BioWorld International Correspondent

LONDON - Shares in Acambis plc were hit Monday when the company announced the U.S. government cancelled an order for 26.5 million doses of smallpox vaccine.

The stock fell 24.25 pence to £2.99, despite a simultaneous announcement that the FDA has lifted its hold on the Phase III trials of the vaccine and accepted Acambis' recommendation that with 2,981 of a proposed 5,440 subjects vaccinated, there is enough data already to assess the safety and immunogenicity of the product.

In the U.S., the stock (NASDAQ:ACAM) fell 91 cents to $10.60.

"We expected an order of 26.5 million doses in the second half of this year. At the end of last week we learned the [Centers for Disease Control and Prevention in Atlanta] was not going to place the order," Gordon Cameron, CEO, said in an analysts' meeting in London. "Obviously, that's not what we thought was going to happen."

Acambis previously forecast 2004 revenues of $80 million to $90 million from the CDC contract. Now the estimate is $65 million to $75 million. The Cambridge, UK-based company already has supplied 182.5 million doses of the ACAM2000 vaccine. Cameron said the CDC concluded that together with supplies of the previous generation Dryvax vaccine that is, "sufficient for the time being for the smallpox vaccine stockpile."

Acambis was able to soothe some of the sting of the cancellation with news that the FDA has agreed to lift the clinical hold on the Phase III trials of ACAM2000, enforced in April, and to close the trial. That paves the way for the company to complete the analysis and submit a biologics license application in 2005. The aim of the trials is to show equivalence between ACAM2000 and Dryvax.

"The outcome is the best it possibly could be for the company," Cameron said. "We could easily have had to restart the trials." Halting recruitment at 53 percent of the proposed number of subjects will increase Acambis' gross margin on the vaccine contracts. "The wait was well worth it, because it has given us clarity on a key product going forward."

The two trials, which aimed to recruit 2,720 vaccine-na ve and 2,720 previously vaccinated subjects, were suspended after three subjects developed myocarditis, a side effect of the Dryvax vaccine. The subsequent analysis showed eight people suffered the side effect, all of whom were in the vaccine-na ve trial. The trial remains blinded so it is not known how many received Dryvax and how many ACAM2000.

Following an investigation by a safety committee and a cardiology advisory group, Acambis responded to the FDA's hold letter. "We recommended we had sufficient data from the 3,000 subjects recruited to allow assessment of safety and immunogenicity, and recruiting more subjects was unlikely to add anything," said Cameron. "The FDA agreed with us."

Acambis now is seeking support from the CDC for the concept of "warm base" manufacturing that would ensure its manufacturing facility is ready to produce smallpox vaccine. Such a contract would be in addition to the existing deal to maintain the vaccine stockpile.

The company also announced smallpox vaccine contracts with three other governments, two in Europe, with a total value to Acambis of £6 million (US$10.7 million). It also is awaiting a decision from the U.S. National Institute of Allergy and Infectious Diseases on a tender to manufacture and test modified vaccine Ankara, an attenuated smallpox vaccine, for protecting people with compromised immune systems.

No Comments