Dec 6 (Reuters) - Novartis AG said its cancer drug, Zykadia, was twice as effective as chemotherapy in slowing the progression of a rare form of lung cancer in a late-stage study.

Patients with anaplastic lymphoma kinase-positive (ALK+) advanced non-small cell lung cancer treated with Zykadia had a median progression-free survival of 16.6 months, compared to 8.1 months for those on chemotherapy.

Overall survival data is still immature, but a positive trend in favor of Zykadia was observed, the Swiss drugmaker said on Tuesday.

Zykadia has already won accelerated approval in the United States as an alternative or second-line treatment in patients who have progressed on or cannot tolerate Pfizer's Xalkori - considered the standard-of-care initial therapy.

Novartis' drug also has conditional approval as a second-line treatment in Europe.

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The drug competes with Roche Holding AG's Alecensa, which is widely seen to have a leg up in the race to secure regulatory approval as a first-line treatment.

Alecensa has already demonstrated a 66 percent reduction in the risk of cancer progression, compared with Xalkori, in previously untreated Japanese patients in a late-stage trial, Roche said in May. http://bit.ly/1Tp4FqD

Novartis had said in September that Zykadia had outperformed chemotherapy, but received a muted response from analysts and investors since Alecensa had already shown to be more effective than Xalkori.

Novartis said on Tuesday that it was initiating discussions with regulators to expand Zykadia's use.

ALK+ non-small cell lung cancer affects between 2 and 7 percent of roughly 1.8 million new lung cancer cases reported annually. (Reporting by Natalie Grover in Bengaluru; Editing by Anil D'Silva)

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