April 4, 2006
Although signs of DFC-related hyperlipasemia had been seen during earlier research, Incyte said that the rates of severe hyperlipasemia had jumped so high in the new phase 2b study, named Study 901, that it was no longer worthwhile to continue developing the drug. Severe hyperlipasemia appeared to be a problem particularly among study volunteers who were switched to DFC off of a failing regimen that included 3TC (lamivudine, Epivir) or FTC (emtricitabine, Emtriva). "Our observed rate of grade 4 hyperlipasemia occurring in DFC-treated patients who are no longer receiving 3TC or FTC as part of their regimen in Study 901 is now well above the 10% to 15% level that we believe is acceptable," said Dr. Paul Freidman, Incyte's president and CEO, in a released statement. "This is an unfortunate and disappointing finding as we have seen clinically meaningful antiviral effects in patients taking the 200 mg dose of DFC without 3TC or FTC." Lower doses of DFC, although less likely to cause hyperlipasemia, were also found to be below the threshold needed for the drug to effectively suppress HIV.
DFC is a nucleoside reverse transcriptase inhibitor (NRTI) that researchers hoped would provide a new option for people who had developed resistance to existing NRTIs, such as 3TC, AZT (zidovudine, Retrovir) and FTC. In earlier studies, DFC appeared to be relatively safe and effective in HIV-positive volunteers who had never before been on treatment. Positive, but less-impressive, results were found in a study of volunteers who were switched to a DFC-containing regimen when their first NRTI-containing regimen had failed.
Incyte has urged people who were a part of the study to contact their study site before they stop taking DFC, to ensure that they can be quickly switched to another effective treatment regimen. Stopping DFC without consulting a doctor first could potentially lead to the development of resistance to other HIV meds, the company warned. Although Incyte has decided to discontinue DFC's development, the company said it would work with the U.S. Food and Drug Administration to decide on the best course of action for people who were participating in the phase 2b study and who may have few remaining HIV treatment options other than DFC.