FDA panel recommends approvalfor Immunomedics' CEA-Scan MoAb

Decision caps long road back for agent

Immunomedics shareholders were taken on a roller-coaster rideon Feb. 16, when the company's stock vacillated wildly in anticipationof a positive regulatory review of the company's lead radiopharmaceuticalimaging agent. When the ride was over, however, everyone who hadhung on was back just about where they started.

The impetus for the stock fluctuation was a meeting of theFood and Drug Administration's Medical Imaging Drugs AdvisoryCommittee (MIDAC), during which panel members examined whetherImmunomedics' monoclonal antibody-based colorectal cancer imagingagent, CEA-Scan, should be recommended for approval by the agency.

A cloud has hung over CEA-Scan's application since 1994, whenthe FDA said the agent's product license application (PLA) was"not approvable" in its form at the time (SCAN 6/1/94).The action caused the Morris Plains, NJ, company's stock to slump36% and prompted a shareholder lawsuit.

Immunomedics and the FDA have engaged in a lengthy back-and-forthsince then in an effort to get the PLA into a form the agencycould find acceptable. Last October, the FDA's Oncologic DrugsAdvisory Committee deferred a decision on CEA-Scan's approvability,recommending instead that the product be reviewed by MIDAC, andthat certain differences regarding data and image interpretationbe resolved.

The stock market was watching closely, then, when the MIDACcommittee met Feb. 16. Immunomedics executives figured a decisionwould be out around 1:30 p.m., but shortly after noon, the stocknose-dived from $8.13 a share to $5.13. Angry brokers called thecompany's headquarters, demanding to know why the stock was crashing.Company executives were -- and still are -- at a loss to explainit.

"I really don't know why the stock reacted the way itdid," said Paul Herron, Immunomedics director of finance."All we know is that there were some (news story) releasesaround noon that coincided with the volatility of the price andit would appear that (those stories) were premature."

After rebounding to $6 a share, trading in Immunomedics stockwas halted. When trading resumed about two hours later, it wasas if "everyone was trying to get through the same door atthe same time," explained one broker. By then the MIDAC panelhad acted on CEA-Scan's PLA with a unanimous recommendation thatit be approved, and the good news prompted the stock to open at$10.13 a share, a leap of more than five points from the previouslow. The stock later retreated to $8.13, where it had startedthe day.

Immunomedics is quick to point out that as with any decisionsmade by an external FDA advisory committee, the recommendationto approve CEA-Scan is just that -- a recommendation, not a finaldecision.

"We still cannot give any absolute assurance on what actionthe FDA will now take," Herron said. "The FDA usuallyfollows the recommendations of its panels and we are very hopefulthat it will follow the MIDAC recommendation and grant our firstU.S. product approval."

The next milestone on the road to approval for U.S. marketingof CEA-Scan would be an approvable letter, generated by the FDAto the company. That letter, if it comes, might not arrive fortwo or more months, but it will be worth the wait.

"To most drug companies, the receipt of an approvableletter means you've made it, but officially they have to issuethe approval, which is another form letter," Herron said.

Until then, Immunomedics plans to line up a sales and marketingpartner for CEA-Scan in the U.S. and is considering several candidates.The company has already recruited a partner in Europe, MallinckrodtMedical BV, to provide sales and distribution of CEA-Scan, whichis being reviewed by regulatory agencies in Europe, as well asin Canada. The company also wants to get started addressing anylabeling and manufacturing concerns.

Immunomedics has other products in the pipeline, such as imagingand therapeutic agents for cancer, as well as imaging agents forinfectious diseases. The company is preparing an application tothe FDA for one of these agents, LeukoScan, which targets infectiousdisease. A similar application has already been filed in Europe.The FDA application should be filed sometime in the next 12 months.

Receiving approval for CEA-Scan from the FDA will cap a decadeof research and development of this agent, which targets the carcinoembryonicantigen (CEA). This tumor marker is expressed by more than 90%of colorectal cancers and a large number of other carcinomas.

In other news related to CEA-Scan, the Third U.S. Circuit Courtof Appeals last month upheld a district court's dismissal of theshareholder lawsuit filed in connection with the FDA's not-approvableletter for CEA-Scan in 1994. The district court had ruled thatthe claims made by the shareholder plaintiff were "an insufficientbasis on which to bring a securities fraud action."