Merck & Co., Inc. announced that the Food and Drug Administration (FDA) has accepted the New Drug Application (NDA) for Zolinza (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 tumour 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."

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-tumour agents under investigation for the treatment of solid tumours 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.

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.