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AustCancer Vaccine Adjuvant Demonstrates Enhanced Immune Response in Prostate Cancer Patients

Posted on: Wednesday, 23 February 2005, 18:00 CST

Results from a Phase I Study Conducted at Memorial Sloan-Kettering Cancer Center Utilizing GPI-0100 Published in Vaccine

Australian Cancer Technology (AustCancer) (ASX:ACU) today announced that Phase I clinical studies utilizing the company's lead vaccine immunostimulant GPI-0100 demonstrated enhanced immune response in patients with relapsed prostate cancer. The results of the study data were reported in an electronic publication of the journal Vaccine (doi:10.1016/j.vaccine.2005.01.072). This is the first report of the use of GPI-0100 in humans.

The Phase I study, led by Susan Slovin, M.D., assistant professor of medicine at Memorial Sloan-Kettering Cancer Center, included patients with progressive prostate disease after primary surgery or radiotherapy. Patients had no evidence of disease except for rising PSA levels. The dose-escalation study sought to determine the optimal (in terms of antibody response) and safe dose range of the adjuvant GPI-0100 when used with a bivalent conjugate vaccine (glycosylated MUC-2-KLH and Globo H-KLH). Cohorts of five patients received vaccine formulations containing the same amount of conjugate but with escalating doses (100, 300, 1,000 or 3,000ug) of GPI-0100 to assess safety.

Subsequent studies in 14 patients at doses of 1,000, 3,000 and 5,000ug were carried out using a more purified GPI-0100. Another cohort of 9 patients was enrolled in a second trial with the same vaccine using the competitive saponin adjuvant QS-21 at 100ug, a dose established in earlier trials.

"Currently, there is no standard of care for patients who have rising PSA levels after primary therapy failed," said Paul Hopper, AustCancer's chief executive officer. "While the development of cancer vaccines is promising, we believe it may be significantly strengthened by the use of GPI-0100 to induce a stronger immune response in cancer patients. We are very encouraged by the results found in this study and intend to evaluate GPI-0100 further in several vaccine development projects including cancer and infectious agent vaccines."

In the prostate cancer patients treated, all of the vaccines containing GPI-0100 were found to be safe. Serologic responses, flow cytometric analysis and the impact on PSA levels were evaluated in all patients. Patients receiving the two GPI-0100 batches showed comparable grade I local reaction but slightly less grade II local reactivity using the more purified GPI-0100. Overall, patients receiving GPI-0100 had significantly less pain or inflammation at the injection sites and fewer systemic symptoms compared to patients receiving QS-21 who had similar antibody titers. The present study shows that GPI-0100 appears to be safe and to stimulate a strong immune response in man, warranting its use in further vaccine studies. The impact of immunotherapies on biomarkers such as PSA and their effects on disease progression has yet to be conclusively validated.

Vaccine adjuvants are integral for use in vaccine development as they help determine the nature of the body's immune response and aid in directing the body to stimulate either the production of antibodies or cell-mediated immunity. Most adjuvants primarily elicit only a humoral response and are not capable of stimulating the production of cytotoxic T lymphocytes (T-cells), potentially limiting their use in protection against certain diseases such as cancer and different viral infections. Certain saponins, naturally occurring glycosides found in many plants, have been shown to stimulate both a humoral and cell-mediated immunity, but their toxicity and instability limits their use in vaccines.

GPI-0100 is AustCancer's lead compound for use in the active immunotherapy of cancer and some chronic infectious diseases. A semi-synthetic compound derived from saponins, GPI-0100 acts by up-regulating the body's immune system and stimulating both humoral and an effective T-cell immunity with CTL production. Different from certain immune stimulatory saponins, GPI-0100 has superior stability and safety profile, making it an ideal candidate for the development of novel therapeutics or preventive vaccines.

Further clinical trials at Memorial Sloan-Kettering are being planned for melanoma, neuroblastoma, breast cancer, ovarian cancer and chronic myeloid leukemia patients using the GPI-0100 adjuvant. GPI-0100 currently is being evaluated in a Phase I study in combination with HER-2 vaccine for breast cancer at the University of Alabama at Birmingham Comprehensive Cancer Center. In addition, a Phase I folate kidney cancer vaccine using GPI-0100 is being studied by Endocyte at Baylor University, Texas.

About Australian Cancer Technology (www.austcancer.com.au)

Australian Cancer Technology (AustCancer) is an international biotechnology company developing a broad oncology-related product portfolio. AustCancer has acquired the North American marketing rights for RP101, a promising pancreatic cancer drug currently in Phase II clinical studies through a subsidiary company, Resistys Inc, a joint venture with Bioaccelerate of New York. AustCancer's Pentrys(TM) anti-cancer vaccine is being evaluated in prostate cancer patients in Phase IIb clinical studies and the company is advancing immune enhancing adjuvants in three Phase I cancer trials. The company also markets revisys(TM), a branded line of medical nutritionals designed for people with special needs, including those undergoing cancer treatments. AustCancer is traded on the Australian Stock Exchange (ASX) under the symbol ACU. The company has established a Level 1 ADR stock program in the U.S. trading under the symbol AUCJY and also is listed on the Xetra exchange, the electronic trading system of the Frankfurt Stock Exchange, trading under the symbol CBS.

Forward-Looking Statements

Statements contained in this press release that are not historical information are forward-looking statements as defined within the Private Securities Litigation Reform Act of 1995. Such forward-looking statements are subject to risks and uncertainties that could cause Australian Cancer Technology's ("company") actual results to differ materially from those projected or implied. Such potential risks and uncertainties relate, but are not limited, to the results of clinical trials, product demand and market acceptance, the impact of competitive products and pricing, effectiveness and pace of current and future product development, and regulatory approval. More detailed information on these and additional factors that could affect the company's operating and financial results are described in the company's annual reports filed or to be filed with the Australian Stock Exchange. The company urges all interested parties to read these reports to gain a better understanding of the many business and other risks that the company faces. The historical results achieved by the company are not necessarily indicative of its future prospects. The company undertakes no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

Source: Business Wire

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