Phase I/II Trial of AEG35156 X-Linked Inhibitor of Apoptosis Protein Antisense Oligonucleotide Combined With Idarubicin and Cytarabine in Patients With Relapsed or Primary Refractory Acute Myeloid Leukemia

X-linked inhibitor of apoptosis protein (XIAP) is an inhibitor of caspases 3 and 9 which are overexpressed in acute myeloid leukemia (AML) and may contribute to chemoresistance. We report on a phase I/II trial of the XIAP antisense oligonucleotide AEG35156 in combination with reinduction chemotherapy. Twenty-four patients with rapidly relapsed or refractory AML were treated with escalating doses of AEG35156 (12 to 250 mg/m(2)) as an intravenous solution over 2 hours and 32 patients were treated with the highest planned dose of 350 mg/m(2) in combination with idarubicin and high-dose cytarabine reinduction chemotherapy. Correlative studies were conducted to determine the effects of AEG35156 on levels of XIAP mRNA. Knockdown of XIAP mRNA during treatment increased with the dose of the antisense. All patients who received 350 mg/m(2) of AEG35156 had higher than 30% target knockdown with a median maximal knockdown of 90% (range, 48% to 100%). The overall response rate was higher among the patients receiving the highest dose of AEG35156. In this group, 15 (47%) of 32 patients achieved complete response (CR)/CR with incomplete platelet count recovery (CRp) compared with only one (4%) of 24 receiving 12 to 250 mg/m(2) AEG35156. Among the patients receiving 350 mg/m(2) of AEG35156 in combination with chemotherapy, 10 (91%) of 11 who were refractory to a single induction chemotherapy regimen achieved CR/CRp after reinduction with AEG35156 and chemotherapy. AEG35156 was well tolerated save for two cases of peripheral neuropathy in patients receiving multiple doses of AEG35156. At the highest dose tested, AEG35156 knocks down its target and appears very effective when combined with chemotherapy in patients with AML refractory to a single induction regimen.