response, relapse, and overall survival were measured. Response was defined as a decrease in disease activity in conjunction with a decrease or elimination of immune-modulating drugs. Relapse was defined as worsening disease activity and/or a requirement for an increase in dose of, or administration of new, immunosuppressive medications. Hematologic recovery occurred in all patients. The overall response rate was 94%, and 44% of those patients remained progression free with a median follow-up of 36 months (range, 1-120 mo) for the 140 patients analyzed together. The overall actuarial and event-free survival across all diseases at 60 months was 90.7% and 20.6%, respectively. High-dose cyclophosphamide without stem cell rescue is well tolerated and induces a high rate of remission in severe autoimmune diseases.

High-dose cyclophosphamide without stem cell rescue for the treatment of refractory Behcet's disease

OBJECTIVE

Behcet's disease (BD) is a systemic inflammatory disorder characterized by recurrent mucocutaneous ulcerations, ocular inflammation, and numerous severe systemic inflammatory manifestations. While most patients respond to standard immunosuppressive therapies, a subset will develop refractory disease. In this report, the use of a novel therapy for the treatment of BD is described.

METHODS

Two patients with severe refractory BD who were treated with nonmyeloablative high-dose cyclophosphamide therapy without stem cell rescue.

RESULTS

After treatment, both patients were completely weaned off immunosuppressive therapy and entered disease-free remissions of 18 and 24 months, respectively.

CONCLUSIONS

These data suggest high-dose cyclophosphamide therapy without stem cell rescue as an alternative for the treatment of refractory BD.

High-dose cyclophosphamide for autoimmunity and alloimmunity

High-dose cyclophosphamide (high-CY) is a potent immunosuppressive regimen that is increasingly used to mitigate both autoimmune and alloimmune conditions. Differential expression of aldehyde dehydrogenase between hematopoietic stem cells and lymphocytes accounts for the differential sensitivity of these cells to high-CY and explains why this regimen is immunosuppressive but not myeloablative. This article describes the clinical translation of high-CY for the treatment of autoimmune and alloimmune conditions.

Butyrate greatly enhances derivation of human induced pluripotent stem cells by promoting epigenetic remodeling and the expression of pluripotency-associated genes

We report here that butyrate, a naturally occurring fatty acid commonly used as a nutritional supplement and differentiation agent, greatly enhances the efficiency of induced pluripotent stem (iPS) cell derivation from human adult or fetal fibroblasts. After transient butyrate treatment, the iPS cell derivation efficiency is enhanced by 15- to 51-fold using either retroviral or piggyBac transposon vectors expressing 4 to 5 reprogramming genes. Butyrate stimulation is more remarkable (>100- to 200-fold) on reprogramming in the absence of either KLF4 or MYC transgene. Butyrate treatment did not negatively affect properties of iPS cell lines established by either 3 or 4 retroviral vectors or a single piggyBac DNA transposon vector. These characterized iPS cell lines, including those derived from an adult patient with sickle cell disease by either the piggyBac or retroviral vectors, show normal karyotypes and pluripotency. To gain insights into the underlying mechanisms of butyrate stimulation, we conducted genome-wide gene expression and promoter DNA methylation microarrays and other epigenetic analyses on established iPS cells and cells from intermediate stages of the reprogramming process. By days 6 to 12 during reprogramming, butyrate treatment enhanced histone H3 acetylation, promoter DNA demethylation, and the expression of endogenous pluripotency-associated genes, including DPPA2, whose overexpression partially substitutes for butyrate stimulation. Thus, butyrate as a cell permeable small molecule provides a simple tool to further investigate molecular mechanisms of cellular reprogramming. Moreover, butyrate stimulation provides an efficient method for reprogramming various human adult somatic cells, including cells from patients that are more refractory to reprogramming.

High-dose cyclophosphamide versus monthly intravenous cyclophosphamide for systemic lupus erythematosus: a prospective randomized trial

OBJECTIVE

Monthly intravenous (IV) cyclophosphamide for 6 months has been the standard induction regimen for lupus nephritis, followed by a maintenance regimen of quarterly infusions for 2 years. We undertook this study to compare the efficacy and safety of the standard regimen versus a high-dose IV cyclophosphamide regimen.

METHODS

We performed a prospective randomized trial comparing monthly IV cyclophosphamide at 750 mg/m(2) body surface area for 6 months followed by quarterly IV cyclophosphamide for 2 years (traditional treatment) against high-dose IV cyclophosphamide (50 mg/kg daily for 4 days) (high-dose treatment). Entry criteria included renal lupus, neurologic lupus, or other organ system involvement with moderate-to-severe activity.

RESULTS

Fifty-one patients were randomized; 3 withdrew before treatment and 1 committed suicide after 2 months of high-dose treatment. Twenty-two had renal lupus, 14 had neurologic lupus, and 11 had other organ involvement. The outcome measure was the Responder Index for Lupus Erythematosus (complete response, partial response, no change, or worsening). At 6 months (the end of induction), 11 of 21 patients (52%) in the high-dose treatment group had a complete response compared with 9 of 26 patients (35%) in the traditional treatment group (P = 0.13). At the final visit (30 months), 10 of 21 patients (48%) in the high-dose treatment group had a complete response compared with 13 of 20 patients (65%) who continued with traditional treatment (P = 0.13). Six patients crossed over from traditional treatment to high-dose treatment because of lack of response, and 3 of those patients became complete responders.

