SOURCE: HarrisMartin Publishing

WEST CHESTER, Pa., Dec. 12 /PRNewswire/ -- The author of a paper set to appear later this month in a cancer research journal says there is reason to doubt claims that oral polio vaccines distributed in recent decades were free of simian virus 40 (SV40), HarrisMartin Publishing reports.

Philadelphia Attorney Stanley P. Kops writes in an upcoming issue of Anticancer Research that legal testimony and internal documents from at least one drug maker should cause researchers to question whether oral polio vaccine lots manufactured since the early 1960s were contaminated with the monkey virus.

Following reports in the late 1950s that polio vaccines were producing tumors in laboratory hamsters, the U.S. Government required that all seeds used to manufacture the vaccines be screened for SV40 and other microbial agents it thought might be causing the tumors.

Kops says that despite passage of the federal mandate in 1961, neither the FDA nor manufacturer Wyeth-Lederle has been able to show for certain that adequate steps were taken to eliminate SV40 from all stages of the manufacturing process, which involved passing the polio virus through monkey kidney tissue.

"Whether SV40 was removed from Sabin Oral Polio Virus strains remains a serious and unanswered question,'' writes Kops, who has represented several plaintiffs in polio vaccine products liability cases.

According to Kops, Lederle told national health officials during a 1997 conference in Bethesda, Md., that all of the master viral strains used to manufacture its oral polio vaccines after 1961 were tested and screened for SV40. Manufacturers are required by law to keep records of screening results.

However, Kops says he has reviewed internal Lederle memos indicating that three out of the first 15 vaccine pools Lederle used to secure licenses for two types of oral polio vaccine -- its monovalent and trivalent doses -- may have contained SV40.

All three pools were used to produce vaccines commercially sold for several years after the licenses were secured in 1962 and 1963, Kops says. The attorney adds that according to the internal memo, a high-ranking federal health official was aware of the possible SV40 contamination.

Kops also references the 1998 deposition of then-Lederle Vice President Dr. Mary Ritchey, who was questioned during the course of a pending products liability lawsuit. According to Kops, Richey testified that Lederle's parent company, American Cyanamid, could not determine that it tested all polio vaccine seeds and virus strains for SV40 because Lederle didn't possess protocols for all such materials.

"The import of this testimony and the referenced Lederle internal documents challenge the conclusions previously advanced in scientific journals that people born after 1963 who tested positive for SV40 either became contaminated as a result of human-to-human contact, or of placental transference,'' Kops' paper says.

Exactly how and when SV40 was introduced into human populations -- especially those inoculated since the government's 1961 mandate -- has stymied researchers for years.

Kops notes that determining the accuracy of Lederle's screening results is of particular importance because scientists recently showed for the first time that, at the cellular level, SV40 plays a role in initiating mesothelioma, a rare cancer that kills between 2,500 and 3,000 people annually.

Mesothelioma is generally attributed to asbestos exposure. However, researchers have found that as many as 80 percent of certain mesotheliomas harbor evidence of SV40's presence, which some believe plays a role in causing the almost always fatal tumor.

"The scientific literature indicates that mesothelioma can be initiated, promoted, and/or accelerated by a combination of various factors including SV40,'' the paper says. "This breakthrough in scientific research now requires a complete appraisal of whether the oral vaccine used in the United States from 1961 until 2000 could have been a contributing cause.''

Until it can be shown by Lederle or the FDA that the process used to manufacture the oral polio vaccine after 1961 was completely SV40-free, the scientific community is impeded in its epidemiologic and oncologic analysis and discussion of the role, if any, SV40 plays in tumor processes, Kops asserts.

Officials at Wyeth-Lederle did not return phone messages seeking comment.

HarrisMartin Publishing is the publisher of Columns-Asbestos, a national monthly magazine that covers asbestos-related disease litigation and recent scientific developments in the SV40 debate. In-depth coverage of the Anticancer Research article will appear in the January 2001 issue. For more information, call (800) 496-4319, or log onto www.harrismartin.com .

Contact: Jeff Andrus, Editorial Director, HarrisMartin Publishing, 800-496-4319, or jandrus@harrismartin.com.