By Ed Susman
ORLANDO, FL -- December 13, 2006 -- The combination of 5-azacitidine (Vidaza) in combination with the experimental histone deacetylase inhibitor, MS-275, produced responses in patients with myelodysplastic syndrome (MDS), chronic myelomonocytic leukemia (CMML) and acute myelogenous leukemia (AML), researchers reported here at the American Society of Hematology (ASH) 48th Annual Meeting and Exhibition.
"The combination is clinically tolerable and leads to substantial remissions," said Steven Gore, MD, associate professor of oncology, Johns Hopkins University School of Medicine, Baltimore, Maryland, who enrolled 31 patients in his study.
The study population included 13 patients with MDS, 4 patients with CMML and 14 patients with AML. Of the AML patients, 7 were identified with trilineage dysplasia -- 4 of whom had relapsed and 3 had primary-refractory disease.
Among the 27 evaluable patients discussed in his presentation, 2 patients achieved complete responses and 4 had partial responses. Another 6 patients exhibited bilineage hematologic improvement, Dr. Gore said in his oral presentation December 11th.
In the phase 1 study, researchers tested patients with a variety of doses. Azacitidine was administered at 30, 40 and 50 mg/m2 per dose; MS-275 was administered at 2, 4, 6 and 8 mg/m2 per dose. Subcutaneous azacitidine was self-administered daily for 10 days. MS-275 was administered on days 3 and 10 of each 28 day treatment cycle.
"Median time to first objective hematologic response was 2 cycles," Dr. Gore said. The time to response ranged from 1 to 5 cycles. "The median time to best hematologic response was 4 cycles," he said. That range was from 2 to 9 cycles.
Based on signals that the combination offered potential in treating these patients, Dr. Gore said MS-275 is being further studied by international researchers. MS-275 is orally bioavailable and has an intriguing 50 hour half-life, he said.
The study was supported by Pharmion.
[Presentation title: Combined Methyltransferase/Histone Deacetylase Inhibition with 5-Azacitidine and MS-275 in Patients with MDS, CMMoL and AML: Clinical Response, Histone Acetylation and DNA Damage. Abstract 517]
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