Gd-Tex Pharmacyclics Inc.

Abstract

Pharmacyclics is developing Gd-Tex (gadolinium texaphyrin) as a radiosensitizer for the potential treatment of various cancers including brain metastases and primary brain tumors, pancreatic tumors, lung tumors and pediatric cancers [196711], [348919]. The compound entered phase III pivotal trials for brain metastases in September 1998 [323929]. Phase I clinical trials for the treatment of primary brain tumors and pancreatic cancer have been initiated while several trials in other cancer types are in the planning stages [367716]. In September 1998, Pharmacyclics announced the initiation of a pivotal phase III trial for the treatment of patients with brain metastases. This multicenter trial originally included 30 sites in the US, Canada and Europe, and was expected to enroll 425 patients. The FDA agreed that this trial qualified for Fast Track review if efficacy end-points are met [301265]. By October 2000, nearly all 450 patients in 50 sites had been completed [375959], [387023]. In September 2000, Pharmacyclics and the National Cancer Institute (NCI) initiated two phase I trials of Gd-Tex. The first was to determine the safety of two different dosing regimens of the drug during preoperative radiotherapy after induction chemotherapy in patients with stage IIA non-small cell lung cancer (NSCLC). The second would examine the use of Gd-Tex in combination with stereotactic Gamma Knife radiosurgery in patients with primary brain tumors known as glioblastoma multiforme [381561]. A phase Ib/II trial, for brain metastases, was conducted in America and France, and involved over 100 patients. At the ASCO 1998 meeting, interim tumor response data were presented for 37 patients. The overall tumor response rate (complete plus partial response rate) was 73%. Furthermore, MRI scanning confirmed that Gd-Tex accumulated selectively in tumors [287459]. Full results were announced in October 1998 at the American Society of Therapeutic Radiology and Oncology. Following ten daily injections followed by whole brain radiation, 77.7% of patients demonstrated a tumor response defined as greater than 50% reduction in tumor volume. Gd-Tex was well tolerated, and liver enzyme elevation was the dose-limiting effect, which was reversible. Death due to tumor progression was seen in 15% of the Gd-Tex group as opposed to 35% in the control group [302872]. In November 1999, Pharmacyclics commenced a phase I trial of Gd-Tex injection, sponsored by the NCI, for treating children with intrinsic pontine glioma. The goals of the phase I dose-ranging study were to determine the Gd-Tex dose and administration schedule that can be safely administered with radiation and to evaluate the localization of Gd-Tex in affected tumors using MRI [348035]. In March 1997 the Decision Network of the NCI voted to sponsor additional clinical indications including adult and pediatric brain tumors, as well as cancers involving the lung, head & neck, pancreas and prostrate. Two phase I trials of Gd-Tex for the treatment of primary brain tumors commenced in August 1998 under a CRADA with the NCI [237538], [295592], [348919]. Pharmacyclics is collaborating with the NCI under a CRADA in phase I trials in primary brain tumors and pancreatic tumors [323929], [323952], [346596]. Analysts expected a filing to occur by the end of 1999 or early 2000, with sales in 2001 [303186].