The invention disclosed herein describes novel biomarkers useful for risk assessment, screening, prognosis and selection and monitoring of therapy for HDAC mediated cell proliferative disorders. In particular, the invention provides the identities of three particular proteins whose expression patterns are strongly predictive of a particular patient's treatment outcome, e.g., non-responsiveness to SAHA. The expression profile, or pattern, whether embodied in nucleic acid expression, protein expression, or other expression formats will find use in identifying and selecting patients afflicted with a particular HDAC mediated cancer who are likely to be non-responsive to SAHA-based therapy and thus candidates for other treatments.