Assessment of clinical outcomes in breast cancer patients treated with taxanes: multi-analytical approach

Design, synthesis, molecular modeling, in vitro and in vivo biological evaluation of potent anthranilamide derivatives as dual P-glycoprotein and CYP3A4 inhibitors

Paclitaxel (PTX) is considered the blockbuster chemotherapy treatment for cancer. Paclitaxel's (PTX) oral administration has proven to be extremely difficult, mostly because of its susceptibility to intestinal P-glycoprotein (P-gp) and cytochrome P450 (CYP3A4). The concurrent local inhibition of intestinal P-gp and CYP3A4 is a promising approach to improve the oral bioavailability of paclitaxel while avoiding potential unfavorable side effects of their systemic inhibition. Herein, we report the rational design and evaluation of novel dual potent inhibitors of P-gp and CYP3A4 using an anthranilamide derivative tariquidar as a starting point for their structural optimizations. Compound 14f, bearing N-imidazolylbenzyl side chain, was found to have potent and selective P-gp (EC50 = 28 nM) and CYP3A4 (IC50 = 223 nM) inhibitory activities with low absorption potential (Papp (A-to-B) <0.06). In vivo, inhibitor 14f improved the oral absorption of paclitaxel by 6 times in mice and by 30 times in rats as compared to vehicle, while 14f itself remained poorly absorbed. Compound 14f, possessing dual P-gp and CYP3A4 inhibitory activities, offered additional enhancement in paclitaxel oral absorption compared to tariquidar in mice. Evaluating the CYP effect of 14f on oral absorption of paclitaxel requires considering the variations in CYP expression between animal species. This study provides further medicinal chemistry advice on strategies for resolving concerns with the oral administration of chemotherapeutic agents.

Impact of Low BMI and Nutritional Status on Quality of Life and Disease Outcome in Breast Cancer Patients: Insights From a Tertiary Cancer Center in India

This study investigates the impact of Body Mass Index (BMI) on Quality of Life (QoL) and treatment outcomes in breast cancer (BC) patients, particularly focusing on underweight individuals with compromised nutritional status. A nonrandomized prospective study comprising 121 newly diagnosed patients across various BMI categories utilized FACT-B & FACIT-Sp-12 questionnaires. Follow-ups occurred at baseline, during (3rd and 6th), and after (12th month) anthracycline-taxane chemotherapy, either sequentially or concomitantly. Patients with low BMI (<18.5 kg/m2; 53.7%) exhibited significantly poorer QoL, marked by compromised nutritional indicators (low MUAC and SFT). Repeated measures ANOVA identified significant correlations between BMI groups in functional, social, and emotional QoL aspects (p < 0.05), with no notable differences in other domains. A Chi-square (ꭓ2) test underscored a significant link between BMI and treatment response (p < 0.0001), showing higher rates of non-responders among underweight patients (p = 4.259e-14). The study advocates pretreatment consultation with a dietitian as standard care for Indian BC patients, offering complimentary nutritional support for improved QoL outcomes and treatment responses.

Breast cancer pharmacogenetics: a systematic review

Breast cancer was declared the most prevalent type of cancer in 2020. Among other factors, treatment response can be affected by genetic polymorphisms - which is the focus of pharmacogenetics - and ethnicity is also a contributing factor in this context. Relevant genes in disease treatment pathways were selected to evaluate treatment response from the pharmacogenetic perspective; polymorphism frequencies and ethnic and continental representation across the available literature were also assessed through a systematic review. The identified associations and gaps have been described in this study with the purpose that, in the future, treatments can be personalized and thus be more effective, safer, and accessible to all.

Single-nucleotide polymorphisms and the effectiveness of taxane-based chemotherapy in premenopausal breast cancer: a population-based cohort study in Denmark

Purpose

Taxane-based chemotherapy is the primary treatment for premenopausal breast cancer. Although being inconsistent, research suggests that variant alleles alter pharmacokinetics through reduced function of OATP transporters (limiting hepatic uptake), CYP-450 enzymes (hampering drug metabolism), and ABC transporters (decreasing clearance). Reduced function of DNA repair enzymes may hamper effectiveness through dose-limiting toxicities. We investigated whether single-nucleotide polymorphisms (SNPs) were associated with breast cancer recurrence or mortality in premenopausal women diagnosed with breast cancer.

