Allos Therapeutics

(ALTH)

reported Saturday median overall survival of almost 15 months for patients with a rare but aggressive form of blood cancer treated with the company's experimental drug pralatrexate.

The updated results come from a pivotal phase II study of pralatrexate presented at the American Society of Clinical Oncology (ACSO) annual meeting being held this weekend in Orlando.

The U.S. Food and Drug Administration is already reviewing pralatrexate, with an approval decision expected by Sept. 24.

Allos is seeking permission to market the drug as a treatment for peripheral T-cell lymphoma (PTCL), a fast-growing cancer that affects white blood cells known as T-cells. There are no approved drugs to treat the disease.

The phase II study enrolled 115 patients with PTCL, 109 of whom were evaluable for response. All patients were previously treated with a variety of chemotherapy drugs but their cancer continued to grow.

After treatment with pralatrexate, 30 patients, or 28%, saw their tumors shrink, including 10 patients, or 9%, who went into complete remission. The median duration of response to pralatrexate was 9.4 months. These results are slightly improved from previous presentations of the data last year.

Newly disclosed information Saturday on pralatrexate was the median overall survival of 14.7 months, with 57% of the responders surviving for a year or more.

Allos was able to submit pralatrexate for FDA approval based on this small phase II study because PTCL is diagnosed in only about 5,000 U.S. patients each year. The FDA didn't require Allos to compare the response rate of pralatrexate to another drug in the study because all the enrolled patients were previously treated, most multiple times, without success.

Pralatrexate, or PDX, is a chemotherapy drug known as an "antifolate" that works by interfering with the ability of cancer cells to divide, resulting in cell death. Allos designed pralatrexate to be more potent than other antifolates, including the widely used drug methotrexate.

Eli Lilly's

(LLY) - Get Report

cancer drug Alimta is another antifolate, approved for the treatment of lung cancer.

Allos is also testing pralatrexate in other forms of non-Hodgkin's lymphoma and lung cancer. One of the lung cancer studies under way pits pralatrexate against Tarceva, a lung cancer drug marketed by

OSI Pharmaceuticals

(OSIP)

and

Genentech

.

Allos shares closed Friday up 6.6% at $7.28.

Adam Feuerstein writes regularly for TheStreet.com. In keeping with TSC's editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet.com. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback;

click here

to send him an email.