Lonza CEO says reviewing biosimilar venture with Teva ZURICH (Reuters) - Swiss specialty chemicals and life sciences group Lonza is reviewing whether it is still worth investing in its joint venture with Teva in "biosimilar" drugs, its Chief Executive said. The expiry of patents on expensive biotech medicines to treat cancer and autoimmune diseases is opening up a new market for lower-cost copies known as "biosimilars" because they are not identical matches of branded medicines. But uncertainty over the regulatory framework for such drugs in the United States as well as the defense strategies from innovator companies have caused delays and prompted some developers to halt projects. Lonza joined forces with Israel's Teva in 2009 to develop biosimilars but suspended its late-stage trial for a biosimilar version of Roche's drug MabThera last October to seek input from regulators on how to proceed. "A joint venture team is reassessing at the moment whether our assumptions from 2009 are still correct," Richard Ridinger said in an interview with Finanz und Wirtschaft published on Saturday. I would like absolute clarity before we make a large investment. The quality of decisions is more important than speed. Ridinger said the cost of developing biosimilars would be "considerably more" than the 100 million Swiss francs ($105.60 million) per biosimilar assumed in 2009 and that Lonza wanted to be completely clear how and whether they wanted to strengthen this area. "It's not clear if this business model, which we acted on in 2009, still works today," Ridinger said. Asked whether the biosimilar project could cease to exist, Ridinger said the company had not yet concluded its evaluation. ($1 = 0.9470 Swiss francs) Reporting by Caroline Copley; editing by Patrick Graham