Shares of Dendreon fell as much as 37 percent Tuesday after the struggling Seattle biotechnology company warned it might restructure its finances with “no guarantee that any such alternative will provide value for the company’s stockholders.”

The stock closed down 72 cents, or 34 percent, at $1.40 in regular trading.

Dendreon has $620 million in debt to repay by January 2016, and its quarterly 10-Q report filed Monday acknowledged for the first time a “significant risk” it will not be able to pay off or refinance that debt.