Ascenta Therapeutics Announces Positive Preliminary Results with AT-101 in Docetaxel Refractory Prostate Cancer
MALVERN, Pa., February 27, 2009 /PRNewswire/ -- Ascenta Therapeutics announced today positive preliminary results from its Phase II study of AT-101 in combination with docetaxel and prednisone (D/P) in men with docetaxel refractory, castrate resistant prostate cancer (CRPC) at the American Society of Clinical Oncology (ASCO) Genitourinary Cancers Symposium in Orlando, FL. AT-101, an oral, pan-Bcl-2 inhibitor currently in double-blinded, randomized Phase II clinical trials in both prostate cancer and non-small cell lung cancer, is the lead compound in Ascenta Therapeutics' portfolio of apoptosis-triggering small molecules.
"This is the first report of several we plan to present this year from a large and growing data set demonstrating the broad therapeutic potential of AT-101," said Mel Sorensen, MD, CEO of Ascenta Therapeutics. "The evidence of resistance reversal from this refractory population supplements the earlier clinical data demonstrating robust activity with the same regimen in docetaxel-naive patients."
Initial findings from the ongoing open-label, multi-center study demonstrates that AT-101 can be administered safely with D/P in these patients. Investigators also observed clinical responses, based on both PSA and RECIST criteria, including four patients with a confirmed PR (partial response, defined as a PSA decline of 50 percent or greater).
"This first look at the data is very encouraging, particularly since all of these patients were truly refractory to docetaxel, having not simply failed to respond but actually experienced disease progression during prior therapy," said James Reeves, MD, principal investigator, Florida Cancer Specialists. "Our results to date suggest that stimulating cancer cell apoptosis through Bcl-2 pathways with AT-101 may in fact extend the clinical utility of docetaxel in this cohort of highly treatment-resistant patients."
The analysis included data from 37 men with docetaxel-refractory CRPC who were treated with D (75 mg/m(2) q3 weeks), P (5 mg b.i.d. on days 1-21) and AT-101 (40 mg b.i.d. on days 1-3 of each 21-day cycle). Safety and efficacy were assessed at three-week intervals, with radiological assessments performed at 6-week intervals for patients with soft tissue disease and bone scans performed after cycle 6 and at completion of therapy. Ten of the 37 patients remain on study.
Thirty-eight percent (14/37) of patients treated had at least a 30 percent decrease in PSA level and 19 percent (7/37) achieved a confirmed PR. Twenty patients had measurable disease, five of whom (25 percent) had a PR by RECIST criteria, with additional patients eligible to achieve a response. Four patients have been on therapy for 6 months or more.
Safety data was available for 22 patients. The most common (10 percent or greater) adverse events included fatigue (50 percent), diarrhea (27 percent), nausea, anorexia, and neutropenia (all 23 percent), vomiting and dizziness (18 percent). The most common Grade 3/4 toxicity was neutropenia (23 percent) and was the only Grade 3/4 adverse event that occurred in more than two patients (5 patients). These adverse events were considered manageable and consistent with the safety profile of D/P.
The American Cancer Society estimates that more than 186,000 new cases of prostate cancer were diagnosed in the United States and that more than 26,000 men died of the disease in 2008, making it the second leading cause of cancer deaths among American men after lung cancer. Approximately half of all patients with prostate cancer suffer recurrent, advanced disease after definitive local therapy with radiation or prostatectomy and systemic treatment. One process by which prostate cancers may develop resistance to systemic treatment is by increasing the expression of proteins that inhibit apoptosis (programmed cell death). The most recognized group of such proteins are the antiapoptotic members of the Bcl-2 family, including Bcl-2, Bcl-XL, and Mcl-1. Overexpression of Bcl-2 family proteins in human tumor specimens has been reported by several groups to be associated with recurrence, more advanced stage, treatment resistance, the development of hormone-resistance, and shortened survival in prostate cancer.
AT-101 is an orally-active, pan-Bcl-2 inhibitor (including Bcl-2, Bcl-xL, Bcl-w, and Mcl-1 inhibition), that has been shown to directly induce apoptosis by operating as a BH3 mimetic and indirectly as an independent upregulator of Noxa and Puma. By blocking the binding of Bcl-2 family members with proapoptotic proteins and upregulating specific proapoptotic factors, AT-101 lowers the threshold for cancer cells to undergo apoptosis in various tumor types. In Phase I and Phase II trials, AT-101 has demonstrated single-agent cytoreductive activity in chronic lymphocytic leukemia (CLL), non-Hodgkins lymphoma (NHL), and prostate cancer. Phase II combination trials are ongoing in hormone-refractory prostate cancer and non-small cell lung cancer (with Taxotere(R) [docetaxel]), B-cell malignancies (with Rituxan(R) [rituximab]), small cell lung cancer (with Hycamtin(R) [topotecan]), glioma (with Temodar(R) [temozolomide], +/- chemoradiotherapy [XRT]) and in esophageal cancer (with docetaxel, 5-fluorouracil and XRT). Recently, two double-blinded, randomized, controlled trials of the docetaxel + AT-101 combination were opened in hormone-refractory prostate cancer and non-small cell lung cancer, both indications in which docetaxel is approved as a single agent.
Ascenta Therapeutics, Inc. is a privately-held, clinical-stage biopharmaceutical company that discovers and develops new medicines for the treatment of cancer. The company is headquartered in Malvern, Pennsylvania, and has a preclinical research facility in Shanghai, China. Its technology, licensed from both the National Institutes of Health and the laboratory of Dr. Shaomeng Wang at the , is focused on discovering molecules that target proteins that prolong cell survival.
Taxotere(R) is a registered trademark of sanofi-aventis U.S. LLC
Rituxan(R) is a registered trademark of Biogen Idec Inc. and Genentech USA, Inc.
Hycamtin(R) is a registered trademark of GlaxoSmithKline
Temodar(R) is a registered trademark of Schering Corporation
CONTACT: Mike Beyer of Sam Brown Inc. for Ascenta Therapeutics,+1-773-463-4211, firstname.lastname@example.org
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Posted: February 2009