}

Belinostat

Chemotherapies

Drug Overview

Belinostat (brand name Beleodaq) is an FDA-approved histone deacetylase (HDAC) inhibitor used in oncology. It is marketed under the brand name Beleodaq and is administered intravenously.

Belinostat is indicated for the treatment of relapsed or refractory peripheral T-cell lymphoma (PTCL) in adults. By inhibiting histone deacetylase enzymes, belinostat promotes accumulation of acetylated histones and proteins, leading to cell cycle arrest, differentiation, and apoptosis in malignant T cells.

Relevant Genes and Their Roles

This guideline focuses on the enzyme UGT1A1, a key phase II drug-metabolizing enzyme found primarily in the liver. UGT1A1 (UDP-glucuronosyltransferase 1A1) adds glucuronic acid to belinostat metabolites, facilitating their elimination in bile and urine.

Genetic variants in UGT1A1 can alter enzymatic activity. Reduced-function alleles decrease glucuronidation, leading to slower drug clearance and higher systemic exposure. Conversely, normal-function alleles maintain expected drug elimination rates.

Impact of Genetics on Drug Response

Patients with different UGT1A1 metabolizer phenotypes may experience differences in belinostat exposure, toxicity risk, and efficacy. Poor metabolizers show higher drug levels and increased adverse reactions, while normal and intermediate metabolizers generally follow standard pharmacokinetics. When genotype is unknown or indeterminate, no specific dosage adjustments are recommended beyond standard care.

Expected Clinical Effects of Genetic Variation

Normal Metabolizer

  • Effect on drug levels: Expected standard clearance and exposure
  • Clinical consequence: Typical efficacy and toxicity profile
  • Side effects: Standard adverse effect incidence (e.g., fatigue, nausea) and severity as per label

Intermediate Metabolizer

  • Effect on drug levels: Slightly reduced clearance; modestly increased exposure
  • Clinical consequence: Generally manageable toxicity with standard dosing
  • Side effects: Mild increase in common adverse effects (e.g., hematologic changes) at expected frequency

Poor Metabolizer

  • Effect on drug levels: Decreased clearance leading to higher systemic concentrations
  • Clinical consequence: Increased risk of severe toxicity
  • Side effects: Higher incidence of hematologic toxicity (neutropenia, thrombocytopenia); severity may be moderate to severe

Indeterminate/Not Available

  • Effect on drug levels: Unknown
  • Clinical consequence: No specific guidance; follow standard dosing with clinical monitoring
  • Side effects: Unknown; monitor for standard adverse effects

Dosing Guidelines

The following dosing guidelines are based on FDA recommendations and UGT1A1 genotype status.

UGT1A1 Dosing Guidelines

Phenotype Clinical Consequence Guideline Recommendation
Normal Metabolizer Expected standard metabolism and clearance Initiate therapy with recommended starting dose
Intermediate Metabolizer Near-normal metabolism with slight exposure increase Initiate therapy with recommended starting dose
Poor Metabolizer Higher systemic concentrations and higher adverse reaction risk Reduce starting dose to 750 mg/m2
Indeterminate Unknown impact Initiate therapy with recommended starting dose
Not available Unknown impact Initiate therapy with recommended starting dose

Alternative Treatment Options

No specific alternate drugs or dosing strategies are included in the current FDA guideline. Clinicians may consider other HDAC inhibitors (e.g., vorinostat, panobinostat) based on patient profile and clinical context.

Sources and References

Disclaimer: This document is for informational purposes only and is not a substitute for medical advice. Clinical decisions should be made by a qualified healthcare professional.

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