Subcutaneous therapy for portal hypertension: PHIN-214, a partial vasopressin receptor 1A agonist.

Cirrhosis is a liver disease that leads to increased intrahepatic resistance, portal hypertension (PH), and splanchnic hyperemia resulting in ascites, variceal bleeding, and hepatorenal syndrome. Terlipressin, a prodrug that converts to a short half-life vasopressin receptor 1 A (V1a) full agonist [8-Lys]-Vasopressin (LVP), is an intravenous treatment for PH complications, but hyponatremia and ischemic side effects require close monitoring. We developed PHIN-214 which converts into PHIN-156, a more biologically stable V1a partial agonist. PHIN-214 enables once-daily subcutaneous administration without causing ischemia or tissue necrosis and has a 10-fold higher therapeutic index than terlipressin in healthy rats. As V1a partial agonists, PHIN-214 and PHIN-156 exhibited maximum activities of 28 % and 42 % of Arginine vasopressin (AVP), respectively. The potency of PHIN-156 and LVP relative to AVP is comparable for V1a (5.20 and 1.65 nM, respectively) and V1b (102 and 115 nM, respectively) receptors. However, the EC50 of PHIN-156 to the V2 receptor was 26-fold higher than that of LVP, indicating reduced potential for dilutional hyponatremia via V2 agonism compared to terlipressin/LVP. No significant off-target binding to 87 toxicologically relevant receptors were observed when evaluated in vitro at 10 µM concentration. In bile duct ligated rats with PH, subcutaneous PHIN-214 reduced portal pressure by 13.4 % ± 3.4 in 4 h. These collective findings suggest that PHIN-214 could be a novel pharmacological treatment for patients with PH, potentially administered outside of hospital settings, providing a safe and convenient alternative for managing PH and its complications.

Modified C-type natriuretic peptide normalizes tumor vasculature, reinvigorates antitumor immunity, and improves solid tumor therapies.

Deficit of oxygen and nutrients in the tumor microenvironment (TME) triggers abnormal angiogenesis that produces dysfunctional and leaky blood vessels, which fail to adequately perfuse tumor tissues. Resulting hypoxia, exacerbation of metabolic disturbances, and generation of an immunosuppressive TME undermine the efficacy of anticancer therapies. Use of carefully scheduled angiogenesis inhibitors has been suggested to overcome these problems and normalize the TME. Here, we propose an alternative agonist-based normalization approach using a derivative of the C-type natriuretic peptide (dCNP). Multiple gene expression signatures in tumor tissues were affected in mice treated with dCNP. In several mouse orthotopic and subcutaneous solid tumor models including colon and pancreatic adenocarcinomas, this well-tolerated agent stimulated formation of highly functional tumor blood vessels to reduce hypoxia. Administration of dCNP also inhibited stromagenesis and remodeling of the extracellular matrix and decreased tumor interstitial fluid pressure. In addition, treatment with dCNP reinvigorated the antitumor immune responses. Administration of dCNP decelerated growth of primary mouse tumors and suppressed their metastases. Moreover, inclusion of dCNP into the chemo-, radio-, or immune-therapeutic regimens increased their efficacy against solid tumors in immunocompetent mice. These results demonstrate the proof of principle for using vasculature normalizing agonists to improve therapies against solid tumors and characterize dCNP as the first in class among such agents.

Retina-Targeted Delivery of 17ß-Estradiol by the Topically Applied DHED Prodrug.

The purpose of this study was to explore retina-targeted delivery of 17ß-estradiol (E2), a powerful neuroprotectant, by its bioprecursor prodrug 10ß,17ß-dihydroxyestra-1,4-dien-3-one (DHED) administered as eye drops in animal models. Compared to the parent hormone, DHED displayed increased transcorneal flux ex vivo both with and without the presence of 2-hydroxypropyl-ß-cyclodextrin used as a penetration-enhancing excipient in rat, rabbit, and pig. In vitro, the prodrug also showed facile bioactivation to E2 in the retina but not in the cornea. After topical administration to rats and rabbits, peak DHED-derived E2 concentrations reached 13 ± 5 ng/g and 18 ± 7 ng/g in the retina of female rats and rabbits, respectively. However, the prodrug remained inert in the rest of the body and, therefore, did not cause increase in circulating hormone concentration, as well as wet uterine and anterior pituitary weights as typical markers of E2's endocrine impact. Altogether, our studies presented here have demonstrated the premise of topical retina-selective estrogen therapy by the DHED prodrug approach for the first time and provide compelling support for further investigation into the full potential of DHED for an efficacious and safe ocular neurotherapy.