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ASH 2014: Pracinostat Combination Shows Significant Clinical Activity in Phase II Study of Newly Diagnosed Acute Myeloid Leukemia

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Key Points

  • Interim data show that 45% patients to date have achieved the primary endpoint of complete response plus complete response with incomplete blood count recovery plus morphologic leukemia-free state.
  • The investigators noted that most responses occurred rapidly, often within the first two cycles, and continued to improve with ongoing therapy
  • Pracinostat plus azacitidine was well tolerated in this population of elderly AML patients, with no unexpected toxicities.

In a phase II study, the histone deacetylase inhibitor pracinostat demonstrated significant clinical activity in combination with azacitadine in elderly patients with newly diagnosed acute myeloid leukemia (AML). Interim data from 33 evaluable patients were presented at the 56th American Society of Hematology (ASH) Annual Meeting and Exposition (Abstract 947).

Study Details

According to the presentation, 15 of 33 patients (45%) to date have achieved the primary endpoint of complete response plus complete response with incomplete blood count recovery plus morphologic leukemia-free state. No patient who achieved a clinical response has progressed.

The study recently completed enrollment with a total of 50 patients, 17 of which are still too early for their initial clinical response assessment. The 60-day mortality rate, is approximately 10% (3 of 33 patients). Currently, 14 patients have exceeded 90 days on study of which 9 (64%) have achieved a complete response, many evolving from a lesser earlier response.

"These data support definitive development of pracinostat in combination with azacitidine in elderly AML patients," concluded Guillermo Garcia-Manero, MD, of The University of Texas MD Anderson Cancer Center, lead author and principal investigator of the study. "Most responses are occurring rapidly, often within the first two cycles, and continue to improve with ongoing therapy. Therefore, the observed response rate, which is already higher than we would expect from azacitidine alone, is likely to increase with longer follow-up of patients."

Adverse Events

Pracinostat in combination with azacitidine was well tolerated in this population of elderly AML patients, with no unexpected toxicities. Six patients to date have received study drug beyond 230 days, reflecting long-term tolerability.

The most common treatment-emergent adverse events included neutropenia, febrile neutropenia, thrombocytopenia, nausea, fatigue, and anemia. Adverse events resulting in dose reductions were uncommon and frequently due to disease under study. Six patients discontinued study therapy due to treatment-emergent adverse events.

The study was sponsored by MEI Pharma. For full disclosures of the study authors, view the study abstract.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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