CONCLUSION

There was not strong evidence that monthly IV cyclophosphamide and high-dose IV cyclophosphamide differed in complete or in any (complete or partial) response to induction or maintenance therapy. However, nonresponders to monthly IV cyclophosphamide can sometimes be rescued with high-dose IV cyclophosphamide.

Managing a pregnant patient with paroxysmal nocturnal hemoglobinuria in the era of eculizumab

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare clonal stem cell disorder, which affects women of child-bearing age. PNH is associated with thrombotic complications, which are the main causes of morbidity and mortality. Management of a pregnant woman with PNH remains a challenge due to high incidence of thrombotic complications and the difficulty of differentiating a PNH crisis from the complications of pregnancy. PNH is associated with an increased rate of premature labor and fetal loss. Eculizumab, a humanized monoclonal antibody directed against the terminal complement protein C5, has revolutionized treatment of PNH. However, the role of eculizumab in pregnancy is unclear. We review the current strategies for the management of pregnant women with PNH, underline the controversies and present our recommendations.

Nonmyeloablative HLA-haploidentical bone marrow transplantation with high-dose posttransplantation cyclophosphamide: effect of HLA disparity on outcome

Although some reports have found an association between increasing HLA disparity between donor and recipient and fewer relapses after allogeneic blood or marrow transplantation (BMT), this potential benefit has been offset by more graft-versus-host disease (GVHD) and nonrelapse mortality (NRM). However, the type of GVHD prophylaxis might influence the balance between GVHD toxicity and relapse. The present study analyzed the impact of greater HLA disparity on outcomes of a specific platform for nonmyeloablative (NMA), HLA-haploidentical transplantation. A retrospective analysis was performed of 185 patients with hematologic malignancies enrolled in 3 similar trials of NMA, related donor, haploidentical BMT incorporating high-dose posttransplantation cyclophosphamide for GVHD prophylaxis. No significant association was found between the number of HLA mismatches (HLA-A, -B, -Cw, and -DRB1 combined) and risk of acute grade II-IV GVHD (hazard ratio [HR] = 0.89; P = .68 for 3-4 vs fewer antigen mismatches). More mismatching also had no detrimental effect on event-free survival (on multivariate analysis, HR = 0.60, P = .03 for 3-4 vs fewer antigen mismatches and HR = 0.55, P = .03 for 3-4 vs fewer allele mismatches). Thus, greater HLA disparity does not appear to worsen overall outcome after NMA haploidentical BMT with high-dose posttransplantation cyclophosphamide.

Cyclophosphamide and cancer: golden anniversary

Cyclophosphamide remains one of the most successful and widely utilized antineoplastic drugs. Moreover, it is also a potent immunosuppressive agent and the most commonly used drug in blood and marrow transplantation (BMT). It was initially synthesized to selectively target cancer cells, although the hypothesized mechanism of tumor specificity (activation by cancer cell phosphamidases) transpired to be irrelevant to its activity. Nevertheless, cyclophosphamide's unique metabolism and inactivation by aldehyde dehydrogenase is responsible for its distinct cytotoxic properties. Differential cellular expression of aldehyde dehydrogenase has an effect on the anticancer therapeutic index and immunosuppressive properties of cyclophosphamide. This Review highlights the chemistry, pharmacology, clinical toxic effects and current clinical applications of cyclophosphamide in cancer and autoimmune disorders. We also discuss the development of high-dose cyclophosphamide for BMT and the treatment of autoimmune diseases.

Immunologic recovery following autologous stem-cell transplantation with pre- and posttransplantation rituximab for low-grade or mantle cell lymphoma

BACKGROUND

Rituximab may improve transplant outcomes but may delay immunologic recovery.

PATIENTS AND METHODS

Seventy-seven patients with low-grade or mantle cell lymphoma received autologous stem-cell transplantation (ASCT) on a phase II study. Rituximab 375 mg/m(2) was administered 3 days before mobilization-dose cyclophosphamide, then weekly for four doses after count recovery from ASCT. Immune reconstitution was assessed.

RESULTS

Sixty percent of transplants occurred in first remission. Actuarial event-free survival (EFS) and overall survival (OS) were 60% and 73%, respectively, at 5 years, with 7.2-year median follow-up for OS in surviving patients. Median EFS was 8.3 years. Older age and transformed lymphomas were independently associated with inferior EFS, whereas day 60 lymphocyte counts did not predict EFS or late infections. Early and late transplant-related mortality was 1% and 8%, with secondary leukemia in two patients. B-cell counts recovered by 1-2 years; however, the median IgG level remained low at 2 years. Late-onset idiopathic neutropenia, generally inconsequential, was noted in 43%.

