Eight patients with widespread metastatic neoplastic diseases following leukopoietic stimulation by leukapheresis were treated on 10 occasions with large doses of HN2, 30 to 280 mg. (0.6 to 4.1 mg./Kg.). Despite severe hematodepression with anemia, leukopenia and thrombocytopenia, hematopoietic recovery occurred in all instances within 16 to 25 days. The recovery from severe hematodepressant doses of HN2 is attributed largely to the previous leukopoietic stimulation. Doses of HN2 at approximately four times the LD50 were unable to eradicate metastatic tissue in Ewings sarcoma and malignant melanoma.
Although hematopoietic protection was evident, the hazard of injuring the next most vulnerable tissues must be considered as larger amounts of cytotoxic agents are employed.