Published papers

Purpose: Edotecarin (J-107088) is a potent indolocarbazole topoisomerase I inhibitor which is structurally distinct from the camptothecins. This study aimed to determine the maximum tolerated dose (MTD), the recommended dose for future Phase II studies and the safety, pharmacokinetic profile, and preliminary antitumor activity of edotecarin in a population of patients with advanced solid tumors. Experimental design: Edotecarin was administered as a single dose by IV infusion over 2 h every 21 days (with 1 week permitted for recovery from toxicities, if needed) in patients with advanced solid tumors. Doses ranged from 8 to 15 mg/m2. Pharmacokinetic assessments were performed during and after the first administration. Results: Twenty-four patients received 61 cycles of therapy. Dose-limiting toxicities (infection, febrile neutropenia, constipation, ileus, and prolonged grade 4 granulocytopenia) were observed in 3 of 5 evaluable patients at the 15 mg/m2 dose, defining the MTD. The most commonly reported non-hematologic toxicities were anorexia, nausea, malaise, and constipation. Diarrhea was neither frequent nor severe. Neutropenia was the most common hematologic toxicity (grade 3-4 in 21/23 patients during cycle 1). Plasma concentrations of edotecarin rose rapidly following the start of the 2-hour infusion, reaching Cmax values of 103 ± 17 ng/ml at the 13 mg/m2 dose, and decreased steeply after the end of the infusion. Plasma concentrations declined to approximately 1-2 ng/ml at 26 h post start of infusion, the last PK sampling time point. The mean apparent plasma half-life of the drug was 20 h, which should be considered a preliminary estimate until results from studies with a longer duration of plasma sampling are available. A mean of 1.4-3.6% of the dose was recovered as unchanged drug in the urine over 48 h. Unconfirmed tumor regression ≥50% was observed in 2 patients, 1 with metastatic gastric carcinoma and 1 with esophageal cancer. Conclusions: The MTD of edotecarin administered IV over 2 h every 21 days was 15 mg/m2. The recommended dose for Phase II studies with a 3-week schedule (with 1 week permitted for recovery from toxicities, if needed) is 13 mg/m2. The observed safety profile and preliminary evidence of antitumor activity warrant further investigation of this drug in solid tumors. © Springer-Verlag 2005.

Background: Oxaliplatin, a platinum compound, has been commonly used around the world for treating advanced colorectal cancer. The generally recommended dose and schedule of oxaliplatin monotherapy is 130 mg/m2 every 3 weeks. This trial was conducted to evaluate the safety and pharmacokinetics of oxaliplatin monotherapy in Japanese patients with solid tumors. Methods: Oxaliplatin was administered as a 2-h intravenous infusion every 3 weeks at a dose of 90 and 130 mg/m2. Blood was collected to determine the total platinum and the ultrafiltrate platinum concentrations in plasma in all cycles. Results: Nine patients were enrolled; three were given oxaliplatin monotherapy at 90 mg/m2 and six received 130 mg/m2. All tumors were colorectal cancer. The major adverse reactions included myelosuppressive, neurological and gastrointestinal toxicities, although most were grades 1 and 2 at both dose levels. Peripheral sensory neuropathy of without movement disturbance (grade 1 or 2) was observed in all patients at both dose levels. The 130 mg/m2 dose level was not found to be the maximum tolerated dose, but was judged to be the recommended dose. No objective responses were seen and five cases of no change were observed. A bi-exponential open model best described the disappearance of platinum in the plasma, and a tri-exponential open model best described the disappearance of ultrafilterable platinum in the plasma at both dose levels. No racial difference was suggested in the pharmacokinetics of oxaliplatin. Conclusions: The oxaliplatin monotherapy dose schedule of 130 mg/m2 every 3 weeks, recommended worldwide, is acceptable for Japanese patients. © 2006 Oxford University Press.