CONCLUSION

ASCT with rituximab can produce durable remissions on follow-up out to 10 years. Major infections do not appear to be significantly increased or to be predicted by immune monitoring.

Severe aplastic anemia associated with paroxysmal nocturnal hemoglobinuria and lymphoplasmacytic lymphoma

An unusual case of aplastic anemia presenting in association with lymphoplasmacytic lymphoma and paroxysmal nocturnal hemoglobinuria is discussed. An insult to the hematological stem cell compartment may result in multiple pathological entities, potentially influencing our approach to the treatment of hematological clonal disorders.

How I treat paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare clonal blood disorder that manifests with hemolytic anemia, bone marrow failure, and thrombosis. Many of the clinical manifestations of the disease result from complement-mediated intravascular hemolysis. Allogeneic bone marrow transplantation is the only curative therapy for PNH. Eculizumab, a monoclonal antibody that blocks terminal complement activation, is highly effective in reducing hemolysis, improving quality of life, and reducing the risk for thrombosis in PNH patients. Insights into the relevance of detecting PNH cells in PNH and other bone marrow failure disorders are highlighted, and indications for treating PNH patients with bone marrow transplantation and eculizumab are explored.

Successful liver transplantation for Budd-Chiari syndrome in a patient with paroxysmal nocturnal hemoglobinuria treated with the anti-complement antibody eculizumab

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired hemolytic anemia caused by somatic mutations in the phosphatidylinositol glycan-complementation class A gene and the resulting absence of a key complement regulatory protein, CD59. Affected red blood cells in patients with PNH undergo intravascular complement-mediated lysis with resulting anemia, hemoglobinuria, and venous thromboses. Hepatic venous outflow thrombosis [Budd-Chiari syndrome (BCS)] is especially common in PNH patients and often fatal. The few case reports of outcomes in patients undergoing liver transplant for BCS secondary to PNH detail instances of recurrent BCS as well as early thrombotic portal vein occlusion and hepatic artery thrombosis requiring retransplantation. PNH is therefore generally considered a contraindication to liver transplantation. Here we present the first report of a patient with PNH and BCS undergoing successful liver transplantation while receiving eculizumab, a humanized monoclonal antibody that blocks the activation of the terminal complement at C5.

Blood and marrow transplantation for sickle cell disease: overcoming barriers to success

PURPOSE OF REVIEW

Sickle cell disease (SCD) is a common health problem in the United States; yet, the only curative therapy, a bone marrow transplant (BMT), is seldom applied. The objective of this report is to review the most recent clinical trials involving blood and BMT for SCD and to discuss novel approaches to overcome the many barriers to successful use of BMT for SCD.

RECENT FINDINGS

In select patients, disease-free and overall survival is greater than 80% following matched sibling BMT for SCD. Unfortunately, most patients with SCD do not have a suitable human lymphocyte antigen-matched sibling donor. In an attempt to expand the donor pool, several groups are beginning to explore the use of alternative sources of stem cells such as haploidentical donors and umbilical cord cell blood.

SUMMARY

The curative potential of BMT in SCD is irrefutable, with outstanding results in children following a myeloablative conditioning regimen and a matched sibling donor transplant. Well tolerated and effective application of alternative sources of stem cells for BMT in SCD could greatly increase the cure rate for this devastating disease.

Intensive immunosuppression with high dose cyclophosphamide but without stem cell rescue for severe autoimmunity: advantages and disadvantages

Hematopoietic stem cell transplantation (HSCT) for the treatment of severe autoimmune disorders continues to show great promise. The morbidity and mortality of the approach is relatively low and clinical benefit has been demonstrated in many, but not all patients. Furthermore, relapse following HSCT is not uncommon. Most centers now prefer nonmyeloablative conditioning regimens using high dose cyclophosphamide prior to SCT; however, emerging data show that high dose cylophosphamide can be administered safely without the need for HSCT. Eliminating the use of HSCT after high dose cyclophosphamide shortens the duration of the procedure by several weeks, markedly reduces the cost of the procedure and eliminates the potential of reinfusing autoreactive lymphoctes with the autograft.

High dose cyclophosphamide performs better than monthly dose cyclophosphamide in quality of life measures

