Yu Sunakawa

CYP2A6 and the plasma level of 5-chloro-2, 4-dihydroxypyridine are determinants of the pharmacokinetic variability of tegafur and 5-fluorouracil, respectively, in Japanese patients with cancer given S-1

S‐1 is an oral anticancer agent composed of tegafur (FT), 5‐chloro‐2,4‐dihydroxypyridine (CDHP), and potassium oxonate. CDHP is added to prevent degradation of 5‐fluorouracil (5‐FU) by inhibiting dihydropyrimidine dehydrogenase. CYP2A6 is involved in the biotransformation of FT to 5‐FU. Thus, we prospectively analyzed the effects of the CYP2A6 genotype, plasma level of CDHP, and patient characteristics on the pharmacokinetic (PK) variability of FT and 5‐FU. Fifty‐four Japanese patients with metastatic or recurrent cancers who received S‐1 were enrolled. The CYP2A6 polymorphisms (*4A, *7, and *9) with deficient or reduced activity were analyzed. All subjects were classified into three groups according to their CYP2A6 genotype: wild type (*1/*1), one‐variant allele (*1/any), or two‐variant alleles (combination other than *1). The PK of FT, 5‐FU, and CDHP were measured on day 1 of treatment. Multivariate regression analysis revealed that oral clearance of FT was associated with the CYP2A6 genotype (analysis of variance [ANOVA], P = 0.000838). The oral clearance of FT seen in patients with the two‐variant alleles was significantly lower than those in wild type and the one‐variant allele (95% confidence intervals 0.75–2.41 and 0.41–1.82, respectively; Tukey‐Kramer test). The area under the time–concentration curve (AUC) of 5‐FU was significantly correlated with the AUC of CDHP (ANOVA, P = 0.00126). The AUC of 5‐FU and CDHP were inversely correlated with creatinine clearance (ANOVA, P = 0.0164 and P = 0.000762, respectively). Although the CYP2A6 variants are the cause of the PK variability of FT, the AUC of CDHP affected by renal function is the key determinant of the variability in the PK of 5‐FU. (Cancer Sci 2008; 99: 1049–1054)

Direct Inhibition and Down-regulation by Uremic Plasma Components of Hepatic Uptake Transporter for SN-38, an Active Metabolite of Irinotecan, in Humans

PurposeClinical study has previously revealed that plasma concentration of 7-ethyl-10-hydroxycamptothecin (SN-38), an active metabolite of irinotecan, was higher in patients with end-stage renal failure than those with normal kidney function although SN-38 is mainly eliminated in the liver. Here, we focused on inhibition by uremic toxins of hepatic SN-38 uptake and down-regulation of uptake transporter(s) by uremic plasma in humans.MethodsWe evaluated SN-38 uptake and its inhibition by uremic toxins, 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF), indoxyl sulfate (Indox), hippuric acid (HA) and indole acetate (IA), with cryopreserved human hepatocytes and HEK293 cells stably expressing hepatic uptake transporters, organic anion transporting polypeptides (OATPs). We also collected plasma samples from patients with severe renal failure to examine their effects on mRNA level of OATPs in primary cultured human hepatocytes.ResultsSN-38 was taken up by hepatocytes, which showed biphasic saturation patterns. The SN-38 uptake by hepatocytes was significantly inhibited by a uremic toxin mixture including clinically relevant concentrations of CMPF, Indox, HA and IA. Kinetic analyses for OATP-mediated transport revealed that the uptake of SN-38 by OATP1B1 was the highest, followed by OATP1B3. Among the uremic toxins, CMPF exhibited most potent inhibition of OATP1B1-mediated SN-38 uptake and directly inhibited the uptake of SN-38 also in hepatocytes. In addition, gene expression of OATP1B1 and OATP1B3 in hepatocytes was significantly down-regulated by the treatment with the uremic plasma.ConclusionsOATP1B1-mediated hepatic uptake of SN-38 was inhibited by uremic toxins, and gene expression of OATP1B1 was down-regulated by uremic plasma.

