ZOLINZA(TM), Merck & Co., Inc.'s Investigational Medicine For Advanced Cutaneous T-Cell Lymphoma (CTCL), To Receive Priority Review From U.S. FDA

WHITEHOUSE STATION, N.J.--(BUSINESS WIRE)--June 7, 2006--Merck & Co., Inc. announced today that the Food and Drug Administration (FDA) has accepted the New Drug Application (NDA) for ZOLINZA(TM) (vorinostat, also known as suberoylanilide hydroxamic acid, SAHA) for the treatment of advanced cutaneous T-cell-lymphoma (CTCL) and that this NDA has been granted priority review by the FDA. A priority review designation is intended for products that address unmet medical needs. Under the Prescription Drug User Fee Act (PDUFA), for NDAs filed in 2006, the FDA's goal is to review and act on NDAs designated as priority review within six months of receipt. Merck expects FDA action on the NDA by early October 2006.

If approved, ZOLINZA would potentially be the first in a new class of anti-cancer therapies called histone deacetylase (HDAC) inhibitors. Histone deacetylation is thought to be a mechanism for silencing some tumor suppressor genes and other genes responsible for cell cycle progression, cell proliferation, programmed cell death (apoptosis), and differentiation (transformation of young cells into specialized cells).

"HDAC inhibitors like ZOLINZA are very exciting to the cancer community," said Stephen H. Friend, M.D., Ph.D., executive vice president, Oncology, Merck Research Laboratories. "ZOLINZA is one of several investigational therapies that represent an important part of the growing Merck Oncology franchise."

About ZOLINZA

ZOLINZA, also known as vorinostat or suberoylanilide hydroxamic acid (SAHA), is Merck's investigational histone deacetylase (HDAC) inhibitor and part of a new class of anti-tumoragents under investigation for the treatment of solid tumors and cancers of the blood (lymphomas). Histone acetylation and deacetylation effect gene regulation by changing the conformation of DNA in chromatin - the dense part of the cell that is comprised of DNA and other proteins, mainly histones. ZOLINZA was granted fast-track and orphan drug designation for CTCL by the FDA.

About CTCL

CTCL, a type of non-Hodgkin's lymphoma, is a slow-growing form of cancer in which some of the body's white blood cells known as T-lymphocytes or T-cells become malignant. Normal T-cells function by regulating the body's immune system in its job of fighting infections and other foreign antigens. In CTCL, the malignant T-cells are drawn to the skin, where some are deposited. Patients usually develop CTCL after age 50. CTCL affects 20,000 patients in the United States, with another 1,500 new cases reported each year.

About Merck Oncology

Merck Oncology focuses on all aspects of cancer care -- prevention, treatment, and supportive care. Through strong internal research capabilities, selective alliances and acquisitions, and enabling technologies such as the Molecular Profiling platform of Rosetta, Merck Oncology is looking to lead in the discovery, development and delivery of targeted anti-cancer therapies customized for patient subpopulations. Today, the Company's areas of research include anti-cancer therapies that target HDAC, Notch, Aurora Kinases, IGFR, PSCA and KSP; preventive and treatment cancer vaccines; and supportive care products. Merck Oncology conducts research at sites in Boston, Seattle, West Point, Japan and Italy.

About Merck

Merck & Co., Inc. is a global research-driven pharmaceutical company dedicated to putting patients first. Established in 1891, Merck currently discovers, develops, manufactures and markets vaccines and medicines to address unmet medical needs. The company devotes extensive efforts to increase access to medicines through far-reaching programs that not only donate Merck medicines but help deliver them to the people who need them. Merck also publishes unbiased health information as a not-for-profit service. For more information, visit www.merck.com.

Forward-Looking Statement

This press release contains "forward-looking statements" as that term is defined in the Private Securities Litigation Reform Act of 1995. These statements are based on management's current expectations and involve risks and uncertainties, which may cause results to differ materially from those set forth in the statements. The forward-looking statements may include statements regarding product development, product potential or financial performance. No forward-looking statement can be guaranteed, and actual results may differ materially from those projected. Merck undertakes no obligation to publicly update any forward-looking statement, whether as a result of new information, future events, or otherwise. Forward-looking statements in this press release should be evaluated together with the many uncertainties that affect Merck's business, particularly those mentioned in the cautionary statements in Item 1 of Merck's Form 10-K for the year ended Dec. 31, 2005, and in its periodic reports on Form 10-Q and Form 8-K, which the company incorporates by reference.

ZOLINZA(TM) is a registered trademark of Merck & Co., Inc.

Contact: Media: Janet Skidmore, 215-652-4156 Michele Rest, 267-305-7891 OR Investors: Graeme Bell, 908-423-5185

Source: Merck & Co., Inc.