Methods

We conducted a population-based cohort study of premenopausal women diagnosed with non-distant metastatic breast cancer in Denmark during 2007‒2011, when guidelines recommended adjuvant combination chemotherapy (taxanes, anthracyclines, and cyclophosphamide). Using archived formalin-fixed paraffin-embedded primary tumor tissue, we genotyped 26 SNPs using TaqMan assays. Danish health registries provided data on breast cancer recurrence (through September 25, 2017) and death (through December 31, 2019). We fit Cox regression models to calculate crude hazard ratios (HRs) and 95% confidence intervals (CIs) for recurrence and mortality across genotypes.

Results

Among 2,262 women, 249 experienced recurrence (cumulative incidence: 13%) and 259 died (cumulative incidence: 16%) during follow-up (median 7.0 and 10.1 years, respectively). Mortality was increased in variant carriers of GSTP1 rs1138272 (HR: 1.30, 95% CI 0.95–1.78) and CYP3A rs10273424 (HR: 1.33, 95% CI 0.98–1.81). SLCO1B1 rs2306283 (encoding OATP1B1) variant carriers had decreased recurrence (HR: 0.82, 95% CI 0.64–1.07) and mortality (HR: 0.77, 95% CI 0.60–0.98).

Conclusion

Docetaxel effectiveness was influenced by SNPs in GSTP1, CYP3A, and SLCO1B1 in premenopausal women with non-distant metastatic breast cancer, likely related to altered docetaxel pharmacokinetics. These SNPs may help determine individual benefit from taxane-based chemotherapy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10549-022-06596-2.

Life-Threatening Docetaxel Toxicity in a Patient With Reduced-Function CYP3A Variants: A Case Report

Docetaxel therapy occasionally causes severe and life-threatening toxicities. Some docetaxel toxicities are related to exposure, and inter-individual variability in exposure has been described based on genetic variation and drug-drug interactions that impact docetaxel clearance. Cytochrome P450 3A4 (CYP3A4) and CYP3A5 metabolize docetaxel into inactive metabolites, and this is the primary mode of docetaxel clearance. Supporting their role in these toxicities, increased docetaxel toxicities have been found in patients with reduced- or loss-of-function variants in CYP3A4 and CYP3A5. However, since these variants in CYP3A4 are rare, little is known about the safety of docetaxel in patients who are homozygous for the reduced-function CYP3A4 variants. Here we present a case of life-threatening (grade 4) pneumonitis, dyspnea, and neutropenia resulting from a single dose of docetaxel. This patient was (1) homozygous for CYP3A4*22, which causes reduced expression and is associated with increased docetaxel-related adverse events, (2) heterozygous for CYP3A4*3, a rare reduced-function missense variant, and (3) homozygous for CYP3A5*3, a common loss of function splicing defect that has been associated with increased docetaxel exposure and adverse events. The patient also carried functional variants in other genes involved in docetaxel pharmacokinetics that may have increased his risk of toxicity. We identified one additional CYP3A4*22 homozygote that received docetaxel in our research cohort, and present this case of severe hematological toxicity. Furthermore, the one other CYP3A4*22 homozygous patient we identified from the literature died from docetaxel toxicity. This case report provides further evidence for the need to better understand the impact of germline CYP3A variants in severe docetaxel toxicity and supports using caution when treating patients with docetaxel who have genetic variants resulting in CYP3A poor metabolizer phenotypes.

Current opinion on the pharmacogenomics of paclitaxel-induced toxicity

Introduction: Paclitaxel is a microtubule stabilizer that is currently one of the most utilized chemotherapeutic agents. Its efficacy in breast, uterine, lung and other neoplasms made its safety profile enhancement a subject of great interest. Neurotoxicity is the most common paclitaxel-associated toxicities. In addition, hypersensitivity reactions, hematological, gastrointestinal, and cardiac toxicities are all encountered.Areas covered: The current review explores paclitaxel-induced toxicities mechanisms and risk factors. Studies investigating these toxicities pharmacogenomic biomarkers are reviewed and summarized. There is a limited margin of consistency between the retrieved associations. Variants in genes related to neuro-sensitivity are the most promising candidates for future studies.Expert opinion: Genome-wide association studies highlighted multiple-candidate biomarkers relevant to neuro-sensitivity. Most of the identified paclitaxel-neurotoxicity candidate genes are derived from congenital neuropathy and diabetic-induced neurotoxicity pathways. Future studies should explore these sets of genes while considering the multifactorial nature of paclitaxel-induced neurotoxicity. In the absence of certain paclitaxel-toxicity biomarkers, future research should avoid earlier studies' caveats. Genes in paclitaxel's pharmacokinetic pathways could not provide consistent results in any of its associated toxicities. There is a need to dig deeper into toxicity-development mechanisms and personal vulnerability factors, rather than targeting only the genes suspected to affect drug exposure.