Genetic testing for UGT1A1*28 and *6 in Japanese patients who receive irinotecan chemotherapy

Polymorphisms of the UDP-glucuronosyltransferase (UGT) 1A1 gene, such as UGT1A1*28 and UGT1A1*6, can cause severe neutropenia and diarrhea in patients who receive irinotecan [1, 2]. Homozygosity for UGT1A1*28 is associated with less efficient glucuronidation of SN-38, the active metabolite of irinotecan, resulting in increased plasma SN-38 concentrations. Four pharmacogenetic trials have demonstrated an association between UGT1A1*28 genotype and irinotecan-induced hematologic toxicity, diarrhea, or both [3]. In response to these findings, the United States Food and Drug Administration has approved genetic testing for UGT1A1*28 and recommends that the initial dose of irinotecan is reduced by at least one level in patients who are homozygous for UGT1A1*28, albeit the effectiveness of such testing remains to be confirmed prospectively. UGT1A1*6 is also associated with severe irinotecan-related toxicity [4]. Given that the area under the time versus concentration curve ratio (SN-38 glucuronide/SN-38) seen in patients homozygous for UGT1A1*28 and *6 are almost equal [4], the impact of these variants on glucuronidation capacity of UGT1A1 for SN-38 is almost the same. The distribution of genotypes associated with these polymorphisms varies considerably among ethnic groups. UGT1A1*28 is found in Japanese and whites, but the allele frequency in Japanese is lower than that in whites [2, 4]. UGT1A1*6 is found in Japanese, but not in whites [4]. Homozygosity for UGT1A1*28 or UGT1A1*6 and heterozygosity for both UGT1A1*6 and UGT1A1*28 are associated with severe irinotecan-related neutropenia in Japanese patients [1, 4]. The Ministry of Health, Labour and Welfare in Japan has therefore recently approved genetic testing for UGT1A1*28 and *6. The value of genetic testing for UGT1A1 depends on genotype frequency and the association of genetic variants with irinotecan-induced toxicity. The higher the frequency of toxicity-related polymorphisms, the greater is the number of patients who would benefit from genetic testing. Large prospective studies are needed to accurately estimate the distribution of UGT1A1 polymorphisms in a given population. We have carried out the largest prospective study to date, examining the distributions of UGT1A1*28 and UGT1A1*6 genotypes in 300 Japanese patients (male/female, 172 of 128) with various solid tumors (200 colorectal, 43 gastric, 15 ovarian, 14 breast, 10 lung, and 18 others). All patients gave written informed consent, and the study protocol was approved by the Institutional Review Board of Saitama Medical University. Genotyping was carried out as described elsewhere [5]. UGT1A1*28 and UGT1A1*6 were in Hardy–Weinberg equilibrium (P > 0.05). Only 2 of 300 patients were UGT1A1*28 homozygotes (0.7%) (Table 1). The frequency of homozygosity for UGT1A1*28 was much lower than that in other prospective studies in Japan (2.3%, 4 of 176) [4]. The frequency of UGT1A1*6 homozygosity was 5.7% (Table 1), higher than that reported previously (2.8%) [4]. Eleven patients were both heterozygous for UGT1A1*6 and UGT1A1*28 (3.7%). The combined frequency of patients with two ‘risk alleles’ (i.e. *28/*28, *6/*6, and *6/*28) was 10.1% (95% confidence interval, 6.8% to 14.0%). Such patients might be at increased risk for irinotecan-related neutropenia. Given the genotype frequencies of UGT1A1*28 and UGT1A1*6, genetic testing for UGT1A1 might not be essential for identifying homozygotes for UGT1A1*28, but useful for identifying homozygotes for UGT1A1*6 as well as heterozygotes for UGT1A1*6 and UGT1A1*28, thereby avoiding severe irinotecan-induced toxicity in Japanese patients. The present results and considerations are likely to have application across East Asia. Prospective evaluations of genetic testing for UGT1A1 polymorphisms, encompassing both medical aspects and cost effectiveness, appear to be warranted, especially in East Asian countries including Japan. Table 1. Genotype frequencies of UGT1A1*28 and UGT1A1*6 in Japanese

Prognostic Impact of Primary Tumor Location on Clinical Outcomes of Metastatic Colorectal Cancer Treated With Cetuximab Plus Oxaliplatin-Based Chemotherapy: A Subgroup Analysis of the JACCRO CC-05/06 Trials

