In addition to precluding heart and blood vessel damage in the animals, RP5063 decreased levels of cytokines, or proteins associated with inflammation.
The study, published in the European Journal of Pharmacology, was titled “RP5063, a novel, multimodal, serotonin receptor modulator, prevents monocrotaline-induced pulmonary arterial hypertension in rats.”
Reviva completed a $4.8 million financing round in May that allowed it to continue developing RP5063 for PAH and other conditions. A Phase 2 clinical trial in PAH patients is expected to begin this year. The company also plans a Phase 3 trial for RP5063 in schizophrenia patients.
RP5063 regulates serotonin receptors in the pulmonary arteries that transport blood to the lungs. The receptors promote the narrowing of arteries and an increase in the growth of their smooth muscle cells, thickening artery walls. The two conditions combine to limit the flow of blood to the lungs.
Rats were first dosed with the chemical monocrotaline, MCT, which can cause PAH. Then they received RP5063.
The treated rats had decreases in blood pressure and pulmonary vascular resistance, and an increase in oxygen levels in their blood, compared with the untreated rats. In addition, their overall health improved. Pulmonary vascular resistance refers to the lungs’ pulmonary artery creating resistance against the blood flowing into it from the heart’s right ventricle.
RP5063 also prevented an increase in inflammatory cytokine levels when the rats were prone to developing PAH. This helped stop harmful remodeling of blood vessels in the lungs.
“In summary, RP5063 improved pulmonary vascular pathology and hemodynamics [blood flow], right ventricular pressure and hypertrophy [increase in muscle mass], systemic oxygen saturation, and overall health of rats treated with MCT,” the team wrote.
“RP5063 represents an attractive compound — with the potential of being a disease-modifying treatment — and needs to be explored further, either as a single agent or used in combination with existing drugs, for the treatment of PAH and associated comorbidities [related diseases],” the researchers concluded.
Several authors of the study are affiliated with Reviva, RP5063’s developer.