In spite of current therapies, the overall health status of patients with SLE is poor. High-dose cyclophosphamide (50 mg/kg for 4 days) with or without stem-cell rescue has been introduced as a new therapy for severe SLE, including renal and central nervous system (CNS)-SLE. Long-term durable responses have been found to be 40%. A randomised clinical trial was completed comparing high-dose cyclophosphamide with monthly intravenous cyclophosphamide (750 mg/m squared bovine serum albumin) in patients with SLE who need cyclophosphamide for the first time. The primary outcome of the trial was complete clinical response. In this report, we compare the treatment groups with respect to quality of life. The patients in this study had a mean age of 35.3 +/- 10.1 years, were of Caucasian (35%), African-American (51%), Hispanic (8%) and Asian (6%) people, and 88% were women. The organ leading to treatment was renal lupus in 29%, CNS-lupus in 45% and other organs in 26%. Quality of life was measured at each visit using the Medical Outcome Study Short-Form 36 (SF-36). At 6 months, the patients in the high-dose cyclophosphamide trial arm had significantly greater improvement than patients in the monthly intravenous cyclophosphamide arm (P = 0.026; P = 0.0082, respectively) in the categories of general health and social functioning. At 18 months, the improvement in the role-physical score was significantly greater in the high-dose cyclophosphamide trial arm than in the monthly-dose cyclophosphamide arm (P = 0.025). At the end of the two and a half-year study, there were no significant differences between the groups with respect to changes in SF-36. By pooling the groups, at 30 months, there was a statistically significant (P < 0.05) improvement over baseline in 6 of the 8 SF-36 domains. This study shows earlier improvement in SF-36 measures at 6 months in the high-dose cyclophosphamide group but equal improvement in both arms at two and one and a half years. Eventual improvements in quality-of-life with both cyclophosphamide regimens are clinically meaningful to both patients and treating physicians.

Glycosylphosphatidylinositol-anchored protein deficiency confers resistance to apoptosis in PNH

OBJECTIVE

Investigate the contribution of PIG-A mutations to clonal expansion in paroxysmal nocturnal hemoglobinuria (PNH).

MATERIALS AND METHODS

Primary CD34+ hematopoietic progenitors from PNH patients were assayed for annexin-V positivity by flow cytometry in a cell-mediated killing assay using autologous effectors from PNH patients or allogeneic effectors from healthy controls. To specifically assess the role of the PIG-A mutation in the development of clonal dominance and address confounders of secondary mutation and differential immune attack that can confound experiments using primary cells, we established an inducible PIG-A CD34+ myeloid cell line, TF-1. Apoptosis resistance was assessed after exposure to allogeneic effectors, NK92 cells (an interleukin-2-dependent cell line with the phenotype and function of activated natural killer [NK] cells), tumor necrosis factor (TNF)-alpha, and gamma-irradiation. Apoptosis was measured by annexin-V staining and caspase 3/7 activity.

RESULTS

In PNH patients, CD34+ hematopoietic progenitors lacking glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-AP(-)) were less susceptible than GPI-AP+ CD34+ precursors to autologous (8% vs 49%; p < 0.05) and allogeneic (28% vs 58%; p < 0.05) cell-mediated killing from the same patients. In the inducible PIG-A model, GPI-AP(-) TF-1 cells exhibited less apoptosis than induced, GPI-AP+ TF-1 cells in response to allogeneic cell-mediated killing, NK92-mediated killing, TNF-alpha, and gamma-irradiation. GPI-AP(-) TF-1 cells maintained resistance to apoptosis when effectors were raised against GPI-AP(-) cells, arguing against a GPI-AP being the target of immune attack in PNH. NK92-mediated killing was partially inhibited with blockade by specific antibodies to the stress-inducible GPI-AP ULBP1 and ULBP2 that activate immune effectors. Clonal competition experiments demonstrate that the mutant clone expands over time under proapoptotic conditions with TNF-alpha.

CONCLUSION

PIG-A mutations contribute to clonal expansion in PNH by conferring a survival advantage to hematopoietic progenitors under proapoptotic stresses.

Salvage transplantation for allograft failure using fludarabine and alemtuzumab as conditioning regimen

Graft failure after allogeneic blood or marrow transplantation, although generally uncommon, can be a devastating complication. This report includes the outcome of nine patients who received a salvage transplant for failure to engraft after one (n=8) or 2 (n=1) prior transplants. Eight patients received allografts from the original donor. All received fludarabine 30 mg/m(2) i.v. and alemtuzumab 20 mg i.v. daily from days -6 to -2. Daily CYA was begun on day -2, and the allograft was infused on day 0. The therapy was well tolerated with low toxicity, and all nine patients engrafted, recovering neutrophils at a median of 12 days after transplant. Four patients died: two of relapse, one of a fungal infection in the setting of GVHD and one of multiple sclerosis. The combination of fludarabine and alemtuzumab is an effective and well-tolerated salvage conditioning regimen for patients who experience graft failure after blood or marrow transplants.

Rebooting the immune system with high-dose cyclophosphamide for treatment of refractory myasthenia gravis

A small but important proportion of patients with myasthenia gravis (MG) are refractory to conventional immunotherapy. We have treated 12 such patients by "rebooting" the immune system with high-dose cyclophosphamide (Hi Cy, 200 mg/kg), which largely eliminates the mature immune system, while leaving hematopoietic precursors intact. The objective of this report is to describe the clinical and immunologic results of Hi Cy treatment of refractory MG. We have followed 12 patients clinically for 1-9 years, and have analyzed their humoral and cellular immunologic parameters. Hi Cy is safe and effective. All but one of the patients experienced dramatic clinical improvement for variable periods from 5 months to 7.5 years, lasting for more than 1 year in seven of the patients. Two patients are still in treatment-free remission at 5.5 and 7.5 years, and five have achieved responsiveness to immunosuppressive agents that were previously ineffective. Hi Cy typically reduced, but did not completely eliminate, antibodies to the autoantigen AChR or to tetanus or diphtheria toxin; re-immunization with tetanus or diphtheria toxoid increased the antibody levels. Despite prior thymectomy, T cell receptor excision circles, generally considered to reflect thymic emigrant T cells, were produced by all patients. Hi Cy treatment results in effective, but often not permanent, remission in most refractory myasthenic patients, suggesting that the immune system is in fact "rebooted," but not "reformatted." We therefore recommend that treatment of refractory MG with Hi Cy be followed with maintenance immunotherapy.