Irinotecan is a key chemotherapeutic drug used to treat many tumors, including cervical and ovarian cancers; however, irinotecan can cause toxicity, particularly in the presence of uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1) gene polymorphisms, which are associated with reduced enzyme activity. Here, we investigated the prevalence of three different variants of UGT1A1 (UGT1A1*6, UGT1A1*27 and UGT1A1*28) and their relationships with irinotecan-induced adverse events in patients with gynecologic cancer, who are treated with lower doses of irinotecan than patients with other types of solid tumors. Fifty-three female patients treated with irinotecan and 362 female patients not treated with irinotecan were screened for UGT1A1*6, UGT1A1*27 and UGT1A1*28. Homozygosity for UGT1A1*6 or heterozygosity for UGT1A1*6/*28 was associated with a high risk of severe absolute neutrophil count decrease or diarrhea (odds ratios: 16.03 and 31.33, respectively). In contrast, serum bilirubin levels were not associated with irinotecan toxicity. Homozygosity for UGT1A1*6/*6 and heterozygosity for UGT1A1*6/*28 were associated with an increased risk of absolute neutrophil count and/or diarrhea in Japanese gynecologic cancer patients, despite the lower doses of irinotecan used in these patients. UGT1A1*6 and UGT1A1*28 are potential predictors of severe absolute neutrophil decrease and diarrhea caused by low-dose irinotecan in gynecologic cancer patients. © 2013 The Japan Society of Human Genetics All rights reserved 1434-5161/13.

An optimal dosage regimen of sitafloxacin was considered based on a pharmacokinetics and pharmacodynamics (PK-PD) analysis in patients with community-acquired respiratory tract infections (RTI). A population pharmacokinetic analysis of sitafloxacin was conducted using clinical data of five clinical pharmacology studies and one clinical PK-PD study in patients with RTIs. The pharmacokinetic parameters in individual patients were estimated by the Bayesian method to examine any correlation between pharmacokinetics and bacteriological efficacy. Efficacy data were obtained from the clinical PK-PD study, in which 50 or 100 mg sitafloxacin was administered twice daily for 7 days. In addition, an efficacy was simulated for a hypothetical dose regimen of 100 mg once daily. The fAUC0-24h/MIC and the fC max/MIC of sitafloxacin at a dose of 50 mg twice daily were 117.5 ± 78.0 and 7.3 ± 4.7 (mean ± SD), respectively. As a result of the univariate logistic regression analysis, the larger the value of fAUC0-24h/MIC or fC max/MIC becomes, the higher the bacteriological efficacies. The eradication rates for fAUC0-24h/MIC ≥ 30 and for fC max/MIC ≥ 2 were 96.4 % and 96.3 %, respectively. The PK-PD target values of sitafloxacin for the treatment of mild to moderate RTIs were considered to be fAUC0-24h/MIC ≥ 30 and fC max/MIC ≥ 2. The PK-PD parameters at the regimen of 50 or 100 mg twice daily in patients with RTIs reached the target values. Furthermore, a 100 mg once-daily regimen was expected to show similar efficacy based on the PK-PD simulations. © 2013 The Author(s).

Purpose: The aim of this study was to investigate the pharmacogenetic determinants of sunitinib-related toxicity and ethnic difference in metastatic renal cell carcinoma (mRCC) among Korean patients. Methods: A pharmacogenetic study was performed in 65 patients with mRCC treated with the standard schedule of sunitinib (50 mg orally once daily for 4 weeks-on/2 weeks-off). Detailed data regarding the toxicity of sunitinib, including thrombocytopenia, neutropenia, anemia, and hand-foot syndrome (HFS), were prospectively collected in a clinical trial program (n = 38) or standard oncology practice (n = 27). Total of 12 genetic polymorphisms in 8 candidate genes (CYP1A1, CYP3A5, ABCB1, ABCG2, PDGFRα, VEGFR2, RET, and FLT3) were analyzed for an association with treatment-related toxicity from sunitinib using Pearson χ 2 test. Results: Common grade 3 or grade 4 treatment-related toxicities were thrombocytopenia (36.9 %, 24/65), neutropenia (18.4 %, 12/65), anemia (7.7 %, 5/65), and HFS (12.3 %, 8/65). Patients carrying an ABCG2 421 AA genotype developed significantly more grade 3 or grade 4 thrombocytopenia, neutropenia, and HFS adjusted for age, sex, and Eastern Cooperative Oncology Group performance status, and body surface area (odds ratio compared with AC/CC genotypes [OR] 9.90, P = 0.04, thrombocytopenia; OR 18.20, P = 0.02, neutropenia; and OR 28.46, P = 0.01, HFS). In addition, total and surface protein ABCG2 protein expression was decreased in ABCG2 421 AA mutant cells compared to wild type. Conclusion: Among 12 genetic polymorphisms, polymorphism in the ABCG2 421C>A gene may be mostly associated with the risk of sunitinib-related toxicity in mRCC patients. Considering the high frequency of 421C>A SNP in Asian, this may be related to differential toxicities among ethnic groups. © 2013 Springer-Verlag Berlin Heidelberg.

