- Age =< 50 years of age with hematologic diseases treatable by allogeneic HSCT who through pre-existing medical conditions or prior therapy are considered to be of high risk for regimen related toxicity associated with a conventional transplant or those patients who refuse a conventional SCT; transplants must be approved for these inclusion criteria by both the participating institution's patient review committee such as the Patient Care Conference (PCC at the Fred Hutchinson Cancer Research Center [FHCRC]) and by the principal investigator