Report

A small-molecule inhibitor of the aberrant transcription factor CBFβ-SMMHC delays leukemia in mice

Science  13 Feb 2015:
Vol. 347, Issue 6223, pp. 779-784
DOI: 10.1126/science.aaa0314

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Toward drugging the undruggable in cancer

Many human cancers are characterized by inappropriate activity of transcription factors. These proteins are attractive drug targets in principle, but normalizing their function requires drugs that modulate specific protein-protein interactions, a goal that has been challenging. In acute myeloid leukemia, a chromosomal translocation creates an aberrant form of the transcription factor CBF-beta, which outcompetes “normal” CBF-beta for binding to another transcription factor called RUNX1, thereby deregulating its activity. Illendula et al. identified and chemically optimized a small molecule that selectively disrupts the interaction between the aberrant CBF-beta and RUNX1 (see the Perspective by Koehler and Chen). This molecule restored normal gene expression patterns and delayed leukemia progression in mice. Thus, transcription factors may not be as undruggable as once thought.

Science, this issue p. 779; see also p. 713

Abstract

Acute myeloid leukemia (AML) is the most common form of adult leukemia. The transcription factor fusion CBFβ-SMMHC (core binding factor β and the smooth-muscle myosin heavy chain), expressed in AML with the chromosome inversion inv(16)(p13q22), outcompetes wild-type CBFβ for binding to the transcription factor RUNX1, deregulates RUNX1 activity in hematopoiesis, and induces AML. Current inv(16) AML treatment with nonselective cytotoxic chemotherapy results in a good initial response but limited long-term survival. Here, we report the development of a protein-protein interaction inhibitor, AI-10-49, that selectively binds to CBFβ-SMMHC and disrupts its binding to RUNX1. AI-10-49 restores RUNX1 transcriptional activity, displays favorable pharmacokinetics, and delays leukemia progression in mice. Treatment of primary inv(16) AML patient blasts with AI-10-49 triggers selective cell death. These data suggest that direct inhibition of the oncogenic CBFβ-SMMHC fusion protein may be an effective therapeutic approach for inv(16) AML, and they provide support for transcription factor targeted therapy in other cancers.

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