HLA-haploidentical bone marrow transplantation for hematologic malignancies using nonmyeloablative conditioning and high-dose, posttransplantation cyclophosphamide

We evaluated the safety and efficacy of high-dose, posttransplantation cyclophosphamide (Cy) to prevent graft rejection and graft-versus-host disease (GVHD) after outpatient nonmyeloablative conditioning and T cell-replete bone marrow transplantation from partially HLA-mismatched (haploidentical) related donors. Patients with advanced hematologic malignancies (n = 67) or paroxysmal nocturnal hemoglobinuria (n = 1) received Cy 50 mg/kg i.v. on day 3 (n = 28) or on days 3 and 4 (n = 40) after transplantation. The median times to neutrophil (>500/microL) and platelet recovery (>20,000/microL) were 15 and 24 days, respectively. Graft failure occurred in 9 of 66 (13%) evaluable patients, and was fatal in 1. The cumulative incidences of grades II-IV and grades III-IV acute (aGVHD) by day 200 were 34% and 6%, respectively. There was a trend toward a lower risk of extensive chronic GVHD (cGVHD) among recipients of 2 versus 1 dose of posttransplantation Cy (P = .05), the only difference between these groups. The cumulative incidences of nonrelapse mortality (NRM) and relapse at 1 year were 15% and 51%, respectively. Actuarial overall survival (OS) and event-free survival (EFS) at 2 years after transplantation were 36% and 26%, respectively. Patients with lymphoid malignancies had an improved EFS compared to those with myelogenous malignancies (P = .02). Nonmyeloablative HLA-haploidentical BMT with posttransplantation Cy is associated with acceptable rates of fatal graft failure and severe aGVHD or cGVHD.

HLA-haploidentical bone marrow transplantation for hematologic malignancies using nonmyeloablative conditioning and high-dose, posttransplantation cyclophosphamide

We evaluated the safety and efficacy of high-dose, posttransplantation cyclophosphamide (Cy) to prevent graft rejection and graft-versus-host disease (GVHD) after outpatient nonmyeloablative conditioning and T cell-replete bone marrow transplantation from partially HLA-mismatched (haploidentical) related donors. Patients with advanced hematologic malignancies (n = 67) or paroxysmal nocturnal hemoglobinuria (n = 1) received Cy 50 mg/kg i.v. on day 3 (n = 28) or on days 3 and 4 (n = 40) after transplantation. The median times to neutrophil (>500/microL) and platelet recovery (>20,000/microL) were 15 and 24 days, respectively. Graft failure occurred in 9 of 66 (13%) evaluable patients, and was fatal in 1. The cumulative incidences of grades II-IV and grades III-IV acute (aGVHD) by day 200 were 34% and 6%, respectively. There was a trend toward a lower risk of extensive chronic GVHD (cGVHD) among recipients of 2 versus 1 dose of posttransplantation Cy (P = .05), the only difference between these groups. The cumulative incidences of nonrelapse mortality (NRM) and relapse at 1 year were 15% and 51%, respectively. Actuarial overall survival (OS) and event-free survival (EFS) at 2 years after transplantation were 36% and 26%, respectively. Patients with lymphoid malignancies had an improved EFS compared to those with myelogenous malignancies (P = .02). Nonmyeloablative HLA-haploidentical BMT with posttransplantation Cy is associated with acceptable rates of fatal graft failure and severe aGVHD or cGVHD.

New insights into paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is an uncommon acquired hemolytic anemia that manifests with abdominal pain, esophageal spasm, fatigue, and thrombosis. The hallmark of PNH at the cellular level is a deficiency in cell surface glycosylphosphatidylinositol anchored proteins; this deficiency on erythrocytes leads to intravascular hemolysis. Free hemoglobin from hemolysis leads to circulating nitric oxide depletion and is responsible for many of the clinical manifestations of PNH, including fatigue, erectile dysfunction, esophageal spasm, and thrombosis. The recently FDA approved complement inhibitor eculizumab has been shown to decrease hemolysis, decrease erythrocyte transfusion requirements, and improve quality of life for PNH patients.

