The role of topoisomerase IIα in predicting sensitivity to anthracyclines in breast cancer patients: a meta-analysis of published literatures

Elucidating the prognostic and therapeutic significance of TOP2A in various malignancies

Topoisomerase IIα (TOP2A) is a crucial enzyme that plays a vital role in DNA replication and transcription mechanisms. Dysregulated expression of TOP2A has been associated with various malignancies, including hepatocellular carcinoma, prostate cancer, colon cancer, lung cancer and breast cancer. In this review, we summarized the prognostic relevances of TOP2A in various types of cancer. The increased expression of TOP2A has been linked to resistance to therapy and reduced survival rates. Therefore, evaluating TOP2A levels could assist in identifying patients who may derive advantages from molecular targeted therapy. The amplification of TOP2A has been linked to a positive response to chemotherapy regimens that contain anthracycline. Nevertheless, the overexpression of TOP2A also indicates a heightened likelihood of disease recurrence and unfavorable prognosis. The prognostic significance of TOP2A has been extensively studied in various types of cancer. The increased expression of TOP2A is associated with poor clinical outcomes, indicating its potential as a valuable biomarker for assessing risk and stratifying treatment in these malignancies. However, further investigation is needed to elucidate the underlying mechanisms by which TOP2A influences cancer progression and to explore its potential as a therapeutic target.

Molecular tests for prediction of tumor sensitivity to cytotoxic drugs

Chemotherapy constitutes the backbone of cancer treatment. Several predictive assays assist personalized administration of cytotoxic drugs and are recommended for use in a clinical setting. The deficiency of DNA repair by homologous recombination (HRD), which is caused by inactivation of BRCA1/2 genes or other genetic events, is associated with high tumor responsiveness to platinum compounds, bifunctional alkylating agents and topoisomerase II poisons. Low activity of MGMT predicts the efficacy of nitrosoureas and tetrazines. Some clinically established pharmacogenetic tests allow for the adjustment of drug dosage, for example, the analysis of DPYD allelic variants for administration of fluoropyrimidines and UGT1A1 genotyping for the use of irinotecan. While there are promising molecular predictors of tumor sensitivity to pemetrexed, gemcitabine and taxanes, they remain in the investigational stage and require additional validation. Comprehensive molecular analysis of tumors obtained from drug responders and non-responders is likely to reveal new clinically useful predictive markers for cytotoxic therapy.

Aconitine linoleate, a natural lipo-diterpenoid alkaloid, stimulates anti-proliferative activity reversing doxorubicin resistance in MCF-7/ADR breast cancer cells as a selective topoisomerase IIα inhibitor

Aconitine linoleate (1) is a lipo-diterpenoid alkaloid, isolated from Aconitum sinchiangense W. T. Wang. The study aimed at investigating the anti-proliferative efficacy and the underlying mechanisms of 1 against MCF-7 and MCF-7/ADR cells, as well as obvious the safety evaluation in vivo. The cytotoxic activities of 1 were measured in vitro. Also, we investigated the latent mechanism of 1 by cell cycle analysis in MCF-7/ADR cells and topo I and topo IIα inhibition assay. Molecular docking is done by Discovery Studio 3.5 and Autodock vina 1.1.2. Finally, the acute toxicity of 1 was detected on mice. 1 exhibited significant antitumor activity against both MCF-7 and MCF-7/ADR cells, with IC50 values of 7.58 and 7.02 μM, which is 2.38 times and 5.05 times more active, respectively than etoposide in both cell lines, and being 9.63 times more active than Adriamycin in MCF-7/ADR cell lines. The molecular docking and the topo inhibition test found that it is a selective inhibitor of topoisomerase IIα. Moreover, activation of the damage response pathway of the DNA leads to cell cycle arrest at the G0G1 phase. Furthermore, the in vivo acute toxicity of 1 in mice displayed lower toxicity than aconitine, with LD50 of 2.2 × 105 nmol/kg and only slight pathological changes in liver and lung tissue, 489 times safer than aconitine. In conclusion, compared with aconitine, 1 has more significant anti-proliferative activity against MCF-7 and MCF-7/ADR cells and greatly reduces in vivo toxicity, which suggests this kind of lipo-alkaloids is powerful and promising antitumor compounds for breast cancer.

