"Interferon" TUMOR TIDBITS, A BIWEEKLY EMAIL NEWSLETTER FROM GULF COAST VETERINARY ONCOLOGY Number 81; December 13, 2002. ======================================================================= THIS WEEK'S TUMOR TIDBIT: Interferon. ======================================================================= ANNOUNCEMENTS FROM GULF COAST VETERINARY ONCOLOGY * Ongoing clinical trials include those for dogs with relapse lymphoma and dogs with splenic hemangiosarcoma. Please call us for additional information and eligibility. * Visit our web site regular for updates and protocols, www.gcvs.com. ======================================================================= Researchers are exploring the science of immunology for new ways to diagnose and treat cancer. The immune system, which helps the body fight bacterial and viral infections, is extremely complex and is widely dispersed through most of the tissues of the body. Its basic constituents are macrophages (first cells to recognize and engulf foreign substances), lymphocytes (white blood cells normally found in blood and lymphoid tissues), antibodies (proteins produced by some lymph cells), and a variety of phagocytic cells (scavenger cells fixed within tissues or carried in the blood). There is considerable evidence that the immune system also plays a major role in the body's response to cancer and that at least some forms of cancer occur when the immune system fails to destroy cancer cells or prevent their growth. Immunotherapy is a term for a broad range of ways in which the body's immune system might by used to treat cancer. Most forms of immunotherapy are considered investigational at this time. Clinical studies to evaluate these treatment methods are currently underway at veterinary centers around the country. Some immunotherapy methods use substances called biological response modifiers. These substances are involved in the body's natural, biological response to the development of cancer or other diseases. The biological response includes the immune system, but also can include other phenomena in the body. Scientists doing basic research in many laboratories have identified a number of substances that may act as biological-response modifiers. Interferon is the best known example, but tests are proceeding with other substances as well. Interferon was first described as a substance that can inhibit the spread of viruses in the body and is produced by the host in response to a viral infection. Much more has become known in recent years since interferon has been produced in sufficient quantities for detailed study. For example it is now known that there are numerous interferons. These are generally divided into three classes. Interferon alphas are all produced by lymphocytes on stimulation by viruses, interferon betas are similarly produced from fibroblast cells, and the gamma type is produced from lymphocytes by immune stimulation rather than virus infection. Great interest in this area has developed with the discovery that interferon also has anticancer effects. A variety of studies have been done or are in progress using a mixture of alpha interferons. This work has shown that interferon has an anticancer effect, and that this can be related to changes in function of the immune system. The anticancer effect is variable, having a greater effect in some tumor types and some patients than others. Interferon treatment has significant side effects and is only routinely recommended for the few patients where alternate treatment is either less effective or more toxic. Interferon is normally produced by the body's own lymphocytes. Scientists have been able to remove the gene which codes for interferon from its chromosome in the lymphocyte and insert it into bacterial (E. Coli) plasmids (genetic material in bacteria). When the gene for interferon is put in the plasmid it is at the same time linked to a gene which makes the bacteria resistant to an antibiotic, neomycin. When normal E. Coli bacteria are mixed with a solution containing the plasmids with the interferon and neomycin resistance genes some of the bacteria ingest (take into themselves) these special plasmids. Then all the bacteria are exposed to neomycin. This kills the bacteria which do not have the neomycin resistance gene (and the interferon gene which is linked to it). Only the bacteria which have the neomycin resistance survive. All of these surviving bacteria produce human interferon because that gene is linked to the neomycin resistance gene. The interferon is extracted from the liquid around the bacteria and made available by drug companies for use as a cancer immunotherapeutic agent. Current trials exploring the use of interferon include dogs with lymphoma, hemangiosarcoma and melanoma along with cats having oral carcinomas. Preliminary results are encouraging for palliation of disease but tumor regressions are not common. ======================================================================= We hope this info helps and don't hesitate to call us Gulf Coast Veterinary Oncology! Kevin A. Hahn, DVM, Phd, Diplomate ACVIM (Oncology), drhahn@gcvs.com Janet K. Carreras, VMD, Diplomate ACVIM (Oncology), drcarreras@gcvs.com Glen K. King, DVM, MS, Diplomate ACVR (Radiology & Radiation Therapy), drking@gcvs.com Gulf Coast Veterinary Diagnostic Imaging & Oncology 1111 West Loop South, Suite 150, Houston, TX 77027 P: 713.693.1166 F: 713.693.1167 W: www.gcvs.com ======================================================================= _______________________________________________________________________ Powered by List Builder To unsubscribe follow the link: http://lb.bcentral.com/ex/sp?c=17415&s=BEF9FC289AB68080&m=48