From 10K:
Under the terms of our credit facility, Hercules could accelerate our payment obligations upon the occurrence of a circumstance that would reasonably be expected to have a material adverse effect, as defined in the credit agreement, or another event of default. If our principal obligations under such credit facility (which totaled approximately $15.0 million as of December 31, 2015) are accelerated, we would need to secure additional financing to fund our operating expense and capital expenditure requirements as early as the middle of April 2016. In the event we are unable to secure the necessary financing, we may need to cease operations or file for bankruptcy protection.