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Merck’s Investigational HIV Therapy, Doravirine (MK-1439), Demonstrates Antiviral Activity in Phase 2B Study of Treatment-Naïve Adults

BOSTON--(BUSINESS WIRE)--Merck (NYSE:MRK), known as MSD outside the United States and Canada, today presented data from the dose-ranging portion of an ongoing Phase 2B clinical trial of doravirine, the company’s investigational next-generation, non-nucleoside reverse transcriptase inhibitor (NNRTI), at the 21st Conference on Retroviruses and Opportunistic Infections (CROI). Interim data demonstrating potent antiretroviral (ARV) activity for four doses (25, 50, 100 and 200 mg) of once-daily, oral doravirine in combination with tenofovir/emtricitabine in treatment-naïve, HIV-1 infected adults after 24 weeks of treatment were presented during a late-breaker oral session. Based on these findings as well as other data from the doravirine clinical program, Merck plans to initiate a Phase 3 clinical trial program for doravirine in combination with ARV therapy in the second half of 2014.

“Building on our long-standing commitment to the HIV community, Merck continues to evaluate new candidates we believe have the potential to make a meaningful difference in the lives of HIV patients,” said Daria Hazuda, Ph.D., vice president, Infectious Diseases, Merck Research Laboratories. “We look forward to advancing doravirine into Phase 3 clinical trials in the second half of 2014.”

Doravirine Clinical Data

This randomized, double-blind clinical trial examined the safety, tolerability and efficacy of once-daily doravirine (25, 50, 100 and 200 mg) in combination with once-daily tenofovir/emtricitabine versus efavirenz (600 mg), in treatment-naïve, HIV-1 infected patients. The primary efficacy analysis was percentage of patients achieving virologic response ( 40 copies/mL).

At 24 weeks, doravirine doses of 25, 50, 100, and 200 mg showed virologic response rates consistent with those observed for efavirenz at a dose of 600 mg. All treatment groups showed increased CD4 cell counts.


Proportion of Patients with Virologic Response at 24 weeks (95% CI)


Mean CD4 Change from Baseline (95% CI)

Treatment*   Dose (mg)   n/N  

% 40 copies/mL




Doravirine   25   32/40   80.0 (64.6, 90.9)   158 (119, 197)
    50   32/42   76.2 (60.5, 87.9)   116 (77, 155)
    100   30/42   71.4 (55.4, 84.3)   134 (100, 167)
    200   32/41   78.0 (62.4, 89.4)   141 (96, 186)
Efavirenz   600   27/42   64.3 (48.0, 78.4)   121 (73, 169)
Missing data approach:   Non-completer = Failure   Observed Failure

*In combination with tenofovir/emtricitabine

The incidence of drug-related adverse events was comparable among the doravirine-treated groups. The overall incidence of drug-related adverse events was lower in the doravirine-treated groups (n=166) than the efavirenz-treated group (n=42), 35 percent and 57 percent, respectively. The most common central nervous system (CNS) adverse events at week 8, the primary time point for evaluation of CNS adverse experiences, were dizziness [3.0% doravirine (overall) and 23.8% efavirenz], nightmare [1.2% doravirine (overall) and 9.5% efavirenz], abnormal dreams [9.0% doravirine (overall) and 7.1% efavirenz], and insomnia [5.4% doravirine (overall) and 7.1% efavirenz].

Based on the 24-week data from this dose-finding study, a single dose of 100 mg doravirine was chosen to be studied for the remainder of this study, up to 96 weeks.

About Doravirine

Doravirine, also known as MK-1439, is an investigational next-generation, NNRTI being evaluated by Merck for the treatment of HIV-1 infection. In preclinical studies, doravirine demonstrated potent antiviral activity against HIV-1 with a characteristic profile of resistance mutations selected in vitro compared with currently available NNRTIs. In early clinical studies, doravirine demonstrated a pharmacokinetic profile supportive of once-daily dosing and did not show a significant food effect.

Merck’s Commitment to HIV

For more than 25 years, Merck has been at the forefront of the response to the HIV epidemic, and has helped to make a difference through our proud legacy of commitment to innovation, collaborating with the community, and expanding global access to medicines. Merck is dedicated to applying our scientific expertise, resources and global reach to deliver healthcare solutions that support people living with HIV worldwide.

About Merck

Today's Merck is a global healthcare leader working to help the world be well. Merck is known as MSD outside the United States and Canada. Through our prescription medicines, vaccines, biologic therapies, and consumer care and animal health products, we work with customers and operate in more than 140 countries to deliver innovative health solutions. We also demonstrate our commitment to increasing access to healthcare through far-reaching policies, programs and partnerships. For more information, visit and connect with us on Twitter, Facebook and YouTube.

Forward-Looking Statement

This news release includes “forward-looking statements” within the meaning of the safe harbor provisions of the United States Private Securities Litigation Reform Act of 1995. These statements are based upon the current beliefs and expectations of Merck’s management and are subject to significant risks and uncertainties. There can be no guarantees with respect to pipeline products that the products will receive the necessary regulatory approvals or that they will prove to be commercially successful. If underlying assumptions prove inaccurate or risks or uncertainties materialize, actual results may differ materially from those set forth in the forward-looking statements.

Risks and uncertainties include but are not limited to, general industry conditions and competition; general economic factors, including interest rate and currency exchange rate fluctuations; the impact of pharmaceutical industry regulation and health care legislation in the United States and internationally; global trends toward health care cost containment; technological advances, new products and patents attained by competitors; challenges inherent in new product development, including obtaining regulatory approval; Merck’s ability to accurately predict future market conditions; manufacturing difficulties or delays; financial instability of international economies and sovereign risk; dependence on the effectiveness of Merck’s patents and other protections for innovative products; and the exposure to litigation, including patent litigation, and/or regulatory actions.

Merck undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events or otherwise. Additional factors that could cause results to differ materially from those described in the forward-looking statements can be found in Merck’s 2013 Annual Report on Form 10-K and the company’s other filings with the Securities and Exchange Commission (SEC) available at the SEC’s Internet site (