{"classes":[{"categories":[{"measurements":[{"groupId":"OG000","value":"1"},{"groupId":"OG001","value":"1"},{"groupId":"OG002","value":"1"},{"groupId":"OG003","value":"2"},{"groupId":"OG004","value":"2"}]}]}],"denoms":[{"counts":[{"groupId":"OG000","value":"14"},{"groupId":"OG001","value":"7"},{"groupId":"OG002","value":"24"},{"groupId":"OG003","value":"7"},{"groupId":"OG004","value":"2"}],"units":"Participants"}],"description":"Dose limiting toxicity will be defined as any irreversible grade 3 or any grade 4 non-hematologic toxicity that is related to busulfan infusion and not graft vs host disease or late infection after recovery from the initial period of myelosuppression. The maximum tolerated dose (MTD) is defined as the dose with probability of dose limiting toxicity (DLT) of 0.25. The dose of continuous infusion IV busulfan based on blood levels derived from a test dose in conjunction with fludarabine and alemtuzumab plus tacrolimus for GVHD prophylaxis.","groups":[{"description":"Target AUC/24 hrs of 4800 micrometer (uM)-min +/-15%","id":"OG000","title":"Dose Level 1"},{"description":"Target AUC/24 hrs of 5760 uM-min +/- 15%","id":"OG001","title":"Dose Level 2"},{"description":"Target AUC/24 hrs of 6912 uM-min +/- 15%","id":"OG002","title":"Dose Level 3"},{"description":"Target AUC/24 hrs of 7603 uM-min+/- 15%","id":"OG003","title":"Dose Level 4"},{"description":"Target AUC/24 hrs of 8363 uM-min+/- 15%","id":"OG004","title":"Dose Level 5"}],"paramType":"NUMBER","reportingStatus":"POSTED","timeFrame":"first 6 weeks or 42 days following stem cell infusion","title":"Number of Participants With Dose Limiting Toxicities (DLTs)","type":"PRIMARY","unitOfMeasure":"DLTs"}