Merck Announces Phase II Study Results of SAHA in Advanced, Refractory Cutaneous T-cell Lymphoma - CTCL - Patients.

WHITEHOUSE STATION, N.J. -- Merck & Co., Inc. announced today results of a Phase II open label study with investigational oral suberoylanilide hydroxamic acid (SAHA), a new class of anti-tumor agents that inhibits histone deacetylase. Investigators from M.D. Anderson Cancer Center in Houston presented results at the annual meeting of the American Society of Clinical Oncology in Orlando. In the study, eight of 33 patients with advanced, refractory CTCL experienced partial responses (physician assessment of >50 percent reduction in overall disease burden), the primary endpoint of the study.

"In this study, SAHA demonstrated encouraging improvements in the overall condition of patients with advanced, refractory, and heavily pretreated CTCL as assessed by their physician's global assessments," said Madeleine Duvic, M.D., professor of medicine and deputy chairman, Department of Dermatology, at M.D. Anderson Cancer Center and lead investigator of the study. "SAHA was shown to reduce the tumor burden and improve pruritus in CTCL patients, especially those with erythroderma and Sezary Syndrome. A second Phase IIb study is underway to confirm these results."

The 33 patients in the study (median age 67) were treated in one of three dosing cohorts. In the first cohort, 13 patients received 400 mg once daily until disease progression or an adverse event. In the second cohort, 11 patients received 300 mg twice a day for three to five days a week for 16 weeks. In the third cohort, nine patients received 300 mg twice a day for 14 days, no therapy for the following seven days, and then 200 mg twice a day continuously.

The most common side effects seen in the study were fatigue (85 percent), diarrhea (58 percent), nausea (61 percent), change in taste (58 percent), dry mouth (42 percent), decreased appetite (21 percent), and low platelet count (30 percent).

About SAHA

SAHA is believed to inhibit the enzyme histone deacetylase (HDAC). Histones are structural proteins around which DNA coils. These proteins may play an important role in the regulation of gene expression. Increased levels of HDAC, which are present in tumor cells, trigger histones to tightly package DNA and limit the transcription of tumor suppressor genes. By changing the balance between acetylated and deacetylated proteins, SAHA causes cell cycle arrest, cell differentiation, and apoptosis.

SAHA was granted fast-track designation and orphan drug designation for CTCL by the U.S. Food and Drug Administration (FDA). Merck is conducting a confirmatory Phase IIb trial with SAHA in CTCL patients.

In addition, Merck currently is pursuing clinical studies with SAHA in diffuse large B-cell lymphoma (DLBCL) and multiple myeloma. For further information about enrolling in SAHA clinical trials, please call 888-577-8839.

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

Merck & Co., Inc. is a global research-driven pharmaceutical company dedicated to putting patients first. Established in 1891, Merck discovers, develops, manufactures and markets vaccines and medicines in more than 20 therapeutic categories. 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.

Forwarding-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 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, 2004, and in its periodic reports on Form 10-Q and Form 8-K, which the company incorporates by reference.