Tibotec unveils results of experimental HIV drug

Johnson & Johnson (NYSE: JNJ) unit Tibotec Pharmaceuticals has reported results from two pivotal Phase III trials comparing its investigational non-nucleoside reverse transcriptase inhibitor TMC278 (rilpivirine) with efavirenz. Each drug was administered once daily with a nucleoside/nucleotide background regimen in treatment-naive, HIV-1-infected adults. And while the experimental HIV drug worked as well as efavirenz with fewer side effects, almost twice as many patients failing to respond to treatment, Reuters reports.

J&J has a deal with Gilead Sciences (NASDAQ: GILD) to develop a single pill combining rilpivirine with Truvada, a drug containing Gilead's tenofovir and emtricitabine. Under the deal, Gilead would keep up to 30 percent of TMC278 sales, Reuters explains.

Pooled results from the ECHO and THRIVE studies showed that 84.3 percent of patients in the TMC278 group reached an undetectable viral load, compared with 82.3 percent of patients in the efavirenz group, according to a company release. The difference between the treatment groups was not significant. In addition, the virologic failure rate was 9 percent in the TMC278 group and 4.8 percent in the efavirenz group.

Physicians are especially concerned about virologic failure--meaning patients' HIV levels either fail to drop or rebound after an initial drop--since it could signal the virus was mutating, making it resistant to drugs in the same class, Reuters notes. And the higher failure rate raises the question of whether Gilead would be able to switch patients from Atripla, which saw sales of $2.4 billion last year, to the new three-drug pill which has been nicknamed Btripla.

However, on a positive note for J&J, adverse events leading to discontinuation in the TMC278 group were 3.4 percent compared with 7.6 percent in the efavirenz group. Serious adverse events at least possibly related to treatment were 15.9 percent in the TMC278 group versus 31.1 percent in the efavirenz group, Tibotec reports.

-read the company's release
- see the story from Reuters