Pharmacyclics, Inc., a pharmaceutical company developing products to improve upon current therapeutic approaches to cancer, atherosclerosis and retinal disease, is planning to conduct an additional Phase 3 clinical trial of its lead product Xcytrin (motexafin gadolinium) Injection to confirm the potential clinical benefits observed in previous clinical trials.
Xcytrin, the first of a new class of drugs called texaphyrins, selectively accumulates in cancer cells and disrupts cellular metabolism by a unique mechanism of action. By interfering with the flow of energy in cancer cells, Xcytrin prevents cancer cells from repairing damage caused by the effects of radiation and chemotherapy without increasing damage to normal tissue.
"After discussions with the U.S. Food and Drug Administration (FDA), we believe the optimal course is to conduct a confirmatory trial in the patients that appeared to benefit the most in our initial Phase 3 trial - those patients with lung cancer, the most common cause of brain metastases," said Richard A. Miller, M.D., president and CEO. "We intend to conduct a new study that will build on the experience and knowledge gained from the initial trial, including identification of prognostic factors and the use of clinically meaningful assessments of neurologic deterioration."
Last year, the company reported results of a randomized controlled Phase 3 trial of Xcytrin in patients with brain metastases, i.e., cancer that has spread to the brain from another part of the body. The study was conducted at more than 50 leading cancer centers in the United States, Canada and Europe and enrolled 401 patients: 251 with lung cancer, 75 with breast cancer and 75 with other tumor types.
This study was designed to compare the safety and efficacy of standard whole brain radiation therapy (WBRT) to standard WBRT plus Xcytrin. Although the trial did not meet its primary endpoints in the entire patient population, there was significant improvement in time to neurologic progression in lung cancer patients receiving Xcytrin, which represented over 60 percent of the total patients on the study. Improvement in time to neurologic progression for the entire study population was found using standard investigator neurologic assessment. There was significant improvement in time to neurocognitive progression in favor of the Xcytrin-treated lung cancer patients.
"Our discussions with FDA have confirmed that time to neurologic progression and neurocognitive function are important measurements of clinical benefit in these patients," added Dr. Miller. "We are in a unique position to address this growing clinical problem and significant unmet medical need. Our increased understanding of appropriate patient eligibility and clinical assessments should improve our chances of conducting a successful study for U.S. registration."
Full results of the initial Phase 3 trial will be presented at the upcoming annual meeting of the American Society of Clinical Oncology (ASCO) on Sunday, May 19 in Orlando, Florida.
The Company has successfully completed Phase 1 and Phase 2 clinical trials with Xcytrin for the treatment of glioblastoma multiforme (primary brain tumors), and is currently planning additional clinical trials for this indication.
Other studies now underway with Xcytrin include those being performed under a cooperative research and development agreement with Pharmacyclics and the National Cancer Institute for the treatment of non small-cell lung cancer, glioblastoma multiforme, childhood gliomas (life-threatening brain tumors in children) and pancreatic cancer.
Pharmacyclics has also begun a Phase 1 trial to investigate Xcytrin's potential to enhance the effects of chemotherapy in the treatment of advanced cancer.
Xcytrin, the first of a new class of drugs called texaphyrins, selectively accumulates in cancer cells and disrupts cellular metabolism by a unique mechanism of action. By interfering with the flow of energy in cancer cells, Xcytrin prevents cancer cells from repairing damage caused by the effects of radiation and chemotherapy without increasing damage to normal tissue.