The adequacy of sitafloxacin clinical dose regimens was assessed by comparing the efficacy of the administration of 100 mg sitafloxacin once daily (100 mg qd group) and 50 mg sitafloxacin twice daily (50 mg bid group). Patients with respiratory tract infections caused by pneumococci were orally treated with sitafloxacin (100 mg qd or 50 mg bid) for 7 days. The clinical efficacy, pneumococci eradication rate, safety, and pharmacokinetic and pharmacodynamic indices of the two groups were then assessed. The clinical efficacy was 93.5 % in both groups. The pneumococci eradication rate was 98.2 % in the 100 mg qd group and 92.7 % in the 50 mg bid group. The mean of the free AUC 0-24h divided by the minimum inhibitory concentration (MIC) (fAUC0-24h/MIC) did not differ significantly between the 100 mg qd (103.24) and the 50 mg bid groups (105.25). The mean of the free C peak divided by the MIC (fC peak/MIC) was higher in the 100 mg qd group (10.19) than in the 50 mg bid group (6.53). The pathogen eradication rate was 98.9 % (89/90) when the fAUC0-24h/MIC was greater than 30, and the eradication rate was 98.9 % (89/90) when the fC peak/MIC was greater than 2. The incidences of adverse drug reactions were 33.7 % in the 100 mg qd group and 40.4 % in the 50 mg bid group. No obvious differences in the efficacy and safety were observed between the dosage groups. For cases in which a sufficiently high C peak is necessary to ensure the susceptibility of the pathogens to the drug, 100 mg sitafloxacin once daily should be administered. © 2013 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases.

We evaluated the clinical and bacteriological efficacy of oral sitafloxacin (STFX) in clinically diagnosed community-acquired pneumonia (CAP) caused by Streptococcus pneumoniae. Additionally, we cultured these patient samples to test the minimal inhibitory concentrations (MICs) of levofloxacin (LVFX), moxifloxacin (MFLX), STFX, and penicillin G (PCG), as well as identified mutations in the quinolone resistance determinant regions (QRDRs) in LVFX-resistant strains. This study is a nested cohort from a prospective, multicenter clinical trial consisting of 139 patients with community-acquired pneumonia (CAP), from which 72 were included in this study. After diagnosis of CAP caused by S. pneumoniae, STFX (50 mg twice daily, or 100 mg once daily) was orally administered for 7 days. Sixty-five patient sputum samples were then cultured for MIC analysis. In a LVFX-resistant strain that was identified, mutations in the QRDRs of the gyrA, gyrB, parC, and parE genes were examined. Of 72 patients eligible for this study, S. pneumoniae was successfully cultured from the sputum of 65 patients, and only 7 patients were diagnosed by urinary antigen only. Clinical improvement of CAP was obtained in 65 of the 69 clinically evaluable patients (65/69, 94.2 %). Eradication of S. pneumoniae was observed in 62 patients of the 65 bacteriologically evaluable patients (62/65, 95.4 %). Additionally, STFX showed the lowest MIC distribution compared with LVFX, MFLX, and PCG, and no major adverse reactions were observed. STFX treatment in patients with CAP caused by S. pneumoniae was found to be highly effective both clinically (94.2 %) and bacteriologically (95.4 %). © 2012 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases.

Aim: This study compared the efficiency of Blood-direct InvaderPlus® with existing methods for detecting genetic polymorphisms by using clinical samples, and to determine whether this new method can be used for future clinical studies. Materials & methods: We developed a new method, called Blood-direct InvaderPlus, for detecting genetic polymorphisms. Whole-blood samples were subjected to genetic analysis with the new method and also the conventional method. Results: The results obtained with the new method were consistent with those of direct sequencing. Blood-direct InvaderPlus was able to detect gene polymorphisms of UGT1A16,27,28,60, VKORC1 -1639G>A, VKORC1 1173T>C and CYP2C92 and3 much faster than the conventional methods. Conclusion: Blood-direct InvaderPlus allowed accurate, simple and rapid detection of genetic polymorphisms. © 2012 Future Medicine Ltd.

