Anti-sFlt-1 Therapy Preserves Lung Alveolar and Vascular Growth in Antenatal Models of Bronchopulmonary Dysplasia

RATIONALE

Pregnancies complicated by antenatal stress, including preeclampsia (PE) and chorioamnionitis (CA), increase the risk for bronchopulmonary dysplasia (BPD) in preterm infants, but biologic mechanisms linking prenatal factors with BPD are uncertain. Levels of sFlt-1 (soluble fms-like tyrosine kinase 1), an endogenous antagonist to VEGF (vascular endothelial growth factor), are increased in amniotic fluid and maternal blood in PE and associated with CA.

OBJECTIVES

Because impaired VEGF signaling has been implicated in the pathogenesis of BPD, we hypothesized that fetal exposure to sFlt-1 decreases lung growth and causes abnormal lung structure and pulmonary hypertension during infancy.

METHODS

To test this hypothesis, we studied the effects of anti-sFlt-1 monoclonal antibody (mAb) treatment on lung growth in two established antenatal models of BPD that mimic PE and CA induced by intraamniotic (i.a.) injections of sFlt-1 or endotoxin, respectively. In experimental PE, mAb was administered by three different approaches, including antenatal treatment by either i.a. instillation or maternal uterine artery infusion, or by postnatal intraperitoneal injections.

RESULTS

With each strategy, mAb therapy improved infant lung structure as assessed by radial alveolar count, vessel density, right ventricular hypertrophy, and lung function. As found in the PE model, the adverse lung effects of i.a. endotoxin were also reduced by antenatal or postnatal mAb therapy.

CONCLUSIONS

We conclude that treatment with anti-sFlt-1 mAb preserves lung structure and function and prevents right ventricular hypertrophy in two rat models of BPD of antenatal stress and speculate that early mAb therapy may provide a novel strategy for the prevention of BPD.

A phase 1 study investigating DX-2930 in healthy subjects

BACKGROUND

DX-2930 is a human monoclonal antibody inhibitor of plasma kallikrein under investigation for long-term prophylaxis of hereditary angioedema.

OBJECTIVE

To assess the safety, tolerability, pharmacokinetics, and pharmacodynamics of DX-2930 in healthy subjects.

METHODS

A single-center, double-blinded study was performed in 32 healthy subjects randomized 3:1 to receive a single subcutaneous administration of DX-2930 or placebo within 1 of 4 sequential, ascending dose cohorts (n = 8 each): 0.1, 0.3, 1.0, or 3.0 mg/kg.

RESULTS

No dose-limiting toxicity was observed. Headache was the most commonly reported treatment emergent adverse event (AE), occurring at a rate of 25% in the DX-2930- and placebo-treated groups; none were severe and all resolved. There were no serious AEs, discontinuations owing to an AE, or deaths. Two subjects had a severe AE reported as related to treatment by the blinded investigator; the 2 AEs were asymptomatic creatinine phosphokinase elevations of 902 U/L in 1 subject receiving 0.1 mg/kg DX-2930 and 1,967 U/L in 1 subject receiving placebo. For the 0.1-, 0.3-, 1.0-, and 3.0-mg/kg dose groups, respectively, mean maximum plasma concentrations were 0.6, 1.4, 5.6, and 14.5 μg/mL and mean elimination half-lives were 20.6, 16.8, 17.6, and 21.2 days. Exploratory biomarker assays, involving ex vivo activation of the kallikrein pathway, showed dose- and time-dependent inhibition of plasma kallikrein, with evidence of sustained bioactivity consistent with the pharmacokinetics profile.

CONCLUSION

A single administration of DX-2930 in healthy subjects up to doses of 3.0 mg/kg was well tolerated without dose-limiting toxicity. Pharmacokinetic and pharmacodynamic data provide evidence for a long-acting biological effect relevant to long-term prophylaxis for hereditary angioedema with C1-inhibitor deficiency.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01923207.