Chiyo K. Imamura

Significant Effect of Polymorphisms in CYP2D6 and ABCC2 on Clinical Outcomes of Adjuvant Tamoxifen Therapy for Breast Cancer Patients

PURPOSE The clinical efficacy of tamoxifen is suspected to be influenced by the activity of drug-metabolizing enzymes and transporters involved in the formation, metabolism, and elimination of its active forms. We investigated relationships of polymorphisms in transporter genes and CYP2D6 to clinical outcome of patients receiving tamoxifen. PATIENTS AND METHODS We studied 282 patients with hormone receptor-positive, invasive breast cancer receiving tamoxifen monotherapy, including 67 patients who have been previously reported. We investigated the effects of allelic variants of CYP2D6 and haplotype-tagging single nucleotide polymorphisms (tag-SNPs) of ABCB1, ABCC2, and ABCG2 on recurrence-free survival using the Kaplan-Meier method and Cox regression analysis. Plasma concentrations of tamoxifen metabolites were measured in 98 patients receiving tamoxifen 20 mg/d. RESULTS CYP2D6 variants were significantly associated with shorter recurrence-free survival (P = .000036; hazard ratio [HR] = 9.52; 95% CI, 2.79 to 32.45 in patients with two variant alleles v patients without variant alleles). Among 51 tag-SNPs in transporter genes, a significant association was found at rs3740065 in ABCC2 (P = .00017; HR = 10.64; 95% CI, 1.44 to 78.88 in patients with AA v GG genotypes). The number of risk alleles of CYP2D6 and ABCC2 showed cumulative effects on recurrence-free survival (P = .000000055). Patients carrying four risk alleles had 45.25-fold higher risk compared with patients with <or= one risk allele. CYP2D6 variants were associated with lower plasma levels of endoxifen and 4-hydroxytamoxifen (P = .0000043 and .00052), whereas no significant difference was found among ABCC2 genotype groups. CONCLUSION Our results suggest that polymorphisms in CYP2D6 and ABCC2 are important predictors for the prognosis of patients with breast cancer treated with tamoxifen.

A genome-wide association study identifies locus at 10q22 associated with clinical outcomes of adjuvant tamoxifen therapy for breast cancer patients in Japanese

Although many association studies of polymorphisms in candidate genes with the clinical outcomes of breast cancer patients receiving adjuvant tamoxifen therapy have been reported, genetic factors determining individual response to tamoxifen are not fully understood. To identify genetic polymorphisms associated with clinical outcomes of patients with tamoxifen treatment, we conducted a genome-wide association study (GWAS). We studied 462 Japanese patients with hormone receptor-positive, invasive breast cancer receiving adjuvant tamoxifen therapy. Of them, 240 patients were analyzed by genome-wide genotyping using the Illumina Human610-Quad BeadChips, and two independent sets of 105 and 117 cases were used for replication studies. In the GWAS, we detected significant associations with recurrence-free survival at 15 single-nucleotide polymorphisms (SNPs) on nine chromosomal loci (1p31, 1q41, 5q33, 7p11, 10q22, 12q13, 13q22, 18q12 and 19p13) that satisfied a genome-wide significant threshold (log-rank P= 2.87 × 10(-9)-9.41 × 10(-8)). Among them, rs10509373 in C10orf11 gene on 10q22 was significantly associated with recurrence-free survival in the replication study (log-rank P= 2.02 × 10(-4)) and a combined analysis indicated a strong association of this SNP with recurrence-free survival in breast cancer patients treated with tamoxifen (log-rank P= 1.26 × 10(-10)). Hazard ratio per C allele of rs10509373 was 4.51 [95% confidence interval (CI), 2.72-7.51; P= 6.29 × 10(-9)]. In a combined analysis of rs10509373 genotype with previously identified genetic makers, CYP2D6 and ABCC2, the number of risk alleles of these three genes had cumulative effects on recurrence-free survival among 345 patients receiving tamoxifen monotherapy (log-rank P= 2.28 × 10(-12)). In conclusion, we identified a novel locus associated with recurrence-free survival in Japanese breast cancer patients receiving adjuvant tamoxifen therapy.