Introduction: Primary tumor location is a critical prognostic factor in metastatic colorectal cancer (mCRC); however, it remains unclear whether tumor location is a predictor of the response to cetuximab treatment. It is also uncertain if BRAF mutation contributes to the impact of tumor location on survival. We assessed the prognostic impact of tumor location on clinical outcomes in mCRC patients treated with first‐line cetuximab chemotherapy. Patients and Methods: The associations of tumor location with overall survival and progression‐free survival were evaluated in mCRC patients with KRAS exon 2 wild‐type tumors who were enrolled onto 2 clinical trials: JACCRO CC‐05 of cetuximab plus FOLFOX (n = 57, UMIN000004197) and CC‐06 of cetuximab plus SOX (n = 61, UMIN000007022). Tumors proximal or from splenic flexure to rectum were defined as right‐sided or left‐sided, respectively. In addition, exploratory RAS and BRAF mutation analyses were performed. Results: A total of 110 patients were assessable for tumor location; 90 had left‐sided tumors. Left‐sided tumors were significantly associated with longer overall survival (36.2 vs. 12.6 months, hazard ratio = 0.28, P < .0001) and progression‐free survival (11.1 vs. 5.6 months, hazard ratio = 0.47, P = .0041) than right‐sided tumors; similar results were obtained in multivariate analysis. A subanalysis showed that the association was evident in the FOLFOX group and that tumor location was an independent prognostic factor irrespective of BRAF status in RAS wild‐type patients. Conclusion: Primary tumor location might be a predictor of survival independent of BRAF status in mCRC patients who receive first‐line cetuximab combined with oxaliplatin‐based chemotherapy. &NA; Primary tumor location is a prognostic factor in metastatic colorectal cancer (mCRC). We assessed the prognostic impact of tumor location on survival and the association between BRAF mutation and tumor sidedness in mCRC patients treated with cetuximab. Tumor location is a prognostic marker for first‐line cetuximab plus oxaliplatin‐based chemotherapy, irrespective of BRAF status.

Molecular classification of gastric adenocarcinoma: translating new insights from the cancer genome atlas research network.

Opinion statementGastric cancer is a heterogenous cancer, which may be classified into several distinct subtypes based on pathology and epidemiology, each with different initiating pathological processes and each possibly having different tumor biology. A classification of gastric cancer should be important to select patients who can benefit from the targeted therapies or to precisely predict prognosis. The Cancer Genome Atlas (TCGA) study collaborated with previous reports regarding subtyping gastric cancer but also proposed a refined classification based on molecular characteristics. The addition of the new molecular classification strategy to a current classical subtyping may be a promising option, particularly stratification by Epstein–Barr virus (EBV) and microsatellite instability (MSI) statuses. According to TCGA study, EBV gastric cancer patients may benefit the programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) antibodies or phosphoinositide 3-kinase (PI3K) inhibitors which are now being developed. The discoveries of predictive biomarkers should improve patient care and individualized medicine in the management since the targeted therapies may have the potential to change the landscape of gastric cancer treatment, moreover leading to both better understanding of the heterogeneity and better outcomes. Patient enrichment by predictive biomarkers for new treatment strategies will be critical to improve clinical outcomes. Additionally, liquid biopsies will be able to enable us to monitor in real-time molecular escape mechanism, resulting in better treatment strategies.

Plastin Polymorphisms Predict Gender- and Stage-Specific Colon Cancer Recurrence after Adjuvant Chemotherapy

Tumor recurrence after curative resection remains a major problem in patients with locally advanced colorectal cancer treated with adjuvant chemotherapy. Genetic single-nucleotide polymorphisms (SNP) may serve as useful molecular markers to predict clinical outcomes in these patients and identify targets for future drug development. Recent in vitro and in vivo studies have demonstrated that the plastin genes PLS3 and LCP1 are overexpressed in colon cancer cells and play an important role in tumor cell invasion, adhesion, and migration. Hence, we hypothesized that functional genetic variations of plastin may have direct effects on the progression and prognosis of locally advanced colorectal cancer. We tested whether functional tagging polymorphisms of PLS3 and LCP1 predict time to tumor recurrence (TTR) in 732 patients (training set, 234; validation set, 498) with stage II/III colorectal cancer. The PLS3 rs11342 and LCP1 rs4941543 polymorphisms were associated with a significantly increased risk for recurrence in the training set. PLS3 rs6643869 showed a consistent association with TTR in the training and validation set, when stratified by gender and tumor location. Female patients with the PLS3 rs6643869 AA genotype had the shortest median TTR compared with those with any G allele in the training set [1.7 vs. 9.4 years; HR, 2.84; 95% confidence interval (CI), 1.32–6.1; P = 0.005] and validation set (3.3 vs. 13.7 years; HR, 2.07; 95% CI, 1.09–3.91; P = 0.021). Our findings suggest that several SNPs of the PLS3 and LCP1 genes could serve as gender- and/or stage-specific molecular predictors of tumor recurrence in stage II/III patients with colorectal cancer as well as potential therapeutic targets. Mol Cancer Ther; 13(2); 528–39. ©2013 AACR.

