Some insulin-dependent diabetics are making medical history by injecting new human insulin made in the laboratory instead of the kind extracted from the pancreas glands of cattle or hogs.
The new insulin is called Humulin.
It is the first human healthcare product to be made by recombinant DNA technology, pioneered by Genentech Inc. of South San Francisco, Calif.
The Food and Drug Administration approved the product Oct. 29. Diabetes specialists are using the new human insulin to determine the types of patients for which it is most appropriate.
Diabetes is a serious, chronic disease for which there is no cure at present. But it can be controlled. It is caused by the body's failure to make use of certain foods in the normal way.
Eleven-million Americans are diabetic and 10 percent have a type that is insulin-dependent. People with this kind of diabetes must take insulin by injection one or more times a day. When it is generally available and their doctors prescribe it, they will be able to use Humulin, made with DNA.
DNA is short for deoxyribonucleic acid. It is DNA within each cell that carries the blueprint for life and enables species to reproduce their own kind.
DNA determines whether an organism is an cat, a dog, a virus, a maple tree or a human being.
Recombinant DNA technology cuts DNA molecules from two different organisms and recombines the fragments to produce biologically functional, hybrid DNA molecules. Other names for this technology are genetic engineering and gene splicing.
'The announcement of the availability in the United States of human insulin created in the laboratory with remcombinant DNA technology is an exciting event in medicine,' said Dr. Irving L. Spratt, president of the American Diabetes Association.
'It demonstrates the melding of intensive research in genetic engineering with complex pharmaceutical production.
'People with insulin-dependent diabetes mellitus will no longer need to rely on animal pancreases as the sole source of insulin.'
Why did a need exist for manmade insulin? Scientist say some patients are allergic to insulin extracted from the pancreas glands of cattle and hogs.
That's not all. Due to the increasing number of diabetics, the possibility of an animal insulin shortage has increased over the past 10 years.
The introduction of DNA insulin means diabetics will be able to receive insulin clinically identical to that produced by the human body.
Dr. Spratt said indications for use of the new insulin will become clearer as further clinical experience is gathered. It is being distributed to selected doctors engaged in that task.
Until the new human insulin is generally available and indications for its use completely spelled out, Spratt said people who are taking insulin should continue their present program and contact their doctors if they have questions.
A highpoint on the road to manmade insulin was reached in 1977. That year scientists spliced a rat insulin gene into a bacterium.
Then, in September 1978, Eli Lilly and Company and Genentech Inc. jointly announced they had succeeded in creating synthetic genes to make human insulin.
Here is how it happened, according to the drug company:
'They had inserted the genes into bacteria, and the bacteria had produced the human insulin.'
Other important dates on the road to DNA insulin:
-July 11, 1980. Lilly had begun testing of its human insulin on human subjects in the United Kingdom. The firm also said it had begun construction of plants to make the manmade insulin. One is in Indianapolis; the other, in Liverpool, England. The bill: $70 million.
When the FDA approved the new insulin, Robert A. Swanson, president of Genentech, called the new medical product 'a tribute to the collaboration of scientists at Eli Lilly and Genentech.
He said approval by the FDA came only four years after scientists at Genentech and City of Hope National Medical Center, working together on the Genentech-funded project, successfully produced human insulin, using recombinant DNA technology.
It is under a licensing agreement with Genentech that Lilly is manufacturing and preparing to market Humulin.
Here are some questions and answers about the new insulin, based on information from the American Diabetes Association:
Q. Is the new human insulin safe and effective?
A. 'Recombinant human insulin is indistinguishable from natural human insulin in its structure and activity. It has been proved safe and effective in extensive clinical trials.'
Q. How is it made?
A. 'Researchers have learned how to manufacture ... DNA which carries the code for human insulin. These laboratory-made genes are spliced onto the natural DNA of a one-celled organism called E. coli, which then makes insulin as if it were just another of the substances than an E. coli normally makes. These E. coli also reproduce, and all their descendants carry the same code and continue to create insuliln that is chemically identical to insulin manufactured by the human pancreas.'
Q. Who should use the new insulin?
A. 'Diabetes specialists will be using the new human insulin in an effort to determine those types of diabetes patients for which it is most appropriate for the treatment and control of their disease. The indications for the use of the new DNA-produced human insulin will become clearer when the results of continued clinical studies and patient usage are accumulated and carefully evaluated by the medical comunity. The American Diabetes Association is working closely with all parties concerned and will issue reports on the results of ongoing studies.'
What other products are on the drawing board, in the pipeline or undergoing clinical testing as a result of DNA technology?
-Human growth hormone. Human clinical studies being conducted by Genentech in medical centers nationwide. It is used to treat hypopituitarism, a condition caused by deficiency in normal growth hormone production.
-Human leukocyte interferons. These are in human clinical studies under direction of Genentech's contractural partner, Hoffmann-La Roche. The once extremely rare and costly interferons now can be tested extensively as potential antiviral, anti-tumor agents.
-Human fibroblast interferon. These are being developed as potential antiviral, anti-tumor agents. Hoffmann-La Roche is the contractural partner.
-Human immune interferon. Preliminary studies suggest this type of interferon may have anti-tumor and broad anti-viral activity.
-Foot and mouth disease vaccine. Developed by Genentech scientists in collaboration with the U.S. Department of Agriculture, this vaccine underwent animal studies at the USDA facility on Plum Island, N.Y. The disease causes widespread destruction of cattle in many countries outside the United States.
-Bovine and porcine growth hormones. Like their human counterpart, these stimulate growth as part of the natural mechanism of development. Their use in cattle and swine may significantly increase production of meat, milk and pork without causing chemical residues in the food chain.
-Human calcitonin. Scientists say it is a potential treatment of bone disease.
-Human serum albumin. This blood protein product has been developed as a treatment for patients suffering trauma and blood losss.
-Urokinase. This is a thrombolytic agent, presently obtained from human kidney and liver cells and in scarce supply. It degrades blood clots.
-Tissue plasminogen activator. This may improve therapy for dissolving blood clots. Laboratory and small scale human studies of this product are underway in Belgium.
-Bovine interferon. This animal inerferon product is being developed as a broad-spectrum anti-viral treatment against such cattle diseases as shipping fever and enteric disease complex.