Single nucleotide polymorphisms as the efficient prognostic markers in breast cancer

BACKGROUND

Breast cancer (BC) is known as the most common malignancy in women. Environmental and genetic factors are associated with BC progression. Genetic polymorphisms have been reported as important risk factors of BC prognosis and drug response. Main body: Therefore, in the present review, we have summarized all single nucleotide polymorphisms (SNPs) which have been significantly associated with drug response in BC patients around the world. We have also categorized the reported SNPs based on their related genes functions to clarify the molecular biology of drug responses in BC.

CONCLUSION

The majority of SNPs were reported in detoxifying enzymes, which introduced such genes as the main genetic risk factors during BC drug responses. This review paves the way for introducing a prognostic panel of SNPs for the BC patients in the world.

Comprehensive pharmacogenetic analysis of DPYD, UGT, CDA, and ABCB1 polymorphisms in pancreatic cancer patients receiving mFOLFIRINOX or gemcitabine plus nab-paclitaxel

Modified FOLFIRINOX (mFOLFIRINOX) and gemcitabine + nab-paclitaxel (GemNab) regimens represent a standard treatment in advanced pancreatic cancer (aPC). DPYD and UGT1A1 variants are relevant predictors of fluoropyrimidine and irinotecan-associated adverse events (AEs). Furthermore, data about the associations between polymorphisms in ABCB and CDA genes and GemNab-related toxicities are still controversial. The present study analyzes the association between DPYD, UGT, ABCB1, CDA variants, and AEs in aPC patients (pts) treated with mFOLFIRINOX or GemNab. Blood samples collected from 104 aPC pts treated with mFOLFIRINOX and 63 with GemNab were tested for DPYD c.1679T>G, IVS14+1G>A, c.2194G>A, c.2846A>T, UGT1A1*28, CDA c.79A>C, and ABCB1 c.1236C>T, c.2677G>T/A, c.3435C>T by real-time PCR and automatic sequencing. In mFOLFIRINOX cohort, DPYD IVS14+1GA genotype was associated with G4 hematological AEs, while the UGT1A1*28 significantly correlated with the risk of thrombocytopenia (p = 0.006). In the GemNab cohort, a significant association between CDA c.79CC and high-grade nausea was observed (p = 0.002). Moreover, the presence of at least a mutant allele in ABCB1 increased the risk of overall hematological AEs (p = 0.01), both further strengthened by the presence of CDA c.79CC (p = 0.0002). DPYD IVS14+1A allele is confirmed to be associated with fluoropyrimidine life-threatening toxicities, and UGT1A1*28 is related with a higher risk of hematologic AEs following irinotecan treatment. CDA c.79C and ABCB1 c.1236T, c.2677T/A, and c.3435T mutant alleles are predictive biomarkers of GemNab-related AEs. All these variants should be considered in aPC pts candidate to mFOLFIRINOX or GemNab treatments.

Impact of variants in ATP-binding cassette transporters on breast cancer treatment

There has been substantial interest in the impact of ATP-binding cassette (ABC) transporter variability on breast cancer drug resistance. Here, we provide a systematic review of ABC variants in breast cancer therapy. Notably, most studies used small heterogeneous cohorts and their identified associations lack statistical stringency, replication and mechanistic support. We conclude that commonly studied ABC polymorphisms are not suitable to accurately predict therapy response or toxicity in breast cancer patients and cannot guide treatment decisions. However, recent research shows that ABC transporters harbor a plethora of rare variants with individually small effect sizes, and we argue that a shift in strategy from target variant interrogation to comprehensive profiling might hold promise to drastically improve the predictive power of outcome models.

