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IACM-Bulletin of 25 June 2000

Science: Tumour promoting effect of THC in animal study

A team of researchers of the University of California at Los Angeles reported that delta-9-tetrahydrocannabinol (THC) can promote tumour growth in animal tests by impairing the immune system. This is the first time that its possible tumour-promoting activity has been reported.

The scientists found in mice that the immune inhibitory cytokines interleukin-10 (IL-10) and transforming growth factor-beta (TGF-beta) were augmented following THC administration. THC also led to more rapid growth of tumour implants and decreased survival in two lung cancer models.

Over a four-week period, the animals were intraperitonealy injected four times per week with either THC (5 mg/kg body weight) or a saline solution. Fourteen days after the injections were started, cancer cells (murine Lewis lung cancer and line 1 alveolar cell cancer) were implanted in the mice. The mice continued to receive THC or saline injections over a period of two weeks.

The researchers found that there was significant enhancement of tumour growth in the THC-treated animals. The study also showed that when lymphocytes from the THC-treated mice were injected into untreated mice, the immune deficit was transferred and tumour growth was accelerated in the normal controls.

The study, already presented at the International Conference of the American Thoracic Society in April 1999, will now be published in the July 2000 issue of the Journal of Immunology.

Dr Steven Dubinett, head of the research team, said that further studies were needed to assess the danger. Dr Lesley Walker, head of scientific information at the British Cancer Research Campaign said: "How relevant it is to human cancers we cannot be sure, but it needs to be ascertained."

Dr. Franjo Grotenhermen (IACM): "We know from animal studies that THC inhibits the production of Th-1 cytokines such as IL-1, IL-2, and IFN-gamma and stimulates the production of Th-2 cytokines such as IL-4, IL-10, and TGF-beta. This would give reason for a causal therapeutic use of THC in certain autoimmune diseases that appear to be Th-1 mediated such as Crohn's disease, a form of chronic intestinal inflammation, and rheumatoid arthritis. On the other hand this action would increase the susceptibility to cancer and infections. But these animal data with high doses of THC cannot easily be extrapolated to the human situation."

(Sources: PRNewswire of 20 June 2000; PA News of 20 and 21 June 2000; Zhu L, et al: THC-mediated IL-10-dependent suppression of anti-tumor immunity in murine lung cancer. Presented at the 1999 International Conference of the American Thoracic Society, San Diego, CA, April, 1999; Melamede R: Possible mechanisms in autoimmune diseases. In: Grotenhermen F, Russo E (eds.). Cannabis and Cannabinoids: Pharmacology, Toxicology and Therapeutic Potential. Binghamton/New York: Haworth Press, in press)

News in brief

USA:
Four years after California voters passed the law on the medical use of marijuana, Nevada County adopted a set of guidelines. A patient is permitted up to two pounds of processed marijuana and to cultivate up to 10 plants at any given time - so long as the plants yield no more than two pounds of processed marijuana. Shasta County allows patients 1.33 pounds of marijuana and two outdoor plants or six indoor plants. Tehama County allows three pounds of marijuana, up to 18 seedlings but no more than three mature plants. Alaska allows one ounce of usable marijuana and six plants but only up to three mature plants. Colorado allows up to two ounces and three mature plants. (Source: Sierra Sun of 22 June 2000)

Science:
More than 100 different drugs are in the pipeline for mental illness, the Pharmaceutical Research and Manufacturers of America (PhRMA) said on 19 June. "This year, pharmaceutical companies will spend an estimated $6 billion to discover and develop medicines for diseases of the central nervous system, including mental illnesses," Alan Holmer, president of PhRMA, said in a statement. Among them is the cannabinoid receptor antagonist SR 141716 (Sanofi-Synthelabo) that is tested against Alzheimer's disease, obesity and schizophrenia. (Source: Reuters of 19 June 2000).

USA:
Hawaii Governor Ben Cayetano signed a bill passed by the Senate in April on 14 June legalizing the medical use of marijuana, making his state the first to pass such a law through the legislature. It makes it legal for seriously ill people to grow, possess and use the drug. Seven other states -- Alaska, Arizona, Nevada, Washington, Oregon, Maine and California, as well as the District of Columbia -- have similar laws, but they were passed as voter initiatives and never tested by lawmakers. (Source: Reuters of 14 June 2000).

Australia:
The state Parliament of Tasmania will investigate whether THC should be legalised for the terminally ill and people with chronic pain. The Parliament's Community Development Committee will investigate THC should be made available in tablet form. Last October, the Australian Medical Association and the NSW Law Society announced a campaign to lobby state governments to allow the use of cannabis for palliative care. (Source: The Mercury of 23 June 2000)

USA:
On 14 June author and medical marijuana advocate Peter McWilliams, 50, was found in his California home, choked to death on his own vomit. After being arrested for selling marijuana to medical buyers' clubs he was denied the right to use marijuana that allowed him to stomach a powerful cocktail of AIDS and cancer drugs. The newspaper Michigan Daily spoke of an "unnecessary death" and said: "The tragic death of Peter McWilliams highlights the government's continued failure to accept the virtues of medical marijuana." (Source: Michigan Daily of 19 June 2000)

Germany:
Eva Gorig, 71, outstanding exponent of the "Gruene Hilfe" (Green Help) died after several months of illness. She was indefatigably engaged with the care for prisoners convicted due to cannabis offences. (Source: Personal communication)

New Zealand:
The Government is discussing with the Green Party which parliamentary committee should hold a review of cannabis laws. Health Minister Annette King said the review should consider health, social and justice issues relating to cannabis laws. "We need to look at whether we need to change the law, to strengthen the law and to minimise harm from this drug," she said. The Government has made a commitment to review the laws but has not made a commitment to changes. (Source: Otago Daily Times of 21 June 2000)

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