We investigated the pharmacokinetics of mizoribine in the acute phase after adult living donor liver transplantation (LDLT). Between February 2004 and October 2009, 16 recipients received immunosuppressive therapy that included mizoribine (100 to 200 mg/d) after undergoing LDLT. We determined the serum levels of mizoribine before (C0) and 3 (C3), 4 (C4), and 10 (C10) hours after administration on postoperative days 3, 7, and 21. We assessed area under the concentration time curve (AUC) (hour · μg/mL), normalized serum concentration (NSC) at C0 [concentration (μg/mL)/dose (mg/kg body weight)], and estimated glomerular filtration rate (eGFR). The mizoribine concentration showed increases at C3 and C4 followed by a decrease at C10 on all days. AUC was 4.3, 5.9, and 8.3 in the 200-mg/d dose group on days 3, 7, and 21, respectively. NSC at C0 increased for 3 weeks after LDLT. There was a significant correlation between the NSC at C0 and eGFR on day 21, but not on days 3 and 7. There were no correlations between the NSC at C0 and either aspartate aminotransferase, total bilirubin, albumin, trough cyclosporine, or trough tacrolimus on any day. The pharmacokinetics of mizoribine in the acute phase after LDLT seems to be affected by postoperative day and renal function. © 2012 Elsevier Inc.

Genetic differences in individuals with regard to opioid-receptor signaling create clinical difficulties for opioid treatment; consequently, useful pharmacodynamic and predictive biomarkers are needed. In this prospective study, we studied gene expression changes in peripheral blood leukocytes using a microarray and real-time RT-PCR analysis to identify pharmacodynamic biomarkers for monitoring the effect of morphine in a cohort of opioid-treatment-naïve cancer patients. We also examined genetic variations in opioid receptor mu 1 (OPRM1, 118A→G) and catechol-O-methyltransferase (COMT, 472G→A) to evaluate predictive biomarkers of the treatment outcome of morphine. The plasma concentration of morphine was measured using a liquid chromatography-tandem mass spectrometry method. Microarray analysis revealed that the mRNA expression levels of arrestin β 1 (ARRB1) were significantly down-regulated by morphine treatment. Real-time RT-PCR analysis against independent samples confirmed the results (P=0.003) and changes during treatment were negatively correlated with the plasma morphine concentration (R=-0.42). No correlation was observed between the genotype of OPRM1 and morphine treatment; however, the plasma concentration of morphine and the required dose of morphine were significantly lower for the A/A genotype of COMT (vs. A/G+G/G, P=0.008 and 0.03). We found that changes in the expression of ARRB1 may be a novel pharmacodynamic biomarker and the COMT 472G→A genotype may be a predictive biomarker of the response to morphine treatment.

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 singlenucleotide 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 5 2.87 3 10-9.9.4× 10-8). Among them, rs10509373 in C10orf11 gene on 10q22 was significantly associated with recurrencefree survival in the replication study (log-rank P 5 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 (logrank P 5 1.26 × 10-10). Hazard ratio per C allele of rs10509373 was 4.51 [95% confidence interval (CI), 2.72-7.51; P 5 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 5 2.28 × 10-12). © The Author 2011. Published by Oxford University Press. All rights reserved.

Purpose: Garenoxacin, a novel des-F(6)-quinolone, possesses potent antibacterial activity against infectious pathogens in the respiratory tract. Population pharmacokinetic/pharmacodynamic (PK/PD) modeling and Monte Carlo simulations were used to optimize garenoxacin dosage regimens. Methods: At the end of phase II stage, the clinical dose of garenoxacin was predicted to be 400 mg once daily by the interim PK/PD analysis using phase I and phase II clinical data. The criteria used to determine an optimal dose were (1) the target attainment of the area under the unbound concentration-time curve divided by the minimum inhibitory concentration (fAUC 0-24/MIC ratio) and (2) the maintenance of a trough concentration above the mutant prevention concentration. In a confirmatory phase III study, garenoxacin was administered 400 mg once daily to 136 patients infected with mild or moderate chronic respiratory diseases. Results: Logistic regression analysis showed that fAUC 0-24/MIC ratio was a significant variable that predicted clinical response (p∈=∈0.0164). Of all subjects, 92.4% reached the target value of fAUC 0-24/MIC ratio∈>∈30 h, and the clinical efficacy rate of this population was 91.8%. On the other hand, there was no significant relationship between exposure values (AUC 0-24 and maximum concentration) and the incidence of adverse events by the Mann-Whitney test. Conclusions: The antimicrobial efficacy of the actual phase III study was consistent with the expectation from the Monte Carlo PD simulation. We were able to show that the optimal garenoxacin dosage regimens were successfully determined using prospective population PK/PD analysis and clinical trial simulations. © 2011 The Author(s).

