Clinical implications of a gain-of-function genetic polymorphism in DPYD (rs4294451) in colorectal cancer patients treated with fluoropyrimidines.

Dihydropyrimidine dehydrogenase (DPD, encoded by the gene) is the rate-limiting enzyme for the detoxification of fluoropyrimidines (FLs). Rs4294451 is a regulatory polymorphism that has recently been functionally characterized and associated with increased DPD expression in the liver. The aim of the present study was to test the clinical implications of being a carrier of rs4294451 in a cohort of 645 FL-treated colorectal cancer patients.

Clinical Benefits and Utility of Pretherapeutic DPYD and UGT1A1 Testing in Gastrointestinal Cancer: A Secondary Analysis of the PREPARE Randomized Clinical Trial.

Importance: To date, the clinical benefit and utility of implementing a DPYD/UGT1A1 pharmacogenetic-informed therapy with fluoropyrimidines and/or irinotecan have not been prospectively investigated.

Objective: To examine clinically relevant toxic effects, hospitalizations, and related costs while preserving treatment intensity and efficacy outcomes in patients with gastrointestinal cancer.

Design, Setting, And Participants: This nonprespecified secondary analysis stems from Pre-Emptive Pharmacogenomic Testing for Preventing Adverse Drug Reactions (PREPARE), a multicenter, controlled, open, block-randomized, crossover implementation trial conducted from March 7, 2017, to June 30, 2020, and includes data from Italy according to a sequential study design.

Increased plasma imatinib exposure and toxicity in chronically treated GIST patients with SARS-CoV-2 infection: a case series.

Introduction: Inflammatory factors released during severe coronavirus disease-19 (COVID-19) caused by acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are known to influence drug exposure, but data on the effect of mild infection are few. Here we describe for the first time an increase in plasma imatinib and norimatinib concentrations observed in a series of 5 patients treated with imatinib for gastrointestinal stromal tumor (GIST) after mild COVID-19.

Methods: The patients were undergoing routine therapeutic drug monitoring (TDM) and pharmacogenetic (PGx) analyses of polymorphisms in genes involved in imatinib metabolism and transport (, , , and ) when SARS-CoV-2 infection occurred.

Quantification of Letrozole, Palbociclib, Ribociclib, Abemaciclib, and Metabolites in Volumetric Dried Blood Spots: Development and Validation of an LC-MS/MS Method for Therapeutic Drug Monitoring.

Therapeutic drug monitoring (TDM) may be beneficial for cyclin-dependent kinase 4/6 inhibitors (CDK4/6is), such as palbociclib, ribociclib, and abemaciclib, due to established exposure-toxicity relationships and the potential for monitoring treatment adherence. Developing a method for quantifying CDK4/6is, abemaciclib metabolites (M2, M20), and letrozole in dried blood spots (DBS) could be useful to enhance the feasibility of TDM. Thus, an optimized LC-MS/MS method was developed using the HemaXis DB10 device for volumetric (10 µL) DBS collection.