Allos Therapeutics Inc will submit a New Drug Application (NDA) to the U.S. Food and Drug Administration (FDA) to market RSR13 (efaproxiral) as a treatment for brain metastases from breast cancer. The company's decision follows a recent pre-NDA meeting with the FDA in which the company reviewed preliminary safety and efficacy data from its recently completed pivotal Phase 3 clinical trial and, specifically, the results in patients with metastatic breast cancer. RSR13 has fast-track designation from the FDA, and the company will begin a rolling submission of the NDA early in the third quarter of 2003. The company expects to complete the application in the fourth quarter of this year.
The results in patients with metastatic breast cancer represented a key observation from the Phase 3 trial. In a subset of 115 patients with metastatic breast cancer who received whole brain radiation therapy (WBRT) plus RSR13, patients achieved a median survival of 8.67 months versus 4.57 months for patients receiving WBRT alone (p=0.006). Overall, patients experienced a 51% reduction in risk of death in the RSR13 arm versus control. The increase in overall survival was further supported by an increased tumor response rate in the brain. Seventy-two percent (72%) of metastatic breast cancer patients receiving RSR13 achieved either a complete or partial response compared to 53% of patients in the control arm (p=0.04). In addition, Kaplan-Meier estimates for survival at 6, 12 and 18 months are 62%, 34% and 30%, respectively, in the RSR13 arm versus 42%, 17% and 0%, respectively, in the control arm.
"The FDA has expressed a clear interest in approving drugs that provide significant clinical benefit to patients, that are safe and that fulfill an unmet medical need," said Michael E. Hart, President and CEO of Allos Therapeutics, Inc. "Our decision to move forward with an NDA submission is based on consistent and compelling data observed in patients with metastatic breast cancer in which median survival was doubled in the RSR13 treatment arm. We will continue to work closely with the FDA during this process."
The company announced preliminary results of its pivotal Phase 3 trial in a press release on April 23, 2003 in which the reported survival benefit observed did not reach statistical significance in either of the pre-specified intent-to-treat groups using a primary unadjusted log-rank analysis of patients who received RSR13 plus WBRT versus patients who received WBRT alone. Further analysis of the intent-to-treat data using a Cox multiple regression analysis indicates that RSR13, when combined with WBRT, resulted in a statistically significant 22.5% reduction in risk of death (p=0.01).