Merck Initiates Phase 3 Study of Letermovir, an Investigational Antiviral for Prevention of Cytomegalovirus (CMV) Infection in High-Risk Bone Marrow Transplant Patients


July 24, 2014 7:30 am ET

Merck (NYSE:MRK), known as MSD outside the United States and Canada,
today announced that the first patient has been enrolled in a global
Phase 3 clinical study of letermovir (MK-8228), an investigational
antiviral agent. The multicenter, randomized, placebo-controlled study
will evaluate the efficacy and safety of letermovir for the prevention
of clinically-significant cytomegalovirus (CMV) infection in adult (18
years and older) CMV-seropositive recipients of allogeneic hematopoietic
stem cell transplants.

“There remains a need for additional therapeutic options in the
prevention of CMV infection in high-risk patients,” said Dr. Michele
Trucksis, executive director, Infectious Diseases, Merck Research
Laboratories. “Merck is pleased to initiate this global Phase 3 study
with letermovir.”

“This study marks a very important step in the development of letermovir
and for AiCuris as licensor of this compound,” said Prof. Helga
Rübsamen-Schaeff, CEO of AiCuris. “We are very excited to have reached
this stage and look forward to the results.”

In the study, letermovir will be administered once daily, either as an
oral tablet or IV formulation, for 14 weeks after transplant. The dose
will be 240 mg once daily for participants receiving concomitant
cyclosporin A and 480 mg once daily for participants not receiving
cyclosporin A. The primary outcome measure of the study will be the
percentage of participants with clinically-significant CMV infection
through 24 weeks after transplant who were administered letermovir
compared to placebo.

Merck expects approximately 540 patients will be enrolled in the study
at more than 70 centers in 20 countries, including the United States.
The estimated study completion date is July 2017.

To learn more about the study, please contact Merck at 1-888-577-8839 or
Additional details can also be found online at

About letermovir

Letermovir is an investigational once-daily antiviral agent under
development for the prevention of human CMV infection. It is derived
from a novel chemical class (quinazolines) and is designed to inhibit
the human CMV viral terminase. Letermovir has been granted Orphan
Product Designation by the European Medicines Agency (EMA) and the U.S.
Food and Drug Administration (FDA) for the prevention of CMV viremia and
disease in at-risk populations and also has been granted Fast Track
Status by the FDA.

Under an agreement signed in 2012, Merck (through a subsidiary)
purchased worldwide rights to develop and commercialize letermovir from
AiCuris GmbH & Co KG (

About CMV

CMV is widely spread in the human population and can cause severe,
life-threatening infections in cases of immune incompetency or immune
deficiency, such as, for example, in transplant recipients. CMV
infection is characterized by fever, leukopenia (very low white blood
cell count) and thrombocytopenia (very low platelet numbers) with or
without specific organ dysfunction. Two main strategies to prevent CMV
infection in transplant recipients at risk have been adopted: anti-CMV
drug prophylaxis or surveillance and pre-emptive treatment of transplant
recipients with evidence of CMV viremia.

About Merck

Today’s Merck is a global healthcare leader working to help the world be
well. Merck is known as MSD outside of 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 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 (

Pam Eisele, 267-305-3558
Robert Consalvo, 908-423-6595
Joseph Romanelli, 908-423-5185
Justin Holko, 908-423-5088

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