Drug Repositioning Based on the Reversal of Gene Expression Signatures Identifies TOP2A as a Therapeutic Target for Rectal Cancer

Rectal cancer is a common disease with high mortality rates and limited therapeutic options. Here we combined the gene expression signatures of rectal cancer patients with the reverse drug-induced gene-expression profiles to identify drug repositioning candidates for cancer therapy. Among the predicted repurposable drugs, topoisomerase II inhibitors (doxorubicin, teniposide, idarubicin, mitoxantrone, and epirubicin) presented a high potential to reverse rectal cancer gene expression signatures. We showed that these drugs effectively reduced the growth of colorectal cancer cell lines closely representing rectal cancer signatures. We also found a clear correlation between topoisomerase 2A (TOP2A) gene copy number or expression levels with the sensitivity to topoisomerase II inhibitors. Furthermore, CRISPR-Cas9 and shRNA screenings confirmed that loss-of-function of the TOP2A has the highest efficacy in reducing cellular proliferation. Finally, we observed significant TOP2A copy number gains and increased expression in independent cohorts of rectal cancer patients. These findings can be translated into clinical practice to evaluate TOP2A status for targeted and personalized therapies based on topoisomerase II inhibitors in rectal cancer patients.

Implications of Topoisomerase (TOP1 and TOP2α) Expression in Patients With Breast Cancer

BACKGROUND/AIM

We evaluated the usefulness of topoisomerases (TOPs) expression as prognostic predictors in breast cancer.

PATIENTS AND METHODS

We retrospectively investigated sixty cases with primary breast cancer. We evaluated the tumor and non-tumor mRNA levels of TOP1 and TOP2α using quantitative reverse-transcription polymerase chain reaction. TOP1/TOP2α positivity was defined as the ratio of the mRNA expression of cancer/normal tissue of >1 for both TOP1 and TOP2α.

RESULTS

TOP1 and TOP2α were markedly overexpressed in breast cancer tissues compared to normal breast tissues. Of the 60 cases, 46 (76.7%) were positive for TOP1/TOP2α. The relapse-free survival was relatively shorter for patients with positive TOP1/TOP2α. There was no recurrent disease among the 14 patients who were negative for TOP1/TOP2α, whereas four of the 46 TOP1/TOP2α-positive patients had disease recurrence.

CONCLUSION

Negative TOP1 or TOP2α expression may be useful for predicting better prognoses in breast cancer patients.

Prognostic and predictive value of the combination of TOP2A and HER2 in node-negative tumors 2 cm or smaller (T1N0) breast cancer

BACKGROUND

We aim to evaluate the prognostic and predictive value of TOP2A and HER2 expression in T1N0 breast cancer patients.

METHODS

299 cases with T1N0 breast cancer were obtained from the Oncomine database (Cohort 1) and 963 of T1N0 breast cancer patients from Sun Yat-sen Memorial Hospital (Cohort 2) were retrospectively enrolled. Kaplan-Meier product was applied to estimate survival curve. Cox proportional hazard models was used to identify prognostic factors. We used PSM (propensity score matching) to balance clinicopathologic characteristics among four groups of different HER2/TOP2A status. Survival between groups and chemotherapy regimens were analyzed, before and after PSM.

RESULTS

In Cohort 1, we found that the group with HER2+ and higher expression of TOP2A mRNA was associated with poor breast cancer-specific survival (BCSS) compared to the group of HER2- with lower expression of TOP2A mRNA. In Cohort 2, HER2+ patients with higher TOP2A protein expression had greater risk of recurrence and distant recurrence compared to HER2- patients with lower expression of TOP2A protein. Among the patients who developed both HER2+ and higher expression of TOP2A protein and received chemotherapy, patients who received an anthracycline-based regimen had a significantly better recurrence-free survival (RFS) than those with a non-anthracycline-based regime.

