Swiss drug maker Roche and U.S. biotechnology company Trimeris on Monday announced that they have halted clinical trials of their experimental antiretroviral drug T-1249, Reuters reports. The two companies developed a similar antiretroviral drug called Fuzeon, which received FDA approval in March 2003 (Pierson/Berkrot, Reuters, 1/6). Fuzeon, which is in a new class of drugs called fusion inhibitors, has encountered resistance from doctors and patients because of its high cost and injection delivery method. The drug costs about $20,000 per patient per year -- double the price of the next most expensive HIV treatments currently on the market. The drug is designed for HIV/AIDS patients who have failed to respond to other medications (Kaiser Daily HIV/AIDS Report, 10/17/03). Roche and Trimeris said that trials of T-1249, which the FDA had agreed to "fast-track" after later trials were completed, were stopped because of problems in the drug's formulation (Reuters, 1/6). "We didn't feel confident we could reproduce it at a large scale," Roche said, according to the Financial Times (Firn, Financial Times, 1/7). However, the companies did not describe the problems, Reuters reports. The companies said that they are still committed to developing fusion inhibitors and signed an agreement to continue research on such drugs, according to Reuters (Reuters, 1/6). In addition, the companies are researching ways to reduce the number of times Fuzeon must be injected from twice a day to once a week or once a month, according to the Raleigh News & Observer (Vollmer, Raleigh News & Observer, 1/6).