Bosentan as Adjunctive Therapy for Persistent Pulmonary Hypertension of the Newborn: Results of the Randomized Multicenter Placebo-Controlled Exploratory Trial.

OBJECTIVE: To evaluate the efficacy, safety, and pharmacokinetics of the endothelin receptor antagonist bosentan as adjunctive therapy for neonates with persistent pulmonary hypertension of the newborn (PPHN). STUDY DESIGN: This was a phase 3, multicenter, randomized, placebo-controlled exploratory trial (FUTURE-4). Eligible patients were >34 weeks gestation, <7 days old, receiving inhaled nitric oxide (iNO) treatment (≥4 hours), and had persistent respiratory failure (oxygenation index [OI] ≥12). After 2:1 randomization, bosentan 2 mg/kg or placebo was given by nasogastric tube twice daily for ≥48 hours and up to 1 day after iNO weaning. RESULTS: Twenty-one neonates received a study drug (13 bosentan, 8 placebo). Compared with the placebo group, the group treated with bosentan had a higher median baseline OI and greater need for vasoactive agents. One treatment failure (need for extracorporeal membrane oxygenation) occurred in the group treated with bosentan. The time to weaning from iNO or mechanical ventilation was not different between the groups. Bosentan was well tolerated and did not adversely affect systemic blood pressure or hepatic transaminase levels. Anemia and edema were more frequent in patients receiving bosentan. Blood concentrations of bosentan were low and variable on day 1, and achieved steady state on day 5. CONCLUSION: Adjunctive bosentan was well tolerated, but did not improve oxygenation or other outcomes in our patients with PPHN. This effect may be related to delayed absorption of bosentan on treatment initiation in critically ill neonates or to more severe illness of the neonates who received bosentan. TRIAL REGISTRATION: ClinicalTrials.gov:NCT01389856.

Randomized trial of clazosentan in patients with aneurysmal subarachnoid hemorrhage undergoing endovascular coiling.

BACKGROUND AND PURPOSE: Clazosentan, an endothelin receptor antagonist, has been shown to reduce vasospasm after aneurysmal subarachnoid hemorrhage (aSAH). CONSCIOUS-3 assessed whether clazosentan reduced vasospasm-related morbidity and all-cause mortality postaSAH secured by endovascular coiling. METHODS: This double-blind, placebo-controlled, phase III trial randomized patients with aSAH secured by endovascular coiling to ≤ 14 days intravenous clazosentan (5 or 15 mg/h) or placebo. The primary composite end point (all-cause mortality; vasospasm-related new cerebral infarcts or delayed ischemic neurological deficits; rescue therapy for vasospasm) was evaluated 6 weeks postaSAH. The main secondary end point was dichotomized extended Glasgow Outcome Scale (week 12). RESULTS: CONSCIOUS-3 was halted prematurely following completion of CONSCIOUS-2; 577/1500 of planned patients (38%) were enrolled and 571 were treated (placebo, n=189; clazosentan 5 mg/h, n=194; clazosentan 15 mg/h, n=188). The primary end point occurred in 50/189 of placebo-treated patients (27%), compared with 47/194 patients (24%) treated with clazosentan 5 mg/h (odds ratio [OR], 0.786; 95% CI, 0.479-1.289; P=0.340), and 28/188 patients (15%) treated with clazosentan 15 mg/h (OR, 0.474; 95% CI, 0.275-0.818; P=0.007). Poor outcome (extended Glasgow Outcome Scale score ≤ 4) occurred in 24% of patients with placebo, 25% of patients with clazosentan 5 mg/h (OR, 0.918; 95% CI, 0.546-1.544; P=0.748), and 28% of patients with clazosentan 15 mg/h (OR, 1.337; 95% CI, 0.802-2.227; P=0.266). Pulmonary complications, anemia, and hypotension were more common in patients who received clazosentan than in those who received placebo. At week 12, mortality was 6%, 4%, and 6% with placebo, clazosentan 5 mg/h, and clazosentan 15 mg/h, respectively. CONCLUSIONS: Clazosentan 15 mg/h significantly reduced postaSAH vasospasm-related morbidity/all-cause mortality; however, neither dose improved outcome (extended Glasgow Outcome Scale).

Ligands for natural killer cell-activating receptors are expressed upon the maturation of normal myelomonocytic cells but at low levels in acute myeloid leukemias.

Natural killer (NK) cell-mediated cytolytic activity against tumors requires the engagement of activating NK receptors by the tumor-associated ligands. Here, we have studied the role of NKG2D and natural cytotoxicity receptors (NCRs) in the recognition of human leukemia. To detect as-yet-unknown cell-surface molecules recognized by NCRs, we developed soluble forms of NKp30, NKp44, and NKp46 as staining reagents binding the putative cognate ligands. Analysis of UL16-binding protein-1 (ULBP1), ULBP2, and ULBP3 ligands for NKG2D and of potential ligands for NKp30, NKp44, and NKp46 in healthy hematopoietic cells demonstrated the ligand-negative phenotype of bone marrow-derived CD34(+) progenitor cells and the acquisition of cell-surface ligands during the course of myeloid differentiation. In acute myeloid leukemia (AML), leukemic blasts from approximately 80% of patients expressed very low levels of ULBPs and NCR-specific ligands. Treatment with differentiation-promoting myeloid growth factors, together with interferon-gamma, upregulated cell-surface levels of ULBP1 and putative NCR ligands on AML blasts, conferring an increased sensitivity to NK cell-mediated lysis. We conclude that the ligand-negative/low phenotype in AML is a consequence of cell maturation arrest on malignant transformation and that defective expression of ligands for the activating NKG2D and NCR receptors may compromise leukemia recognition by NK cells.

Reconstitution of dendritic and natural killer-cell subsets after allogeneic stem cell transplantation: effects of endogenous flt3 ligand.

Recovery of dendritic cells (DCs) and natural killer (NK) cells after allogeneic stem cell transplantation (SCT) is important for allograft responses and antitumor immunity and thus for treatment outcome. Regulation of this regenerative process is not well understood. We investigated the influence of endogenous cytokines on the recovery and diversification of DC and NK cell subsets up to 6 months after SCT. Reconstitution of circulating DCs and NK cells was rapid but accompanied by prolonged skewing of cell subsets. The speed of recovery of CD11c(+)CD123(low) DC1 exceeded that of CD11c(-) CD123(+) DC2, and correlated with plasma levels of flt3 ligand (FL), but not with granulocyte or granulocyte-macrophage colony-stimulating factors and stem cell factor. There was a 5-fold increase in interferon-gamma-producing CD56(high)CD16(-)/low NK cells and a corresponding reduction in the CD56(low)CD16(high) subset, accompanied by strongly reduced NK cell cytotoxicity. In vitro data implicate an inhibitory effect of cyclosporin A on NK cell differentiation and cytotoxicity. NK cell numbers did not correlate with plasma levels of FL or interleukin 15. Our results demonstrate that endogenous FL has distinct effects on the kinetics of reconstitution of DCs and NK cells and have potential implications for the modulation of immune responses after allogeneic SCT.