Uridine triacetate for severe 5-fluorouracil toxicity in a patient with thymidylate synthase gene variation: Potential pharmacogenomic implications

Case report: Uridine triacetate in the management of delayed onset 5-fluorouracil toxicity: A case report and review of literature

5-fluorouracil (5FU) and capecitabine are fluoropyrimidine anti-neoplastic drugs commonly used in the treatment of different types of cancer. Hereditary dihydropyrimdine deaminase (DPD), thymidylate synthase mutations and drug overdose may lead to life-threatening toxicities. Uridine triacetate (UTA) is an emergency treatment for overdoses and early onset, severe or life-threatening toxicities from fluoropyrimidines. It is approved for use in adults and children within 96 h of last fluoropyrimidine administration. We present the case of a 64-year-old male treated with 5-FU and oxaliplatin as adjuvant systemic therapy for stage IIIA rectal cancer who developed delayed central nervous system toxicity 18 days after initiating chemotherapy. He had rapidly worsening encephalopathy and ataxia. Laboratory workups, MRI brain and EEG were negative. He was started on UTA with concerns of 5-FU toxicity due to the life-threatening nature of his condition even beyond the recommended 96-h time cut-off. He had rapid improvement in clinical status and resolution of encephalopathy. DPD deficiency testing later resulted as heterozygous for IVS14+1G>A allele indicating enzyme deficiency. This report demonstrates the importance of identifying delayed side effects with fluoropyrimidine therapy and potential treatment for reversing these effects. We also did an extensive literature review and obtained reports from the uridine triacetate clinical trials on patients receiving UTA after the 96-h cut-off. Based on our experience and previous published reports, a patient developing life-threatening delayed 5-FU toxicity should also be considered for UTA on a case-by-case basis.

Rare Presentation of Cardiotoxicity Related to 5-Fluorouracil

5-Fluorouracil (5-FU) is a chemotherapeutic agent frequently used for the treatment of solid tumors. In a few cases, 5-FU can be associated with coronary vasospasm, cardiac ischemia, or life-threatening arrhythmias. Recognition of 5-FU cardiotoxicity is clinically important as after the rapid sensation of therapy, cardiotoxicity can be completely reversible, and on the other hand, readministration may lead to serious damage of the heart and even death. A 70-year-old male came to the emergency department (ED) with chest pain which started while receiving an infusion of 5-FU. The patient did not have a personal history or risk factors of coronary artery disease and his electrocardiogram (ECG) before starting chemotherapy was completely normal. In the ED, his ECG had ischemic changes, troponin was elevated, and echocardiogram showed anterior wall hypokinesis. However, emergent coronary angiogram did not reveal any acute coronary occlusion. 5-FU-induced cardiotoxicity was suspected; the patient was admitted to a progressive care unit for close monitoring and infusion of calcium channel blockers was initiated. The patient's symptoms and ECG findings gradually resolved, and two days later on discharge, patient was chest pain free and ECG was normal. This case supports the vasospastic hypothesis of 5-FU cardiac toxicity, describes its clinical course, and emphasizes the importance of better awareness and early recognition of the rare side effect as it may allow physicians to reduce the risk of life-threatening complications.

Fluoropyrimidine-induced toxicity and DPD deficiency.. A case report of early onset, lethal capecitabine-induced toxicity and mini review of the literature. Uridine triacetate: Efficacy and safety as an antidote. Is it accessible outside USA?

Fluoropyrimidine-based regimens are among the most commonly used chemotherapy combinations for the treatment of solid tumors. Several genetic polymorphisms that are implicated with fluoropyrimidine anabolism and catabolism have been associated with the development of life-threatening toxicities. Uridine triacetate is an FDA-approved antidote for 5-fluorouracil or capecitabine overdose and early-onset, life-threatening toxicity within 96 h of last chemotherapy dose. To date, it is not accessible for Greek patients as per the current summary of product characteristic's time restrictions. We report and discuss the course and outcome of capecitabine toxicity in a 66-year-old female colorectal cancer patient with heterozygous dihydropyrimidine dehydrogenase deficiency. This paper highlights the difficulty in timely access of this lifesaving medication for Greek and possibly other European patients.

Clinical Value of Pharmacogenomic Testing in a Patient Receiving FOLFIRINOX for Pancreatic Adenocarcinoma

Pharmacogenomic testing may have clinical value in the treatment of patients with gastrointestinal malignancies such as colorectal and pancreatic cancer. These types of cancer are often treated with combination chemotherapy regimens. These regimens can lead to severe adverse effects in patients with diminished drug tolerability potentially due to certain genetic variants in the enzymes involved in the metabolism of the chemotherapies. Genetic variants resulting in decreased enzymatic activity of uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) and dihydropyrimidine dehydrogenase (DPD) are known to increase irinotecan and 5-fluorouracil-related toxicity, respectively. We report a case of a patient with pancreatic adenocarcinoma who was found to be not only homozygous for the UGT1A1^∗28 allele, but also heterozygous for a DPYD variant through pharmacogenomic testing. Potentially severe adverse effects were prevented in this patient’s case by implementing preemptive dose reductions. On the basis of the significant implications of chemotherapy-related toxicity in this and other similar cases, we report on the clinical value of integrating pharmacogenomic testing into clinical practice to allow for preemptive and/or point-of-care dose reductions in patients potentially at risk for increased toxicity. This is even more important in an era where combinatorial triplet chemotherapies are increasingly being used.