A Phase I Study of Clofarabine & Cytosine Arabinoside Therapy for Older Adults With Acute Myeloid Leukemia

This phase I/II trial will include an initial dose escalation of clofarabine with a fixed standard dose of Ara-C in phase I to determine the 'optimal phase II dose'. Patients will be enrolled into phase I in cohorts of 3-6 beginning at Dose Level I of clofarabine (30 mg/m2/day, days 2-6). If 0/3 or 1/6 patients experience dose-limiting toxicity (DLT), clofarabine will be escalated to Dose Level II (40mg/m2/day, days 2-6). If >1/3 or ≥2/6 patients experience DLT on Dose Level II, then Dose Level I will be declared the optimal phase II dose. However, if 0/3 or 1/6 patients experience DLT on Dose Level II, then Dose Level II will be declared the optimal phase II dose. In the event that ≥2 patients experience DLT at Dose Level I, clofarabine will be dose reduced to Dose Level -I (22.5mg/m2/day, days 2-6). Accrual will continue in cohorts of 3-6 patients, in a phase I fashion. If 0/3 or 1/6 patients experience DLT, then Dose Level -I will be declared the 'optimal phase II dose'. In the event that ≥2 patients experience DLT at Dose Level -I, clofarabine will be further dose reduced to Dose Level -II (15mg/m2/day, days 2-6). Accrual will again proceed in cohorts of 3-6 patients. If 0/3 or 1/6 experience DLT, then Dose Level -II will be declared the 'optimal phase II dose'. In the event that ≥2 patients experience DLT at Dose Level -II, accrual to the protocol will be halted. Enrollment will proceed at the optimal phase II dose in a Simon 2-stage design to determine the CR rate and treatment-related mortality initially in 16 patients; if the CR rate and TRM is acceptable , then enrollment will continue to approximately 46 patients or until complete. Induction Therapy (cycle 1) * 7 day cycle Day 1 Aggressive Hydration x12-24hrs, followed by Ara-C 100mg/m2/day by 24hr IV continuous infusion days 1-7 * PK analysis Ara-C alone on Day 1 (plasma \& intracellular) Day 2 Dexamethasone 10mg IV QD prior to clofarabine days 2-6 Clofarabine 2 hour daily infusion days 2-6 * PK analysis of Ara-C \& clofarabine on Day 2 * Bone Marrow Apoptosis analysis (plasma \& intracellular) Day 3 \*Bone Marrow Apoptosis analysis (plasma \& intracellular) Day 6 \*PK analysis of Ara-C and clofarabine (plasma only) (UAB only) Day 8 Initiation of prophylactic antibiotic, antifungal \& antiviral therapy Day 15 \*QOL analysis Day 15-22 Restaging BM Re-Induction if appropriate (see below) Day 16 GM-CSF 250μg/m2 daily until ANC >1,500/μl (if D15 BM aplasia, no residual AML) Day 28-49 Outcome BM, assessment of response Re-Induction (PR) or Post-Remission therapy (CR) * QOL analysis 2 weeks after hospital discharge (approximately Day 42) Re-Induction (cycle 2 if appropriate) (if Partial Remission after Induction, day 15-49) \*5 day cycle Aggressive Hydration x12-24hrs Day 1 Dexamethasone 10mg IV QD days 1-5 Day 1 Clofarabine 2 hour daily infusion days 1-5 Day 1 Ara-C 100mg/m2/day days 1-5 (begin 4 hours after end of clofarabine infusion) Day 7 GM-CSF 250μg/m2 daily may be used until recovery ANC >1,500/μl Day 7 Initiation of prophylactic antibiotic, antifungal \& antiviral therapy Post-Remission Therapy (cycles 2 \& 3 if appropriate) (if Complete Remission after Induction; must have ANC>1,000/μl , platelets >100/μl) \*5 day cycle Aggressive Hydration x12-24hrs Day 1 Dexamethasone 10mg IV QD days 1-5 Day 1 Clofarabine 2 hour daily infusion days 1-5 Day 1 Ara-C 100mg/m2/day days 1-5 (begin 4 hours after end of clofarabine infusion) Day 7 GM-CSF 250μg/m2 daily may be used until recovery ANC >1,500/μl Day 7 Initiation of prophylactic antibiotic, antifungal \& antiviral therapy Follow-up Monthly x 12 months 3-monthly x 2 years 4-monthly x 1 year 6-monthly x 1 year Annually thereafter