Dihydro pyrimidine dehydrogenase deficiency in patients treated with capecitabine-based regimens: A retrospective tertiary care centre experience.

Abstract

712 Background: Capecitabine is an integral part of treatment of gastrointestinal cancers. Dihydropyrimidine dehydrogenase (DPD) enzyme is rate limiting in the metabolism of capecitabine, deficiency of which leads to myelsuppression, mucositis, diarrhea, hand foot syndrome (HFS) and rarely, death. Data regarding the toxicity of capecitabine in patients with DPD deficiency in the Indian context is scarce. Methods: 506 patients were treated with capecitabine containing regimens with a dose range of 1250 mg/m2/day to 2000 mg/m2/day during the period from June 2013 to May 2015 in the Gastrointestinal Medical Oncology Unit of our institution. Patients with Grade 3/4 toxicities requiring in-patient care (life threatening complications) were planned for DPD activity testing by Peripheral Blood PCR sequencing. Results: 27 patients developed Gr 3/4 toxicities during cycle 1 of capecitabine. It included mucositis in 22 (81.5 %), diarrhea in 25 (92.6%), HFS in 10 (37%) and myelosuppression in 4 (14.8%). 19 were found to be DPD deficient with 5 patients negative for DPD mutation. 3 patients did not do the DPD analysis as advised. Homozygous mutations were seen in 9 (33.3%) and heterozygous mutations in 10 (27%) of patients. More than one mutation was seen in 10 patients (37%). The relative frequencies of mutation were Exon 14 (44.4%), Exon 2 (25.9%), Exon 13 (25.9%), Exon 6 (11.1%) and Exon 18 (7.4 %). Post Cycle 1 of capecitabine, the drug was stopped in 5 patients (18.5%), regimen changed in 2 (7.4%) and dose reduction by 50% of the drug was done in the remaining patients. Despite dose reduction and change in therapy during Cycle 2, patients still had Grade 3/4 toxicities including mucositis in 7(25.9%), diarrhoea in 10 (37%), HFS in 7 (25.9 %) and myelosuppression in 6 (22%) of patients. Conclusions: Capecitabine can also lead to severe toxicities in DPD-deficient patients. Dose reduction of capecitabine in DPD deficient patients may not completely ameliorate the future risk of life – threatening complications. Screening for DPD deficiency prior to administration of capecitabine in toxicity prone nutritionally deficient Indian patients should be further evaluated based on this data.