Xoma Corp. responded bluntly on Monday to a prominentmarket analyst's negative assessment of its E5 treatment forgram-negative sepsis, which has been waiting for a final FDAreview since September.

Investors pushed down Xoma shares $2 to $22.50 afterOppenheimer & Co. analyst Jeffrey Casdin reported that hisreview of mortality data for the drug led him to conclude that"there is no hope for any approval of E5."

In response, Xoma President Pat Scannon called Casdin'sapproach "scientifically wrong and irresponsible."

Casdin said his re-examination of data presented to an FDAadvisory committee meeting in September indicated thatmortality was higher for E5 patients without major morbiditiesthan for those patients receiving a placebo. By comparison,Casdin wrote, patients with major mobidities -- adultrespiratory distress syndrome, acute renal failure anddisseminated intravascular coagulation -- who showedimproved mortality data comprised a smaller subgroup of thetest population.

"There is no question that there is a strong trend here toward ahigher death rate in a major subgroup, 74 percent of thepatients in the trial, of patients who took E5," Casdin wrote. "Ifour calculations are correct and are statistically significant, aswe believe both are, then this means that E5 could be toxic andcausing a higher mortality," he said.

"We stand ready to be corrected," Casdin said. "But if we areright, we believe there is no hope for approval of E5."

Xoma's Scannon disputed Casdin's analysis, telling BioWorldthat "E5 doesn't increase mortality. This has been shown notonly in the study Casdin mentioned, but also in four otherstudies.

"In terms of looking at what he did, he looked at a single value,Day 14, not even the midrange of the study, of an isolatedsubgroup of only one of the several clinical trials."

Casdin's approach "is scientifically wrong and irresponsible onhis part because it leads to conclusions that are absolutely nottrue," Scannon said.

"Our (FDA) review is ongoing, and we are confident that we willproceed on to approval," said Scannon, who declined tocomment on timetables for regulatory action.

Casdin concluded that E5 is unlikely to receive simultaneousapproval with Centocor Inc.'s competing Centoxin antibody, orto be approved only for acute renal failure so that it will notsignificantly compete with Centoxin.

With Centocor shares still 30 percent lower than his lastrecommendation, Casdin recommended more aggressivepurchase of the stock (NASDAQ:CNTO). It closed Monday at$38.75, up $2. The stock has not recouped its losses sincethe FDA on Feb. 19 asked the Malvern, Pa., company formore information in its final review of the drug's marketingapplication.

-- Steve Usdin BioWorld Washington Bureau

(c) 1997 American Health Consultants. All rights reserved.