"...there are an astonishing number of coincidences between etoposide and cyclosporine. the first coincidence was that etoposide and cyclosporine were both found and developed on the chemical and biological side by the same groups, those of the present authors and their specific biological effects were discovered by one of us; second, both compounds were approved by the united states food and drug administration on the same day in november 1983, although they had been submitted by different companies; furthermore, both drugs act via an effect on an intranuclear isomerase, topoisomerase ii, and peptide "cis-trans-"isomerase, respectively; both compounds are potent immunosuppressants; etoposide as well as cyclosporine are used in the treatment of leukemias or other malignancies; the latter after bone marrow transplantation to prevent graft-versus-host disease, the former also being used in conjunction with bone marrow transplantation; sometimes, the two compounds are used concomitantly, exploiting the capacity of cyclosporine to reduce certain types of multidrug resistance or to modify immunity against tumors cured by etoposide; in the development of both drugs, galenical problems arose, related to poor water solubility and absorption from intestinal tract, and experience gained with etoposide in this area was crucial for overcoming, several years later, difficulties of a similar type with cyclosporine. it is left to the reader to make assumptions about the heuristic aspects of these surprising coincidences..."