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Combination Trial of Xcytrin With Rituxan and Zevalin for B-Cell Lymphoma Initiated
"The use of Xcytrin in combination with Rituxan and Zevalin represents a new mechanistic approach to therapy of relapsed B-cell lymphomas and is based on the inherent sensitivity of lymphoma cells to reactive oxygen species produced by Xcytrin," said Leo I. Gordon M.D., Professor of Medicine and Chief of the Division of Hematology/Oncology, at Northwestern University's Feinberg School of Medicine in Chicago. "The tumor selectivity of Xcytrin along with its synergistic cytotoxic effects when combined with both the monoclonal antibody, Rituxan, and the radiation emitted from Zevalin is an exciting new concept for the treatment of B-cell lymphoma."
The clinical study will evaluate the safety and efficacy of increasing doses of Xcytrin given in combination with Rituxan and Zevalin. Successive cohorts of patients will receive four daily injections of Xcytrin along with a single injection of Rituxan. One week later, these patients receive another four injections of Xcytrin with a single injection of yttrium-90 labeled Zevalin. Patients will be evaluated for safety and tumor response. Tumor localization of Xcytrin and the antibody will be assessed using MRI and nuclear imaging, respectively.
"Our clinical programs with Xcytrin continue to expand and now include hematologic malignancies. We are very excited about this trial, which is evaluating an innovative treatment regimen aimed at taking advantage of Xcytrin's unique mechanism of action," said Richard A. Miller, M.D., president and chief executive officer of Pharmacyclics. "Preclinical evidence has shown that lymphomas are a particularly good target for our drug based on its tumor selectivity and the sensitivity of lymphoma cells to reactive oxygen species produced by Xcytrin. We are planning additional trials in lymphomas with Xcytrin as a single agent and in combination with chemotherapy."
Xcytrin is the first of an investigational class of drugs called texaphyrins, which are rationally designed small molecules that have a unique way of working inside diseased cells. Xcytrin targets tumors in a new way. After administration, Xcytrin selectively localizes and accumulates inside cancer cells where it disrupts cellular metabolism, interferes with the flow of energy, and produces cytotoxic substances known as reactive oxygen species. Reactive oxygen species are potent inducers of programmed cell death, or apoptosis, particularly in lymphoma cells.
Preclinical studies have shown that Xcytrin induces apoptosis in many types of lymphoma cells. Rituxan also induces apoptosis in lymphoma cells expressing the CD20 cell surface antigen. In laboratory studies, Xcytrin enhances both the cytotoxicity of Rituxan and the effects of radiation providing the rationale for the investigational use of Xcytrin with Rituxan and Zevalin.
Preclinical studies have shown that Xcytrin enhances the efficacy of standard radiation therapy and that of several commonly used chemotherapy agents. Currently, Xcytrin is being investigated as a potential therapeutic in combination with radiation therapy and/or chemotherapy and as a single agent for various types of cancers in several clinical trials sponsored by Pharmacyclics and/or the National Cancer Institute.
Non-Hodgkins lymphomas are tumors derived from lymphoid cells. They are usually widely disseminated at disease presentation commonly involving multiple lymph node sites, the bone marrow and other organs. Although they often respond to initial chemotherapy, most patients with relapsed B-cell non-Hodgkins lymphomas are not cured with existing treatments.
Source: Pharmacyclics, Inc.