CONCLUSION

Patients with both HER2+ and high expression level of TOP2A protein predicts poor prognosis in T1N0 breast cancer patients. Patients with double positive for TOP2A protein and HER2 may benefit from anthracycline-based regimens.

The pathological complete response and secreted protein acidic and rich in cysteine expression in patients with breast cancer receiving neoadjuvant nab-paclitaxel chemotherapy

Biomarkers that can accurately predict treatment response are required for indicating optimal neoadjuvant treatments. The current study assessed the predictive value of secreted protein acidic and rich in cysteine (SPARC) mRNA expression for the response to neoadjuvant nab-paclitaxel (nab-PTX) therapy in patients with breast cancer. It was hypothesized that SPARC expression can affect the response to albumin-bound taxanes, including nab-PTX since SPARC binds albumin with a high affinity. Pre-therapeutic specimens of core needle biopsies were analyzed from 50 patients in a phase II trial of neoadjuvant nab-PTX and the factors that were associated with a pathological complete response (pCR) were assessed. The pre-therapeutic tumor mRNA levels of chemotherapy-related proteins were quantified, including SPARC, and the correlations with post-therapeutic clinicopathological factors were assessed, including with pCR. The results demonstrated that pre-therapeutic SPARC mRNA expression was significantly higher in non-pCR patients compared with patients with pCR (92.37±55.33 vs. 56.53±30.19; P=0.027). A cutoff point of 48.5 was determined using receiver operating characteristic (ROC) curve analysis (sensitivity, 83.3%; specificity, 50.0%), and patients were classified into low and high SPARC expression groups. High SPARC expression was associated with histological grade (P=0.035), estrogen receptor expression (P=0.037), and progesterone receptor expression (P=0.002) but not with HER2 (P=0.895), and Ki-67 LI (P=0.743) expression. The results of the current study indicated that a high SPARC mRNA expression was a negative predictor of pCR following neoadjuvant nab-PTX therapy regardless of breast cancer subtype. The phase II study was conducted in accordance with the Declaration of Helsinki, and the protocol was approved by the Ethics Committee of the National Hospital Organization Takasaki General Medical Center (Registration nos. H23-9 and H23-33).

Topoisomerases and cancer chemotherapy: recent advances and unanswered questions

DNA topoisomerases are enzymes that catalyze changes in the torsional and flexural strain of DNA molecules. Earlier studies implicated these enzymes in a variety of processes in both prokaryotes and eukaryotes, including DNA replication, transcription, recombination, and chromosome segregation. Studies performed over the past 3 years have provided new insight into the roles of various topoisomerases in maintaining eukaryotic chromosome structure and facilitating the decatenation of daughter chromosomes at cell division. In addition, recent studies have demonstrated that the incorporation of ribonucleotides into DNA results in trapping of topoisomerase I (TOP1)–DNA covalent complexes during aborted ribonucleotide removal. Importantly, such trapped TOP1–DNA covalent complexes, formed either during ribonucleotide removal or as a consequence of drug action, activate several repair processes, including processes involving the recently described nuclear proteases SPARTAN and GCNA-1. A variety of new TOP1 inhibitors and formulations, including antibody–drug conjugates and PEGylated complexes, exert their anticancer effects by also trapping these TOP1–DNA covalent complexes. Here we review recent developments and identify further questions raised by these new findings.

Metabolic and non-metabolic pathways that control cancer resistance to anthracyclines

Anthracyclines Doxorubicin, Epirubicin, Daunorubicin and Idarubicin are used to treat a variety of tumor types in the clinics, either alone or, most often, in combination therapies. While their cardiotoxicity is well known, the emergence of chemoresistance is also a major issue accounting for treatment discontinuation. Resistance to anthracyclines is associated to the acquisition of multidrug resistance conferred by overexpression of permeability glycoprotein-1 or other efflux pumps, by altered DNA repair, changes in topoisomerase II activity, cancer stemness and metabolic adaptations. This review further details the metabolic aspects of resistance to anthracyclines, emphasizing the contributions of glycolysis, the pentose phosphate pathway and nucleotide biosynthesis, glutathione, lipid metabolism and autophagy to the chemoresistant phenotype.

