Using a gene therapy approach, tumor cells that wereengineered to pump out large quantities of interleukin-4 andreimplanted in mice have prompted immune destruction of thetumor.

This application of the immune messenger IL-4 suggests a newtherapeutic approach to human cancer.

Several companies are testing IL-4 itself in clinical trialsagainst cancers, but the gene therapy approach provides alocal, tumor-killing effect of IL-4 without the risk of toxicside effects.

"The lymphokine is produced only at the tumor site, therebyproducing a strong immune response with no systemictoxicity," noted the Johns Hopkins University and University ofTokyo researchers in their report last week in Science.

Cells from a spontaneous kidney cancer were taken from miceand were altered to carry the gene for mouse IL-4 before beinginjected back into the animals. The immunized mice not onlywere cured of their existing cancer, but "efficiently rejected"further challenges with tumor cells injected at a differentsite, even with large amounts of cells injected or with pre-established tumors, the researchers reported.

Cures lasting at least 160 days were obtained in the miceseeded with tumors and then treated with the gene therapy.About 50 percent of the mice that were still free of cancer at100 days and that were re-injected with the tumor cellsrejected this renewed tumor challenge.

A similar gene therapy has been tested by others using IL-2.Different immune cells are responsible for the tumor attacksseen with the two interleukin approaches. The researchers didnot speculate whether either of the gene therapies might offermore promise in human cancers.

Sterling Winthrop, which has licensed IL-4 from Immunex Corp.(NASDAQ:IMNX), is conducting Phase II studies of the cytokinein kidney cancer, B cell lymphoma and melanoma.

Schering-Plough, which has an issued patent on IL-4, is alsoconducting Phase II testing of the cytokine in solid tumors,leukemias and lymphomas.110491IL4

-- Roberta Friedman, Ph.D. Special to BioWorld

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