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Objective & methods: This study tested associations of genotype-predicted activity of CYP3A4, other pharmacogenes, SLC28A7 (rs11648166) and ALPPL2 (rs28845026) with systemic concentrations of the endocrine therapies anastrozole and fulvestrant in SWOG S0226 trial participants. Results: Participants in the anastrozole-only arm with low CYP3A4 activity (i.e. CYP3A4*22 carriers) had higher systemic anastrozole concentrations than patients with high CYP3A4 activity (β-coefficient = 10.03; 95% CI: 1.42, 18.6; p = 0.025). In an exploratory analysis, participants with low CYP2C9 activity had lower anastrozole concentrations and higher fulvestrant concentrations than participants with high CYP2C9 activity. Conclusion: Inherited genetic variation in CYP3A4 and CYP2C9 may affect concentrations of endocrine therapy and may be useful to personalize dosing and improve treatment outcomes.

Chemotherapy-induced peripheral neuropathy (CIPN) is a common and debilitating condition associated with a number of chemotherapeutic agents. Drugs commonly implicated in the development of CIPN include platinum agents, taxanes, vinca alkaloids, bortezomib, and thalidomide analogues. As a drug response can vary between individuals, it is hypothesized that an individual's specific genetic variants could impact the regulation of genes involved in drug pharmacokinetics, ion channel functioning, neurotoxicity, and DNA repair, which in turn affect CIPN development and severity. Variations of other molecular markers may also affect the incidence and severity of CIPN. Hence, the objective of this review was to summarize the known biological (molecular and genomic) predictors of CIPN and discuss the means to facilitate progress in this field.

Taxanes are a widely used class of anticancer agents that play a vital role in the treatment of a variety of cancers. However, toxicity remains a major concern of using taxane drugs as some toxicities are highly prevalent, they can not only adversely affect patient prognosis but also compromise the overall treatment plan. Among all kinds of factors that associated with taxane toxicity, taxane exposure has been extensively studied, with different pharmacokinetic (PK) parameters being used as toxicity predictors. Compared to other widely used predictors such as the area under the drug plasma concentration curve versus time (AUC) and time above threshold plasma drug concentration, maximum plasma concentration (Cmax) is easier to collect and shows promise for use in clinical practice. In this article, we review the previous research on using Cmax to predict taxane treatment outcomes. While Cmax and toxicity have been extensively studied, research on the relationship between Cmax and efficacy is lacking. Most of the articles find a positive relationship between Cmax and toxicity but several articles have contradictory findings. Future clinical trials are needed to validate the relationship between Cmax and treatment outcome and determine whether Cmax can serve as a useful surrogate endpoint of taxane treatment efficacy. [ABSTRACT FROM AUTHOR]

PurposeDiscovery of SNPs that predict a patient's risk of docetaxel-induced neuropathy would enable treatment individualization to maximize efficacy and avoid unnecessary toxicity. The objectives of this analysis were to discover SNPs associated with docetaxel-induced neuropathy and mechanistically validate these associations in preclinical models of drug-induced neuropathy.Experimental designA genome-wide association study was conducted in metastatic castrate-resistant prostate cancer patients treated with docetaxel, prednisone and randomized to bevacizumab or placebo on CALGB 90401. SNPs were genotyped on the Illumina HumanHap610-Quad platform followed by rigorous quality control. The inference was conducted on the cumulative dose at occurrence of grade 3+ sensory neuropathy using a cause-specific hazard model that accounted for early treatment discontinuation. Genes with SNPs significantly associated with neuropathy were knocked down in cellular and mouse models of drug-induced neuropathy.ResultsA total of 498,081 SNPs were analyzed in 623 Caucasian patients, 50 (8%) of whom experienced grade 3+ neuropathy. The 1,000 SNPs most associated with neuropathy clustered in relevant pathways including neuropathic pain and axonal guidance. An SNP in VAC14 (rs875858) surpassed genome-wide significance (P = 2.12 × 10-8, adjusted P = 5.88 × 10-7). siRNA knockdown of VAC14 in stem cell-derived peripheral neuronal cells increased docetaxel sensitivity as measured by decreased neurite processes (P = 0.0015) and branches (P < 0.0001). Prior to docetaxel treatment, VAC14 heterozygous mice had greater nociceptive sensitivity than wild-type litter mate controls (P = 0.001).ConclusionsVAC14 should be prioritized for further validation of its potential role as a predictor of docetaxel-induced neuropathy and biomarker for treatment individualization. Clin Cancer Res; 22(19); 4890-900. ©2016 AACR.

