Pharmacogenetic testing for drugs used in malignancy

Abstract

Introduction: The aim was to assess the use of pharmacogenetic testing in local practice for drugs prescribed in malignancy. Methods: Drugs used in malignancy available on the Maltese Government Formulary List (GFL) were identified. The Pharmacogenomics Knowledgebase (PharmGKB) was used to identify the drugs with pharmacogenetic implications and which are annotated as ‘Testing required’. The European Medicines Agency (EMA) Summary of Product Characteristics (SmPC) and the US Food and Drug Administration (FDA) drug label were compared for each drug. Discussion with the Chair of Haematology and Oncology at Sir Anthony Mamo Oncology Centre was held to assess local pharmacogenetic testing practice for the identified drugs. Results: Twenty-two drugs on the GFL (July 2018) used in malignancy have pharmacogenetic implications; thirteen of these drugs are annotated as ‘Testing required’ in PharmGKB. The EMA SmPC and FDA drug label are in agreement that pharmacogenetic testing is required before prescribing for six drugs (dabrafenib, erlotinib, everolimus, imatinib, trametinib, trastuzumab). Six drugs (anastrazole, exemestane, letrozole, rasburicase, tamoxifen, tretinoin) only have the FDA drug label available which indicates pharmacogenetic testing as required before prescribing. There is discrepancy between annotations for lenalidomide since the FDA drug label is annotated as ‘Testing required’ and the EMA SmPC is annotated as ‘Informative pharmacogenetics’ rather than ‘Testing required’. The oncologist confirmed that locally pharmacogenetic testing is being requested before prescribing for all thirteen drugs annotated as ‘Testing required’ in PharmGKB. Conclusion: Local practice for requesting a pharmacogenetic test prior to prescribing drugs with pharmacogenetic implications in the oncology setting conforms to international specifications.