It was just a peek at the newcomer, doravirine (MK-1439), looking at data from the first 24 weeks of the first part of a two-segment 96-week trial comparing doravirine to the current standard of care, efavirenz (Bristol-Myers Squibb’s Sustiva).

 

“This study is really the first data we have,” apart from a very small, very short monotherapy study, said Dr. Hedy Teppler, executive director, infectious diseases at Merck Clinical Research, who was also an investigator on the trial.

 

This was a Phase 2 trial (Phase 3 will come later in 2014), in which a range of once-daily doses, 25 milligrams, 50 mg, 100 mg and 200 mg, were used in combination with once-daily doses of emtricitabine/tenofovir disoproxil fumarate, Gilead Sciences’ Truvada.

 

“It certainly performed at least as well as efavirenz,” she tells DDNews. Merck is hoping doravirine will be better in terms of both tolerability and potency that existing drugs, and with less central nervous system toxicity.

 

“Each dose compared well,” according to Teppler—in fact, the data didn’t distinguish one dosage as being more effective than the others. Additional information, though, led to the choice of 100 milligrams to be the dose for the remainder of the 96-week trial and other further studies.

 

Teppler says those factors included providing a reasonable dosage level to discover potential negative drug interactions, and to explore the drug’s overall usefulness.

 

“Choosing the 100-milligram dose should protect against needing to do any dosage adjustment,” Teppler says.

 

For those not candidates for efavirenz (such as women of child-bearing age or people with central nervous system issues), another study offers hope. Merck’s drug Isentress (raltegravir), the first integrase inhibitor approved by the FDA (in 2007), featured in a new study by the AIDS Clinical Trials Group. It compared Isentress given twice daily against atazanavir (Bristol-Myers Squibb’s Reyataz) and darunavir (Tibotec’s Prezista), both given once daily. (All patients also got Truvada daily.)

 

While Merck itself had looked at Isentress versus efavirenz, and found positive results, the ACTG “felt there was a need to look at options in patients who were not candidates for efavarinz,” said Randi Leavitt, senior director, clinical research, global clinical development—infectious disease at Merck, such as women of childbearing age or people with central nervous system issues.

 

The 96-week ACTG study (ACTG 5257) looked at 1,800 treatment-naive patients, a quarter of whom were women, 34 percent non-Hispanic white, 42 percent non-Hispanic black and 22 percent Hispanic.

 

The study found encouraging news for Merck, Leavitt tells DDNews. First, “all three regimens were basically equivalent with regard to efficacy.” But when combining that result with tolerability, “raltegravir was superior to the other two regimens.”

 

And while Isentress has been criticized for being a twice-daily medicine up against once-daily competitors, the results showed that “if the drugs are well tolerated, people will be compliant with a twice-a-day regimen,” Leavitt said.

 

Nevertheless, the company is working on a reformulation to make a once-daily 1,200-mg dose available. That follows on the 2011 report of the failure of tests of an 800-mg daily dose; Leavitt said those results “provided a lot of information” that have improved expectations for the new formulation.