How Cancer Cells Resist Chemotherapy: Design and Development of Drugs Targeting Protein-Protein Interactions

Background:

Resistance toward chemotherapeutics is one of the main obstacles on the way to effective cancer treatment. Personalization of chemotherapy could improve clinical outcome. However, despite preclinical significance, most of the potential markers have failed to reach clinical practice partially due to the inability of numerous studies to estimate the marker’s impact on resistance properly.

Objective:

The analysis of drug resistance mechanisms to chemotherapy in cancer cells, and the proposal of study design to identify bona fide markers.

Methods:

A review of relevant papers in the field. A PubMed search with relevant keywords was used to gather the data. An example of a search request: drug resistance AND cancer AND paclitaxel.

Results:

We have described a number of drug resistance mechanisms to various chemotherapeutics, as well as markers to underlie the phenomenon. We also proposed a model of a rational-designed study, which could be useful in determining the most promising potential biomarkers.

Conclusion:

Taking into account the most reasonable biomarkers should dramatically improve clinical outcome by choosing the suitable treatment regimens. However, determining the leading biomarkers, as well as validating of the model, is a work for further investigations.

Drug resistance in topoisomerase-targeting therapy

Drug resistance is a well-known phenomenon that occurs when initially responsive to chemotherapy cancer cells become tolerant and elude further effectiveness of anticancer drugs. Based on their mechanism of action, anticancer drugs can be divided into cytotoxic-based agents and target-based agents. An important role among the therapeutics of the second group is played by drugs targeting topoisomerases, nuclear enzymes critical to DNA function and cell survival. These enzymes are cellular targets of several groups of anticancer agents which generate DNA damage in rapidly proliferating cancer cells. Drugs targeting topoisomerase I are mostly analogs of camtothecin, a natural compound isolated from the bark of a tree growing in China. Drugs targeting topoisomerase II are divided into poisons, such as anthracycline antibiotics, whose action is based on intercalation between DNA bases, and catalytic inhibitors that block topoisomerase II at different stages of the catalytic cycle. Unfortunately, chemotherapy is often limited by the induction of drug resistance. Identifying mechanisms that promote drug resistance is critical for the improvement of patient prognosis. Cancer drug resistance is a complex phenomenon that may be influenced by many factors. Here we discuss various mechanisms by which cancer cells can develop resistance to topoisomerase-directed drugs, which include enhanced drug efflux, mutations in topoisomerase genes, hypophosphorylation of topoisomerase II catalytic domain, activation of NF-κB transcription factor and drug inactivation. All these events may lead to the ineffective induction of cancer cell death. Attempts at circumventing drug resistance through the inhibition of cellular efflux pumps, use of silencing RNAs or inhibition of some important mechanisms, which can allow cancer cells to survive therapy, are also presented.

miR-139-5p Modulates Radiotherapy Resistance in Breast Cancer by Repressing Multiple Gene Networks of DNA Repair and ROS Defense

Radiotherapy is essential to the treatment of most solid tumors and acquired or innate resistance to this therapeutic modality is a major clinical problem. Here we show that miR-139-5p is a potent modulator of radiotherapy response in breast cancer via its regulation of genes involved in multiple DNA repair and reactive oxygen species defense pathways. Treatment of breast cancer cells with a miR-139-5p mimic strongly synergized with radiation both in vitro and in vivo, resulting in significantly increased oxidative stress, accumulation of unrepaired DNA damage, and induction of apoptosis. Several miR-139-5p target genes were also strongly predictive of outcome in radiotherapy-treated patients across multiple independent breast cancer cohorts. These prognostically relevant miR-139-5p target genes were used as companion biomarkers to identify radioresistant breast cancer xenografts highly amenable to sensitization by cotreatment with a miR-139-5p mimetic.Significance: The microRNA described in this study offers a potentially useful predictive biomarker of radiosensitivity in solid tumors and a generally applicable druggable target for tumor radiosensitization. Cancer Res; 78(2); 501-15. ©2017 AACR.

