Clinical and immunological follow-up of patients with AIDS-associated Kaposi's sarcoma treated with an anti-IL-6 monoclonal antibody.

Ten AIDS patients with Kaposi's sarcoma (four in stage II A, four in stage III A, one in stage III B and one in stage IV of the disease) were treated for 14 days with B-E8, an anti-IL-6 monoclonal antibody (IgG1), at a daily dose of 10 mg. No side-effects were observed, but no patients experienced a complete or partial response. No modification was noted in the analysis of lymphocyte subsets, except for a transient decline in the number of cells expressing CD56, accompanied by altered NK activity in four of the seven evaluable patients. Anti-IL-6 mAb prevented the binding of IL-6 to its cell membrane receptor, as documented by the decline in C reactive protein levels. However, anti-IL-6 mAb induced the circulation of significant amounts of IL-6, probably in the form of monomeric immune complexes. The sera, analysed on B9 cell line, demonstrated a stimulating activity, indicating that hypersensitive cells were able to cleave these complexes. This observation, together with the clinical inefficacy of the treatment, should prompt us to be careful with the use of unmanipulated single monoclonal antibodies, especially in cancer patients.