Pharmacyclics Announces Data and Publication Characterizing Highly-Selective HDAC...( SUNNYVALE Calif. Feb. 11 /- Pharm...),Health

SUNNYVALE, Calif., Feb. 11 /PRNewswire-FirstCall/ -- Pharmacyclics, Inc. (Nasdaq: PCYC) today announced publication of data characterizing the company's novel highly-selective histone deacetylase (HDAC) inhibitor. The study, entitled "A novel histone deacetylase 8 (HDAC8)-specific inhibitor PCI-34051 induces apoptosis in T-cell lymphomas," appears in the February 7 issue of Leukemia.

Histone deacetylases are a family of related enzymes important in managing a multitude of cellular functions. HDAC inhibitors are a new class of drugs that modulate transcriptional activity in cells and may block angiogenesis and cell cycling, key components of tumor proliferation. HDAC inhibitors also appear to promote apoptosis (cell death) in tumor cells. Scientists have been searching for more selective inhibitors, which may offer the potential for treating a variety of diseases including cancer and inflammatory disorders while improving safety.

Results from the in-vitro study demonstrate that Pharmacyclics' proprietary HDAC inhibitor, PCI-34051, inhibits HDAC8 with 200-1000 fold selectivity over other HDAC enzymes. Studies showed that selective inhibition of HDAC8 inhibits cell growth and induces apoptosis in cell lines derived from T-cell lymphoma and leukemia, but not in other hematopoietic or solid tumor lines. This work also showed that HDAC8 selective inhibitors have a unique mechanism of action, and could play a role in T-cell lymphoma and other immune mediated diseases.

"To our knowledge, this is the first description of a truly selective HDAC isoform specific inhibitor," said Joseph J. Buggy, Ph.D., vice president of research for Pharmacyclics. "This study also confirms that individual HDAC isoforms have unique roles in cell
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