The NPR1 agonist antibody XXB750 in heart failure: a phase 2 randomized trial.
Summary
In a phase 2 randomized trial of 136 patients with LVEF <50%, the NPR1-agonist antibody XXB750 increased NT-proBNP, reduced cGMP, and was associated with more death or worsening HF events compared with sacubitril/valsartan or placebo, prompting early termination. Findings suggest paradoxical functional antagonism of endogenous natriuretic peptides in human HF.
Key Findings
- At 16 weeks, XXB750 increased NT-proBNP (ratio 1.34, 95% CI 1.07–1.66) and reduced cGMP (ratio 0.77, 95% CI 0.65–0.91).
- Death or worsening HF occurred in 25% with XXB750 vs 8% with sacubitril/valsartan and 0% with placebo.
- Trial was stopped early due to excess HF events in the XXB750 arms, indicating paradoxical antagonism of endogenous natriuretic peptide signaling.
Clinical Implications
Do not extrapolate benefit from NPR1 activation in HF; careful biomarker and clinical monitoring are essential in early-phase HF pharmacology. Sacubitril/valsartan remains biomarker-favorable relative to experimental NPR1 agonism.
Why It Matters
This rigorously conducted RCT overturns expectations for NPR1 agonism in HF and provides an important negative signal that will redirect drug development strategies in the natriuretic peptide pathway.
Limitations
- Early termination and modest sample size limit precision of effect estimates
- Open-label sacubitril/valsartan comparator may introduce performance bias
Future Directions
Elucidate receptor-level pharmacodynamics and tissue signaling to explain paradoxical effects; explore alternative natriuretic peptide pathway targets or delivery strategies. Design mechanistic trials with invasive hemodynamics and PET imaging.
Study Information
- Study Type
- RCT
- Research Domain
- Treatment
- Evidence Level
- I - High-quality randomized controlled trial evidence.
- Study Design
- OTHER