Washington Editor

Allos Therapeutics Inc. expects its rolling new drug application for a candidate shown to double median survival time in breast cancer patients to be completed by the end of the year.

The NDA would seek approval for a product called RSR13 as an adjunct to whole-brain radiation therapy (WBRT) for the treatment of brain metastases originating from breast cancer. Allos, of Westminster, Colo., presented data Saturday from its pivotal Phase III trial of RSR13 for patients with brain metastases at the 8th annual meeting of the Society for Neuro-Oncology in Keystone, Colo.

David Bouchey, analyst with CE Unterberg Towbin in Denver who attended the meeting, on Monday told BioWorld Today he believes the FDA will accept Allos' NDA, and likely will ask the Oncologic Drug Advisory Committee to review the application.

"In terms of whether or not the FDA will give it final approval, it is probably more likely that the FDA will require a second confirmatory pivotal trial," he said. "But it is possible that the FDA will grant approval and then require post-marketing trials."

RSR13 (efaproxiral injection) is a synthetic small molecule that increases the release of oxygen from hemoglobin, which is important in treating hypoxia in connection with radiation treatments for cancerous tumors. It is designed to make radiation therapy more effective.

Initiated in February 2000, the Phase III included 538 patients suffering from brain metastases that originated from different types of cancer. Specifically, 56 percent of participants had non-small-cell lung cancer (NSCLC), 21 percent had breast cancer and 23 percent had other cancers.

A preliminary analysis of the trial released in April sent the company's stock tumbling 44.1 percent, or $1.50, to close at $1.90 when it was discovered that the trial didn't meet a statistical endpoint in the overall group. However, the company noticed a glimmer of hope in breast cancer. (See BioWorld Today, April 24, 2003.)

Allos' stock (NASDAQ:ALTH) rose 24 cents Monday to close at $2.99.

Median survival time in breast cancer patients with brain metastases showed a near doubling, from about 4.6 months in the control group to 8.7 months in the treatment arm, the company said. That subset included 115 patients.

Allos' stock jumped 61.5 percent, or $1.42, to close at $3.73 in May when the company said it planned to file based on the breast cancer data. (BioWorld Today, May 30, 2003.)

In its presentation titled "A Phase III, Randomized, Open-Label, Comparative Study of Standard Whole Brain Radiation Therapy with Supplemental Oxygen, With or Without RSR13, in Patients with Brain Metastases," the company Saturday said patients receiving RSR13 plus WBRT experienced a 17.6 percent improvement in median survival, compared to patients receiving WBRT alone (about 5.3 months vs. 4.5 months; p=0.17; n=538). The risk of death in all patients treated was reduced by 22 percent when RSR13 was added to whole-brain radiation therapy.

Monique Greer, Allos' director of corporate communications, told BioWorld Today the company has been granted fast-track status for RSR13 in brain metastases. However, Bouchey said since the company is filing on a subset of the original indication, he's not sure whether the fast-track status would apply.

Allos is considering partnering the drug either on a worldwide basis or in Europe.

Greer said the company plans to continue to study RSR13 in other cancers.