Anti Cancer Drugs
PXD101: A Small Molecule HDAC Inhibitor for Advanced Solid Tumors
May 17, 2005 - 8:42:38 AM

CuraGen Corporation (Nasdaq: CRGN - News) and TopoTarget A/S announced that preliminary Phase I data on PXD101, a small molecule histone deacetylase (HDAC) inhibitor, for the treatment of advanced solid tumors were presented today at the American Society of Clinical Oncology (ASCO) Annual Meeting in Orlando, Florida.

This Phase I open-label study was designed to determine the safety, maximum-tolerated dose (MTD), pharmacokinetics, and pharmacodynamics of intravenously administered PXD101, as well as initial assessment of the pharmacokinetics of orally administered PXD101.

PXD101 was administered as a single agent to patients with advanced solid tumors whose disease was refractory to standard therapy or for whom no standard therapy existed.

Preliminary data reported on 28 patients receiving PXD101 suggests that this compound is well-tolerated following intravenous and oral administration.

The most common adverse events were fatigue, nausea, vomiting and phlebitis. No hematological toxicities were noted. Clinical investigators described toxicities as mild with no grade 4 toxicity observed.

Histone hyperacteylation, a biomarker of the activity of PXD101 on its target, was noted to increase proportionally with dose escalation and lasted from 6-24 hours after administration. To date, disease stabilization lasting four cycles or longer (range 4 to 8 cycles) was noted in 5 of 28 patients.

"We are very pleased with the preliminary data from this Phase I trial for solid tumors, as well as the data indicating that both IV and oral dosing are potential routes of administration for PXD101," stated Timothy M. Shannon, M.D., Executive Vice President Research and Development and Chief Medical Officer at CuraGen. "We are also encouraged by the fact that we see evidence of prolonged activity with this drug, observing histone hyperacetylation, a measure of drug target activity, for up to 24 hours after administration."

Based upon these Phase I results and recently reported preclinical data, a Phase Ib study evaluating PXD101 plus 5-fluorouracil (5-FU) for the treatment of solid tumors, including colorectal cancer, will begin enrolling patients by the third quarter of 2005. Furthermore, additional proof-of-concept studies for other types of solid tumors will be initiated throughout 2005 evaluating PXD101 either alone or in combination with other active anti-cancer treatments.

The companies also reported than an abstract discussing a second Phase I clinical trial of PXD101 for patients with advanced hematologic cancers, such as multiple myeloma, was published in the ASCO 2005 Proceedings. Preliminary results from this Phase I study suggest safety and tolerability similar to those reported for patients with advanced solid tumors. CuraGen and TopoTarget anticipate that additional results from this ongoing trial will be presented at a medical conference during 2005. The findings of this study are being further explored in the ongoing Phase II clinical trial for patients with advanced multiple myeloma, a deadly form of blood cancer. This Phase II clinical trial is expected to be complete by mid-2006. Additional proof-of- concept studies in other hematologic cancers will also be initiated in 2005.

About HDAC inhibitors

A growing body of research highlights the role of histone deacetylases (HDAC) in regulating gene expression, particularly the expression of cancer- related genes. HDAC inhibitors represent a new mechanistic class of anti- cancer therapeutics that target HDAC enzymes, and have been shown to: arrest growth of cancer cells (including drug resistant subtypes); induce apoptosis, or programmed cell death; promote differentiation; inhibit angiogenesis; and sensitize cancer cells to overcome drug resistance phenotype when used in combination with other anti-cancer agents. HDAC inhibitors are believed to play a role in a wide range of solid malignancies such as breast, colon, lung and ovarian cancers, and hematological malignancies, such as lymphomas, leukemias and myeloma.

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