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Irinotecan is effective for the treatment of metastatic colorectal cancer (mCRC) and advanced pancreatic cancer (aPC). However, these treatments are often limited due to the incidence of severe neutropenia. We identified risk factors for severe neutropenia in patients with mCRC or aPC, receiving irinotecan-based chemotherapy regimens. The study selected 104 patients (mCRC: 53 and aPC: 51) who received irinotecan-based chemotherapy between January 2014 and May 2018 and who were included in the present study. The initial dose of irinotecan was 150 mg/m 2 in all patients, and patients with a lower initial dose of irinotecan were excluded. Severe neutropenia (grade ≥ 3) occurred in 56 patients (53.8%). Multivariable Cox proportional hazards analysis indicated that modified FOLFIRINOX (mFOLFIRINOX) and serum total bilirubin (T-Bil) were significant risk factors for severe neutropenia. Moreover, with receiver-operating characteristic (ROC) curve analysis, the cutoff for T-Bil was found to be 0.7 mg/dL. Among patients treated with mFOLFIRINOX therapy, the incidence of severe neutropenia was significantly higher in patients with high level of T-Bil (> 0.7 mg/dL) than in those without it (93.8% vs 55.0%, P = 0.006). A chemotherapy regimen (modified FOLFIRINOX therapy) and T-Bil > 0.7 mg/dL were significant risk factors for severe neutropenia in patients receiving 150 mg/m 2 irinotecan.

Purpose: Irinotecan is effective for metastatic colorectal cancer (mCRC). SN-38 is an active metabolite of irinotecan, which is formed by carboxylesterase and inactivated by UDP-glucuronyltransferase (UGT) 1A1. The UGT enzyme activity is reduced in patients with homozygous mutation in UGT1A1 genes (*6/*6, *28/*28 and *6/*28); thus dose reduction is required for prevention of severe adverse events associated with irinotecan. The present study was designed to investigate the relationship between UGT1A1 polymorphisms and the incidence of adverse events or the therapeutic effect in mCRC patients who received irinotecan., Methods: Sixty-three mCRC patients who received irinotecan during January 2014 and May 2018 were the subjects of this study. The incidence of adverse events, including diarrhea and neutropenia, and the therapeutic effect of irinotecan were compared among homozygous group, heterozygous group and wild-type group. The initial dose of irinotecan was 150 mg/m 2 in the heterozygous group and wild-type group, while the dose was reduced by 20% (120 mg/m 2 ) in the homozygous group., Results: The UGT1A1 polymorphisms occurred in 15.9%, 33.3%, and 50.8% for homozygous group, heterozygous group, and wild-type group, respectively. The average dose of irinotecan during overall cycles was not significantly different among three groups, despite the reduction of initial dose in homozygous group. There were no significant differences in the incidence rates of adverse events, tumor response, or time to treatment failure among three groups., Conclusion: The present study demonstrated that dose reduction by 20% ensured safety and efficacy of irinotecan in mCRC patients with homozygous mutation in UGT1A1 genes.

While modified FOLFIRINOX therapy is effective for treating advanced pancreatic cancer, it frequently causes severe neutropenia. The present study investigated the effect of severe neutropenia on clinical outcomes in advanced pancreatic cancer patients who received modified FOLFIRINOX. The study subjects were 51 patients (30 males and 21 females) with advanced pancreatic cancer who received modified FOLFIRINOX (2h bolus injection of oxaliplatin at 85 mg/m2, 2 h bolus injection of L-leucovorin at 200 mg/m2, 90min bolus injection of irinotecan at 150 mg/m2, followed by continuous infusion of 5-fluorouracil for 46 h at 2400 mg/m2 without bolus 5-fluorouracil) during the period from January 2014 to May 2018. No patients had prior history of chemotherapy. Adverse events, including neutropenia, were graded according to the Common Terminology Criteria for Adverse Events, version 4.0. Median overall survival (OS) was the primary endpoint, while median time to treatment failure (TTF), overall response rate (ORR), and the incidence of other adverse events were secondary endpoints. Severe neutropenia (grade ≥3) occurred in 39 patients (76.4%), and Cox proportional hazard analysis identified high total bilirubin level as a significant risk factor. Median duration of OS was significantly longer in patients with severe neutropenia than in those without it (21.3 months versus 8.9 months, p = 0.020). Moreover, there was a significant correlation between OS and the grade of neutropenia (r = 0.306, p = 0.029). ORR tended to be higher, though not significantly, in patients with severe neutropenia. In contrast, the incidence rates of other adverse events were not different between the two groups. Severe neutropenia is an independent predictor of prognosis in advanced pancreatic cancer patients received modified FOLFIRINOX therapy. [ABSTRACT FROM AUTHOR]