AimsIn the SWOG S0226 trial the combination of anastrozole plus fulvestrant (n = 349) was superior to anastrozole alone (n = 345) in hormone receptor (HR)-positive metastatic breast cancer. Here we report a pharmacokinetic subset analysis investigating a possible drug interaction between anastrozole and fulvestrant.MethodsPost-menopausal patients with HR-positive metastatic breast cancer were randomized to anastrozole with or without concurrent fulvestrant. Blood samples were collected at 2, 4, 6 and 8 months, just prior to receiving the next dose of anastrozole and fulvestrant. Drug concentrations were measured via LC/MS-MS. Anastrozole concentration was compared in patients on anastrozole alone vs. patients on concomitant fulvestrant. Comparisons were made at each time point using parametric tests and over time using a linear mixed effects model.ResultsA total of 483 anastrozole concentration measurements were included, 224 samples from 64 patients on the anastrozole alone arm and 259 from 73 patients on the combination arm. The mean anastrozole concentration in the combination arm was significantly lower than that in the anastrozole alone arm at each sample collection time (all P

Purpose of review This review aims to provide insights into persistent taxane-induced peripheral neuropathy (TIPN). The primary objective is to describe the incidence, predictors, and consequences of TIPN lasting at least 1 year after the end of taxane treatment. Recent findings Studies show varying rates of TIPN persistence, with an estimated 30-40% and 40-60% resolving by 1- and 3-year post-treatment. TIPN in the feet and motor symptoms show less resolution post-treatment. Patients who are older or have higher body weight may experience less TIPN resolution, but results may be confounded by TIPN development during treatment. Persistent TIPN negatively impacts long-term functional ability, including gait, balance, and the ability to work. It also reduces overall quality of life (QOL), particularly affecting physical and social aspects. Summary Clinicians should be aware of the potential for persistent TIPN and its impact on patients' function and QOL. Future research should focus on large prospective studies with systematic TIPN assessments during and after treatment to better understand which symptoms and patient characteristics predict resolution. This information can guide treatment decisions, balancing the need for effective chemotherapy with minimizing long-term impairments in function and QOL. [ABSTRACT FROM AUTHOR]

Patients carrying DPYD variant alleles have increased risk of severe toxicity from systemic fluoropyrimidine chemotherapy. There is a paucity of data regarding risk of toxicity from topical 5‐fluorouracil (5‐FU) treatment in these patients, leading to inconsistent guideline recommendations for pretreatment testing and topical 5‐FU dosing. The objective of this retrospective cohort study was to investigate whether DPYD variant allele carriers have increased risk of toxicity from topical 5‐FU. Treatment and toxicity data were retrospectively abstracted from the electronic medical records. Genotypes for the five DPYD variants that are associated with increased toxicity from systemic fluoropyrimidine chemotherapy (DPYD*2A, DPYD*13, DPYD p.D949V, DPYD HapB3, and DPYD p.Y186C) were collected from a genetic data repository. Incidence of grade 3+ (primary end point) and 1+ (secondary end point) toxicity was compared between DPYD variant carriers vs. wild‐type patients using Fisher's exact tests. The analysis included 201 patients, 7% (14/201) of whom carried a single DPYD variant allele. No patients carried two variant alleles or experienced grade 3+ toxicity. DPYD variant allele carriers did not have a significantly higher risk of grade 1+ toxicity (21.4% vs. 10.2%, odds ratio = 2.40, 95% confidence interval: 0.10–2.53, P = 0.19). Given the low toxicity risk in patients carrying a single DPYD variant allele, there is limited potential clinical benefit of DPYD genetic testing prior to topical 5‐FU. However, the risk of severe toxicity in patients with complete DPD deficiency remains unknown and topical 5‐FU treatment should be avoided in these patients. [ABSTRACT FROM AUTHOR]