(Adds details throughout, comment from CEO)
ZURICH, Oct 19 (Reuters) - Roche's third-quarter sales rose 6 percent, the world's biggest cancer drug maker said on Thursday, beating analyst forecasts thanks to better-than-expected revenue from its new multiple sclerosis medicine Ocrevus.
Third-quarter sales were 13.1 billion Swiss francs($13.37 billion), compared to the 13.04 billion francs average estimate by analysts in a Reuters poll. The company expects to hit its full-year sales and profit targets.
Sales of Ocrevus were 308 million francs, beating the poll average of 228 million and accelerating from 192 million francs in the second quarter.
Sales of Tecentriq, Roche's new cancer immunotherapy, doubled to 118 million francs, though they missed analyst estimates of 146 million francs amid market share losses to Merck & Co's rival Keytruda.
So far, Roche is making good on its promise to grow sales by developing new drugs like Ocrevus and Tecentriq as its older medicines' patents expire, exposing them to competition from biosimilars -- medicines that are highly similar to the original drug, making them safe and effective to use -- made by rivals.
"I am confident that we will achieve our full-year targets," Chief Executive Severin Schwan said. "The growth is largely driven by new product launches."
For 2017, Roche expects sales to grow at a mid-single-digit rate at constant exchange rates. Core earnings per share are seen growing broadly in line with sales, with a dividend increase planned.
The full impact of rivals' cut-price biosimilars on Roche's $21 billion-per-year trio of Rituxan, Avastin and Herceptin will not set in until after 2019, when Roche will also forego lucrative royalties from manufacturing patents.
Third-quarter sales of Rituxan, also known as Mabthera, rose 1 percent to 1.78 billion francs, despite the arrival of biosimilar versions from rivals including Novartis.
Sales of Herceptin, Roche's mainstay breast cancer medicine, were flat at 1.69 billion francs, while Avastin revenue slipped 4 percent to 1.59 billion francs. Perjeta, which Roche aims to increasingly combine with Herceptin, rose 17 percent to 552 million francs.
($1 = 0.9801 Swiss francs) (Reporting by John Miller; Editing by Michael Shields)