Novel Immune System Stimulant Shows Anti-Tumor Potential

By Pam Harrison

TORONTO, Aug. 30 2000 (Reuters Health) - An immune system stimulant given subcutaneously every other week causes significant lesion regression in cancer patients whose immune systems are reasonably competent.  The study results were presented here at the 28th World Congress of the International Society of Hematology.

Dr. Floyd Taub, chairman, Lifetime Pharmaceuticals, College Park, Maryland, reported results from the first phase I/II study of beta-alethine, a disulfide.  Every 14 days for 3 months, researchers at McGill University, Montreal, Canada, gave 2 micrograms of beta-alethine to patients with low-grade B-cell lymphoma and maximal response to therapy, or indolent disease that did not yet require therapy.

Dr. Taub reported that, to date, eight lymphoma patients and six myeloma patients in a separate protocol, five of whom had undergone stem cell transplantation, have received beta-alethine for up to 1 year.   The investigators have observed virtually no adverse effects from the biweekly regimen.

Prior to treatment, patients underwent delayed-type hypersensitivity testing to assess the competency of their immune system.  "Three out of four patients whose immune systems could be activated ended the trial with less tumor than they began," Dr. Taub noted in an interview with Reuters Health.  

In contrast, three out of four patients who had a poor immune response on delayed hypersensitivity testing continued to progress, "a difference between the two groups which did reach statistical significance," Dr. Taub noted.  One patient who remained on the study drug for 1 year had a 50% decrease in tumor burden, he added.

Dr. Taub explained that beta-alethine appears to stimulate an orchestrated, coordinated cytokine response.  "T cells also become activated and more cytotoxic," he said, "and tumor necrosis factor on the surface of lymphocytes is increased, which takes the drug right into the cancer."

He noted that he and his group chose to test the drug in the cancer setting not because they felt that this was where it was most likely to work, but because it was where they could ethically gather toxicity data.  A more ideal setting, he believes, would be patients with either early or premalignant disease, where the cancer has not yet overwhelmed the immune system.

Dr. Taub also suggests that beta-alethine might work well in patients with hepatitis C, "where perhaps a small amount of immune stimulation would be all that"s needed for the body to win out over the virus." 

In addition to the ongoing Canadian trial, the drug is now under investigation in four sites in the US for the treatment and potential prevention of various cancers.


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