Cytochrome P450 3A4, 3A5, and 2C8 expression in breast, prostate, lung, endometrial, and ovarian tumors: relevance for resistance to taxanes

Enzymes of the cytochrome P450 (CYP) subfamily 3A and 2C play a major role in the metabolism of taxane anticancer agents. While their function in hepatic metabolism of taxanes is well established, expression of these enzymes in solid tumors may play a role in the in situ metabolism of drugs as well, potentially affecting the intrinsic taxane susceptibility of these tumors. This article reviews the available literature on intratumoral expression of docetaxel- and paclitaxel-metabolizing enzymes in mammary, prostate, lung, endometrial, and ovarian tumors. Furthermore, the clinical implications of the intratumoral expression of these enzymes are reviewed and the potential of concomitant treatment with protease inhibitors (PIs) as a method to inhibit CYP3A4-mediated metabolism is discussed.

Impact of gene polymorphisms on the systemic toxicity to paclitaxel/carboplatin chemotherapy for treatment of gynecologic cancers

PURPOSE

Gynecologic malignancies are often detected in advanced stages, requiring chemotherapy with taxane/platinum combinations, which may cause severe toxicities, such as neutropenia and peripheral neuropathy. Gene polymorphisms are suspected as possible causes for the interindividual variability on chemotherapy toxicities.

OBJECTIVE

To evaluate the role of ABCB1 1236C>T, 3435C>T; CYP2C8*3; CYP3A5*3C variants on paclitaxel/carboplatin toxicities.

METHODS

A cohort of 503 gynecologic cancer patients treated with paclitaxel/carboplatin at the Brazilian National Cancer Institute (INCA-Brazil) was recruited (2013-2017). Polymorphisms were genotyped by real-time PCR, and toxicities were evaluated by patients' interviews at each chemotherapy cycle and by data collection from electronic records. The association of clinical features and genotypes with severe toxicities was estimated using Pearson's Chi square tests and multiple regression analyses, with calculation of adjusted odds ratios (OR_adjusted), and respective 95% confidence intervals (95% CI).

RESULTS

CYP2C8*3 was significantly associated with increased risks of severe (grades 3-4) neutropenia (OR_adjusted 2.11; 95% CI 1.24-3.6; dominant model) and severe thrombocytopenia (OR_adjusted 4.93; 95% CI 1.69-14.35; recessive model), whereas ABCB1 variant genotypes (OR_adjusted 2.13; 95% CI 1.32-3.42), in association with CYP2C8*3 wild type (GG) (OR_adjusted 1.93; 95% CI 1.17-3.19), were predictive of severe fatigue.

CONCLUSIONS

The present study suggests that CYP2C8*3 is a potential predictor of hematological toxicities related to paclitaxel/carboplatin treatment. Since hematological toxicities, especially neutropenia, may lead to dose delay or treatment interruption, such prognostic evaluation may contribute to clinical management of selected patients with paclitaxel-based chemotherapy.

Influence of ABCB1 C3435T and C1236T gene polymorphisms on tumour response to docetaxel-based neo-adjuvant chemotherapy in locally advanced breast cancer patients of South India

WHAT IS KNOWN AND OBJECTIVE

Variable response to docetaxel-based neo-adjuvant chemotherapy (NACT) in breast cancer patients had been reported. Genetic polymorphisms in the ABCB1 gene coding for the efflux transporter MDR1 (P-glycoprotein, P-gp) could result in altered tumour response. Hence, this study was proposed to assess the effect of single nucleotide polymorphisms (SNPs) of ABCB1 gene on tumour response in locally advanced breast cancer patients (LABC) of South India who have a distinct genetic makeup.

METHODS

Out of 162 LABC patients recruited, 129 patients were included for the final analysis. DNA was extracted by "phenol-chloroform extraction method" from the WBCs, and genotyping for SNPs rs1045642 (C3435T) and rs1128503 (C1236T) in ABCB1 gene was performed with real-time PCR system using validated TaqMan^® SNP genotyping assay method. Tumour response was assessed by RECIST criteria based on the MRIs taken before and after completion of four cycles of docetaxel therapy.