Low Tumor Mitochondrial DNA Content Is Associated with Better Outcome in Breast Cancer Patients Receiving Anthracycline-Based Chemotherapy

Purpose: In this study, we aimed to explore whether low levels of mitochondrial DNA (mtDNA) content in the primary tumor could predict better outcome for breast cancer patients receiving anthracycline-based therapies. We hypothesized that tumor cells with low mtDNA content are more susceptible to mitochondrial damage induced by anthracyclines, and thus are more susceptible to anthracycline treatment.Experimental Design: We measured mtDNA content by a qPCR approach in 295 primary breast tumor specimens originating from two well-defined cohorts: 174 lymph node-positive patients who received adjuvant chemotherapy and 121 patients with advanced disease who received chemotherapy as first-line palliative treatment. The chemotherapy regimens given were either anthracycline-based (FAC/FEC) or methotrexate-based (CMF).Results: In both the adjuvant and advanced settings, we observed increased benefit for patients with low mtDNA content in their primary tumor, but only when treated with FAC/FEC. In multivariable Cox regression analysis for respectively distant metastasis-free survival and progression-free survival, the HR for the FAC/FEC-treated mtDNA low group in the adjuvant setting was 0.46 [95% confidence interval (CI), 0.24-0.89; P = 0.020] and in the advanced setting 0.49 (95% CI, 0.27-0.90; P = 0.022) compared with the FAC/FEC-treated mtDNA high group. We did not observe these associations in the patients treated with CMF.Conclusions: In our two study cohorts, breast cancer patients with low mtDNA content in their primary tumor had better outcome from anthracycline-containing chemotherapy. The frequently observed decrease in mtDNA content in primary breast tumors may be exploited by guiding chemotherapeutic regimen decision making. Clin Cancer Res; 23(16); 4735-43. ©2017 AACR.

Vulvar and vaginal melanoma: A unique subclass of mucosal melanoma based on a comprehensive molecular analysis of 51 cases compared with 2253 cases of nongynecologic melanoma

BACKGROUND

Optimal treatments for vulvar and vaginal melanomas (VVMs) have not been identified. Herein, the authors compare molecular profiles between VVM and nongynecologic melanoma (NGM) subtypes with the objective of identifying novel, targetable biomarkers.

METHODS

In total, 2304 samples of malignant melanoma that were submitted to Caris Life Sciences between 2009 and 2015 were reviewed. In situ hybridization and immunohistochemistry were used to assess copy numbers and protein expression of selected genes. Sequenced variants were analyzed using a proprietary cancer panel.

RESULTS

In total, 51 VVMs (14 vaginal and 37 vulvar melanomas) were compared with 2253 malignant NGMs, including 2127 cutaneous, 105 mucosal, and 21 acral melanomas. In VVMs, B-Raf proto-oncogene serine/threonine kinase (BRAF) was the most frequently mutated gene (26%) compared with 8.3% of mucosal NGMs (P = .008). In BRAF-mutated tumors, fewer VVMs (50%), compared with NGMs (82.1%), had a variant within the valine codon 600 (V600) domain. The KIT mutation rate was highest in VVMs (22%) compared with 3% in cutaneous (P < .001) and 8.8% in mucosal (P = .05) melanoma subtypes. NRAS mutations were rare in VVMs compared with cutaneous (25.9%; P = .009) and acral (40.6%; P = .002) melanoma subtypes. PD-L1 (56%) and PD-1 (75%) were frequently expressed in VVM, whereas PI3KCA pathway mutations and estrogen receptor/progesterone receptor expression were rare. Compared with VVMs that had KIT mutations, wild-type KIT VVMs were more likely to express molecular markers suggestive of platinum resistance (ERCC1), alkylating sensitivity (MGMT), and anthracycline sensitivity (TOP2A).

