In recent years, Northwest Biotherapeutics (NWBO has spent millions of dollars to build out and staff grand exhibition booths at cancer conferences like the American Society of Clinical Oncology annual meeting.

These days, the struggling, cash-strapped biotech company can't afford the extravagance, so its presence at the American Association for Cancer Research (AACR) meeting underway in Washington D.C. is limited to a far corner of the exhibition hall in a space not much larger than an area rug.

There are no fancy visualizations of Northwest Bio's long-delayed brain cancer vaccine in action, no leather couches or an espresso machine for visitors. The booth contains just a couple of small tables with chairs. Thumbnail drives stamped with the Northwest Bio logo are stuffed in a cookie jar.

Standing alone in the Northwest Bio booth is Marnix Bosch, the company's chief technical officer. Bosch oversees regulatory affairs at Northwest Bio. A big part of Bosch's job entails communicating with the FDA and its counterparts in Europe, so he should know why regulators placed a crippling clinical hold on Northwest Bio's most important project -- the phase III clinical trial of the personalized cancer vaccine DCVax-L in glioblastoma multiforme, an aggressive form of brain cancer.

I asked him.

"I don't know why the study was placed on clinical hold," Bosch told me, as we stood in the Northwest Bio booth at AACR on Monday.

Huh. That's strange, and quite frankly, unbelievable given Bosch's job responsibilities at Northwest Bio. But his response also fits a long-held pattern of unkept promises, missed timelines and obstinate secrecy at the company led by CEO Linda Powers, a former Enron executive.

Northwest Bio's inability to resolve the problems that froze the crucial DCVax-L clinical trial -- and management's refusal to offer a public explanation for why it happened in the first place -- is now putting the company closer to financial insolvency and shutdown than ever before.

The FDA or the European Medicines Agency (we still don't know which agency) first placed the clinical hold on the DCVax-L phase III study in August 2015. At that time, Northwest Bio said the halt was temporary and only stopped enrollment of new GBM patients. Once "certain information" was submitted to regulators "within a couple of weeks," the clinical hold could be lifted, the company claimed.

Weeks turned to months without any resolution or statement from Northwest Bio offering more information about the DCVax-L clinical hold. Powers' publicly stated promise to complete patient enrollment into the trial by the end of September 2015 came and went; so did the pledge to wrap up the study and announce top-line results by the end of 2015.

Northwest Bio had been trying to push the DCVax-L study in GBM across the finish line for 10 years.

In July 2015, one month before the DCVax-L clinical hold, Northwest Bio shares reached an all-time high of $12. By the end of 2015, the stock was trading for $3, a fall of 75%.

Incredibly, all of 2016 passed while the company remaining silent about why regulators were refusing to allow the DCVax-L study to enroll more patients. Without additional patients, Northwest Bio was unable to complete the study. The stock price plummeting another 75% to 35 cents per share. The fall hasn't stopped--as of close Tuesday the shares were at 24 cents.

The Nasdaq booted Northwest Bio for violating compliance rules, forcing the company to trade over the counter. The company ran short of money. To maintain operations, Northwest Bio raised small amounts of cash in highly dilutive, toxic financings.

Still, Powers and the other executives refused to explain the clinical hold on the DCVax-L study, despite it clearly being a material -- and value-destroying -- event for the company. Shareholders suffered but the Securities and Exchange Commission took no action. The stock was never halted and no regulator compelled Northwest Bio to be more transparent.

In early February, Northwest Bio issued a press release to announce that the FDA agreed to remove the clinical hold on the DCVax-L phase III study. The company also said no additional patients would enter the study, even though that meant falling short of the planned enrollment number.

But even this apparent resolution of the problem remains unconfirmed. A European database of clinical trials still lists the DCVax-L phase III study as being "temporarily halted." ClinicalTrials.gov, the companion clinical trials database for the U.S., never listed the DCVax-L study has being halted, even dating back to August 2015. The FDA will not confirm or deny the lifting of the clinical halt.

Even more concerning, Northwest Bio failed to file an 8-K with the SEC to declare the resolution of the DCVax-L clinical trial hold. Publicly traded companies can be loose with facts in press releases, but lying to the government in SEC filings is a serious no-no.

Northwest Bio has not filed a 10-K for 2016. The company's most recent prospectus supplement filed with the SEC on March 22 still describes the DCVax-L phase III study as remaining on a "partial clinical hold."

Why? Bosch, standing alone in a tiny AACR conference exhibition booth, shrugs his shoulders and pleads ignorance.

Just over his shoulder, a few steps away, are a set of bathrooms.

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.