We propose a novel formulation of the projection method for Smoothed Particle Hydrodynamics (SPH). We combine a symmetric SPH pressure force and an SPH discretization of the continuity equation to obtain a discretized form of the pressure Poisson equation (PPE). In contrast to previous projection schemes, our system does consider the actual computation of the pressure force. This incorporation improves the convergence rate of the solver. Furthermore, we propose to compute the density deviation based on velocities instead of positions as this formulation improves the robustness of the time-integration scheme. We show that our novel formulation outperforms previous projection schemes and state-of-the-art SPH methods. Large time steps and small density deviations of down to 0.01 percent can be handled in typical scenarios. The practical relevance of the approach is illustrated by scenarios with up to 40 million SPH particles.

Background-ARC1779 is a therapeutic aptamer antagonist of the A1 domain of von Willebrand Factor (vWF), the ligand for receptor glycoprotein 1b on platelets. ARC1779 is being developed as a novel antithrombotic agent for use in patients with acute coronary syndromes. Methods and Results-This was a randomized, double-blind, placebo-controlled study in 47 healthy volunteers of doses of ARC1779 from 0.05 to 1.0 mg/kg. Pharmacodynamic effects were measured by an ELISA for free vWF A1 binding sites and by a platelet function analyzer. In terms of pharmacokinetics, the concentration-time profile of ARC1779 appeared monophasic. The observed concentration and area under the curve were dose proportional. The mean apparent elimination half-life was Ϸ2 hours, and mean residence time was Ϸ3 hours. The mean apparent volumes of distribution (at steady state and during terminal phase) were approximately one half the blood volume, suggesting that ARC1779 distribution is in the central compartment. The mean clearance ranged from Ϸ10% to Ϸ21% of the glomerular filtration rate, suggesting that renal filtration may not be a major mechanism of clearance of ARC1779. Inhibition of vWF A1 binding activity was achieved with an EC 90 value of 2.0 g/mL (151 nmol/L) and of platelet function with an EC 90 value of 2.6 g/mL (196 nmol/L). ARC1779 was generally well tolerated, and no bleeding was observed. Adverse events tended to be minor and not dose related. Conclusions-This is the first-in-human evaluation of a novel aptamer antagonist of vWF. ARC1779 produced dose-and concentration-dependent inhibition of vWF activity and platelet function with duration of effect suitable for the intended clinical use in acute coronary syndromes.

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Vascular inflammation, infusion reactions, glomerulopathies, and other potentially adverse effects may be observed in laboratory animals, including monkeys, on toxicity studies of therapeutic monoclonal antibodies and recombinant human protein drugs. Histopathologic and immunohistochemical (IHC) evaluation suggests these effects may be mediated by deposition of immune complexes (ICs) containing the drug, endogenous immunoglobulin, and/or complement components in the affected tissues. ICs may be observed in glomerulus, blood vessels, synovium, lung, liver, skin, eye, choroid plexus, or other tissues or bound to neutrophils, monocytes/macrophages, or platelets. IC deposition may activate complement, kinin, and/or coagulation/fibrinolytic pathways and result in a systemic proinflammatory response. IC clearance is biphasic in humans and monkeys (first from plasma to liver and/or spleen, second from liver or spleen). IC deposition/clearance is affected by IC composition, immunomodulation, and/or complement activation. Case studies are presented from toxicity study monkeys or rats and indicate IHC-IC deposition patterns similar to those predicted by experimental studies of IC-mediated reactions to heterologous protein administration to monkeys and other species. The IHC-staining patterns are consistent with findings associated with generalized and localized IC-associated pathology in humans. However, manifestations of immunogenicity in preclinical species are generally not considered predictive to humans.