Impact of cytochrome P450 2C19 polymorphisms on the pharmacokinetics of tacrolimus when coadministered with voriconazole

This study evaluated the effects of cytochrome P450 (CYP) 2C19 polymorphisms on tacrolimus pharmacokinetics when coadministered with voriconazole. Eighteen healthy volunteers, including 6 individuals in each CYP2C19 genotype (extensive metabolizers [EMs], intermediate metabolizers [IMs], and poor metabolizers [PMs]), received a single oral dose of 3 mg tacrolimus alone or in combination with 200 mg voriconazole twice daily at steady state. When tacrolimus was coadministered with voriconazole, a significant increase in area under its concentration‐time curve (AUC0‐24) was observed for all genotypes. AUC0‐12 of voriconazole in IMs and PMs were significantly higher than that in EMs (P < .05 and P < .01, respectively). Consequently, AUC0‐24 of tacrolimus in combination with voriconazole in IMs and PMs were also significantly higher than that in EMs (P < .05). These results demonstrate that CYP2C19 genotypes influenced the exposure of tacrolimus when coadministered with voriconazole, although tacrolimus is mainly metabolized by CYP3A.

Health services: How can we address cancer care after a natural disaster?

On 11 March 2011, a magnitude 9.0 earthquake and subsequent tsunami caused unprecedented devastation in Japan. Over 20,000 people lost their lives or went missing and more than 100,000 people had to evacuate their homes. Many victims are patients with chronic diseases, including cancer, who face interrupted or discontinued therapy.

Phase I study of salazosulfapyridine in combination with cisplatin and pemetrexed for advanced non‐small‐cell lung cancer

Spliced variant isoforms of CD44 (CD44v) are a marker of cancer stem cells in solid tumors. They stabilize the xCT subunit of the transporter system xc(–) and thereby promote synthesis of the antioxidant glutathione. Salazosulfapyridine (SASP) is an inhibitor of xCT and suppresses the proliferation of CD44v‐positive cancer cells. Chemotherapy‐naïve patients with advanced non‐squamous non‐small‐cell lung cancer were enrolled in a dose‐escalation study (standard 3 + 3 design) of SASP in combination with cisplatin and pemetrexed. The primary end‐point was the percentage of patients who experience dose‐limiting toxicity. Fifteen patients were enrolled in the study. Dose‐limiting toxicity was observed in one of six patients at a SASP dose of 1.5 g/day (elevation of aspartate and alanine aminotransferase levels, each of grade 3), two of five patients at 3 g/day (hypotension or pneumonitis, each of grade 3), and two of three patients at 4.5 g/day (anorexia of grade 3). The maximum tolerated dose was thus 3 g/day, and the recommended dose was 1.5 g/day. The overall response rate was 26.7% and median progression‐free survival was 11.7 months, much longer than that for cisplatin–pemetrexed alone in previous studies. Exposure to SASP varied markedly among individuals according to ABCG2 and NAT2 genotypes. The serum concentration of free CD44v protein was increased after the first cycle of treatment, possibly reflecting death of cancer stem cells. Salazosulfapyridine was thus given safely in combination with cisplatin–pemetrexed, with the addition of SASP tending to prolong progression‐free survival. This trial is registered in the UMIN Clinical Trials Registry as UMIN000017854.

Dynamic changes in CD44v-positive cells after preoperative anti-HER2 therapy and its correlation with pathologic complete response in HER2-positive breast cancer