RESULTS AND DISCUSSION

A total of 102 (79.1%) patients were found to be responders and 27 (20.9%) patients were found to be non-responders to docetaxel therapy. Patients with "CT/TT" genotypes (response rate: 83.3%) of ABCB1 (C1236T) gene showed better tumour response than those with "CC" genotype (response rate: 16.6%) [OR = 2.94 (CI: 1.15-7.52); P = 0.03]. However, on performing binary logistic regression, neither the studied SNPs nor the non-genetic factors like age, BMI, postmenopausal status, laterality of the tumour, ER status, PR status and Her-2/neu status were found to be associated with tumour response to docetaxel (P > 0.05).

WHAT IS NEW AND CONCLUSION

The tumour response to docetaxel was significantly influenced by the SNP C1236T of ABCB1 gene coding for the P-gp. However, when adjusted for other non-genetic factors, neither of the ABCB1 variants were found to be associated with tumour response to docetaxel-based NACT in LABC patients of South India.

Pharmacogenetic impact of docetaxel on neoadjuvant treatment of breast cancer patients

AIM

This study aimed to investigate the effect of CYP3A4 and CYP3A5 genotypes on clinical outcomes of docetaxel treatment.

PATIENTS & METHODS

In the PROMIX trial, 150 breast cancer patients received docetaxel preoperatively. CYP3A4 and CYP3A5 genotype combinations were transformed into total CYP 3A phenotypes.

RESULTS

Seven patients were characterized as poor metabolizer (PM), 22 patients as extensive metabolizer and 121 patients as intermediate metabolizer. The frequency of grade 3/grade 4 adverse events was higher in the PM group (p = 0.002). One PM subject who basically lacked enzyme activity died from typhlitis. Total 45 recurrences were reported after a median of 5-year follow-up; none of these was PM.

CONCLUSION

The allelic variants CYP3A4*22 and CYP3A5*3 contribute to the interpatient variations of docetaxel.

Catfish Taguchi-Based Binary Differential Evolution Algorithm for Analyzing Single Nucleotide Polymorphism Interactions in Chronic Dialysis

Single-nucleotide polymorphism (SNP)-SNP interactions are crucial for understanding the association between disease-related multifactorials for disease analysis. Existing statistical methods for determining such interactions are limited by the considerable computation required for evaluating all potential associations between disease-related multifactorials. Identifying SNP-SNP interactions is thus a major challenge in genetic association studies. This paper proposes a catfish Taguchi-based binary differential evolution (CT-BDE) algorithm for identifying SNP-SNP interactions. In the search space, the catfish effect prevents the premature convergence of the population, and the Taguchi method improves the search ability of the BDE algorithm. Hence, the proposed algorithm enables obtaining a favorable solution regarding the identification of high-order SNP-SNP interactions. Additionally, the proposed algorithm applies an effective fitness function derived from a multifactor dimensionality reduction (MDR) operation to evaluate the solutions from BDE-based algorithms. Simulated and real data sets were used to evaluate the ability of several BDE-based algorithms in identifying specific SNP-SNP interactions. We compared the fitness function derived from the MDR operation with that derived according to the difference between cases and controls, by using the different BDE-based algorithms. The results showed that the proposed CT-BDE algorithm applying the fitness function derived from the MDR operation exhibited a superior ability in identifying SNP-SNP interactions compared with the other BDE-based algorithms.

SNPs in predicting clinical efficacy and toxicity of chemotherapy: walking through the quicksand

In the "precision medicine" era, chemotherapy still remains the backbone for the treatment of many cancers, but no affordable predictors of response to the chemodrugs are available in clinical practice. Single nucleotide polymorphisms (SNPs) are gene sequence variations occurring in more than 1% of the full population, and account for approximately 80% of inter-individual genomic heterogeneity. A number of studies have investigated the predictive role of SNPs of genes enrolled in both pharmacodynamics and pharmacokinetics of chemotherapeutics, but the clinical implementation of related results has been modest so far. Among the examined germline polymorphic variants, several SNPs of dihydropyrimidine dehydrogenase (DPYD) and uridine diphosphate glucuronosyltransferases (UGT) have shown a robust role as predictors of toxicity following fluoropyrimidine- and/or irinotecan-based treatments respectively, and a few guidelines are mandatory in their detection before therapy initiation. Contrasting results, however, have been reported on the capability of variants of other genes as MTHFR, TYMS, ERCC1, XRCC1, GSTP1, CYP3A4/3A5 and ABCB1, in predicting either therapy efficacy or toxicity in patients undergoing treatment with pyrimidine antimetabolites, platinum derivatives, irinotecan and taxanes. While formal recommendations for routine testing of these SNPs cannot be drawn at this moment, therapeutic decisions may indeed benefit of germline genomic information, when available. Here, we summarize the clinical impact of germline genomic variants on the efficacy and toxicity of major chemodrugs, with the aim to facilitate the therapeutic expectance of clinicians in the odiern quicksand field of complex molecular biology concepts and controversial trial data interpretation.

