Seattle Genetics says leukemia drug fails trial

* Lintuzumab development program dropped

* Results of lymphoma trials expected within next 6 weeks

* Shares down 13.5 pct

LOS ANGELES, Sept 13 (Reuters) - Seattle Genetics SGEN.O said on Monday it would discontinue development of its experimental drug lintuzumab after a trial found it did not extend the lives of patients with acute myeloid leukemia and its shares fell 13.5 percent.

Wall Street analysts had modest expectations for lintuzumab, which was licensed by Seattle Genetics in 2005 after PDL BioPharma Inc PDLI.O decided not to pursue the antibody following disappointing results from leukemia trials using a lower dose of the drug.

The Phase IIb study was designed to show whether lintuzumab, or SGN33, in combination with low-dose chemotherapy, improved survival for people over the age of 60 who have acute myeloid leukemia, the most common type of the blood cancer in adults, compared to chemotherapy alone.

Seattle Genetics said the difference in overall survival between the treatment arms was not statistically significant, and patients in both groups lived longer than had been seen in previous studies of the chemotherapy regimen used in the trial.

“We continue to focus on advancing our lead program, brentuximab vedotin, or SGN35,” Clay Siegall, the company’s chief executive officer, told Reuters in a telephone interview.

He expects to have data from a trial of brentuximab vedotin in patients with Hodgkin lymphoma within the next few weeks, followed a few weeks later by results from a different Phase 3 trial in patients with anaplastic large cell lymphoma (ALCL).

Unlike lintuzumab, which is an older “naked” antibody, SGN35 is a conjugate made up of a tumor-targeting antibody linked to a chemotherapy drug called monomethyl auristatin E.

It targets an antigen expressed on Hodgkin lymphoma (HL), several types of T-cell lymphoma and other hematologic malignancies.

The company is developing the drug in partnership with Takeda Pharmaceutical Co Ltd 4502.T.

Seattle Genetics plans to file for U.S. regulatory approval of brentuximab vedotin as a treatment for HL in the first half of 2011 and may also file for ALCL at the same time, depending on results from the upcoming trial. (Reporting by Deena Beasley; Editing by Derek Caney)