UPDATE 2-Infinity halts drug trials, shares fall

* Stops trials for chondrosarcoma, bone marrow disorder

* Says no plans to conduct more trials on drug saridegib

* Shares fall as much as 21 pct

June 18 (Reuters) - Infinity Pharmaceuticals stopped two mid-stage trials of its experimental drug to treat a rare bone marrow disorder and a type of bone cancer, sending its shares down as much as 21 percent.

This is not the first time that Infinity is facing disappointment with the drug saridegib. In January, the company had stopped another trial in which the drug was being studied as a treatment for pancreatic cancer.

Infinity said it does not plan to conduct any more trials on saridegib, and plans instead to focus on developing its drugs for non-small-cell lung cancer and advanced forms of blood cancers.

Infinity's trials on saridegib and advanced blood cancer are funded under a partnership with UK-based Mundipharma International Corp Ltd till end 2013.

The company decided to stop its bone cancer trial after an independent data monitoring committee said saridegib would not perform better than a placebo in increasing survival in patients without the cancer worsening.

Infinity also pulled the plug on a trial to treat myelofibrosis, a rare bone marrow disorder, after initial data did not satisfy its criteria for expanding the trial.

"These two in our view were more exploratory and risky ... to me it does not come as a surprise," ThinkEquity analyst Mani Mohindru said.

The company's drug for non-small cell lung cancer, IPI-504, is being tested in a mid-stage study, while its advanced blood cancer drug, IPI-145, is in early stage trials.

The company plans to report results from both trials in the second half of the year.

Shares of Infinity, which has a market capitalization of about $373 million, were down 10 percent at $12.50 on Monday on the Nasdaq.