B-cell maturation antigen (BCMA) expression has been proposed as a marker for the identification of malignant plasma cells in patients with multiple myeloma (MM). Nearly all MM tumor cells express BCMA, while normal tissue expression is restricted to plasma cells and a subset of mature B cells. Consistent BCMA expression was confirmed on MM biopsies (29/29 BCMA+), and it was further demonstrated that BCMA is expressed in a substantial number of lymphoma samples, as well as primary chronic lymphocytic leukemia B cells. To target BCMA using redirected autologous T cells, lentiviral vectors (LVV) encoding chimeric antigen receptors (CARs) were constructed with four unique anti-BCMA single-chain variable fragments, fused to the CD137 (4-1BB) co-stimulatory and CD3ζ signaling domains. One LVV, BB2121, was studied in detail, and BB2121 CAR-transduced T cells (bb2121) exhibited a high frequency of CAR + T cells and robust in vitro activity against MM cell lines, lymphoma cell lines, and primary chronic lymphocytic leukemia peripheral blood. Based on receptor quantification, bb2121 recognized tumor cells expressing as little as 222 BCMA molecules per cell. The in vivo pharmacology of anti-BCMA CAR T cells was studied in NSG mouse models of human MM, Burkitt lymphoma, and mantle cell lymphoma, where mice received a single intravenous administration of vehicle, control vector-transduced T cells, or anti-BCMA CAR-transduced T cells. In all models, the vehicle and control CAR T cells failed to inhibit tumor growth. In contrast, treatment with bb2121 resulted in rapid and sustained elimination of the tumors and 100% survival in all treatment models. Together, these data support the further development of anti-BCMA CAR T cells as a potential treatment for not only MM but also some lymphomas.

Paroxysmal nocturnal hemoglobinuria (PNH) is characterized by complementmediated intravascular hemolysis because of the lack from erythrocyte surface of the complement regulators CD55 and CD59, with subsequent uncontrolled continuous spontaneous activation of the complement alternative pathway (CAP), and at times of the complement classic pathway. Here we investigate in an in vitro model the effect on PNH erythrocytes of a novel therapeutic strategy for membranetargeted delivery of a CAP inhibitor. TT30 is a 65 kDa recombinant human fusion protein consisting of the iC3b/C3d-binding region of complement receptor 2 (CR2) and the inhibitory domain of the CAP regulator factor H (fH). TT30 completely inhibits in a dose-dependent manner hemolysis of PNH erythrocytes in a modified extended acidified serum assay, and also prevents C3 fragment deposition on surviving PNH erythrocytes. The efficacy of TT30 derives from its direct binding to PNH erythrocytes; if binding to the erythrocytes is disrupted, only partial inhibition of hemolysis is mediated by TT30 in solution, which is similar to that produced by the fH moiety of TT30 alone, or by intact human fH. TT30 is a membranetargeted selective CAP inhibitor that may prevent both intravascular and C3-mediated extravascular hemolysis of PNH erythrocytes and warrants consideration for the treatment of PNH patients. (Blood. 2012;119(26):6307-6316) IntroductionParoxysmal nocturnal hemoglobinuria (PNH) is a blood disorder clinically characterized by intravascular hemolysis, thrombophilia, and bone marrow failure. 1-3 A unique feature of PNH is the presence of clonal populations of blood cells that are defective in glycosylphosphatidylinositol (GPI)-anchor biosynthesis, 4 because they derive from stem cells harboring an acquired somatic mutation in the phosphatidylinositol glycan class A (PIG-A) gene. 5,6 GPIlinked surface proteins include CD55 (also known as decayaccelerating factor [DAF]) 7,8 and CD59 (or membrane inhibitor of reactive lysis [MIRL]), 9,10 2 major complement regulators on the cell surface. Because of the lack of these 2 regulators, PNH erythrocytes (red blood cells [RBCs]) are exquisitely vulnerable to complement activation. Indeed, the main mechanism of hemolysis in PNH is the intravascular destruction of CD59 deficient RBCs by the membrane attack complex (MAC; supplemental Figure 1, available on the Blood Web site; see the Supplemental Materials link at the top of the online article). 11 MAC formation in patients can be abrupt and massive when complement is triggered by specific conditions, as with an infection, explaining the paroxysms of hemoglobinuria that have given PNH its name. However, at a lower rate, hemolysis in PNH is continuous, and it is accounted for by the so-called tickover of the complement alternative pathway (CAP). Tickover occurs through spontaneous hydrolysis of C3, binding of factor B to this form of C3, and subsequent formation of a C3 cleavage and activating multiprotein complex designated a C3 convertase (supplemental Figure 1). 12,1...

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