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Arsenic Trioxide & MDS: Leukemia
Arsenic trioxide in patients with myelodysplastic syndromes (MDS): Preliminary results of a phase II clinical study.
A. F. List, G. J. Schiller, J. Mason, D. Douer, R. Ellison;
H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL; University of California, Los Angeles, CA; Scripps Cancer Center, San Diego, CA; USC/Norris Cancer Center, Los Angeles, CA; Cell Therapeutics, Inc, Seattle, WA
Abstract: Background: Trisenox (arsenic trioxide ¨C ATO) is a novel anticancer agent approved for the treatment of relapsed or refractory acute promyelocytic leukemia.
ATO has unique mechanisms of action that impact apoptotic threshold and differentiation in leukemia cell lines and hematopoietic malignancies. To investigate the activity of ATO in MDS, we performed a study in pts from Low/Int-1 (LR) and Int-2/High risk (HR) IPSS categories.
Methods: Pts received ATO at 0.25 mg/kg via a 1-2 hour IV infusion, Monday to Friday, 2 consecutive wks every 28 days. Disease response and toxicity were assessed using the International Working Group (IWG) criteria and NCI CTC v2, respectively. Results: 53 pts are enrolled: 4 received no study drug and 3 are too early in treatment to assess.
Among the 46 evaluable pts (29 M/17 F; median age 69, [35-93]), FAB categories were RA (6 pts), RARS (9), RAEB (18), RAEB-t (11), and CMML (2). Twenty-five pts were HR and 21 were LR MDS. The median interval from diagnosis to first dose was 7 months (0-81).
Thirty-five pts were transfusion-dependent (TD).
Hematologic responses were observed in 12 of 46 evaluable pts (26%); 8/21 LR pts (38%), and 4/25 HR pts (16%). Responses included 9 erythroid (5 major, including 1 CR), 3 major platelet, and 2 major neutrophil.
Confirmed responses were seen after 2 to 6.1 months of treatment and lasted from 2 to >8 months on study, with 1 pt maintaining response for >21 months off study. Four TD pts became transfusion-independent, and transfusion requirements in 3 others decreased by ¡Ý50%. Stable disease lasting >8 weeks was observed in 8 additional HR pts.
Grades (gr) 3-4 adverse events considered drug-related that were observed in ¡Ý2 pts included fatigue, febrile neutropenia, dyspnea, urinary tract infection, hyperglycemia, congestive heart failure, hypoxia, herpes infection, and pleural effusion.
Some cytopenias were exacerbated, resulting in 1 gr 3 and 2 gr 4 neutropenias, and 3 gr 3 and 1 gr 4 thrombocytopenias.
Conclusions: ATO demonstrates multilineage hematopoietic activity in both LR and HR MDS pts. ATO is well tolerated, as most treatment-related adverse events were mild to moderate.
Abstract No: 6512