Reduced intensity HLA-haploidentical BMT with post transplantation cyclophosphamide in nonmalignant hematologic diseases

Allogeneic blood or marrow transplantation (BMT) is potentially curative for a variety of life-threatening nonmalignant hematologic diseases such as paroxysmal nocturnal hemoglobinuria (PNH) and hemoglobinopathies. The application of BMT to treat these disorders is limited by the lack of suitable donors and often end-organ damage from the underlying disease. We treated three patients with thrombotic PNH, one of whom also had sickle cell disease, with a nonmyeloablative, HLA-haploidentical BMT with post-transplant CY. Rapid engraftment without GVHD occurred in two of the patients, including the patient with sickle cell disease. Both patients are disease free with full donor chimerism and require no immunosuppressive therapy, with follow-up of 1 and 4 years, respectively. Nonmyeloablative, HLA-haploidentical BMT with post-transplant CY is a promising approach for patients with life-threatening nonmalignant hematologic disease who lack an HLA-matched sibling donor.

Reduction of disease activity and disability with high-dose cyclophosphamide in patients with aggressive multiple sclerosis

OBJECTIVE

To explore the safety and effectiveness of high-dose cyclophosphamide (HiCy) without bone marrow transplantation in patients with aggressive multiple sclerosis (MS).

DESIGN

A 2-year open-label trial of patients with aggressive relapsing-remitting multiple sclerosis (RRMS) given an immunoablative regimen of HiCy (50 mg/kg/d for 4 consecutive days) with no subsequent immunomodulatory therapy unless disease activity reappeared that required rescue therapy.

SETTING

The Johns Hopkins University Multiple Sclerosis Center, Baltimore, Maryland. Patients A total of 21 patients with RRMS were screened for eligibility and 9 patients were enrolled in the trial. Patients were required to have 2 or more gadolinium-enhancing lesions on each of 2 pretreatment magnetic resonance imaging scans, at least 1 clinical exacerbation in the 12 months prior to HiCy treatment, or a sustained increase of 1.0 point or higher on the Expanded Disability Status Scale (EDSS) in the preceding year. Intervention Patients received 50 mg/kg/d of cyclophosphamide intravenously for 4 consecutive days, followed by 5 mug/kg/d of granulocyte colony-stimulating factor 6 days after completion of HiCy treatment, until the absolute neutrophil count exceeded 1.0 x 10(9) cells/L for 2 consecutive days.

MAIN OUTCOME MEASURES

The primary outcome of the study was the safety and tolerability of HiCy in patients with RRMS. Secondary outcome measures included a change in gadolinium-enhancing lesions on magnetic resonance images and a change in disability measures (EDSS and Multiple Sclerosis Functional Composite).

RESULTS

Nine patients were treated and followed up for a mean period of 23 months. Eight patients had failed conventional therapy and 1 was treatment naive. The median age at time of entry was 29 years (range, 20-47 years). All patients developed transient total or near-total pancytopenia as expected, followed by hematopoietic recovery in 10 to 17 days, stimulated by granulocyte colony-stimulating factor. There were no deaths or unexpected serious adverse events. There was a statistically significant reduction in disability (EDSS) at follow-up (mean [SD] decrease, 2.11 [1.97]; 39.4%; P = .02). The mean (SD) number of gadolinium-enhancing lesions on the 2 pretreatment scans were 6.5 (2.1) and 1.2 (2.3) at follow-up (81.4% reduction; P = .01). Two patients required rescue treatment with other immunomodulatory therapies during the study owing to MS exacerbations.

CONCLUSION

Treatment with HiCy was safe and well tolerated in our patients with MS. Patients experienced a pronounced reduction in disease activity and disability after HiCy treatment. This immunoablative regimen of cyclophosphamide for patients with aggressive MS is worthy of further study and may be an alternative to bone marrow transplantation. Published online June 9, 2008 (doi:10.1001/archneurol.65.8.noc80042).

High-dose cyclophosphamide without stem cell rescue in scleroderma

OBJECTIVE

To investigate the safety and tolerability of high-dose cyclophosphamide without stem cell rescue in scleroderma.

METHODS

An open-label, single-site, uncontrolled study design entered patients with active diffuse cutaneous scleroderma. Patients were treated with cyclophosphamide (50 mg/kg) intravenously daily for 4 consecutive days (total 200 mg/kg) followed by granulocyte colony-stimulating factor (5 microg/kg/day). The primary clinical efficacy end point was the modified Rodnan skin score (mRSS). Secondary end points included the Health Assessment Questionnaire-Disability Index (HAQ-DI), physician global assessment (PGA) and pulmonary function tests.

RESULTS

Six patients (4 men, 2 women) aged 19-60 years were entered into the study. One patients died early in the protocol, thus five patients had follow-up data. The percentage reduction of the mRSS in these five evaluable patients within 1 month of treatment was 60%, 55%, 41%, 31% and 0%. The patient with no decline in skin score at 1 month showed a decrease in skin score from 41 to 26 by the 3-month visit, a 37% improvement. Three patients sustained the improvement after treatment for 24, 12 and 12 months. Two patients relapsed at 12 and 6 months after treatment. The PGA and HAQ-DI scores improved in five of the six patients by 72% and 79% respectively at 3 months. The only serious adverse event was a death that occurred owing to infection after neutrophil count recovery.

CONCLUSIONS

High-dose cyclophosphamide without stem cell rescue can lead to a clinically significant improvement in skin score and measures of disease severity in patients with diffuse cutaneous scleroderma.

