June 9, 2009

Apricitabine Trial Continues, With Changes

The experimental antiretroviral drug apricitabine (ATC) has received approval from a data safety monitoring board (DSMB) to continue with its Phase III trial beyond week 16. However, according to a Monday announcement from apricitabine’s Australia-based manufacturer Avexa, the DSMB also recommended that everyone receiving the higher dose of apricitabine continue the study on the lower dose.

Apricitabine is a second-generation nucleoside reverse transcriptase inhibitor (NRTI) designed to work against virus that’s resistant to lamivudine (found in Epivir, Combivir, Epzicom and Trizivir). The Phase III study was originally designed to compare the safety and efficacy of two apricitabine doses—800 mg and 1,200 mg—with lamivudine in people who have become resistant to lamivudine.

The reason for discontinuing the 1,200 mg dosing group was not stated in the Avexa press release. Typically, a DSMB recommends such changes when there is a safety or efficacy concern. The Avexa announcement simply states that “[t]he 800 mg dose is considerably easier to formulate into fixed dose combinations” and that patients in an earlier study, using the 800 mg dose, “have been successfully treated with ATC for up to three years.”

All patients originally randomized to the 1,200 mg dosing group will be switched to the 800 mg dose. The study is designed to continue for 96 weeks, with additional data analysis at 24 and 48 weeks.

Clarification: In an e-mail dated June 16 to AIDSmeds.com, Avexa noted the reason for the discontinuation of the 1,200 mg dose in the Phase III study reported here. Because there were no differences in either the effectiveness or side effects between the two doses at week 16—there were no ATC-related serious safety issues in any patients treated in the study—those on the 1,200 mg dose have been transitioned onto the 800 mg dose because this has been determined to be the optimal dose for therapy. There are no safety concerns regarding the 1,200 mg dose.

Search: Apricitabine, ATC, Avexa, Phase III study

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