Medarex Reports Interim Data From Ongoing Ipilimumab Combination Phase 1 Studies In Prostate Cancer At American Association For Cancer Research

Main Category: Prostate / Prostate Cancer
Also Included In: Endocrinology;  Clinical Trials / Drug Trials;  Pharma Industry / Biotech Industry
Article Date: 16 Apr 2008 - 0:00 PDT

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Medarex, Inc. (Nasdaq: MEDX) announced interim results from two ongoing Phase 1 trials in hormone refractory prostate cancer (HRPC) demonstrating dose-dependent T-cell activation and clinical activity of ipilimumab, an investigational anti-CTLA-4 antibody. These studies were done in combination with antigen-releasing immunotherapies based on GM-CSF, a cytokine that stimulates the proliferation of white blood cells and augments immune responses, and results were presented in two separate oral presentations by investigators at the Annual Meeting of the American Association for Cancer Research (AACR), being held April 12-16, 2008 in San Diego.

"The interim results demonstrating clinical activity in these ongoing trials lend additional support to the concept of ipilimumab as part of a therapeutic regimen in treating prostate cancer," said Geoffrey M. Nichol, M.B.Ch.B., Senior Vice President of Product Development at Medarex. "We will continue to explore the prospects of ipilimumab in HRPC, and we expect further data in prostate cancer for ipilimumab monotherapy and in combination with other antigen-releasing agents at this year's ASCO conference in June."

-- "Dendritic and T cell functions in patients with metastatic hormone-refractory prostate cancer treated with GVAX immunotherapy for prostate cancer and ipilimumab" (Abstract #2538)

Interim data from the ongoing Phase 1 study of escalating doses of ipilimumab in combination with the Cell Genesys, Inc. GVAX immunotherapy for prostate cancer (an investigational agent comprised of whole tumor cells modified to secrete GM-CSF) were presented by Saskia JAM Santegoets, Ph.D., from the Department of Medical Oncology and Pathology of Vrije Universiteit Medical Center located in Amsterdam, Netherlands. The data suggested an ipilimumab dose-related association with increased T-cell activation, as well as associated anti-tumor activity from the initial 12 patients that was previously reported at the June 2007 American Society of Clinical Oncology (ASCO) meeting.

In the Phase 1 clinical trial, 28 patients with metastatic HRPC have been enrolled, including 12 patients in the dose-escalation cohort (0.3, 1, 3 or 5 mg/kg ipilimumab) and 16 patients in the expansion cohort (3 mg/kg ipilimumab). The dose of GVAX immunotherapy for prostate cancer used in this combination trial is comparable to that currently being evaluated in Cell Genesys' ongoing Phase 3 program. The treatment combination was generally well-tolerated. Adverse events associated with this regimen are consistent with data previously reported from this study.

-- "CTLA-4 blockade for hormone refractory prostate cancer: dose-dependent induction of CD8+ T cell activation and clinical responses" (Abstract #2539)

Preliminary data from an ongoing Phase 1 study of escalating doses of ipilimumab in combination with GM-CSF (sargramostim) were presented by Lawrence Fong, Ph.D., from the University of California, San Francisco, San Francisco. Of the six patients treated at 3 mg/kg ipilimumab, three experienced confirmed decreases in prostate-specific antigen (PSA) serum levels of over 50%, and one of these patients experienced a partial response in hepatic metastases.

In the Phase 1 clinical trial, 26 patients with HRPC received treatment with a 28-day cycle of daily doses of 250 mg/m2 of GM-CSF for 14 days in combination with ipilimumab administered on the first day of the 28-day cycle for up to four cycles. Ipilimumab dosing initially ranged from 0.5 mg/kg to 3 mg/kg. Additional patients are now being treated with higher doses (5 mg/kg and 10 mg/kg) of ipilimumab. The treatment combination was generally well-tolerated. Adverse events associated with ipilimumab treatment are consistent with data previously reported from this study and from other clinical trials of ipilimumab.

About Medarex

Medarex is a biopharmaceutical company focused on the discovery, development and potential commercialization of fully human antibody-based therapeutics to treat life-threatening and debilitating diseases, including cancer, inflammation, autoimmune disorders and infectious diseases. Medarex applies its UltiMAb(R) technology and product development and clinical manufacturing experience to generate, support and potentially commercialize a broad range of fully human antibody product candidates for itself and its partners. More than 40 of these therapeutic product candidates derived from Medarex technology are in human clinical testing or have had INDs submitted for such trials, with seven of the most advanced product candidates currently in Phase 3 clinical trials or the subject of regulatory applications for marketing authorization. Medarex is committed to building value by developing a diverse pipeline of antibody products to address the world's unmet healthcare needs. For more information about Medarex, visit its website at http://www.medarex.com.

Medarex Statement on Cautionary Factors

Except for the historical information presented herein, matters discussed herein relating to the interim data from ongoing ipilimumab combination Phase 1 studies may constitute forward-looking statements that are subject to certain risks and uncertainties that could cause actual results to differ materially from any future results, performance or achievements expressed or implied by such statements. Statements that are not historical facts, including statements preceded by, followed by, or that include the words "preliminary"; "interim"; "potential"; "may"; or similar statements are forward-looking statements. Medarex disclaims, however, any intent or obligation to update these forward-looking statements. Risks and uncertainties include risks associated with product development, unforeseen safety issues resulting from the administration of antibody products in humans, as well as risks detailed from time to time in Medarex's public disclosure filings with the U.S. Securities and Exchange Commission (SEC), including its Annual Report on Form 10-K for the fiscal year ended December 31, 2007 and its quarterly reports on Form 10-Q. There can be no assurance that future milestone payments will be paid, whether the product development efforts will succeed, or whether other developed products will receive required regulatory clearance or that, even if such regulatory clearance were received, such products would ultimately achieve commercial success. Copies of Medarex's public disclosure filings are available from its investor relations department.

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