By Mary Welch

Xoma Ltd., on the direction of an independent data safety monitoring board (DSMB), will continue enrolling patients in its Phase III Neuprex meningococcemia trial until the overall mortality number called for in the statistical plan is met.

¿It¿s a horrible disease and we¿re making every effort to do this trial right for the children,¿ said Peter Davis, chief financial officer for the Berkeley, Calif., company. ¿We¿re trying to get the proper power to show statistical significance and make the trial work.¿

The DSMB has not identified any safety issues, and also told Xoma that continuing the trial would not be a futile effort, Davis said.

Meningococcemia is a blood-borne bacterial infection caused by Neisseria meningitidis, a bug responsible for meningitis. A seasonal infection, the disease is caused when Gram-negative bacteria enter the bloodstream, where they and their endotoxins can fuel a systemic inflammatory response that can lead, within hours, from flu-like symptoms to shock, organ failure and death. Survivors may suffer loss of limbs and neurological damage.

Neuprex works by punching holes in the outer shell of bacteria and killing them. It also enhances antibiotics, and binds and neutralizes endotoxin, a poisonous molecule produced in the cell walls of Gram-negative bacteria.

In a 1995 open-label pilot study with 26 severely ill patients, 25 survived after taking Neuprex. Pivotal trials began in the U.S. in 1996 and a year later in the U.K. Patients ranged from 3 months to 18 years.

¿I never would have believed that we would have gotten 370 patients when we started the trials,¿ Davis said. ¿The disease is so rare. But we started getting a large number of patients in our U.K. sites.¿

However, while the number of patients enrolled increased, the mortality rate ¿ the trial¿s endpoint ¿ is only now approaching the statistical plan¿s target.

¿We don¿t know why,¿ Davis said. ¿It¿s all speculation; it¿s a blinded study. What we do know is that we are close to reaching the specified number of our original proposal, which will allow us to conclude accrual with the statistical power called for in our trial design.¿

The company is in consultation with European and U.S. regulatory authorities about its filings. Once enrollment is complete there will be a 90-day follow-up period on the final patients enrolled before results are available to be analyzed.

Xoma¿s stock (NASDAQ:XOMA) closed Monday at $3.125, up 12.5 cents. n