Prolonged remissions in adults with acute leukemia following late intensification chemotherapy and immunotherapy

Sixty-two patients with acute leukemia who remained in continuous complete remission for 8 to 45 months received three courses of intensified therapy with new chemotherapeutic agents, after which they received no further chemotherapy. Immunotherapy with BCG was then administered to 55 of these patients. They have been observed for up to 117 months off all chemotherapy, and 37 patients have relapsed. Thirty-two relapses occurred within 24 months, and 22 occurred within six months after completion of late intensification therapy. Only 1 of 24 patients who remained in unmaintained remission for four years after late intensification therapy has relapsed subsequently. Toxicity from intensification therapy was usually mild, and the most serious side effects were liver function abnormalities. These results suggest that late intensification therapy plus BCG immunotherapy results in prolonged disease-free survival for some patients with acute leukemia.