Association of Allelic Interaction of Single Nucleotide Polymorphisms of Influx and Efflux Transporters Genes With Nonhematologic Adverse Events of Docetaxel in Breast Cancer Patients

PURPOSE

Nonhematologic adverse events (AEs) of docetaxel constitute an extra burden in the treatment of cancer patients and necessitate either a dose reduction or an outright switch of docetaxel for other regimens. These AEs are frequently associated with genetic polymorphisms of genes encoding for proteins involved docetaxel disposition. Therefore, we investigated that association in Malaysian breast cancer patients.

MATERIALS AND METHODS

A total of 110 Malaysian breast cancer patients were enrolled in the present study, and their blood samples were investigated for different single nucleotide polymorphisms using polymerase chain reaction restriction fragment length polymorphism. AEs were evaluated using the Common Terminology Criteria for Adverse Events, version 4.0.

RESULTS

Fatigue, nausea, oral mucositis, and vomiting were the most common nonhematologic AEs. Rash was associated with heterozygous and mutant genotypes of ABCB1 3435C>T (P < .05). Moreover, patients carrying the GG genotype of ABCB1 2677G>A/T reported more fatigue than those carrying the heterozygous genotype GA (P < .05). The presence of ABCB1 3435-T, ABCC2 3972-C, ABCC2 1249-G, and ABCB1 2677-G alleles was significantly associated with nausea and oral mucositis. The coexistence of ABCB1 3435-C, ABCC2 3972-C, ABCC2 1249-G, and ABCB1 2677-A was significantly associated with vomiting (P < .05).

CONCLUSION

The prevalence of nonhematologic AEs in breast cancer patients treated with docetaxel has been relatively high. The variant allele of ABCB1 3435C>T polymorphism could be a potential predictive biomarker of docetaxel-induced rash, and homozygous wild-type ABCB1 2677G>A/T might predict for a greater risk of fatigue. In addition, the concurrent presence of specific alleles could be predictive of vomiting, nausea, and oral mucositis.

Influence of the ABCB1 polymorphisms on the response to Taxane-containing chemotherapy: a systematic review and meta-analysis

PURPOSE

Multidrug resistance mediated by ABCB1 has been perceived to be one of the obstacles for cancer chemotherapy. This meta-analysis was performed to verify the effect of the ABCB1 rs1045642 and rs1128503 polymorphisms on the response to Taxane-containing chemotherapy.

METHODS

Pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were employed to evaluate the impact of these two ABCB1 polymorphisms. R scripts were developed to perform the meta-analysis.

RESULTS

A total of nine articles (including nine studies for rs1045642 and five for rs1128503) were collected in our systematic review. However, our meta-analysis showed no significant effect of these two ABCB1 polymorphisms on the response to Taxane-containing regimens.

CONCLUSIONS

This study highlights the unsuitability of relying on the ABCB1 rs1045642 and rs1128503 polymorphisms as therapeutic response biomarkers of Taxane-containing chemotherapy. Further polycentric studies in larger and multiracial populations are needed to validate the conclusions.

Independent replication of polymorphisms predicting toxicity in breast cancer patients randomized between dose-dense and docetaxel-containing adjuvant chemotherapy

Introduction

Although pharmacogenomics has evolved substantially, a predictive test for chemotherapy toxicity is still lacking. We compared the toxicity of adjuvant dose-dense doxorubicin-cyclophosphamide (ddAC) and docetaxel-doxorubicin-cyclophosphamide (TAC) in a randomized multicenter phase III trial and replicated previously reported associations between genotypes and toxicity.

