(Fixes Allergan's stock symbol in penultimate paragraph to AGN.N from GAN.N)
ZURICH, June 20 (Reuters) - A Novartis drug to treat a leading cause of vision loss in people over 65 does not need to be injected as frequently as a rival medicine from Regeneron Pharmaceuticals to be effective, clinical trials showed on Tuesday.
Novartis said the trials showed its RTH258 drug would reduce the injection burden for patients with neovascular age-related macular degeneration (nAMD).
Novartis shares were up 0.8 percent, with analysts saying the trial results gave RTH258 a competitive advantage over rival treatments.
Head-to-head late-stage trials showed RTH258, which goes by the generic name brolucizumab, worked as well as Regeneron's Eylea, with just over half the patients needing doses every 12 weeks, rather than every eight weeks for Eylea.
While the data appeared to be negative for Regeneron, its shares surprisingly surged 6.7 percent to $503.59, a level not seen since February 2016.
Leerink Partners analyst Geoffrey Porges said the data removes an uncertainly for Regeneron investors who had been on the sidelines and were now looking to take advantage of the positive sales trajectory of Dupixent, the company's recently approved treatment for severe atopic dermatitis.
He added that it appeared the potential negative impact of Novartis data was already fully priced into the Regeneron stock.
Still, analysts at Jefferies called the trial result "a significant differentiator and competitive advantage for RTH258."
Cutting the frequency of injections could also give RTH258 an edge over Lucentis, a best-selling eye drug that Roche sells in the United States and Novartis sells elsewhere. Lucentis patients generally receive doses every four weeks.
"It exceeds our expectations and we're looking forward to filing in 2018" for regulatory approval, Vas Narasimhan, Novartis's drug development chief, said in an interview.
"We had hoped to see 40 percent or greater" of patients responding positively to injections every 12 weeks, he said. "Now that we see it well into the 52 to 57 percent range, we feel very good about the result."
Novartis expects eventual annual sales to top $1 billion.
Zuercher Kantonalbank analyst Michael Nawrath said the data should help Novartis win back share in a highly lucrative market of 20 million to 25 million patients.
Eylea, which was developed with Bayer, has powered much of Regeneron's growth since late 2011. However, the drug's sales growth has slowed, mainly due to competition from Lucentis. Lucentis topped $3.2 billion in sales in 2016 for Roche and Novartis.
Regeneron is betting on Dupixent and its also just approved Kevzara for rheumatoid arthritis, both with blockbuster potential, to reduce its reliance on Eylea, which accounts for nearly 70 percent of its revenue.
Competition for nAMD patients is likely to grow even more intense, with data from trials on Abicipar, an investigational medicine being developed by Allergan and Switzerland's Molecular Partners, set for release in 2018.
Allergan is also banking on reduced injection frequency compared to Lucentis and Eylea to win over eye doctors and patients, should its drug win approval. (Additional reporting by Bill Berkrot in New York; Editing by David Clarke and Bernadette Baum)