Phase I study of the ribonucleotide reductase inhibitor 3-aminopyridine-2-carboxaldehyde-thiosemicarbazone (3-AP) in combination with high dose cytarabine in patients with advanced myeloid leukemia

Abstract High dose cytarabine (HiDAC) is the most effective single agent for the treatment of acute myeloid leukemia (AML); clofarabine (CLOF) is also an active agent in AML. Preclinical data suggest synergy between cytarabine and clofarabine. We conducted a two step limited phase I trial of sequential HiDAC (2g/m2 over 3 hours) followed by CLOF (30 or 40 mg/m2 infused over 2 hours), each given daily for 5 days, in adults with AML in first or second relapse or refractory to initial induction chemotherapy. Patients with persistent leukemia on day 12–14 received a second course of HiDAC→CLOF; phase I toxicity evaluation was based on cycle 1 data only. Nine patients (6 men and 3 women) were treated. The median age was 55.5 years (range 29.2 – 68.1). All had relapsed AML; two had prior autologous stem cell transplant. The initial cohort of 3 patients received clofarabine 30 mg/m2 with one dose limiting toxicity (DLT); an additional 3 patients were treated in cohort 1. The second cohort was treated with CLOF 40 mg/m2, the target dose for a planned phase II trial of HiDAC→CLOF. Hematologic toxicities and infections were not considered DLT. In the first cohort (30 mg/m2; n = 6) there was 1 DLT - grade 4 skin rash in a patient who subsequently died on day 17 with sepsis-related multi-organ failure; 3 patients had reversible grade 3 elevations in AST/ALT, 1 had grade 3 skin toxicity. In cohort 2 (40 mg/m2 ; n = 3) there was no DLT; 1 patient had grade 3 AST/ALT; 2 had grade 3 skin. Three of nine patients received a second course of induction HiDACCLOF. Two of six patients in cohort 1 achieved complete remission (CR), 1/3 patients in cohort 2 achieved CRi(CRp). Two of three CR/CRi patients received one course and one received two courses of HiDAC→CLOF induction. Conclusion: HiDAC→CLOF was associated with transient elevation in AST/ALT (4/9) and skin rash (3/9; primarily extensive palmar/plantar); skin toxicity appeared especially prominent in patients with palmar/plantar toxicity during prior therapy with HiDAC. Toxicities (other than skin) were comparable to other salvage regimens for relapsed and refractory AML. This combination is active in relapsed AML with 3/9 CR/CRp. A phase II trial of HiDAC→CLOF is underway; prophylactic intravenous hydrocortisone has been incorporated in an attempt to decrease skin toxicity.

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A phase I study of GTI-2040 (G), an antisense to ribonucleotide reductase (RNR), in combination with high-dose AraC (HiDAC) in acute myeloid leukemia (AML)

Journal of Clinical Oncology ◽

10.1200/jco.2006.24.18_suppl.6561 ◽

2006 ◽

Vol 24 (18_suppl) ◽

pp. 6561-6561

Author(s):

G. Marcucci ◽

R. B. Klisovic ◽

W. Wei ◽

S. Liu ◽

P. Paschka ◽

...

Keyword(s):

Phase I ◽

Ribonucleotide Reductase ◽

Dose Escalation ◽

Myeloid Leukemia ◽

High Dose ◽

Phase Ii Trials ◽

Refractory Aml ◽

Dna Incorporation ◽

Count Recovery

6561 Background: RNR converts ribonucleotides to deoxyribonucleotides for DNA synthesis. AraC is converted into AraC triphosphate (AraCTP) and competes with deoxycytidine for DNA incorporation. We hypothesized that RNR downregulation by G leads to lower deoxycytidine levels, preferential AraCTP incorporation into DNA and increased cytotoxicity. A CTEP-sponsored Phase I dose escalation study of G +HiDAC in relapsed/refractory AML tested this hypothesis. Methods: Cohort I (18–59 yrs) received G (dose level (DL) 1: 3.5 mg/m2/d) by continuous IV infusion (CIVI) on d 1–6 + AraC IV q12 hrs on d 2, 4, 6 (DL1: 2500 mg/m2/dose). Cohort II (≥60 yrs) received G CIVI on d 1–6 +AraC IV on d 2 −6 (DL1: 1500 mg/m2/d). An ELISA-based assay measured plasma and intracellular concentration (IC) of G. Results: To date, cohort I included 9 pts with relapsed and 9 with refractory AML; 9 had intermediate and 9 adverse risk cytogenetics (CyG); 8 received prior HiDAC. Cohort II included 10 pts with relapsed and 6 with refractory AML; 8 pts had intermediate and 8 high risk CyG; 5 pts received prior HiDAC. Toxicities were comparable to HiDAC alone. The younger pts had higher AUC and longer t1/2. Of 16 pts evaluable in cohort I (median time to 1st relapse 6 mos), 6 had complete remission (CR) and 1 incomplete CR (no disease and incomplete blood count recovery). In cohort II, no responses were observed. At 120 hrs of antisense infusion, median G IC in marrow cells was higher (i.e., 175 vs75 nM) in younger than in older pts. A median 50% decrease in RNR protein was noted in 5/9 and 5/10 pts in cohort I and II, respectively. In cohort I, a median 50% decrease and 200% increase in RNR was noted in CR (n=4) and non-responder (NR; n=9) pts, respectively. In cohort II R2 downregulation did not predict response. In cohort I 62% of the ICs was in nucleus and 21.2% in cytoplasm in CR pts (n=3) vs. 20.3% and 53.5% in NR pts(n=5). Conclusions: G/HiDAC is feasible. Robust plasma and IC levels of G and target downregulation are achievable in vivo. Responses (41%) were observed only in the younger cohort, where CR pts had higher G nuclear IC and target downregulation than NR pts. Dose escalation continues in the younger cohort to establish a dose for Phase II trials. No significant financial relationships to disclose.

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