Results

646 patients (97%) were evaluable for toxicity (grade 2 and higher). Whereas AN was more frequent after ddAC (P < 0.001), TAC treated patients more often had PNP (P < 0.001). We could replicate 2 previously reported associations: TECTA (rs1829; OR 4.18, 95% CI 1.84-9.51, P = 0.001) with PNP, and GSTP1 (rs1138272; OR 2.04, 95% CI 1.13-3.68, P = 0.018) with PNP.

Materials and methods

Patients with pT1-3, pN0-3 breast cancer were randomized between six cycles A60C600 every 2 weeks or T75A50C500 every 3 weeks. Associations of 13 previously reported single nucleotide polymorphisms (SNPs) with the most frequent toxicities: anemia (AN), febrile neutropenia (FN) and peripheral neuropathy (PNP) were analyzed using logistic regression models.

Conclusions

In this independent replication, we could replicate an association between 2 out of 13 SNPs and chemotherapy toxicities. These results warrant further validation in order to enable tailored treatment for breast cancer patients.

ABCB1 gene polymorphisms and response to chemotherapy in breast cancer patients: A meta-analysis

The ABCB1 gene encodes the P-glycoprotein, an efflux pump for some antineoplastic agents which acts as a resistance mechanism to chemotherapy. Three SNPs (C3435T, C1236T and G2677T/A), are the most widely studied in ABCB1. The inconsistent conclusions about the association of these polymorphisms and the response to chemotherapy in breast cancer (BC) patients prompted us to conduct a meta-analysis. A total of nine (770 patients), five (566 patients) and three studies (367 patients) relating the ABCB1 C3435T, C1236T and G2677T/A polymorphisms respectively, were included. The main analysis revealed a lack of association between ABCB1 polymorphisms and response to chemotherapy in every genetic model: C3435T (dominant OR: 0.888; 95%CI: 0.558-1.413), C1236T (dominant OR: 1.968; 95%CI: 0.609-6.362) and G2677T/A (GG vs GT + GA + TT + TA + AA OR: 0.854; 95%CI: 0.418-1.744). Stratification by ethnicity, cancer type and response criteria did not change the pattern of results. The available evidence indicates that three polymorphisms within ABCB1; C3435T, C1236T and G2677T/A, cannot be considered a reliable predictor of response to chemotherapy in BC patients.

Immodin and its immune system supportive role in paclitaxel therapy of 4T1 mouse breast cancer

It is evident that standard chemotherapy agents may have an impact on both tumor and host immune system. Paclitaxel (PTX), a very potent anticancer drug from a taxane family, has achieved prominence in clinical oncology for its efficacy against a wide range of tumors including breast cancer. However, significant toxicity, such as myelosuppression, limit the effectiveness of Paclitaxel-based treatment regimens. Immodin (IM) is low molecular dialysate fraction of homogenate made from human leukocytes. It contains a mixture of substances from which so far have been described e.g. Imreg 1 and Imreg 2 formed by the dipeptide tyrosine-glycine and the tripeptide tyrosine-glycine-glycine, respectively. The aim of this study was to explore immunopharmacological activities of IM, using the strongly immunogenic 4T1 mouse breast cancer model, and evaluate its effect on the reactivity and the efficiency of PTX cancer therapy. The results highlight a potentially beneficial role for IM in alleviating PTX-induced toxicity, especially on the nonspecific immunity, during breast cancer therapy. Co-treatment exhibited an antitumor effect including reduced tumor growth, prolonged survival of tumor bearing mice, increased number of monocytes and lymphocytes in peripheral blood. In spleens, IM+PTX therapy elevated proportion of whole lymphocytes in the account of myelo-monocytic cells characteristic with low expression of CD11c+ and bearing Fc receptor (CD16/32) as well as T-lymphocytes, NK cells and dendritic cells. Accumulation of tumor-associated granulocytes in stroma of PTX-treated group and intensive 4T1-necrosis/apoptosis in tumors after co-treatment were also recorded. These findings suggest the possibility of using IM alongside PTX treatment for maintaining the immune system functions and increasing patient survival.

