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HIV Drug PA-457 Gains FDA's Fast Track Review
"We believe that PA-457 has great potential as a new approach to treat HIV/AIDS and are very pleased that the FDA has chosen to grant Fast Track status, which we believe will allow us to expedite development of this drug," commented Dr. Graham Allaway, Panacos' Chief Operating Officer. "There is a major need for treatments effective against drug-resistant strains of HIV, which appear in most patients receiving therapy and are the leading cause of treatment failure. PA-457 has a different mechanism of action than approved HIV drugs and as a result it potently inhibits HIV strains resistant to currently available treatments as well as wild-type virus."
Panacos has completed single dose (Phase Ia) and multiple dose (Phase Ib) studies of PA-457 in uninfected volunteers, demonstrating that the drug is well tolerated with pharmacokinetics supporting once-daily oral dosing. Furthermore, the Company recently announced positive results from a proof-of- concept Phase I/II clinical trial of PA-457 in HIV-infected patients, where a single oral dose of the drug gave a significant reduction in plasma viral load from baseline, of up to approximately 0.7 log10 at the higher dose levels. Full results of the Phase Ib and Phase I/II clinical trials of PA-457 will be provided at the 12th Conference on Retroviruses and Opportunistic Infections to be held in Boston, MA, during February, 2005.
In December 2004, the Company initiated a Phase IIa clinical trial of PA- 457. This study, being performed at multiple sites in the U.S., is designed to evaluate the antiviral potency of PA-457 following once-daily oral dosing for 10 days, in HIV-infected patients who are not on other antiretroviral therapy. Dr. David E. Martin, Senior Vice President of Drug Development at Panacos, said: "We were excited to see a significant reduction in viral load following a single oral dose of PA-457 and we anticipate an even greater viral load reduction in the multiple dose Phase IIa study. The granting of Fast Track status will enable us to get rapid input and feedback from FDA on our clinical program, and we believe that it will help us move PA-457 quickly into late stage clinical development." Results of the Phase IIa clinical trial are expected in Q2, 2005. During the second half of 2005, Panacos intends to initiate Phase IIb studies of PA-457 designed to pave the way for pivotal Phase III studies beginning in 2006.
PA-457 is a small molecule, orally bioavailable HIV drug candidate. It inhibits HIV replication by disrupting virus maturation, the last step in the virus life-cycle. This novel mechanism was discovered by Panacos scientists and is different from the mode of action of approved drugs or other drugs in development. Specifically, PA-457 blocks a key step in the processing of a viral core protein called capsid. Preclinical studies have shown that PA-457 retains full activity against drug-resistant virus and is effective in an animal model of HIV infection. The form of PA-457 currently being tested in human clinical trials is designated PA-103001-01.
Source: Panacos Pharmaceuticals, Inc.