Influence of dihydropyrimidine dehydrogenase gene (DPYD) coding sequence variants on the development of fluoropyrimidine-related toxicity in patients with high-grade toxicity and patients with excellent tolerance of fluoropyrimidine-based chemotherapy

Abstract

Alterations in dihydropyrimidine dehydrogenase gene (DPYD) coding for the key enzyme (DPD) of fluoropyrimidines (FPs) catabolism contribute to the development of serious FPs-related toxicity. We performed mutation analysis of DPYD based on cDNA sequencing in 76 predominantly colorectal cancer patients treated by FPs with early development of high (grade 3-4) hematological and/or gastrointestinal toxicity. Six previously described [85T>C (C29R), 496A>G (M166V), 775A>G (K259E), 1601G>A (S534N), 1627A>G (I543V), IVS14+1G>A, 2194G>A (V732I)] and two novel [187A>G (K63E) and 1050 G>A (R357H)] non-synonymous DPYD variants were found in 56/76 (73.7%) high-toxicity patients. Subsequently, these alterations were analyzed in 48 patients with excellent long-term tolerance of FPs and in 243 controls and were detected in 37/48 (77.1%) and 166/243 (68.3%) cases, respectively. Analysis of these alterations as risk factors for development of toxicity in pooled FPs-treated population demonstrated that C29R negatively correlated with overall gastrointestinal toxicity (OR = 0.48; 95%CI 0.23-1.0) and M166V in women protected against overall hematological toxicity and neutropenia (both OR = 0.26; 95%CI 0.07-0.89), whereas IVS14+1G>A (found in five high-toxicity patients only) increased risk of mucositis in overall population (OR = 7.0; 95%CI 1.1-44.53), and thrombocytopenia in women (OR = 10.8; 95%CI 1.24-93.98). Moreover, we identified a strong association of V732I with leucopenia (OR = 8.17; 95%CI 2.44 -27.31) and neutropenia (OR=2.78; 95% CI 1.03-7.51). Our data enabled characterization of "high risk" haplotypes (carriers of IVS14+1G>A or V732 lacking M166V) representing small (22% female and 11% male patients), population in high risk of serious hematological toxicity development, and in patients with "lower risk" that unlikely develop serious hematological toxicity [carriers of M166V without IVS14+1G>A and V732I in females (32% women), and non-carriers of C29R, M166V, IVS14+1G>A, and V732I in males (46% men)]. Our results indicate that genotyping of several DPYD variants may lead to stratification of patients with respect to the risk of serious hematological toxicity development during FPs treatment. Key words: dihydropyrimidine dehydrogenase gene [DPYD], fluoropyrimidines, 5-fluorouracil toxicity, mutation analysis, haplotypes, association study* Corresponding author † These authors contributed equally to this work.Fluoropyrimidines -5-fluorouracil (5-FU) and its derivates (e.g. capecitabine) -belong to the most frequently used anticancer drugs in treatment of solid cancers. Mechanism of action of 5-FU involves its anabolic conversions to 5-fluoropyrimidine nucleotides that exert profound inhibitory effect on thymidylate synthetase activity and interfere with RNA and DNA metabolism [1]. The development of severe toxicity is the critical complication of 5-FU-based therapy. It occurs in nearly one third of cases with progression to life-threatening complications in approximately 0.5% patients [2].About 80% of 5-FU is quickly ina...

Comparative Functional Analysis of DPYD Variants of Potential Clinical Relevance to Dihydropyrimidine Dehydrogenase Activity

“…Three additional clinical association studies failed to establish any link between M166V and 5-FU-related toxicities (4, 11, 28). A fourth study suggested that M166V may protect against hematological toxicity and neutropenia following administration of 5-FU; however, the association was observed only in women (12). The P1023T variant is rare in European populations and is more common in individuals of African ancestry (Supplementary Table S2).…”

“…For instance, the M166V variant was shown to strongly associate with grade III and IV toxicity in a cohort of patients with breast, gastroesophageal, or colorectal cancer treated with 5-FU-based therapy (10); however additional reports failed to confirm a link between the variant and 5-FU toxicity (4, 11). Further studies have suggested that M166V might be protective against specific 5-FU-related toxicities in women (12). …”

Pharmacokinetic and Metabolism Determinants of Fluoropyrimidines and Oxaliplatin Activity in Treatment of Colorectal Patients

“…The c.1129-5923C/G mutation in intron 10 created a cryptic splice donor site and as a consequence, a 44 bp fragment of intron 10 was inserted in the mature DPD mRNA, reducing its activity. Really, conflicting data exist as to weather the c.1236G/A mutation is associated with an increased risk of development of severe 5-FU-associated toxicity [75,80], because of its apparently high mutation prevalence in the normal population. These data refer the necessity to confirm the genetic screening for this mutation in cancer patients prior to the start of 5-FU-containing chemotherapy…”

“…On this basis, subsequently, various strategies have been proposed to screen for patients with a DPD deficiency, including genotyping [74,75]. The evidence that DPYD heliotype not containing any no synonymous or splice-site mutations was associated with 5-FU toxicity suggested the presence of additional genetic variations in the nonbonding region of DPYD [74].…”

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“…86,87 Deenen et al found that 100% of patients carrying the IVS14+1 polymorphism developed severe toxicity. 88 Measuring DPYD activity has been suggested to be a better biomarker for fluoropyrimidine-induced toxicity than DPYD genotyping, although recent findings confirm that genotyping and haplotyping could be acceptable options for stratifying patients according to risk of toxicity 89 or establishing dose recommendations for capecitabine and as shown by the Pharmacogenetics Working Group of the Royal Dutch Pharmacists Association. 90 …”