Food and Drug Administration Grants Fast Track Status for Panacos Pharmaceuticals' HIV Drug Candidate PA-457, the First-in-Class Maturation Inhibitor

GAITHERSBURG Md. -- Panacos Pharmaceuticals, Inc. today announced that the U.S. Food and Drug Administration (FDA) has granted Fast Track designation for PA-457, the Company's once-daily oral drug candidate for the treatment of HIV infection. PA-457 is the first in a new class of HIV drugs called maturation inhibitors. Fast Track is a process designed to expedite development and approval of new drugs that may have the potential to improve treatment for serious or life-threatening diseases. In granting Fast Track status for the form of PA-457 that is currently being tested in human clinical trials, FDA noted that this is a drug to treat a serious or life-threatening condition with an unmet medical need. Developers of Fast Tracked products have greater access to FDA resources as well as eligibility for rolling NDA submissions. In addition, Fast Track designation may enable priority FDA review and accelerated approval.

"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 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 Untied States, 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.

Source: Panacos Pharmaceuticals, Inc.