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ZURICH, Oct 6 (Reuters) - Swiss pharma group Novartis AG said on Monday it would work with Bristol-Myers Squibb Co to test the U.S. drugmaker's immuno-oncology drug Opdivo in combination with three of its own experimental lung cancer drugs.

The clinical collaboration will help Novartis advance its efforts in the field of immunotherapy, one of the hottest areas in biotech right now, following the acquisition of CoStim Pharmaceuticals Inc this year, the drugmaker said.

Novartis currently lags rivals such as Roche, Merck , AstraZeneca and Bristol-Myers in the race to develop immunotherapies - drugs that fight cancer by harnessing the body's immune system.

The two companies will test the combination of three molecularly targeted compounds with Bristol-Myers' investigational PD-1 immune checkpoint inhibitor Opdivo (nivolumab) in phase I and II studies, Novartis said, adding it would conduct both studies.

"Preclinical data suggests that combining molecularly targeted agents with immunotherapies such as nivolumab may have synergistic effects and lead to better outcomes for patients," Alessandro Riva, global head of Novartis oncology development and medical affairs, said in the statement.

Opdivo is part of a closely watched class of drugs known as anti-PD-1 therapies, which block a tumour's ability to camouflage itself from attack by the immune system's cells.

The drug is approved in Japan for the treatment of unresectable melanoma and is under review by the U.S and European health regulators. It is also being tested as a treatment for a range of other cancers.

One of the Novartis studies will evaluate Opdivo with Novartis' Zykadia, which was approved by the U.S. Food and Drug Administration (FDA) in April as a treatment for late-stage non-small cell lung cancer.

The second study will test Opdivo with two investigational drugs, INC280 and EGF816.

Novartis is also developing Chimeric Antigen Receptor T-cell, or CAR-T, immunotherapies, which involves engineering a patient's own T-cells to identify proteins on cancer cells.

(Reporting by Silke Koltrowitz and Caroline Copley; ediing by Ryan Woo and Susan Thomas)