Trophoblast differentiation defect in human embryonic stem cells lacking PIG-A and GPI-anchored cell-surface proteins

Pluripotent human embryonic stem (hES) cells can differentiate into various cell types derived from the three embryonic germ layers and extraembryonic tissues such as trophoblasts. The mechanisms governing lineage choices of hES cells are largely unknown. Here, we report that we established two independent hES cell clones lacking a group of cell surface molecules, glycosyl-phosphatidyl-inositol-anchored proteins (GPI-APs). The GPI-AP deficiency in these two hES clones is due to the deficiency in the gene expression of PIG-A (phosphatidyl-inositol-glycan class A), which is required for the first step of GPI synthesis. GPI-AP-deficient hES cells were capable of forming embryoid bodies and initiating cell differentiation into the three embryonic germ layers. However, GPI-AP-deficient hES cells failed to form trophoblasts after differentiation induction by embryoid body formation or by adding exogenous BMP4. The defect in trophoblast formation was due to the lack of GPI-anchored BMP coreceptors, resulting in the impairment of full BMP4 signaling activation in the GPI-AP-deficient hES cells. These data reveal that GPI-AP-enhanced full activation of BMP signaling is required for human trophoblast formation.

Discovery and development of the complement inhibitor eculizumab for the treatment of paroxysmal nocturnal hemoglobinuria

The complement system provides critical immunoprotective and immunoregulatory functions but uncontrolled complement activation can lead to severe pathology. In the rare hemolytic disease paroxysmal nocturnal hemoglobinuria (PNH), somatic mutations result in a deficiency of glycosylphosphatidylinositol-linked surface proteins, including the terminal complement inhibitor CD59, on hematopoietic stem cells. In a dysfunctional bone marrow background, these mutated progenitor blood cells expand and populate the periphery. Deficiency of CD59 on PNH red blood cells results in chronic complement-mediated intravascular hemolysis, a process central to the morbidity and mortality of PNH. A recently developed, humanized monoclonal antibody directed against complement component C5, eculizumab (Soliris; Alexion Pharmaceuticals Inc., Cheshire, CT, USA), blocks the proinflammatory and cytolytic effects of terminal complement activation. The recent approval of eculizumab as a first-in-class complement inhibitor for the treatment of PNH validates the concept of complement inhibition as an effective therapy and provides rationale for investigation of other indications in which complement plays a role.

Paroxysmal nocturnal hemoglobinuria: stem cells and clonality

Paroxysmal nocturnal hemoglobinuria is a clonal hematopoietic stem cell disease that manifests with intravascular hemolysis, bone marrow failure, thrombosis, and smooth muscle dystonias. The disease can arise de novo or in the setting of acquired aplastic anemia. All PNH patients to date have been shown to harbor PIG-A mutations; the product of this gene is required for the synthesis of glycosylphosphatidylinositol (GPI) anchored proteins. In PNH patients, PIG-A mutations arise from a multipotent hematopoietic stem cell. Interestingly, PIG-A mutations can also be found in the peripheral blood of most healthy controls; however, these mutations arise from progenitor cells rather than multipotent hematopoietic stem cells and do not propagate the disease. The mechanism of whereby PNH stem cells achieve clonal dominance remains unclear. The leading hypotheses to explain clonal outgrowth in PNH are: 1) PNH cells evade immune attack possibly, because of an absent cell surface GPI-AP that is the target of the immune attack; 2) The PIG-A mutation confers an intrinsic resistance to apoptosis that becomes more conspicuous when the marrow is under immune attack; and 3) A second mutation occurs in the PNH clone to give it an intrinsic survival advantage. These hypotheses may not be mutually exclusive, since data in support of all three models have been generated.

Advances in the diagnosis and therapy of paroxysmal nocturnal hemoglobinuria

PNH is an uncommon acquired hemolytic anemia that often manifests with hemoglobinuria, abdominal pain, smooth muscle dystonias, fatigue, and thrombosis. The disease results from the expansion of hematopoietic stem cells harboring a mutation in a gene, PIG-A, that is required for the biosynthesis of a lipid moiety, glycosylphosphatidylinositol (GPI), that attaches dozens of different proteins to the cell surface. Thus, PNH cells are deficient in cell surface GPI anchored proteins; this deficiency on erythrocytes leads to intravascular hemolysis since certain GPI anchored proteins normally function as complement regulators. Free hemoglobin released from intravascular hemolysis leads to circulating nitric oxide depletion and is responsible for many of the clinical manifestations of PNH, including fatigue, erectile dysfunction, esophageal spasm, and thrombosis. Interestingly, rare PIG-A mutations can be found in virtually all healthy control subjects leading to speculation that PIG-A mutations in hematopoietic stem cells are common benign events. However, recent data reveals that most of these mutations in healthy controls are not derived from stem cells. The recently FDA approved complement inhibitor eculizumab has been shown to decrease hemolysis, decrease erythrocyte transfusion requirements, decrease the risk for thrombosis and improve quality of life for PNH patients.

