Implementation and clinical benefit of DPYD genotyping in a Danish cancer population

BACKGROUND

In 2020, the European Medicines Agency recommended testing patients for dihydropyrimidine dehydrogenase (DPD) deficiency before systemic treatment with fluoropyrimidines (FP). DPD activity testing identifies patients at elevated risk of severe FP-related toxicity (FP-TOX). The two most used methods for DPD testing are DPYD genotyping and DPD phenotyping (plasma uracil concentration). The primary objective of this study was to compare the overall frequency of overall grade ≥3 FP-TOX before and after the implementation of DPYD genotyping.

PATIENTS AND METHODS

Two hundred thirty Danish, primarily gastrointestinal cancer patients, were DPYD-genotyped before their first dose of FP, and blood was sampled for post hoc assessment of P-uracil. The initial dose was reduced for variant carriers. Grade ≥3 FP-TOX was registered after the first three treatment cycles of FP. The frequency of toxicity was compared to a historical cohort of 492 patients with post hoc determined DPYD genotype from a biobank.

RESULTS

The frequency of overall grade ≥3 FP-TOX was 27% in the DPYD genotype-guided group compared to 24% in the historical cohort. In DPYD variant carriers, DPYD genotyping reduced the frequency of FP-related hospitalization from 19% to 0%. In the control group, 4.8% of DPYD variant carriers died due to FP-TOX compared to 0% in the group receiving DPYD genotype-guided dosing of FP. In the intervention group, wild-type patients with uracil ≥16 ng/ml had a higher frequency of FP-TOX than wild-type patients with uracil <16 ng/ml (55% versus 28%).

CONCLUSIONS

We found no population-level benefit of DPYD genotyping when comparing the risk of grade ≥3 FP-TOX before and after clinical implementation. We observed no deaths or FP-related hospitalizations in patients whose FP treatment was guided by a variant DPYD genotype. The use of DPD phenotyping may add valuable information in DPYD wild-type patients.

DPYD genotyping and dihydropyrimidine dehydrogenase (DPD) phenotyping in clinical oncology. A clinically focused minireview

BACKGROUND

In clinical oncology, systemic 5-fluorouracil (5-FU) and its oral pro-drugs are used to treat a broad group of solid tumours. Patients with dihydropyrimidine dehydrogenase (DPD) enzyme deficiency are at elevated risk of toxicity if treated with standard doses of 5-FU. DPYD genotyping and measurements of plasma uracil concentration (DPD phenotyping) can be applied as tests for DPD deficiency. In April 2020, the European Medicines Agency recommended pre-treatment DPD testing to reduce the risk of 5-FU-related toxicity.

OBJECTIVES

The objective of this study is to present the current evidence for DPD testing in routine oncological practice.

METHODS

Two systematic literature searches were performed following the PRISMA guidelines. We identified studies examining the possible benefit of DPYD genotyping or DPD phenotyping on the toxicity risk.

FINDINGS

Nine and 12 studies met the criteria for using DPYD genotyping and DPD phenotyping, respectively.

CONCLUSIONS

The evidence supporting either DPYD genotyping or DPD phenotyping as pre-treatment tests to reduce 5-FU toxicity is poor. Further evidence is still needed to fully understand and guide clinicians to dose by DPD activity.

[Phenotype- or genotype test for dihydropyrimidin dehydrogenase deficiency before treatment with a fluoropyrimidine]

Some patients may have partial or complete deficiency of dihydropyrimidin dehydrogenase (DPD) and be more likely to experience severe toxicity with 5-fluorouracil. Since the spring of 2020, the Danish Medicines Agency has recommended genotype or phenotype testing before treatment with a fluoropyrimidine, but the most appropriate test strategy is debated. In this review, we present polymorphisms in the genes coding for DPD and summarise the evidence for DPD-enzyme deficiency testing and pharmacokinetic guided dosing.

Progenitor cells with the capacity to differentiate into sympathetic-like neurons are transiently detected in mammalian embryonic dorsal root ganglia

We have identified a population of progenitor cells in embryonic dorsal root ganglia (DRG) of the mouse. These cells can be induced into proliferating and differentiating into neurons that display multiple characteristics of the sympathetic lineage by a brief exposure to a defined medium. The sympathetic neuronal characteristics include immunoreactivity for the transcription factors MASH-1 and Phox2a and for the neurotransmitter markers tyrosine hydroxylase, choline acetyltransferase, and NPY. The progenitor cells are detected in DRG from embryonic day 11.5 (E11.5) to E15. An identical time course is observed in primary cultures of neural crest, suggesting that the competency of these cells is intrinsically regulated. We also present evidence that the environment of the sensory ganglion, unlike that of a sympathetic ganglion, prevents these cells from differentiating into neurons.

Postponement of Death by Pharmacological Heart Failure Treatment: A Meta-Analysis of Randomized Clinical Trials

BACKGROUND

Outcome postponement has been proposed as an effect measure for preventive drug treatment. It describes the average delay of the investigated unwanted clinical event, achieved by taking medication. The objective was to estimate postponement of death for the following heart failure medications compared to placebo: beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), ARB added to ACE inhibitors, aldosterone antagonists, ivabradine, and renin antagonists.

METHODS

We searched Medline and Embase from inception of databases until October 2017. Eligibility criteria were randomized placebo-controlled heart failure trials, including at least 1000 participants, with survival as a prespecified outcome and a minimum trial duration of 1 year. We calculated the outcome postponement by modeling the area between survival curves. This area was modeled on the basis of the hazard ratio or relative risk, the rate of mortality in the placebo group, and the trial duration. All results were standardized to a 3-year trial duration to ensure comparability between treatments.

RESULTS

We identified 14 eligible trials, with a total of 52,014 patients. The results in terms of postponement of all-cause mortality was: beta-blockers 43.7 days (95% confidence interval [95% CI], 20.8-66.5), ACE inhibitors 41.0 days (95% CI, 18.8-63.3), and aldosterone-antagonists 41.3 days (95% CI, 14.3,68.4).

CONCLUSION

The modeled outcome postponement estimates reiterate beta-blockers, ACE inhibitors, and aldosterone antagonists as the mainstay of heart failure treatment. Furthermore, ivabradine or ARBs added to ACE inhibitors results in no statistically significant gain in survival.