AstraZeneca plc (AZN) - Get Report shares traded higher Monday after the drugmaker said its key lung cancer treatment delayed progression of the deadly disease.

Astrazeneca said its Imfinzi plus Tremelimumab treatment met the endpoint for success in a crucial phase III 'Poseidon' trial for first line treatment of stage IV non-small cell lung cancer.  The treatment, which is a major rival to Merck & Co.'s (MRK) - Get Report Keytruda -- which notched $2.6 billion in second quarter sales -- suffered disappointing results in a Phase III study of patients with metastatic lung cancer earlier this summer.

"The Poseidon trial provides evidence of the efficacy of Imfinzi in patients with Stage IV non-small cell lung cancer," said oncology R&D vice president José Baselga. "Clinical benefit was observed in a trial population that included a high proportion of patients with squamous disease and multiple choices of chemotherapy regimens."

"Additionally, the potential to add tremelimumab to Imfinzi and chemotherapy may present an important treatment approach in this challenging setting, especially taking into consideration the favourable safety profile," he added.

AstraZeneca shares were marked 2.2% higher in London following release of the trial results and changing hands at £75.46 each in the final hour of trading on the London Stock Exchange.

Merck shares were seen 1.35% lower at $81.12 each following the release, against a 2.12% gain for the S&P 500.