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Introgen's Novel P53 Cancer Vaccine Sensitizes Tumors to Platinum and Taxane Chemotherapies

Posted on: Monday, 16 May 2005, 09:00 CDT

ORLANDO, Fla., May 16 /PRNewswire-FirstCall/ -- Introgen Therapeutics, Inc. today reported interim results of its Phase 2 trial of INGN 225, its investigational cancer vaccine, in patients with advanced small cell lung cancer (SCLC) previously treated with chemotherapy. Following INGN 225 treatment, 67 percent of the evaluable patients in the study had objective responses (greater than 50 percent tumor reduction) to subsequent chemotherapy. The data were presented yesterday (Abstract #2543) at the 41st Annual Meeting of the American Society of Clinical Oncology (ASCO) in Orlando. Researchers at the H. Lee Moffitt Cancer Center are conducting the study in collaboration with Introgen.

"These results are very encouraging given the surprisingly substantial proportion of patients who responded to second-line chemotherapy following treatment with INGN 225," said Scott Antonia, M.D., Ph.D., associate professor in the Interdisciplinary Oncology Program at the H. Lee Moffitt Cancer Center and the leading clinical investigator in the study. "This high rate of response is not typically seen in this patient population, and the results observed so far suggest that INGN 225 may sensitize cancer cells to the effects of chemotherapy. This is a promising finding and suggests that INGN 225 may have important utility in the future treatment of small cell lung cancer."

INGN 225 is a therapeutic vaccine consisting of a cancer patient's dendritic cells, a type of immune cell, treated with an adenovector carrying the human p53 gene (Ad-p53). The abstract described results from patients with advanced SCLC. Eight weeks following the last dose of first line chemotherapy, dendritic cells were collected from each patient and treated in the laboratory with Ad-p53, to generate the INGN 225 vaccine. Initial results show that the vaccine was well tolerated, with no appreciable INGN 225 related toxicity in any of the treated patients.

After vaccine therapy, eighteen patients with progressive disease were treated with second-line chemotherapy. To date, 12 patients (66.7 percent) had objective responses or tumor reduction greater than 50%. Historically the expected objective response rate in these patients is between 20 and 30 percent. There was a statistically significant correlation between the development of a p53 immunological response to vaccination and objective responses to second line chemotherapy (p = 0.032).

"The expression of p53 is tightly regulated in normal cells, but becomes abnormally over expressed in a large number of cancers," said Dmitry Gabrilovich, M.D., Ph.D., associate professor of Oncology at the H. Lee Moffitt Cancer Center and principal investigator of the study. "The accumulation of high levels of p53 protein in cancer cells relative to normal cells makes the protein an excellent target for a cancer-specific immunotherapy. We are evaluating the mechanism by which INGN 225 appears to sensitize cancer cells to the effects of chemotherapy, which is an exciting finding that may help to further our understanding how p53-based cancer therapies may be used in clinical practice."

Robert E. Sobol, M.D., Introgen's senior vice president of Scientific and Medical Affairs said, "Our data in lung cancer patients indicate that INGN 225 may sensitize tumors to the effects of platinum and taxane chemotherapies. Of particular interest, patients with highly aggressive disease (termed Platinum resistant) showed improved response rates and increased survival compared to historical controls. Some patients refractory to chemotherapy became responsive to chemotherapy re-treatment after receiving INGN 225 vaccine. These findings are consistent with the results observed in lung and breast cancer patients with another of our p53 targeted therapies, ADVEXIN, that increased the expected effects of cisplatin, taxane and doxorubicin chemotherapies. As platinum, taxanes and doxorubicin are among the most common types of cancer chemotherapies, these findings have important future implications for improving the efficacy of these widely utilized cancer treatments."

INGN 225 is also being evaluated in a Phase 1/2 trial in patients with breast cancer. Introgen is also developing the Ad-p53 formulation, ADVEXIN(R), for the treatment of a variety of cancers.

Background on Chemotherapy

Platinum, Taxanes and Doxorubicin are widely employed drugs in the treatment of cancer that include Platinol (cisplatin) and Paraplatin (carboplatin) (marketed by Bristol-Myers Squibb), paclitaxel (Taxol(R) marketed by Bristol-Myers Squibb), docetaxel (Taxotere(R) marketed by Sanofi Aventis) and doxorubicin (Adriamycin marketed by Bedford Laboratories). These agents are among the most widely utilized forms of cancer chemotherapy. It is estimated by the American Cancer Society that approximately 650,000 patients are treated with chemotherapy annually in the United States.

About Introgen

Introgen is a leading developer of biopharmaceutical products designed to induce therapeutic protein expression using non-integrating gene agents for the treatment of cancer and other diseases. Introgen maintains integrated research, development, manufacturing, clinical and regulatory departments and operates a commercial-scale, CGMP manufacturing facility.

Certain statements in this press release that are not strictly historical may be "forward-looking" statements, which are based on current expectations and entail various risks and uncertainties. Such forward-looking statements include, but are not limited to, those relating to Introgen's future success with its clinical development program for INGN 225 for lung and other cancers. There can be no assurance that Introgen will be able to commercially develop gene-based drugs, that necessary regulatory approvals will be obtained or that any clinical trials or studies undertaken will be successful or that the proposed treatments will prove to be safe and/or effective. The actual results may differ from those described in this press release due to risks and uncertainties that exist in Introgen's operations and business environment, including, but not limited to, Introgen's stage of product development and the limited experience in the development of gene- based drugs in general, Introgen's dependence upon proprietary technology and the current competitive environment, history of operating losses and accumulated deficits, reliance on collaborative relationships, and uncertainties related to clinical trials, the safety and efficacy of Introgen's product candidates, the ability to obtain the appropriate regulatory approvals, Introgen's patent protection and market acceptance, as well as other risks detailed from time to time in Introgen's filings with the Securities and Exchange Commission including its annual report on Form 10-K filed with the Securities and Exchange Commission on March 15, 2005 and its quarterly report on Form 10-Q filed with the Securities and Exchange Commission on May 10, 2005. Introgen undertakes no obligation to publicly release the results of any revisions to any forward-looking statements that reflect events or circumstances arising after the date hereof.

Editor's Note: For more information on Introgen Therapeutics, or for a menu of archived press releases, please visit Introgen's Website at: http://www.introgen.com/

Contact:

Introgen Therapeutics, Inc.

C. Channing Burke

(512) 708 9310 Ext. 322

(512) 965-0907 (mobile)

Email: c.burke@introgen.com

Introgen Therapeutics, Inc.

CONTACT: C. Channing Burke of Introgen Therapeutics, Inc.,+1-512-708-9310 Ext. 322, or +1-512-965-0907 mobile, c.burke@introgen.com

Web site: http://www.introgen.com/

Source: PRNewswire-FirstCall

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