Fuzeon, the first of a new class of AIDS drug known as fusion inhibitors designed to fight resistant strains of HIV, works well even after two years of treatment, its maker said on Monday.

But Switzerland’s Roche Holding AG, which developed the medicine with U.S. biotechnology firm Trimeris Inc, said many people were not taking it because it must be injected, resulting in disappointing sales since its launch last year.

New data presented at the 15th International AIDS Conference showed Fuzeon plus conventional antiretroviral therapy for the disease took the proportion of patients with the virus reduced to undetectable levels after two years up to 26 percent - twice as many as those on standard treatment.

They also continued to show improvements in the immune system with a steady increase in levels of CD4 cells, the immune system cells that are attacked by HIV in a process that eventually leads to acquired immune deficiency syndrome.

In all, 55 percent of patients who started treatment in a clinical trial were still taking the drug two years later. Of those who quit, only seven percent did so because of soreness at the site of their injections.

Other reasons for stopping included the fact the virus eventually developed resistance to Fuzeon in some patients - a fate common to all AIDS drugs - and various adverse side effects, including nausea and diarrhea, caused by taking a cocktail of medicines.

Roche’s head of HIV medicine, David Reddy, said the Fuzeon drop-out rate was surprisingly low given that many standard, non-AIDS medicines often lost 25-30 percent of patients.

PRICE “NOT THE ISSUE”

The unique problem for Fuzeon, however, is that it must be given as an injection twice a day, unlike tablet-based AIDS drugs. It is also the most expensive anti-AIDS drug at around $20,000 per patient a year - but Reddy said price was not the reason for the drug’s poor take-up.

“The issue isn’t price. The issue is that this is an injectable drug,” Reddy told Reuters, noting that Fuzeon costs were being reimbursed in all major European markets, apart from Portugal, as well as most U.S. states.

Roche, which conducted a survey of doctors, estimates only one out of every five patients eligible for Fuzeon treatment are getting the medicine because of concerns among patients and their doctors over the need to inject it.

Roche has stepped up efforts to get doctors and nurses to work more closely with patients during the first three months of treatment, by which time the benefits of the drug should be seen and self-injection should have become routine.

Reddy said the policy, pioneered by a group of doctors in France, was starting to bear fruit in major markets and sales of Fuzeon were picking up after a weak performance in 2003.

“It’s a far more encouraging picture now,” he said.

In the first quarter of this year, worldwide sales of Fuzeon totaled $24 million, a 36 percent increase over the fourth quarter of 2003.

But that performance was still a long way short of the annual peak sales of between 500 million and 1.0 billion Swiss francs ($408-815 million), which Roche has forecast the drug will generate eventually.