CYP2D6 is a key enzyme responsible for the metabolism of tamoxifen to active metabolites, endoxifen, and 4-hydroxytamoxifen. The breast cancer patients who are heterozygous and homozygous for decreased-function and null alleles of CYP2D6 showed lower plasma concentrations of endoxifen and 4-hydroxytamoxifen compared to patients with homozygous-wild-type allele, resulting in worse clinical outcome in tamoxifen therapy. We recruited 98 Japanese breast cancer patients, who had been taking 20 mg of tamoxifen daily as adjuvant setting. For the patients who have one or no normal allele of CYP2D6, dosages of tamoxifen were increased to 30 and 40 mg/day, respectively. The plasma concentrations of tamoxifen and its metabolites were measured at 8 weeks after dose-adjustment using liquid chromatography-tandem mass spectrometry. Association between tamoxifen dose and the incidence of adverse events during the tamoxifen treatment was investigated. In the patients with CYP2D6*1/*10 and CYP2D6*10/*10, the mean plasma endoxifen levels after dose increase were 1.4- and 1.7-fold higher, respectively, than those before the increase (P < 0.001). These plasma concentrations of endoxifen achieved similar level of those in the CYP2D6*1/*1 patients receiving 20 mg/day of tamoxifen. Plasma 4-hydroxytamoxifen concentrations in the patients with CYP2D6*1/*10 and CYP2D6*10/*10 were also significantly increased to the similar levels of the CYP2D6*1/*1 patients according to the increasing tamoxifen dosages (P < 0.001). The incidence of adverse events was not significantly different between before and after dose adjustment. This study provides the evidence that dose adjustment is useful for the patients carrying CYP2D6*10 allele to maintain the effective endoxifen level. © 2011 Springer Science+Business Media, LLC.

A population pharmacokinetic (PK) model for meropenem in Japanese pediatric patients with various infectious diseases was developed based on 116 plasma concentrations from 50 pediatric patients. The population PK parameters developed in this analysis are useful for calculation of the percent time above minimum inhibitory concentration (%T>MIC) and for optimal dosing of meropenem in pediatric patients. After dosing at 20mg/kg t.i.d. by 0.5-h infusion (approved standard dose for pediatric patients in Japan), the target value of 50%T>MIC was achieved, indicating that 20mg/kg t.i.d. by 0.5-h infusion is effective for susceptible bacteria. In contrast, for bacteria with higher MICs such as Pseudomonas aeruginosa (MIC ≥ 2 μg/mL), the probability of target attainment of 50%T>MIC was 60.7% at a dose of 40mg/kg t.i.d. by 0.5-h infusion (highest dose approved for pediatric patients in Japan). The simulations described in this article indicated that 40 mg/kg t.i.d. with a longer infusion duration (e.g., 4 h) is more effective against bacteria with a MIC higher than 2 μg/mL. The predicted probability of target attainment for 50%T>MIC (97.0%) was well correlated not only to the microbiological efficacy rate (97.0%) but also to the clinical efficacy rate (95.9%) in the present phase 3 study. © 2011 by the Japanese Society for the Study of Xenobiotics (JSSX).

The objectives of this study were to develop a population pharmacokinetic (PK) model of meropenem, to simulate the percent time above minimum inhibitory concentration (%T > MIC) at various MICs, and to estimate effective dosage regimens by calculating the target attainment rates against various strains of bacteria. A total of 209 plasma samples (1-3 concentrations per patient) were obtained from 98 adult Japanese patients with febrile neutropenia in an open-labeled Phase 3 study. The final population PK model was fit to a two-compartment model with zero-order input. Creatinine clearance had a positive significant correlation with CL. Gender had a significant effect on Vc; however, this effect was small, and the PK profile in male patients was similar to that in female patients. The population PK parameters developed in this study are useful in simulating PK profiles of meropenem at various dosage regimens precisely for calculation of %T > MIC. The PK-PD analysis indicated that 0.5 g every 6 h (q6h) was more effective than 1 g q12h, although provided 2 g per day in total. A meropenem dosage regimen of 1 g q8h and/or longer infusion duration was better against a pathogen of comparatively low sensitivity, Pseudomonas aeruginosa (for MIC ≥2 μg/ml). Although causative bacteria were identified in a small number of patients, the target attainment rates at 75%T > MIC (89%) were comparable to microbiological response (89%). The present PK-PD analyses under various conditions are useful in the treatment of febrile neutropenia. © 2011 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases.

