At an all-day meeting for investors last month in a posh Manhattan event space, executives at Merck couldn’t have been more excited about a new HIV drug, MK-8591. They mentioned it 25 times, calling it “a game changer” and talking up its “remarkable properties.”
Why? If effective, it could be used in a new drug combination that might have fewer side effects, the company says. More excitingly, it might be fashioned into an implant that could be given only once a year to prevent patients at high risk from contracting HIV, a boon to public health.
The first results on both approaches are being presented this week in Mexico City at the annual meeting of the International AIDS Society. The data on the implant is being released Tuesday, and the drug combination data will be presented on Wednesday.
Not everyone is as enthralled as Merck. Jefferies analyst Michael Yee said the new drug does not represent a concern for investors in Merck rival Gilead, which is the leader in the HIV market. “While interesting, we do not see MK-8591 as an immediate threat as it is several years from approval, requires daily oral dosing (or an implant), and will still need to be combined” with other drugs, Yee wrote in a note to investors earlier this month.
One of the benefits of MK-8591 is that it builds up in the body, and it could be given as an implant that might only need to be replaced once a year. By contrast, Gilead’s HIV pill Truvada, given to patients at high risk of HIV, is a once-a-day pill.
Researchers randomly assigned four patients to receive a placebo implant, six to receive an implant with a 54-milligram dose of MK-8591, and six with a 62-mg dose, and followed them for four months. Based on blood levels of the drug, the researchers predicted that the 54-mg implant could prove effective for between eight and 10 months, and the 62-mg implant should protect against HIV infection for a year. Larger, longer studies will need to be completed to see if that promise bears out.
At the Merck meeting in June, the company’s chief marketing officer, Mike Nally, said the company expects the new drug to become “a foundational anchor for two-drug combinations,” adding that it “offers the potential benefit of avoiding the toxicity associated with many of the current backbone therapies.” The company will say more on that on Wednesday.
The drug also got a new name this week: islatravir. It is the first drug with the root “travir,” an indication, Merck said, that the medicine is a new drug class, called a nucleoside reverse transcriptase and translocation inhibitor.
MK-8591 has a colorful history, having been at one point licensed from soy sauce maker Yamasa. One of the key players in developing the drug was Daria Hazuda, the company’s vice president of infectious disease discovery. Hazuda was also the biologist who championed Merck’s existing HIV drug, Isentress, which was approved in 2007 and generated $1.1 billion in annual sales last year.
At the meeting in June, Hazuda said Merck researchers are now working on long-acting versions of other existing HIV drug classes to better pair with MK-8591. She also said that she feels the new medicine is an opportunity she thought she’d never get again after Isentress: the chance to launch an important new HIV medicine.
“I can’t tell you how super-excited I’m about 8591,” she said. “It really is, at least for me, in HIV, almost a once-in-a-lifetime molecule. If you would have told me even a few years ago that you could find a molecule in any infectious disease, let alone HIV, that you could dose once a day, once a week, once a month, that had the pharmacology and potency that would allow it to be formulated in a long-acting formulation that could deliver and release effective drug levels for a year, I would have never ever believed it.”