Discovery of TD-0212, an Orally Active Dual Pharmacology AT Antagonist and Neprilysin Inhibitor (ARNI).

Dual inhibition of angiotensin-converting enzyme (ACE) and neprilysin (NEP) by drugs such as omapatrilat produces superior antihypertensive efficacy relative to ACE inhibitors but is associated with a higher risk of life-threatening angioedema due to bradykinin elevations. We hypothesized that dual AT (angiotensin II type 1 receptor) blockade and NEP inhibition with a single molecule would produce similar antihypertensive efficacy to omapatrilat without the risk of angioedema since ACE (the rate limiting enzyme in bradykinin metabolism) would remain uninhibited. Merging the structures of losartan (an AT antagonist) and thiorphan (a NEP inhibitor) led to the discovery of a novel series of orally active, dual AT antagonist/NEP inhibitors (ARNIs) exemplified by compound (TD-0212).

Concomitant angiotensin AT1 receptor antagonism and neprilysin inhibition produces omapatrilat-like antihypertensive effects without promoting tracheal plasma extravasation in the rat.

Dual inhibition of angiotensin-converting enzyme (ACE) and neprilysin (NEP) by drugs such as omapatrilat produces superior antihypertensive efficacy but cause high incidence of angioedema. We examined whether dual inhibition of angiotensin AT1 receptor (ARB) and NEP (ARB-NEPI, valsartan-candoxatril) provides similar efficacy to omapatrilat without the risk of angioedema. Activity of test compounds at the targets was assayed using fluorescence-based enzyme assays (ACE, NEP, aminopeptidase P) or competition binding assays (AT1).

Processing of DNA for nonhomologous end-joining is controlled by kinase activity and XRCC4/ligase IV.

Nonhomologous end-joining (NHEJ) repairs DNA double-strand breaks created by ionizing radiation and V(D)J recombination. To repair the broken ends, NHEJ processes noncompatible ends into a ligatable form but suppresses processing of compatible ends. It is not known how NHEJ controls polymerase and nuclease activities to act exclusively on noncompatible ends.

Assays for nonhomologous end joining in extracts.

In mammalian cells, nonhomologous end-joining (NHEJ) repairs DNA double strand breaks created by ionizing radiation and V(D)J recombination. Using human whole cell extracts prepared by the method of Baumann and West (1998), we have described a cell-free system for NHEJ that joins both compatible and noncompatible DNA ends (Budman and Chu, 2005). To measure joining efficiency and assess the processing of DNA ends, we developed a quantitative polymerase chain reaction assay for the joining of two specific DNA ends.

Processing of DNA for nonhomologous end-joining by cell-free extract.

In mammalian cells, nonhomologous end-joining (NHEJ) repairs DNA double-strand breaks created by ionizing radiation and V(D)J recombination. We have developed a cell-free system capable of processing and joining noncompatible DNA ends. The system had key features of NHEJ in vivo, including dependence on Ku, DNA-PKcs, and XRCC4/Ligase4.