SEATTLE ( TheStreet) -- Seattle Genetics (SGEN) will seek to expand the approved use of its Hodgkin lymphomadrug Adcetris following positive results from a phase III study, the company announced Monday.

In the study (known as AETHERA), treatment with Adcetris in "high risk" Hodgkin lymphomapatients immediately after a stem-cell transplant led to a 43% reduction in the risk of disease progression compared to placebo. The result was statistically significant and met the primary endpoint of the study.The Hodgkin lymphoma patients enrolled in the study were deemed to be "high risk" because they had at least one factorthat made them more susceptible to disease relapse.

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Despite delaying disease progression, treatment with Adcetris did not prolong survival compared to placebo in the phase III study at this analysis, which the company blames partly on placebo patients "crossing over" to receive Adcetris once their disease progressed. Another survival analysis of the study will be conducted in 2016. Adcetris' safety profile was "generally consistent" with previous studies, the company said. No further details were disclosed, pending presentation of the results at a future medical meeting.

Adcetris is already approved to treat more advanced Hodgkin patients who don't respond to a stem cell transplant or who are not eligible for stem cell transplants. Seattle Genetics plans to submit the results from the AETHERA trial to the FDA, seeking approval to expand the drug's use.

Seattle Genetics estimates there are about 1,000 to 1,500 post-transplant Hodgkin lymphoma patients. This represents a modest increase in the number of patients eligible for Adcetris and not as significant a commercial opportunity as treating newly diagnosed Hodgkin lymphoma patients. Studies investigating Adcetris' role in front-line Hodgkin are underway but not yet completed.

Seattle Genetics shares are up 4% to $43 in Monday pre-market trading.

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Seattle Genetics Seeks Expanded Use of Lymphoma Drug Following Study Win