(Adds details on drug, rival drugs, new treatment approach)
Aug 21 (Reuters) - An experimental new psoriasis treatment from Eli Lilly and Co proved superior to Amgen Inc's blockbuster Enbrel, drawing it closer to a potential marketing battle with new products being developed by Amgen and Novartis AG.
Based on favorable results from Phase III trials, Lilly said Thursday it would seek marketing approval in the first half of 2015 for its drug ixekizumab for patients with moderate-to-severe plaque psoriasis.
Cowen and Company analysts have forecast that ixekizumab, if approved, could generate annual sales for Lilly of $600 million by 2020. That would make it a mid-sized product for the company, which has annual sales of about $20 billion.
Lilly needs new drugs to restore earnings growth, as profits have dropped for several years due to the expiration of patents on big products.
Like rival injectable drugs being tested by Amgen and Novartis, Lilly's treatment works by blocking an inflammation-causing protein called IL-17, deemed to be a major culprit in the skin disease.
Enbrel, Amgen's older drug, is the most widely prescribed treatment for psoriasis and works by blocking a different protein, called tumor necrosis factor.
After 12 weeks, patients treated with ixekizumab had significantly greater clearance of raised skin patches that are a hallmark of psoriasis, compared with those who took placebos or Enbrel (etanercept) in the large trials, Lilly said.
In all three studies, patients received either a placebo or ixekizumab every two or four weeks, for three months. In two of those studies, called UNCOVER-2 and 3, patients could receive Enbrel twice weekly. In UNCOVER-1, those responding to treatment continued to take either placebos or ixekizumab for up to 60 weeks.
Among patients treated with Lilly's drug, 78 to 90 percent experienced at least a 75 percent reduction of skin plaque at 12 weeks, based on a standard scale of psoriasis area and severity.
Moreover, some 31 to 41 percent achieved clear skin. That compared with 5 to 7 percent of those treated with Enbrel in the UNCOVER-2 and 3 studies. In the UNCOVER-1 study, high levels of effectiveness were maintained through 60 weeks of treatment.
The overall rate and severity of side effects for ixekizumab were similar to those seen for Enbrel, including stuffy nose and reactions at the injection site, Lilly said.
Novartis' treatment against IL-17, secukinumab, recently met all its primary and secondary goals in late-stage trials, showing superiority to Enbrel in one study.
Amgen and its partner AstraZeneca Plc in May reported favorable results for their anti-IL-17 drug, called brodalumab, in a late-stage trial.
Psoriasis is a chronic autoimmune disease in which the growth cycle of skin cells is accelerated.
The most common form, plaque psoriasis, appears as raised, red patches covered with a silvery white buildup of dead skin cells. About 17 percent of an estimated 125 million psoriasis patients worldwide have moderate-to-severe plaque psoriasis.
Lilly shares were little changed in afternoon trading.
(Additional reporting by Natalie Grover in Bangalore; Editing by Bernadette Baum)