Tegafur-uracil (UFT) in lower doses is safe for the treatment of colorectal cancer in patients with partial dihydropyrimidine dehydrogenase deficiency: a proof of principle

The Prognostic and Predictive Value of Dihydropyrimidine Dehydrogenase-Related Indicators in Clinical Outcomes of Chemotherapy in Colorectal Cancer Patients: a Systematic Review and Meta-Analysis

Colorectal cancer (CRC) is the third most common cancer worldwide. Predictive biomarkers are needed to predict patients' outcomes and to select a chemotherapy regimen. We assessed whether dihydropyrimidine dehydrogenase (DPD)-related indicators can predict CRC patients' outcomes. We searched the studies in PubMed, EmBase, and the Cochrane Library up to March 4, 2018. We mainly analyzed different CRC patients' outcomes according to specific DPD-related indicators. Twenty-five articles were included in the meta-analysis. The results showed that for disease-free survival (DFS), low DPD expression was significantly superior to high expression (I² = 72%; HR: 1.59; 95%CI: 1.21-2.09; p = 0.001). However, this result had a potential publication bias (Begg's test: p = 0.007; Egger's test: p = 0.004). Among patients treated with chemotherapy, a high thymidylate phosphorylase (TP)/DPD ratio was advantageous for DFS (I² = 63.7%; HR: 0.65; 95%CI: 0.46-0.92; p = 0.015), and this result did not have a publication bias. For overall survival (OS), low DPD expression was superior to high expression (I² = 74.4%; HR: 2.11; 95%CI: 1.48-3.00; p < 0.001), although this result had a publication bias (Egger's test: p = 0.003; Begg's test: p = 0.010). There was no difference in OS according to the TP/DPD ratio (I² = 0%; HR: 0.92; 95%CI: 0.75-1.13; p = 0.420). DFS and OS were better in CRC patients with low DPD expression than in those with high DPD expression. However, because of publication bias, more DPD indicator-related studies, especially with negative results, are still needed. Patients with a high TP/DPD ratio have better DFS but not OS.

Germline oncopharmacogenetics, a promising field in cancer therapy

Pharmacogenetics (PGx) is the study of the relationship between inter-individual genetic variation and drug responses. Germline variants of genes involved in drug metabolism, drug transport, and drug targets can affect individual response to medications. Cancer therapies are characterized by an intrinsically high toxicity; therefore, the application of pharmacogenetics to cancer patients is a particularly promising method for avoiding the use of inefficacious drugs and preventing the associated adverse effects. However, despite continuing efforts in this field, very few labels include information about germline genetic variants associated with drug responses. DPYD, TPMT, UGT1A1, G6PD, CYP2D6, and HLA are the sole loci for which the European Medicines Agency (EMA) and the US Food and Drug Administration (FDA) report specific information. This review highlights the germline PGx variants that have been approved to date for anticancer treatments, and also provides some insights about other germline variants with potential clinical applications. The continuous and rapid evolution of next-generation sequencing applications, together with the development of computational methods, should help to refine the implementation of personalized medicine. One day, clinicians may be able to prescribe the best treatment and the correct drug dosage based on each patient's genotype. This approach would improve treatment efficacy, reduce toxicity, and predict non-responders, thereby decreasing chemotherapy-associated morbidity and improving health benefits.