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


March 5, 2014 12:15 pm ET

Merck Plans to Initiate Phase 3 Clinical Development Program in Second Half of 2014

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




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

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
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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 (

Caroline Lappetito, 267-305-7639
Sarra Herzog, 201-669-6570
Carol Ferguson, 908-423-4465
Justin Holko, 908-423-5088

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