Purpose We sought to demonstrate the relevance of a lymphoblastoid cell line (LCL) model in the discovery of clinically relevant genetic variants affecting chemotherapeutic response by comparing LCL genome-wide association study (GWAS) results to clinical GWAS results. Experimental Design A GWAS of paclitaxel-induced cytotoxicity was performed in 247 LCLs from the HapMap Project and compared to a GWAS of sensory peripheral neuropathy in breast cancer patients (n=855) treated with paclitaxel in the Cancer and Leukemia Group B (CALGB) 40101 trial. Significant enrichment was assessed by permutation resampling analysis. Results We observed an enrichment of LCL cytotoxicity-associated single nucleotide polymorphisms (SNPs) in the sensory peripheral neuropathy-associated SNPs from the clinical trial with concordant allelic directions of effect (empirical P = 0.007). Of the 24 SNPs that overlap between the clinical trial (P < 0.05) and the preclinical cytotoxicity study (P < 0.001), 19 of them are expression quantitative trait loci (eQTLs), which is a significant enrichment of this functional class (empirical P = 0.0447). One of these eQTLs is located in RFX2, which encodes a member of the DNA-binding regulatory factor X family. Decreased expression of this gene by siRNA resulted in increased sensitivity of NS-1 (rat pheochromocytoma) cells to paclitaxel as measured by reduced neurite outgrowth and increased cytotoxicity, functionally validating the involvement of RFX2 in nerve cell response to paclitaxel. Conclusions The enrichment results and functional example imply that cellular models of chemotherapeutic toxicity may capture components of the underlying polygenic architecture of related traits in patients.

Despite major advances in breast cancer therapy, annual mortality remains significant with a sizeable proportion of patients eventually succumbing to metastatic disease. Clearly, optimizing approaches for identification and management of women at heightened risk for breast cancer will reduce overall morbidity and mortality from the disease. Over the past few decades, advances in molecular genetics and linkage analyses have allowed for the identification of specific germline mutations underlying a significant fraction of hereditary breast cancer. Genome-wide association studies have been developed as a powerful tool in identifying lower penetrance mutations, and it is believed that such genome-level variations may act in concert to give rise to the majority of inherited breast cancer risk. Controversies and uncertainties remain in clinical application of newly identified genomic loci that confer genetic susceptibility. This article reviews the well-characterized breast cancer susceptibility genes, highlights recent publications pertaining to the less well known and lower penetrance genetic polymorphisms, summarizes challenges in translating research findings to the clinical scenario, and offers some recommendations for clinical practice.

Objective Clinical use of paclitaxel is limited by variable responses and the potential for significant toxicity. To date, studies of association between variants in candidate genes and paclitaxel effects have yielded conflicting results. We sought to evaluate relationships between global gene expression and paclitaxel sensitivity. Methods We utilized well-genotyped lymphoblastoid cell lines derived from the International HapMap Project to evaluate relationships between cellular susceptibility to paclitaxel and global gene expression. Cells were exposed to varying concentrations of paclitaxel to evaluate paclitaxel-induced cytotoxicity and apoptosis. Among the top genes, we identified solute carrier (SLC) genes associated with paclitaxel sensitivity and narrowed down the list to those that had single nucleotide polymorphisms (SNPs) associated with both their expression level of the SLC gene and also with paclitaxel sensitivity. We performed independent validation in an independent set of cell lines and also conducted functional studies using RNA interference. Results Of all genes associated with paclitaxel-induced cytotoxicity at p<0.05 (1713 genes), there was a significant enrichment of SLC genes (31 genes). A subset of SLC genes, namely SLC31A2, SLC43A1, SLC35A5, and SLC41A2, were associated with paclitaxel sensitivity and had regulating SNPs that were also associated with paclitaxel-induced cytotoxicity. Multivariate modeling demonstrated that those 4 SLC genes jointly explain 20% of the observed variability in paclitaxel susceptibility. Using RNA interference, we demonstrated increased paclitaxel susceptibility with knockdown of 3 SLC genes, SLC31A2, SLC35A5, and SLC41A2. Conclusions Our findings are novel and lend further support to the role of transporters, specifically solute carriers in mediating cellular susceptibility to paclitaxel.

