New HCV Therapy Shows Promise in Early Trials
A December 2009 study published in the journal Science has shown the potential of a new type of treatment for patients with the hepatitis C virus (HCV), an alternative therapy that affects the virus's capacity to replicate. SPC3649 was developed by Santaris Pharma A/S. The lead investigator of the study was Robert E. Lanford, PhD, Southwest Foundation for Biomedical Research in San Antonio, TX.
The current standard for HCV treatment is a combination therapy of interferon and ribavirin. Although this combination effectively treats many chronic HCV patients, nearly 50% do not respond to it. Further, patients who do respond, often experience debilitating side effects that can last the duration of the treatment - either 24 or 48 weeks. Interferon side effects include severe flulike symptoms, depression, fatigue and insomnia. Ribavirin can cause anemia, skin rash and itching, fatigue and birth defects.
In contrast to other anti-viral treatments that target the virus itself, the new DNA-based therapy actually targets a small RNA molecule in the liver, miR-122, that is crucial for HCV replication. By hampering this molecule, SPC3649 reduces HCV levels in the liver and in the bloodstream. In the future, the new drug could replace interferon or be added to it and ribavirin.
Lanford and fellow researchers administered SPC3649 intravenously to four HCV-positive chimpanzees for 12 weeks. In chimps that received the highest dose, HCV levels were reduced by 350-fold. Further, the drug's efficacy continued for months after treatment ended. Unlike other antivirals, SPC3649 did not produce a viral rebound or resistance, and there were no adverse effects in the chimps.
"It is a conceptually new approach. Instead of directly targeting the virus, the drug targeted a liver-specific molecule necessary for replication," said Lanford. "If we take that away from the virus, it can't replicate anymore." Though encouraged, researchers still have to establish whether SPC3649 can ensure a "durable response", preventing potential relapse when the patient is taken off the drug.
Phase 2 trials in patients with HCV are expected begin in 2010. While successful human trials could demonstrate a viable therapy, it would still be years before the drug is available for patients.
Santaris Pharma A/S is a Denmark-based biopharmaceutical company specializing in RNA-targeted therapies for metabolic disorders, infectious and inflammatory diseases, oncology and rare genetic disorders.
The study was published online in the December 3, 2009, edition of Science.
Source: HealthDay, December 3, 2009