Thioguanine as primary treatment for chronic granulocytic leukaemia.

In an attempt to convert the bone-marrow population from Philadelphia-chromosome (Ph-1) positivt to partially or wholly Ph-1 negative, thioguanine was used as primary therapy in seven patients with chronic granulocytic leukaemia (C.G.L.). Although eight episodes of neutropenia were induced, prolonged remission or conversion to Ph-1-negativity was not achieved in any patient. However, thioguanine was at least as effective as busulphan for initial therapy in C.G.L., and had the advantage of rapid reversibility of haemopoietic depression when discontinued. Thioguanine merits further evaluation as an agent for the management of C.G.L. in its chronic phase.