Background: Individual responses to oxaliplatin (L-OHP)-based chemotherapy remain unpredictable. The objective of our study was to find candidate protein markers for tumor sensitivity to L-OHP from intracellular proteins of human colorectal cancer (CRC) cell lines. We performed expression difference mapping (EDM) analysis of whole cell lysates from 11 human CRC cell lines with different sensitivities to L-OHP by using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS), and identified a candidate protein by liquid chromatography/mass spectrometry ion trap time-of-flight (LCMS-IT-TOF).Results: Of the qualified mass peaks obtained by EDM analysis, 41 proteins were differentially expressed in 11 human colorectal cancer cell lines. Among these proteins, the peak intensity of 11.1 kDa protein was strongly correlated with the L-OHP sensitivity (50% inhibitory concentrations) (P < 0.001, R 2 = 0.80). We identified this protein as Protein S100-A10 (S100A10) by MS/MS ion search using LCMS-IT-TOF. We verified its differential expression and the correlation between S100A10 protein expression levels in drug-untreated CRC cells and their L-OHP sensitivities by Western blot analyses. In addition, S100A10 protein expression levels were not correlated with sensitivity to 5-fluorouracil, suggesting that S100A10 is more specific to L-OHP than to 5-fluorouracil in CRC cells. S100A10 was detected in cell culture supernatant, suggesting secretion out of cells.Conclusions: By proteomic approaches including SELDI technology, we have demonstrated that intracellular S100A10 protein expression levels in drug-untreated CRC cells differ according to cell lines and are significantly correlated with sensitivity of CRC cells to L-OHP exposure. Our findings provide a new clue to searching predictive markers of the response to L-OHP, suggesting that S100A10 is expected to be one of the candidate protein markers. © 2011 Suzuki et al; licensee BioMed Central Ltd.

Background: Eldecalcitol is an analog of 1,25-dihydroxyvitamin D 3 that improves bone mineral density; however, the effect of eldecalcitol on the risk of fractures is unclear. The objective of this study is to examine whether eldecalcitol is superior to alfacalcidol in preventing osteoporotic fractures. This trial is registered with ClinicalTrials.gov, number NCT00144456. Methods and results: This 3year randomized, double-blind, active comparator, superiority trial tested the efficacy of daily oral 0.75μg eldecalcitol versus 1.0μg alfacalcidol for prevention of osteoporotic fractures. 1054 osteoporotic patients 46 to 92years old were randomly assigned 1:1 to receive eldecalcitol (n=528) or alfacalcidol (n=526). Patients were stratified by study site and serum 25-hydroxyvitamin D level. Patients with low serum 25-hydroxyvitamin D levels (<50nmol/L) were Supplemented with 400IU/day vitamin D 3. Primary end point was incident vertebral fractures. Secondary end points included any non-vertebral fractures and change in bone mineral density and bone turnover markers. Compared with the alfacalcidol group, the incidence of vertebral fractures was lower in eldecalcitol group after 36months of treatment (13.4 vs. 17.5%; hazard ratio, 0.74; predefined 90% confidence interval [CI], 0.56-0.97). Eldecalcitol reduced turnover markers and increased bone mineral density more strongly than alfacalcidol. Eldecalcitol reduced the incidence of three major non-vertebral fractures, which was due to a marked reduction in wrist fractures by a post-hoc analysis (1.1 vs. 3.6%; hazard ratio, 0.29; 95% CI, 0.11-0.77). Among the adverse events, the incidence of increase in serum and urinary calcium was higher in the eldecalcitol group, without any difference in glomerular filtration rate between the two groups. Conclusions: Eldecalcitol is more efficacious than alfacalcidol in preventing vertebral and wrist fractures in osteoporotic patients with vitamin D sufficiency, with a safety profile similar to alfacalcidol. © 2011 Elsevier Inc.