Chemotherapy has been reported to increase the proportion of cancer stem cells (CSCs) and to promote epithelial-mesenchymal transition (EMT) phenotype changes. Anti-HER2 therapy may provide a strategy for eliminating CSC and EMT, which contribute to therapeutic resistance. No study has determined the changes in the quantity or characteristics of CSCs or circulating tumor cells (CTCs) with EMT phenotype during preoperative anti-HER2 therapy, and whether these changes correlate to response to dual anti-HER2 therapy. In a prospective clinical trial to evaluate pharmacodynamic biomarkers, 18 patients with operable primary HER2-positive breast cancer received dual anti-Her2 preoperative therapy with trastuzumab and lapatinib with paclitaxel. Proportions of tumor cells with CSC characteristics and EMT markers in CTCs were estimated at baseline, after 6 and 18 weeks of preoperative therapy to determine the quantitative cutoff value to predict pathologic complete response (pCR). Out of 18 patients, 8 (44%) had a pCR; 5 of these 8 patients (62%) were positive for CD44v at baseline and none were positive on the 6-week biopsy. In contrast, 6 of the 10 patients without pCR exhibited persistent levels, or enrichment of CD44v proportion and expression at 6 and 18 weeks (p=0.0128). Other biomarkers were not statistically significant predictors of pCR. Enrichment of CD44v-positive tumor cells after dual anti-HER2 therapy alone may predict poor response to dual anti-HER2 therapy plus chemotherapy.

The effects of advanced age and serum α1‐acid glycoprotein on docetaxel unbound exposure and dose‐limiting toxicity in cancer patients

Aim α1‐Acid glycoprotein (AAG), which is a major binding protein of docetaxel, is considered to be a determinant for docetaxel pharmacokinetics. However, there are no reports about the impact of serum AAG on pharmacokinetics and pharmacodynamics in elderly patients treated with docetaxel. The aim of this prospective study was to elucidate the effects of advanced age and serum AAG on docetaxel unbound exposure and neutropenia, dose‐limiting toxicity, in cancer patients. Methods Docetaxel was administered at 60 mg m−2 to 51 patients with non‐small cell lung cancer, 17 of whom were ≥75 years of age. Pharmacokinetics, unbound fraction (fu), neutropenia, serum protein levels of AAG and albumin, as well as baseline absolute neutrophil count (ANC) were assessed during the first course. Population pharmacokinetic and pharmacodynamic analyses were performed to evaluate the influence of clinically relevant factors on docetaxel pharmacokinetics and neutropenia. Results Clearance of docetaxel and degree of fu were significantly associated with serum AAG level, but not with age. Area under the concentration–time curve of unbound docetaxel (fu·AUC) was significantly higher in patients aged ≥75 years (0.389 μg·h ml−1, 95% CI; 0.329–0.448 μg·h ml−1) compared with patients aged <75 years (0.310 μg·h ml−1, 95% CI; 0.268–0.352 μg·h ml−1). Percent decrease in ANC at nadir related to fu·AUC, and was dependent on baseline ANC. Conclusion Regardless of ageing, serum level of AAG determines docetaxel unbound exposure and related dose‐limiting toxicity. Serum AAG level and ANC at baseline appear to be predictive of neutropenia for patients of all ages following the administration of docetaxel.

Abstract 211: Sulfasalazine (SSZ) works cancer stem-like cells (CSCs) via inhibiting xCT signal pathway: Phase 1 study in patients with gastric cancer (EPOC 1205)

