The association between UGT1A1 polymorphisms and treatment toxicities of liposomal irinotecan.

BACKGROUND: Initial dose adjustment is recommended for patients with known UGT1A1∗28 homozygosity for both conventional irinotecan and liposomal irinotecan (nal-IRI). A recent population pharmacokinetic (PK) study showed that Asian patients had a lower prevalence of UGT1A1∗28 homozygosity but a significantly higher maximum blood concentration of SN-38 (SN-38 Cmax) and a higher incidence of grade ≥3 neutropenia after nal-IRI administration than Caucasian patients. The current study investigated the association of UGT1A1 polymorphisms, including the Asian prevalent UGT1A1∗6, PK and toxicities of nal-IRI-based therapy in the Asian population. PATIENTS AND METHODS: A total of 162 patients with nal-IRI-based therapy and available UGT1A1∗6 and UGT1A1∗28 genotyping were included, with 82 Asian patients from six previous phase I or II studies of nal-IRI (cohort 1) and another 80 patients with nal-IRI + 5-fluorouracil/leucovorin every 2 weeks as real-world practice in a single institute in Taiwan (cohort 2). RESULTS: The frequency of UGT1A1∗6 or UGT1A1∗28 homozygosity/compound heterozygosity was 9.3%, with UGT1A1∗6/∗6 in 2.5%, UGT1A1∗28/∗28 in 1.9% and UGT1A1∗6/∗28 in 4.9%. Among the 53 patients in cohort 1 with available PK data, all 7 patients with homozygosity/compound heterozygosity harbored UGT1A1∗6 and had a significantly higher level of median dose-normalized area under the concentration-time curve (AUC) and Cmax of SN-38 than those with single heterozygosity/wild type. Of the entire study population, the incidence of grade ≥3 neutropenia and diarrhea was significantly higher in patients with homozygosity/compound heterozygosity than in those with single heterozygosity/wild type, 73.3% versus 38.1% (P = 0.012, Fisher's exact test) and 33.3% versus 9.5% (P = 0.018, Fisher's exact test), respectively. CONCLUSION: The results suggest that the recommendation of a lower starting dose of nal-IRI for patients with UGT1A1∗28 homozygosity should be extended to include patients with UGT1A1∗6 homozygosity/compound heterozygosity.

Phase I study of nanoliposomal irinotecan (PEP02) in advanced solid tumor patients.

PURPOSE: To define the dose-limiting toxicity (DLT), maximum tolerated dose (MTD) and pharmacokinetics (PK) of PEP02, a novel liposome-encapsulated irinotecan, in patients with advanced refractory solid tumors. METHODS: Patients were enrolled in cohorts of one to three to receive escalating dose of PEP02 in a phase I trial. PEP02, from 60 to 180 mg/m(2), was given as a 90-min intravenous infusion, every 3 weeks. RESULTS: A total of 11 patients were enrolled into three dose levels: 60 (one patient), 120 (six patients) and 180 mg/m(2) (four patients). DLT was observed in three patients, one at 120 mg/m(2) (grade 3 catheter-related infection) and two at 180 mg/m(2) (grade 4 neutropenia lasting for >3 days in one, grade 4 hematological toxicities and grade 4 diarrhea in the other). MTD was determined as 120 mg/m(2). Comparing with those after free-form irinotecan in the literature, the dose-normalized PK of SN-38 (the active metabolite) after PEP02 was characterized by lower C max, prolonged terminal half-life and higher AUC but with significant inter-individual variation. One patient who died of treatment-related toxicity had significantly higher C max and AUC levels of SN-38 than those of the other three patients at 180 mg/m(2). Post hoc pharmacogenetic study showed that the patient had a combined heterozygosity genotype of UGT1A1*6/*28. Two patients had objective tumor response. CONCLUSIONS: PEP02 apparently modified the PK parameters of irinotecan and SN-38 by liposome encapsulation. The MTD of PEP02 monotherapy at 3-week interval is 120 mg/m(2), which will be the recommended dose for future studies.

A KRAS mutation status-stratified randomized phase II trial of gemcitabine and oxaliplatin alone or in combination with cetuximab in advanced biliary tract cancer.

BACKGROUND: Previous clinical trials have not proved that adding epidermal growth factor receptor inhibitors to chemotherapy confers a survival benefit for patients with advanced biliary tract cancer (ABTC). Whether the KRAS mutation status of tumor cells confounded the results of past studies is unknown. PATIENTS AND METHODS: ABTC patients stratified by KRAS status, Eastern Cooperative Oncology Group performance status, and primary tumor location were randomized 1 : 1 to receive GEMOX (800 mg/m(2) gemcitabine and 85 mg/m(2) oxaliplatin) or C-GEMOX (500 mg/m(2) cetuximab plus GEMOX) every 2 weeks. The primary end point was objective response rate (ORR). RESULTS: The study enrolled 122 patients between December 2010 and May 2012 (62 treated with C-GEMOX and 60 with GEMOX). Compared with GEMOX alone, C-GEMOX was associated with trend to better ORR (27% versus 15%; P = 0.12) and progression-free survival (PFS, 6.7 versus 4.1 months; P = 0.05), but not overall survival (OS, 10.6 versus 9.8 months; P = 0.91). KRAS mutations, which were detected in 36% of tumor samples, did not affect the trends of difference in ORR and PFS between C-GEMOX and GEMOX. The two treatment arms had similar adverse events, except that more patients had skin rashes, allergic reactions, and neutropenia in the C-GEMOX arm. Of patients with C-GEMOX, the presence of a grade 2 or 3 skin rash was associated with significantly better ORR, PFS, and OS. CONCLUSIONS: Addition of cetuximab did not significantly improve the ORR of GEMOX chemotherapy in ABTC, although a trend of PFS improvement was observed. The trend of improvement did not correlate with KRAS mutation status. CLINICAL TRIALS NUMBER: This study is registered at ClinicalTrials.gov (NCT01267344). All patients gave written informed consent.