Treatment of hepatitis-associated aplastic anemia with high-dose cyclophosphamide

OBJECTIVE

Demonstrate that high-dose cyclophosphamide (CY) is effective therapy for hepatitis-associated aplastic anemia (HAA).

BACKGROUND

HAA is a sequence of seronegative hepatitis followed by aplastic anemia. Optimal treatment is matched-sibling allogeneic bone marrow transplantation (BMT). The combination of antithymocyte globulin (ATG) and cyclosporine (CSA) has also been studied, but there are scarce data regarding treatment of HAA.

PROCEDURE

Five patients (median age 14 years; range 6-17 years) with HAA and without an HLA-matched sibling were treated with high-dose CY (50 mg/kg/day IV x 4 days) followed by granulocyte-colony stimulation factor (G-CSF).

RESULTS

After at least 1 year of follow-up, four of five patients are in remission without further immune suppression beyond high-dose CY. Of the 4 responders, median time to absolute neutrophil count (ANC) >500 microl(-1) was 51 days (range 44-369). Median time to transfusion independence for erythrocytes and platelets was 109 (range 57-679) and 160 (range 48-679) days, respectively. The fifth patient did not respond and proceeded to an unrelated donor transplant. One patient met criteria for autoimmune hepatitis (AIH) in addition to HAA. In this case, high-dose CY successfully induced remission of both diseases.

CONCLUSIONS

High-dose CY induces durable remissions in HAA and may be an effective treatment for AIH.

Effect of the complement inhibitor eculizumab on thromboembolism in patients with paroxysmal nocturnal hemoglobinuria

Hemolysis and hemoglobinemia contribute to serious clinical sequelae in hemolytic disorders. In paroxysmal nocturnal hemoglobinuria (PNH) patients, hemolysis can contribute to thromboembolism (TE), the most feared complication in PNH, and the leading cause of disease-related deaths. We evaluated whether long-term treatment with the complement inhibitor eculizumab reduces the rate of TE in patients with PNH. Clinical trial participants included all patients in the 3 eculizumab PNH clinical studies, which recruited patients between 2002 and 2005 (n = 195); patients from these studies continued treatment in the current multinational open-label extension study. Thromboembolism rate with eculizumab treatment was compared with the pretreatment rate in the same patients. The TE event rate with eculizumab treatment was 1.07 events/100 patient-years compared with 7.37 events/100 patient-years (P < .001) prior to eculizumab treatment (relative reduction, 85%; absolute reduction, 6.3 TE events/100 patient-years). With equalization of the duration of exposure before and during treatment for each patient, TE events were reduced from 39 events before eculizumab to 3 events during eculizumab (P < .001). The TE event rate in antithrombotic-treated patients (n = 103) was reduced from 10.61 to 0.62 events/100 patient-years with eculizumab treatment (P < .001). These results show that eculizumab treatment reduces the risk of clinical thromboembolism in patients with PNH. This study is registered at http://clinicaltrials.gov (study ID no. NCT00122317).

PIG-A mutations in paroxysmal nocturnal hemoglobinuria and in normal hematopoiesis

PIG-A is an X-linked gene that is essential for the first step in the biosynthesis of glycosylphosphatidyl-inositol (GPI) anchors. A rare clonal hematopoietic stem cell disease, paroxysmal nocturnal hemoglobinuria (PNH), is caused by mutations in the PIG-A gene. PNH is an acquired disease that may arise de novo or emanate from aplastic anemia. PNH blood cells have an absence or marked deficiency of all GPI anchored proteins. Interestingly, rare GPI anchor deficient blood and marrow cells that harbor PIG-A mutations can also be found in most healthy controls. This review examines the clinical and biological relevance of PIG-A mutations in PNH, aplastic anemia and healthy controls.

Graft-versus-host reactions and the effectiveness of donor lymphocyte infusions

We retrospectively analyzed 83 consecutive recipients of donor lymphocyte infusions (DLI) after allogeneic transplantation for factors associated with disease response and graft-versus-host disease (GVHD). DLI was highly effective in relapsed chronic phase chronic myeloid leukemia (CML), with 71% of patients achieving durable complete remissions (CR). In relapsed acute myeloid leukemia, DLI led to durable CRs in 31% of patients; the rate was <20% in all other diseases. Achieving full donor chimerism and GVHD were predictive of CR. Grade II or higher acute or chronic GVHD occurred in 36 (43%) patients and contributed to death in 13 (16%). Even more patients, 33 (40%), died of their underlying malignancy, including 10 who developed active GVHD. In relapsed CML, most durable CRs occurred without clinically apparent GVHD, yet all responders achieved full donor chimerism, including 6 with coincident normal host hematopoiesis at the time of DLI. Thus, in CML, potent lymphohematopoietic graft-versus-host reactions occurred even in the absence of clinically apparent GVHD; this confirms the ability to dissociate these processes and argues against a leukemia-specific immunologic effect. DLI clearly has efficacy in the treatment of relapsed disease after allogeneic transplantation. However, with the exception of CML, most patients die of their underlying disease because of insufficient antitumor activity even with active GVHD.