Developing DPYD Genotyping Method for Personalized Fluoropyrimidines Therapy.

BACKGROUND: Fluoropyrimidine drugs are widely used in chemotherapy to treat solid tumors. However, severe toxicity has been reported in 10% to 40% of patients. The DPYD gene encodes the rate-limiting enzyme dihydropyrimidine dehydrogenase responsible for fluoropyrimidine catabolism. The DPYD variants resulting in decreased or no enzyme activity are associated with increased risk of fluoropyrimidine toxicity. This study aims to develop a pharmacogenetic test for screening DPYD variants to guide fluoropyrimidine therapy. METHODS: A multiplex allele-specific polymerase chain reaction (AS-PCR) assay, followed by capillary electrophoresis, was developed to detect 5 common DPYD variants (c.557A > G, c.1129-5923C > G, c.1679T > G, c.1905 + 1G > A, and c.2846A > T). Deidentified population samples were used for screening positive controls and optimizing assay conditions. Proficiency testing samples with known genotypes were analyzed for test validation. All variants detected were confirmed by Sanger sequencing. RESULTS: From the deidentified population samples, 5 samples were heterozygous for c.557A > G, 2 samples were heterozygous for c.1129-5923C > G (HapB3), and 1 sample was heterozygous for c.2846A > T. The 20 proficiency samples matched with their assigned genotypes, including 13 wild-type samples, 3 samples heterozygous for c.1679T > G, 2 samples heterozygous for c.1905 + 1G > A, and 2 samples heterozygous for c.2846A > T. One of the 3 patient samples was heterozygous for c.1129-5923C > G (HapB3). All the variants detected by the multiplex AS-PCR assay were concordant with Sanger sequencing results. CONCLUSIONS: A robust multiplex AS-PCR assay was developed to rapidly detect 5 variants in the DPYD gene. It can be used for screening DPYD variants to identify patients with increased risk of toxicity when prescribed fluoropyrimidine therapy.

Small Particle DEBIRI TACE as Salvage Therapy in Patients with Liver Dominant Colorectal Cancer Metastasis: Retrospective Analysis of Safety and Outcomes.

The aim of this study was to examine the safety and efficacy of 40 µm and 75 µm calibrated irinotecan-eluting beads (DEBIRI-TACE) for the treatment of colorectal cancer metastases. We conducted a retrospective review of 36 patients with unresectable liver metastases from colorectal cancer who were treated with DEBIRI-TACE between 2017 to 2020. Patients who received at least one session of DEBIRI were included in our analysis. A total of 105 DEBIRI sessions were completed. 86% of patients (n = 31) underwent one round of treatment, 14% of patients (n = 5) underwent two distinct rounds of treatment. The majority of patients were discharged the next day (92%, n = 33 patients) with no 30-day post-DEBIRI mortality. Five high-grade adverse events occurred, including longer stay for pain management (n = 2), postembolization syndrome requiring readmission (n = 2), and liver abscess (n = 1). The average survival from diagnosis of metastatic disease was 33.3 months (range 11-95, median 28). Nine of 36 patients are still alive (December 2020) and have an average follow-up time of 36.8 months from T0 (range 12-63, median 39). Small particle DEBIRI is safe and well-tolerated in the salvage setting, with outcomes comparable to that of larger bead sizes.