The majority of clinical trials of neo-adjuvant therapy for breast cancer have been conducted in resource-rich countries. We chose Nigeria, a resource-poor country, as the major site for a phase II feasibility open-label multicenter clinical trial designed to evaluate the efficacy, safety, and tolerability of neo-adjuvant capecitabine in locally advanced breast cancer (LABC). Planned treatment consisted of 24 weeks of capecitabine at a dose of 1,000 mg/m2 twice daily (2,000 mg/m2 total per day). The primary endpoints were overall, partial, complete clinical response rate (OCR, PCR, CCR) and complete pathologic response (cPR). A total of 16 patients were recruited from August 2007 to April 2010. The study was terminated early as a result of slow accrual. After the first three cycles of therapy, PCR were seen in five of 16 patients (31%; 95% CI 11–59%). Of the remaining 11 patients, eight had no response (NR) or stable disease (SD), and three had progressive disease (PD). Seven patients proceeded with further therapy of which had SD. OCR at the end of eight cycles was 44% (95% CI 20–70%). Clinical response and radiologic response by ultrasonomammography were highly concordant (spearman correlation 0.70). The most common adverse effect was Grade 1 hand–foot syndrome, which was seen in 75% of patients. Despite several limitations, we successfully carried out this phase II feasibility study of neo-adjuvant capecitabine for LABC in Nigeria. Capecitabine monotherapy showed good overall response rates with minimal toxicity and further studies are warranted.

BackgroundVarying the rate of continuous intravenous infusions of 5-fluorouracil (5FU) chemotherapy over a 24-hour period has been reported to improve patient outcomes. It has been hypothesized that circadian variation in drug disposition is a contributing factor. We analyzed 5-FU concentrations during a 24-hour continuous 5-FU infusion.MethodsSixty-four subjects with advanced malignancies including pancreatic, hepatocellular, colorectal as well as other epithelial malignancies and either abnormal hepatic or renal function were treated on a phase I and pharmacokinetic study of weekly 24-hour intravenous infusions of 5-FU and leucovorin. No other concomitant anticancer therapy was administered. Blood samples were collected every three hours from 61 subjects for measurement of plasma 5-FU during the first two weekly infusions.ResultsAfter adjusting for differences in dose, elapsed time from start of infusion and infusion number (2 versus 1), mean 5-FU concentration was highest at 6 am and lowest at 3 pm, with an overall change in the mean from 3 pm to 6 am of +20 percent (95% CI = 12–28%). However, this variation in mean concentration associated with time of day was comparable in magnitude to the between-patient differences, within-patient differences between infusions, and the residual variation within infusion (coefficient of variation = 21%).ConclusionsOur data show systematic variation by time of day in plasma concentrations of 5-FU administered at a constant rate over 24 hours, but it is small compared to the total variation in plasma concentration contributed by other sources. Circadian variation in men was more pronounced than in women.

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Few clinical protocols have focused on patients with therapy-related myeloid neoplasms (t-MN). Therefore, we enrolled 32 patients with previously untreated t-MN on a clinical trial testing the effectiveness of a unified induction regimen of high-dose cytarabine and mitoxantrone. The complete remission (CR) rate was 66% (95% CI 47-81%) and the partial remission (PR) rate was 16% (95% CI 5-33%), for an overall response rate of 82%. Day 30 treatment mortality was 9% (3/32), and the most serious induction toxicity was cardiac dysfunction. Among the patients with CR, 13 (62%) received consolidation therapy using an allogeneic hematopoietic cell transplant (HCT), four (21%) received an autologous HCT, and three (16%) received further chemotherapy. We observed long-term disease-free survival in patients who received all three types of consolidation therapy. The remission induction of high-dose cytarabine and mitoxantrone for t-MN is a well-tolerated efficacious combination, which allows aggressive consolidation and long-term disease-free survival.

Purpose Several cytotoxic chemotherapy regimens are active against metastatic breast cancer; however, benefits are modest and overall prognosis remains limited. For anthracycline and taxane-pretreated metastatic breast cancer, there remains a relative paucity of therapies with significant activity. This Phase II study evaluated the combination of capecitabine and oxaliplatin (XELOX) among patients with metastatic breast cancer being treated in the first or second-line setting. Methods Patients received oxaliplatin 85 mg/m2 on days 1 and 15, and capecitabine 1500 mg/m2 twice daily on days 1-7 and 15-21 of a 28 day cycle. Patients were treated until progression or intolerable toxicity. The primary objective was to estimate the objective response rate by the Response Evaluation Criteria in Solid Tumors (RECIST) criteria with tumor assessments every 8 weeks. Results 10 patients were treated of which 3 had received prior neurotoxic therapy in the metastatic setting. There were no confirmed complete responses, 5 patients had partial response, 4 patients had stable disease for at least 24 weeks, and one patient was unevaluable. Median time to progression (TTP) was 10.4 months (95% lower confidence bound [LCB]: 5.75 months), median progression free survival (PFS) was 14.2 months (95% LCB: 6.14 months), and median overall survival (OS) was 19 months (95% LCB: 12.8 months). Multiple patients experienced pain syndromes and unusual neuropathies. Other common toxicities included fatigue, diarrhea, and nausea. Conclusions XELOX is a promising regimen for anthracycline-pretreated metastatic breast cancer although careful patient selection is indicated and alternate dosing schedules should be explored to minimize neurologic morbidity.