Increased Plasma Concentrations of Unbound SN-38, the Active Metabolite of Irinotecan, in Cancer Patients with Severe Renal Failure

PurposeDelayed plasma concentration profiles of the active irinotecan metabolite SN-38 were observed in cancer patients with severe renal failure (SRF), even though SN-38 is eliminated mainly via the liver. Here, we examined the plasma concentrations of unbound SN-38 in such patients.MethodsPlasma unbound concentrations were examined by ultrafiltration. Physiologically-based pharmacokinetic (PBPK) models of irinotecan and SN-38 were established to quantitatively assess the principal mechanism for delayed SN-38 elimination.ResultsThe area under the plasma unbound concentration-time curve (AUCu) of SN-38 in SRF patients was 4.38-fold higher than that in normal kidney patients. The unbound fraction of SN-38 was also 2.6-fold higher in such patients, partly because SN-38 protein binding was displaced by the uremic toxin 3-carboxy-4-methyl-5-propyl-2-furanpropionate (CMPF). This result was supported by correlation of the unbound fraction of SN-38 with the plasma CMPF concentration, which negatively correlated with renal function. PBPK modeling indicated substantially reduced influx of SN-38 into hepatocytes and approximately one-third irinotecan dose for SRF patients to produce an unbound concentration profile of SN-38 similar to normal kidney patients.ConclusionThe AUCu of SN-38 in SRF cancer patients is much greater than that of normal kidney patients primarily because of the reduced hepatic uptake of SN-38.

Regimen Selection for First-line FOLFIRI and FOLFOX Based on UGT1A1 Genotype and Physical Background is Feasible in Japanese Patients with Advanced Colorectal Cancer

OBJECTIVE We examined the feasibility of regimen selection for first-line irinotecan, 5-fluorouracil and leucovorin or oxaliplatin, 5-fluorouracil and leucovorin in Japanese patients with advanced colorectal cancer based on UDP-glucuronosyltransferase 1A1 genotype as well as physical status of patients related to diarrhea. METHODS As first-line irinotecan, 5-fluorouracil and leucovorin is a little bit superior to oxaliplatin, 5-fluorouracil and leucovorin with respect to efficacy and toxicity, patients without risk factors of irinotecan-induced toxicity were first assigned to irinotecan, 5-fluorouracil and leucovorin. Patients with UDP-glucuronosyltransferase 1A1 28/ 28, 6/ 6, 28/ 6 or 28/ 27 and those with ascites, peritoneal dissemination or diarrhea first received oxaliplatin, 5-fluorouracil and leucovorin to avoid the irinotecan-induced neutropenia and diarrhea, respectively. We retrospectively evaluated the feasibility of this strategy by assessing toxicity and total progression-free survival in first- and subsequent second-line therapies in all patients studied. RESULTS In the first-line irinotecan, 5-fluorouracil and leucovorin (n = 61), Grade 4 neutropenia, febrile neutropenia and Grade 3 diarrhea occurred in 8.2, 3.3 and 3.3% of patients, respectively. In the first-line oxaliplatin, 5-fluorouracil and leucovorin (n = 26), Grade 4 neutropenia, febrile neutropenia, Grade 3 thrombocytopenia and Grade 3 neuropathy were observed in 11.5, 3.8, 3.8 and 7.7% of patients, respectively. In the second-line oxaliplatin, 5-fluorouracil and leucovorin (n = 38), Grade 3 diarrhea occurred in 2.6% of patients. In the second-line irinotecan monotherapy (n = 11), Grade 4 or febrile neutropenia occurred in 18% of patients and Grade 3 diarrhea in 9.1% of patients. In second-line S-1 (n = 9), Grade 3 anemia occurred in 2 patients. Median total progression-free survival in all 87 patients was 11.5 months. CONCLUSIONS Present regimen selection strategy would be feasible, since it causes less toxicity and similar efficacy comparing to previous studies. Determination of appropriate reduced dose in the second-line irinotecan monotherapy or other standard second-line therapy for patients with high-risk to irinotecan-induced toxicity might make this strategy more effective.

