Shares of Amgen (AMGN - Get Report) gained more than 5% on Monday after the company announced positive initial results from its experimental drug used to treat non-small-cell lung cancer patients.

In a statement, Amgen said that a small, early-stage trial indicated that its AMG 510 experimental drug that targets a specific genetic mutation significantly reduced tumor size in half of evaluated patients with advanced lung cancer.

Out of 10 heavily pre-treated lung cancer patients given the oral drug AMG510 daily, five had tumors shrink in size by at least 50%, including one with no evidence of the malignancy, the company said.

Analysts and investors have been closely following Amgen's initial treatment that could become the first approved medicine targeting a mutated form of a gene known as KRAS - one of the most common mutations found in non-small cell lung cancer (NSCLC).

Learn how @Amgen is driving the next generation of innovation in cancer treatment to help cancer patients and their families. #ASCO19 pic.twitter.com/y0gMpkrtAk

— Amgen Oncology (@AmgenOncology) June 1, 2019

NSCLC accounts for up to 85% of lung cancers, by far the leading cause of cancer death among men and women, according to the American Cancer Society.

The trial also enrolled patients with colorectal cancer and cancer of the appendix.

Amgen presented its findings at the 55th Annual Meeting of the American Society of Clinical Oncology in Chicago.

Shares of Amgen were up 5.49%, or $9.15, at $175.86 in late morning trading on the Nasdaq Stock Market. 

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