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Back ground: CD44 is an adhesion molecule expressed in cancer stem-like cells (CSCs). Our group recently reported that CD44 splice variant (CD44v) is expressed in CSCs and interacts with xCT, a glutamate-cystine transporter, keeping high levels of the intracellular reduced glutathione (GSH). Thus, CSCs with a high expression of CD44v have an enhanced capacity for GSH synthesis and defense against reactive oxygen species (ROS), resulting in resistance to various therapeutic stresses (Cancer Cell 2011; Cancer Res 2013). Sulfasalazine (SSZ) as an xCT inhibitor suppressed CD44v-dependent tumor growth and increased sensitivity to cytotoxic drugs in vivo study. Methods: A phase 1 dose escalation study in patients with advanced gastric cancer who had received one or more standard chemotherapies was conducted to determine the optimal dose, change in CD44v expression and intra-tumor level of GSH pre- and post SSZ exposure and pharmacokinetics. SSZ was given fourth-daily oral administration with 2 weeks as one cycle, which were continued until progression of disease, unacceptable toxicity, or other discontinuation criteria were met. A 3+3 escalation was used to evaluate a MTD. Tumor tissues were obtained pre- and post SSZ administration to evaluate expression of CD44v and intra-tumor level of GSH by immunohistochemistry and boron doped diamond microelectrode (Sci Rep 2012), respectively. Results: Eleven patients were dosed from 8 g to 12 g/day; median age: 71 years (61-78); median number of prior chemotherapies: 3 (1-4). There was two DLT of grade 3 anorexia and nausea among patients who were treated with 12 g/day. One additional patients required frequent dose interruption with grade 2 anorexia and nausea. Therefore 12g/day was judged as MTD. No DLT was observed among patients with 8g/day. Among the 5 patients with high CD44v expression, 4 patients achieved reduced expression of CD44v after the administration of SSZ for 2 weeks. GSH was also apparently decreased in 2 of 5 patients. Further exploratory biomarker analyses are still ongoing. The individual variability of SSZ exposure was explainable in terms of the genotypes of ABCG2 and NAT2 which influence SSZ pharmacokinetics. Conclusions: Optimal dose of SSZ was considered as 8g/day. Down regulation of CD44v expression and decreased level of GSH is confirmed as a pharmacodynamic marker of drug-on-target effect and mode of action of SSZ for CSCs, which warrants further investigation for combination with chemotherapy or other targeting agents. Clinical trial information: UMIN000010254 Citation Format: Kohei Shitara, Shunji Takahashi, Takako Nakajima, Hironaka Shuichi, Osamu Nagano, Chiyo Imamura, Taisei Mushiroda, Yasuaki Einaga, Miki Fukunani, Akihiro Sato, Atsushi Ohtsu, Hideyuki Saya, Toshihiko Doi. Sulfasalazine (SSZ) works cancer stem-like cells (CSCs) via inhibiting xCT signal pathway: Phase 1 study in patients with gastric cancer (EPOC 1205). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 211. doi:10.1158/1538-7445.AM2014-211

How can we address cancer care after a natural disaster

On 11 March 2011, a magnitude 9.0 earthquake and subsequent tsunami caused unprecedented devastation in Japan. Over 20,000 people lost their lives or went missing and more than 100,000 people had to evacuate their homes. Many victims are patients with chronic diseases, including cancer, who face interrupted or discontinued therapy.

Individualized Dosing of Axitinib Based on First-Dose Area Under the Concentration–Time Curve for Metastatic Renal-Cell Carcinoma

Background Previous studies have revealed that higher exposure of axitinib leads to better prognosis in metastatic renal‐cell carcinoma. We thus assessed individualized dosing of axitinib on the basis of the first‐dose area under the concentration–time curve from 0 to 12 hours (AUC0‐12) for sunitinib‐pretreated metastatic renal‐cell carcinoma patients. Patients and Methods In this prospective single‐arm trial, the starting dose of axitinib was 5 mg twice daily. A series of blood samples were taken at predetermined times after the first dose to calculate AUC0‐12. On day 15 of axitinib administration, the dose was adjusted to ensure ≥ 150 ng·h/mL AUC0‐12 at steady state according to first‐dose AUC0‐12. The primary end point was the 6‐month progression‐free survival rate. Results Twenty‐six Japanese patients were enrolled. The median recommended dose based on the first‐dose AUC0‐12 was 2.5 mg (range, 1‐16 mg) twice daily. The 6‐month progression‐free survival rate for all enrolled patients and per‐protocol set, from which 3 patients were excluded for not adjusting to the recommended dose on day 15, was 84.6% (95% confidence interval, 65.5‐94.1) and 82.6% (95% confidence interval, 61.8‐93.3), respectively. The most common nonhematologic adverse events were hypertension, hand–foot syndrome, fatigue, and decreased appetite. Eighteen patients (75%) developed grade 3 hypertension; however, actual blood pressure could be controlled using antihypertensive agents. Other adverse events were manageable during the protocol treatment. Conclusion Individualized dosing of axitinib based on the first‐dose AUC0‐12 might have promising efficacy and manageable toxicity. Micro‐Abstract Individualized dosing of axitinib based on drug exposure remains unknown. In this study we evaluated the efficacy and safety of the recommended axitinib dose on the basis of the first‐dose area under the concentration–time curve from 0 to 12 hours in metastatic renal‐cell carcinoma. Adjusting to the recommended dose lead to promising efficacy and manageable toxicity. The current study provides novel information to develop individualized axitinib treatment.