Association of variants in genes encoding for macrophage-related functions with clinical outcome in patients with locoregional gastric cancer

BACKGROUND Nuclear factor-kappaB (NF-κB) and CCL2/CCR2 chemokine axis play a central role in tumor progression such as stimulation of angiogenesis, acceleration of tumor invasion and migration, and suppression of innate immunosurveillance in the macrophage-related functions. There have been few reports regarding association of the macrophage function-related genes with the clinical outcome in gastric cancer. We hypothesized that variants in genes encoding for NF-κB and CCL2/CCR2 axis may predict prognosis in gastric cancer and tested whether the functional single-nucleotide polymorphisms (SNPs) will be associated with clinical outcome in patients with gastric cancer across two independent groups. PATIENTS AND METHODS This study enrolled two cohorts which consisted of 160 Japanese patients and 104 US patients with locoregional gastric cancer. Genomic DNA was analyzed for association of 11 SNPs in NFKB1, RELA, CCL2, and CCR2 with clinical outcome using PCR-based direct DNA sequencing. RESULTS The univariable analysis showed four SNPs had significant association with clinical outcome in the Japanese cohort, NFKB1 rs230510 remained significant upon multivariable analysis. The patients with the A allele of the NFKB1 rs230510 had significantly longer overall survival (OS) compared with those with the T/T genotype in both the Japanese and US cohort in the univariable analysis. In contrast, genotypes with the T allele of CCL2 rs4586 were significantly associated with shorter OS compared with the C/C genotype in the US cohort [hazard ratio (HR) 2.43; P = 0.015] but longer OS in the Japanese cohort (HR 0.58; P = 0.021), resulting in the statistically significant opposite impact on OS (P = 0.001). CONCLUSIONS Our study provides the first evidence that the NFKB1 rs230510 and CCL2 rs4586 are significantly associated with the clinical outcome in patients with locoregional gastric cancer. These results also suggest that the genetic predisposition of the host may dictate the immune-related component of the tumor for progression in gastric cancer.

A Phase I Study of Infusional 5-Fluorouracil, Leucovorin, Oxaliplatin and Irinotecan in Japanese Patients with Advanced Colorectal Cancer Who Harbor UGT1A1*1/*1,*1/*6 or *1/*28

Objective: To evaluate the safety and efficacy of combination chemotherapy with 5-fluorouracil (5-FU), leucovorin, irinotecan and oxaliplatin (FOLFOXIRI) in Japanese patients with advanced colorectal cancer. Methods: This phase I dose-finding study was designed to determine the maximum tolerated dose (MTD), recommended dose (RD) or both of FOLFOXIRI. Patients with UDP-glucuronosyltransferase (UGT) 1A1*6/*6, *28/*28 and *6/*28 genotypes were excluded, because these UGT1A1 genotypes are linked to severe neutropenia in Japanese. Results: A total of 10 Japanese patients with advanced colorectal cancer were studied. The MTD of FOLFOXIRI in these Japanese patients was 165 mg/m2 irinotecan, 85 mg/m2 oxaliplatin and 2,400 mg/m2 5-FU. Accordingly, the RD of FOLFOXIRI was determined to be 150 mg/m2 irinotecan, 85 mg/m2 oxaliplatin and 2,400 mg/m2 5-FU. Toxic effects, evaluated until the completion of 4 cycles, were manageable. Grade 3–4 neutropenia occurred in 27% of cycles, but there was no febrile neutropenia. Among the 9 assessable patients, the objective response rate was 89%. Conclusions: We thus determined the RD of FOLFOXIRI in Japanese patients with advanced colorectal cancer who do not have UGT1A1*28/*28, *6/*6 or *6/*28 genotypes. Our results indicate that FOLFOXIRI is a well-tolerated regimen for these Japanese patients.