The U.S. Food and Drug Administration has given full approval to AstraZeneca PLC’s (AZN) Tagrisso, a lung cancer drug, for the treatment of patients with metastatic epidermal growth factor receptor, or EGFC,  T790M mutation-positive non-small cell lung cancer — or NSCLC. (See also: AstraZeneca's NMOSD Drug Gets EU Orphan Drug Status.)

According to AstraZeneca’s press release, the approval covers patients whose disease has advanced on or after an EGFR tyrosine kinase inhibitor (TKI) therapy. Tagrisso is the first and only drug approved in the U.S. for NSCLC patients who are EGFR T790M mutation positive, according to AZN.

Tagrisso, initially approved by the FDA in 2015, is already in over 45 countries including the U.S., the European Union countries, China and Japan. The drug brought in roughly $423 million in 2016 — its first full year in the market, when it hadn’t launched in China. What’s more, Asia is expected to be an important market for the drug given that between 40 and 45 percent of lung cancer patients in Asia have tested positive to EGFR mutation, according to AstraZeneca.

The pharmaceutical company’s top line has dipped by over $10 billion due to the patent expiration of its top selling drugs — acid reflux drug Nexium and cholesterol pill Crestor. The company has since looked in the direction of oncology to bring back growth.

During Q4 2016 earnings call, Chief Financial Officer Marc Dunoyer said AstraZeneca has doubled its investment in oncology since 2013, and it plans to keep investing heavily in the area. The company said its oncology pipeline attracted over 40 percent of its R&D investment in 2016, with the results exceeding its expectations.

Analysts also seem bullish on AZN’s chances in oncology. Analysts at Berenberg Bank wrote earlier this year that the growth of the oncology business should help the company’s “margins rebound towards peer average levels of 35 percent.” The analysts expect AZN to post double-digit earnings growth well beyond 2017, oncology being a major driver.

Analysts polled by Thomson Reuters expect Tagrisso to generate up to $2.5 billion by 2022.

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