Shares of Endocyte Inc. plummeted more than 60 percent Tuesday morning after clinical trial results showed the company’s experimental ovarian cancer drug led to shorter survival times than treatment with a standard cancer drug.

The West Lafayette-based company was quick to note that the study results did not include enough patients to be statistically meaningful in terms of patient survival. Also, it noted that survival rates for patients taking standard therapy were several months longer than seen in any other study.

“It was significantly underpowered for an overall survival analysis,” Endocyte Ron Ellis said of the Phase 2 study of the company’s EC145 drug. He added, “We really don’t know if there’s a benefit or not with the treatment of EC145.”

Previous clinical trial results released by Endocyte have shown that EC145 significantly increases the length of progression-free survival for ovarian cancer patients who have cancers that are resistant to treatment with common platinum-based drugs.

Investors, however, assumed the worst. The company’s stock price was down more than 63 percent late Tuesday morning, falling from an opening price of $10.29 per share to $3.76 on significantly higher trading volume.

Endocyte plans to apply in 2012 for early approval of EC145 in Europe, based on its Phase 2 trial results. During a conference call Tuesday morning with analysts and investors, the first question was whether Endocyte had communicated these trial results to the European Medicines Agency, which will make the decision on whether EC145 goes to market in Europe.

Endocyte will launch a much larger Phase 3 trial of EC145 before applying for market approval in the United States. Analysts had previously estimated EC145 could win U.S. approval in 2014.

To support its products on the market, Endocyte plans to station its commercial team in Indianapolis.

In the Phase 2 trial results reported Tuesday, patients taking EC145 in combination with the cancer drug Doxil survived a median length of 14.1 months, which was longer than in any previous study of the drug. But patients taking Doxil alone experienced median survival rates of 16.9 months.