Drug transporters in breast cancer: response to anthracyclines and taxanes

Despite the advances that have taken place in the past decade, including the development of novel molecular targeted agents, cytotoxic chemotherapy remains the mainstay of cancer treatment. In breast cancer, anthracyclines and taxanes are the two main chemotherapeutic options used on a routine basis. Although effective, their usefulness is limited by the inevitable development of resistance, a lack of response to drug-induced cancer cell death. A large body of research has resulted in the characterization of a plethora of mechanisms involved in resistance; ATP-binding cassette transporter proteins, through their function in xenobiotic clearance, play an important role in resistance. We review here the current evidence for drug transporters as biomarkers and the benefit of adding drug transporter modulators to conventional chemotherapy.

The effect of ABCB1 polymorphisms on the outcome of breast cancer treatment

The ABCB1 gene encodes a permeability glycoprotein, which is one of the most extensively studied human adenosine-triphosphate (ATP)-dependent efflux transporters. Permeability glycoprotein is expressed in the apical membranes of tissues such as intestine, liver, blood–brain barrier, kidney, placenta, and testis and contributes to intracellular drug disposition. It is also highly expressed in tumor cells conferring drug resistance, which is one of the major problems in the efficacy of cancer chemotherapy treatment. ABCB1 is highly polymorphic, and three well-known single-nucleotide polymorphisms such as 1236C>T, 2677G>T/A, and 3435C>T have been found to be associated with altered messenger RNA levels, protein folding, and drug pharmacokinetics. Many association studies and meta-analyses have demonstrated the clinical impact of ABCB1 polymorphisms in breast cancer treatment outcomes with respect to therapeutic response, chemotoxicity, and overall survival. Therefore, the aim of this review was to evaluate the effects of ABCB1 polymorphisms on the outcome of breast cancer treatment which, in future, would be important for tailoring individualized anticancer therapy.

Are pharmacogenomic biomarkers an effective tool to predict taxane toxicity and outcome in breast cancer patients? Literature review

PURPOSE

Breast cancer is a heterogeneous disease, characterized by various molecular phenotypes that correlate with different prognosis and response to treatments. Taxanes are some of the most active chemotherapeutic agents for breast cancer; however, their utilization is limited, due to hematologic and cumulative neurotoxicity on treated patients. To understand why only some patients experience severe adverse effects and why patients respond and develop resistance with different rates to taxane therapy, the metabolic pathways of these drugs should be completely unraveled. The variant forms of several genes, related to taxane pharmacokinetics, can be indicative markers of clinical parameters, such as toxicity or outcome.

METHODS

The search of the data has been conducted through PubMed database, presenting clinical data, clinical trials and basic research restricted to English language until June 2015.

RESULTS

We studied the literature in order to find any possible association between the major pharmacogenomic variants and specific taxane-related toxicity and patient outcome. We found that the data of these studies are sometimes discordant, due to both the small number of enrolled patients and the heterogeneity of the examined population.

CONCLUSIONS

Among all analyzed genes, only CYP1B1 and ABCB1 resulted the strongest candidates to become biomarkers of clinical response to taxane therapy in breast cancer, although their utilization still remains an experimental procedure. In the future, greater studies on genetic polymorphisms should be performed in order to identify differentiating signatures for patients with higher toxicity and with resistant or responsive outcome, before the administration of taxanes.

Differentially expressed proteins in human MCF-7 breast cancer cells sensitive and resistant to paclitaxel

Resistance of cancer cells to chemotherapeutic agents is one of the main causes of treatment failure. In order to detect proteins potentially involved in the mechanism of resistance to taxanes, we assessed differences in protein expression in MCF-7 breast cancer cells that are sensitive to paclitaxel and in the same cells with acquired resistance to paclitaxel (established in our lab). Proteins were separated using two-dimensional electrophoresis. Changes in their expression were determined and proteins with altered expression were identified using mass spectrometry. Changes in their expression were confirmed using western blot analysis. With these techniques, we found three proteins expressed differently in resistant MCF-7 cells, i.e., thyroid hormone-interacting protein 6 (TRIP6; upregulated to 650%), heat shock protein 27 (HSP27; downregulated to 50%) and cathepsin D (downregulated to 28%). Silencing of TRIP6 expression by specific siRNA leads to decreased number of grown resistant MCF-7 cells. In the present study we have pointed at some new directions in the studies of the mechanism of resistance to paclitaxel in breast cancer cells.