Repligen Corp. delivered another disappointment Thursday, disclosing that the FDA canceled the advisory committee meeting scheduled for May 31 to review pancreatic imaging candidate RG1068. The company expects to receive a complete response letter requesting additional clinical data to support its new drug application (NDA) for RG1068, which has a PDUFA date of June 21.

In response, investors dumped the stock, with shares (NASDAQ:RGEN) plummeting 40.2 percent to close at $4.34, with more than 2.2 million shares traded – nearly 17 times average volume.

In a statement, Walter C. Herlihy, president and CEO of the Waltham, Mass.-based biotech, vowed to continue working with the FDA "to assess a potential path forward for RG1068," maintaining the agent is safe and effective for imaging the pancreatic ducts.

How far apart the two parties might be over RG1068 remains to be seen. Herlihy did not respond to interview requests from BioWorld Today.

RG1068, a synthetic version of human secretin, was evaluated in a Phase III study to improve detection of pancreatic duct abnormalities in combination with magnetic resonance imaging (MRI) in patients with known or suspected pancreatitis. That study showed statistically significant improvements in detecting pancreatic disease. (See BioWorld Today, March 15, 2011.)

The 258-patient Phase III study compared RG1068 in combination with MRI vs. MRI alone to determine improvements in sensitivity of detecting structural abnormalities of the pancreatic ducts as co-primary endpoints. The original analysis of the study, completed in 2010, was determined to be flawed by regulators, so Repligen conducted a re-read of the data, bringing on board a new contract research organization and three new radiologists.

The data showed that all three radiologists achieved a clinically and statistically significant improvement in sensitivity, all with a "p" value of less than 0.0001, with minimal loss of specificity – less than 7.5 percent specificity was required. Images from RG1068 scans also showed highly significant improvements on image quality and diagnostic confidence when compared to MRI alone.

Despite the more positive findings, Repligen's shares actually lost 1 cent when the results were disclosed.

The company's investors were, perhaps, looking beyond the imaging agent's limited market. Just a few weeks earlier, Repligen had been hit even harder after RG2417, its oral formulation of uridine, disappointed in a Phase IIb bipolar depression trial. (See BioWorld Today, March 8, 2011.)

Nevertheless, the company filed the RG1068 NDA in December 2011, which the FDA accepted in February, granting it priority review based on its orphan drug and fast-track designations.

Last month, Repligen also submitted a marketing authorization application to the European Medicines Agency (EMA), which was accepted for full review by the EMA's Committee for Medicinal Products for Human Use.

Repligen also is conducting a pilot study to evaluate the ability of RG1068 to improve detection and characterization of pancreatic cancer in combination with contrast-enhanced MRI and computed tomography. That study also is evaluating which imaging technique is optimal for pancreatic tumor detection, staging and evaluation for surgery.