A fresh study of Laetrile's effect on two types of malignant human tumors has shown the derivative of ground-up apricot pits to be a useless treatment of cancer.

The tests were done under the auspices of the National Cancer Institutue at the Battelle Memorial Institute in Columbus, Ohio.

In them, Laetrile, used to treat human breast and colon tumors induced in colonies of "nude" mice, proved to be completely worthless in arresting the growth of either type of tumor.

"There was no effect of the Laetrile whatsoever," said Dr. David P. Houchens, who is co-director of a three-year study of anti-cancer drugs on nude mice being done at Battelle. "The tumors induced in the mice and treated with the Laetrile just kept growing, no worse and no better than if they'd been left alone."

"Nude" mice are hairless mutants chosen for the Laetrille studies because they have no power to fight infections. The reason is that their immunology systems don't work, which means they don't recognize implanted human tumors as coming from another species.

"This means human tumors will flourish and grow in nude mice," Houchens said. "All other laboratory animals reject human cancers as a foreign species," so they can't be used in such tests.

Battelle scientists tested two different doses of Laetirle on breast and colon tumors implanted in colonies of four to six mice.

One dose involved injecting Laetrile alone; the second dose was of Laetrile and beta glucasidase, an enzyme identified as the active agent in Laetrile tha triggers the release molecule.Laetrile'e proponents contend that cyanide released from the drug selectively kills cancer cells.

Houchens and his co-investigator, Dr. Arienmio Ovejera, said that the Laetrile injections proved worthless to the mice. The Laetrile plus the enzyme was toxic, meaning it did more harm to the mice than if they were injected with nothing.

In contrast, breast and colon cancers implanted in similar colonies of nude mice and treated with cancer drugs like cytoxan for breast tumors and methyl CCNU for colon tumors responded favorably to the treatment. Both drugs slowed tumor growth or caused them to shrink in the mice.

The Battelle tests are understood to be the first where Laetrile was used to treat human cancers. Other institutions like Sloan-Kettering Cancer Center in New York have tested Laetrile on animal cancers, and have found it to be useless.

Battelle has what is believed to be the world's largest facility for testing drugs on nude mice, a laboratory animal whose use has increased dramatically the last 10 years.

Battelle now tests drugs on about 10,000 mude mice a week. Laetrile is one of 15,000 drugs tried on the mice in the last year.