BROOMFIELD - Arca Biopharma Inc. has "substantial doubt" about its ability to continue operations beyond September, according to documents filed with the Securities and Exchange Commission this week.

The publicly traded biotechnology firm in Broomfield (Nasdaq: ARCA) lost $4.3 million in 2012 following a loss of $5.4 million in 2011, according to its annual report.

The company is developing the drug Gencaro to treat cardiovascular diseases, including heart failure and atrial fibrillation, the formal name for irregular heartbeat.

Officials said in the SEC documents they hope to continue development of Gencaro by pursuing an underwritten public offering to fund its general and administrative costs, as well as clinical trials for the drug.

Arca said it may seek additional interim funding that could allow it to operate while pursing financing options, a strategic combination, partnering and licensing opportunities.

"If we are delayed in obtaining funding or are unable to complete a strategic transaction, we may discontinue our development activities on Gencaro or discontinue our operations," Arca said in the documents.

Arca has been in danger of being delisted from the Nasdaq stock exchange on several occasions because its stock price has fallen below $1 per share.

In the past 52 weeks, the stock has traded in a range between 23 cents and $1.15. Arca has received delisting notices from Nasdaq in each of the past three years, according to SEC documents. The company regained compliance in 2010, 2011 and 2012.

Arca completed a reverse stock split to raise its per-share trading price and regain compliance with Nasdaq stock market rules on March 4. As a result of the reverse split, every six shares of issued and outstanding common stock were combined into one.

Arca's stock was trading at $2.57 per share as of midday Friday.