Presidio Pharmaceuticals Selects PPI-1301 as Second Hepatitis C Virus NS5A Inhibitor for Development

SUMMARY: Presidio Pharmaceuticals announced late last month that it has selected a second hepatitis C virus (HCV) NS5A inhibitor -- designated PPI-1301 -- for further testing in clinical trials. The function of the NS, or non-structural, 5A sequence in the HCV genome is not fully understood, but it appears to play a role in viral replication. Combining NS5A inhibitors with HCV protease (NS3/4A) and polymerase (NS5B) inhibitors may increase antiviral potency and slow emergence of drug resistance.

Below is an excerpt from a recent Presidio press release describing the selection of PPI-1301.

Presidio Pharmaceuticals, Inc. Selects SecondClinical Candidate From Hepatitis C Virus NS5A Inhibitor Program

San Francisco, CA -- May 26, 2010 -- Presidio Pharmaceuticals, Inc. announced today that they have selected a second clinical candidate, PPI-1301, from their hepatitis C virus (HCV) NS5A program for advancement into clinical development. Presidio's first NS5A inhibitor, PPI-461, is currently undergoing evaluation in a Phase 1a clinical study.

Inhibitors of the HCV NS5A protein represent an exciting, highly potent class that is distinct from other classes of HCV antivirals that target the viral protease or replicase. With poor response and tolerance issues associated with the current standard of care treatment -- pegylated-IFN [interferon] and ribavirin -- there is clear need for more potent and better tolerated inhibitors that can be administered orally in future combination therapies.

PPI-1301 was derived from a chemical series that is distinct from PPI-461, but similar to PPI-461, exhibits potent and selective activity against all HCV genotypes in HCV replicon assays. PPI-1301 also shows good oral bioavailability and tolerance in animal studies, with elevated liver concentrations relative to serum levels, as well as the potential for once daily dosing in humans. IND-enabling studies for PPI-1301 are currently underway.

"The selection of PPI-1301 underscores Presidio's continued commitment to generating best-in class compounds for treating HCV," commented Richard Colonno, PhD, Chief Scientific Officer, who added, "The advancement of PPI-1301 further demonstrates the breadth and depth of our NS5A program pipeline."

About Presidio Presidio Pharmaceuticals, Inc. is a San Francisco-based specialty pharmaceutical company dedicated to the discovery and development of small-molecule antiviral therapeutics for novel and validated targets. For more information, please visit our website at: http://www.presidiopharma.com/.

6/15/10

SourcePresidio Pharmaceuticals. Presidio Pharmaceuticals, Inc. Selects Second Clinical Candidate From Hepatitis C Virus NS5A Inhibitor Program. Press release. May 26, 2010.

http://www.hivandhepatitis.com/hep_c/news/2010/0615_2010_a.html