The approval was based on results from a late-stage study, which showed the Tecentriq regimen helped patients with metastatic non-squamous non-small cell lung cancer (NSCLC) live significantly longer, compared with Avastin and chemotherapy, the company said in a statement.

The drug on Wednesday had also won priority review from the U.S. regulator for treating patients with untreated extensive-stage small cell lung cancer.

Tecentriq is already approved in the United States to treat certain types of lung cancers, as well as a type of bladder and urinary tract cancer.

The drug, however, has trailed Merck's Keytruda and Bristol Myers Squibb's Opdivo in revenue as those medicines beat it to market in other indications.

An estimated 234,000 Americans will be diagnosed with lung cancer in 2018, with non-small cell lung cancer accounting for 85 percent of all lung cancers, the drugmaker said, citing data from American Cancer Society.

The long-awaited FDA decision is a shot in the arm to Roche's aspirations of boosting Tecentriq sales in earlier lines of lung cancer treatment, but first-mover advantage of Merck's Keytruda has dented the medicine's prospects in one of cancer treatment's most-lucrative segments.

The FDA's blessing is based on Roche's IMpower 150 trial, in which Tecentriq -- also known as atezolizumab -- was tested in combination with Avastin, carboplatin and paclitaxel for the initial treatment of people with NSCLC.

Though the drug cocktail had won speedy review from U.S. regulators, they had pushed back their decision in September by another three months. Roche said the pause was meant to allow the company to provide more information to its application, without giving specifics.

Tecentriq's 524 million Swiss francs ($528 million) in sales through September -- in later-stage lung cancer treatment, as well as for bladder cancer -- were just a fraction of revenue posted by Keytruda and Bristol-Myers Squibb's Opdivo.