The CancerWeb Report, What's New In Cancer: November, 1996
AIDS-Related Cancer

• Why should a pregnancy hormone, human chorionic gonadotrophin, affect Kaposi's sarcoma? - Patients with AIDS are more prone to develop certain cancers of which the most common is Kaposi's sarcoma. Treatment for Kaposi's sarcoma includes radiotherapy, interferon-alpha, and chemotherapy, but it is at best only palliative. An article by an international group of researchers including Dr. Robert Gallo, in the October 24, 1996 issue of the New England Journal of Medicine, reported that Kaposi's sarcoma nodules regressed when injected directly with the A.P.L. preparation of human chorionic gonadotrophin (hCG), a peptide hormone that is normally released from the placenta during pregnancy. The study included 36 patients of whom 24 received injections of between 250 and 2,000 IU of the hormone. It appeared that the injection induced apoptosis, programmed death, within the tumor cells. (Gill, New Engl J Med 335:1261, 1996)

  Editor's Comment: - There is a great need for new approaches to the treatment of Kaposi's sarcoma in patients with AIDS. Earlier work by some of the authors of this article (see Lunardi-Iskandar, Nature 374:64, 1995) had shown that a cell line derived from human Kaposi's sarcoma which grew well in mice, failed to grow in pregnant mice; this was the stimulus for the present study. The most unusual feature of the findings is that the antitumor activity was not due to hCG itself, but rather to one or more other peptides which were impurities in the injected material. Preparations of hCG may contain as little as 24% of the active hormone. The researchers tested different preparations in mice and used only the most active one in patients. The individual preparations, and even different batches of each preparation, contained variable amounts of impurity and differed in antitumor activity. When tested in mice, highly purified hCG had very little activity, whereas certain peptides derived from the beta chain of the two-chain hormone molecule were very active. These fragments closely resembled various growth factors. There needs to be further study to identify and purify the material(s) actually responsible for antitumor activity. Intravenous dosing with the active substance(s) would be far preferable to direct injection into the nodules (termed intralesional injection), which is only feasible if they are few in number, and may be purely of cosmetic value otherwise.