Analysis of Data from Two Phase 3 Studies Shows DIFICID® Offered Faster Diarrheal Symptom Improvement than Oral …

SAN DIEGO, May 16, 2012 /PRNewswire/ -- Optimer Pharmaceuticals, Inc. (OPTR) today announced the results of a retrospective subpopulation analysis of 183 patients with cancer from the company's two large Phase 3 trials, which showed the cancer patients with Clostridium difficile-associated diarrhea (CDAD) who were treated with DIFICID (fidaxomicin) tablets experienced resolution of their diarrheal symptoms approximately two days faster than those treated with oral vancomycin. These results will be presented on June 2nd at the 2012 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, IL.

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"CDAD is a serious complication for cancer patients and potentially can disrupt the effects of cancer treatment and result in dehydration, impaired functioning, fatigue and, in severe cases, death," said Kathleen Mullane, D.O., Associate Professor of Medicine, Section of Infectious Diseases and Global Health, at the University of Chicago. "The results of this analysis indicate DIFICID may provide faster resolution of diarrhea when compared to vancomycin in a subset of cancer patients. While further studies are needed to confirm these findings, the results suggest the drug may serve as an important treatment option for this population and others at heightened risk for CDAD."

The analysis assessed treatment outcomes between patients with active cancer and patients without cancer who were treated with either DIFICID or oral vancomycin in two large, pivotal, Phase 3 studies. Results showed that overall, cancer patients with CDAD had slower time to resolution of diarrhea (TTROD) than non-cancer patients (100 hours vs. 55 hours, respectively; K-M log rank p<0.001). However, when treatment outcomes were compared between cancer patients receiving DIFICID or oral vancomcyin, patients treated with DIFICID experienced resolution of diarrhea two days faster than those treated with vancomycin (74 hours vs. 123 hours, respectively; K-M log rank p=0.045). The overall safety profile was similar between the DIFICID and vancomycin treatment groups.

"Fast resolution of diarrhea is critically important for patients undergoing cancer treatment to help resume focus on their primary cancer treatment as quickly as possible," said Sherwood L. Gorbach, M.D., Chief Scientific Officer and Senior Vice President of Optimer Pharmaceuticals, Inc. "These results further support the strong efficacy profile of DIFICID."

Additional results from the retrospective subpopulation analysis that demonstrate the effectiveness of DIFICID in treating CDAD in cancer patients recently were presented at the 22nd European Congress of Clinical Microbiology and Infectious Diseases (ECCMID). These results showed that DIFICID was five times more likely than vancomycin to produce a clinical response and three times more likely to lead to a sustained response, while patients treated with vancomycin had a 2.6 fold greater risk of experiencing recurrence. Specifically, DIFICID provided superior response compared to vancomycin across all clinical endpoints studied: clinical response (97.3% vs. 87.5%, 95% CI 1.07-23.98; p=0.041), sustained response (83.6% vs. 61.3%, 95% CI 1.50-6.91; p=0.003) and disease recurrence (14.1% vs. 30.0%, 95% CI 0.16-0.89; p=0.025).

Infections caused by C. difficile and the resulting CDAD pose a significant threat to cancer patients, primarily those with compromised immune systems due to chemotherapy or stem cell transplants. Cancer patients also are at risk for CDAD due to prolonged hospitalization and exposure to antibiotics. In fact, cancer patients with solid tumor or hematologic malignancies account for 16% of hospital CDAD cases.

About the Study

The results are based on two randomized, double-blind, non-inferiority Phase 3 trials conducted at sites in North America and Europe. Subjects with confirmed CDAD received either 200 mg DIFICID (fidaxomicin) dosed orally twice daily or 125 mg vancomycin dosed orally four times daily for 10 days. The primary objective of the trials was to compare the safety and efficacy of a 10-day course of DIFICID versus a 10-day course of vancomycin for the treatment of CDAD in adults. These studies served as the basis of approval for DIFICID by the U.S. Food and Drug Administration (FDA) in May 2011.

The subpopulation analysis evaluated the treatment of 183 CDAD patients with active cancer compared to 922 CDAD patients without cancer who were among the modified intent to treat population of the Phase 3 studies (N=1105). To be included in the analysis, patients must have had a current diagnosis of cancer at the time of CDAD diagnosis and were receiving various forms of treatment. Patients with active cancer (solid tumor or hematologic malignancy) were identified from medical history, concomitant medication indications, and adverse event entries in the case report forms. The analysis assessed the number of unformed bowel movements (UBM) per 24 hours to determine time to resolution of diarrhea (TTROD) defined as the duration of passing UBMs following initial treatment, with an active response considered as <3 UBM/24 hours. TTROD was defined as hours from first dose of treatment to last UBM on the day preceding two days of <3 UBM/24 hours.

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Analysis of Data from Two Phase 3 Studies Shows DIFICID® Offered Faster Diarrheal Symptom Improvement than Oral ...