CONCLUSIONS

The unique molecular features of VVM render this disease a distinct subtype of melanoma. Gene-based molecular therapy and immunotherapies may be promising and should be evaluated in clinical trials. Cancer 2017;123:1333-1344. © 2016 American Cancer Society.

The stepwise evolution of the exome during acquisition of docetaxel resistance in breast cancer cells

BACKGROUND

Resistance to taxane-based therapy in breast cancer patients is a major clinical problem that may be addressed through insight of the genomic alterations leading to taxane resistance in breast cancer cells. In the current study we used whole exome sequencing to discover somatic genomic alterations, evolving across evolutionary stages during the acquisition of docetaxel resistance in breast cancer cell lines.

RESULTS

Two human breast cancer in vitro models (MCF-7 and MDA-MB-231) of the step-wise acquisition of docetaxel resistance were developed by exposing cells to 18 gradually increasing concentrations of docetaxel. Whole exome sequencing performed at five successive stages during this process was used to identify single point mutational events, insertions/deletions and copy number alterations associated with the acquisition of docetaxel resistance. Acquired coding variation undergoing positive selection and harboring characteristics likely to be functional were further prioritized using network-based approaches. A number of genomic changes were found to be undergoing evolutionary selection, some of which were likely to be functional. Of the five stages of progression toward resistance, most resistance relevant genomic variation appeared to arise midway towards fully resistant cells corresponding to passage 31 (5 nM docetaxel) for MDA-MB-231 and passage 16 (1.2 nM docetaxel) for MCF-7, and where the cells also exhibited a period of reduced growth rate or arrest, respectively. MCF-7 cell acquired several copy number gains on chromosome 7, including ABC transporter genes, including ABCB1 and ABCB4, as well as DMTF1, CLDN12, CROT, and SRI. For MDA-MB-231 numerous copy number losses on chromosome X involving more than 30 genes was observed. Of these genes, CASK, POLA1, PRDX4, MED14 and PIGA were highly prioritized by the applied network-based gene ranking approach. At higher docetaxel concentration MCF-7 subclones exhibited a copy number loss in E2F4, and the gene encoding this important transcription factor was down-regulated in MCF-7 resistant cells.

CONCLUSIONS

Our study of the evolution of acquired docetaxel resistance identified several genomic changes that might explain development of docetaxel resistance. Interestingly, the most relevant resistance-associated changes appeared to originate midway through the evolution towards fully resistant cell lines. Our data suggest that no single genomic event sufficiently predicts resistance to docetaxel, but require genomic alterations affecting multiple pathways that in concert establish the final resistance stage.

Use of Biomarkers to Guide Decisions on Adjuvant Systemic Therapy for Women With Early-Stage Invasive Breast Cancer: American Society of Clinical Oncology Clinical Practice Guideline

PURPOSE

To provide recommendations on appropriate use of breast tumor biomarker assay results to guide decisions on adjuvant systemic therapy for women with early-stage invasive breast cancer.

METHODS

A literature search and prospectively defined study selection sought systematic reviews, meta-analyses, randomized controlled trials, prospective-retrospective studies, and prospective comparative observational studies published from 2006 through 2014. Outcomes of interest included overall survival and disease-free or recurrence-free survival. Expert panel members used informal consensus to develop evidence-based guideline recommendations.

RESULTS

The literature search identified 50 relevant studies. One randomized clinical trial and 18 prospective-retrospective studies were found to have evaluated the clinical utility, as defined by the guideline, of specific biomarkers for guiding decisions on the need for adjuvant systemic therapy. No studies that met guideline criteria for clinical utility were found to guide choice of specific treatments or regimens.

RECOMMENDATIONS

In addition to estrogen and progesterone receptors and human epidermal growth factor receptor 2, the panel found sufficient evidence of clinical utility for the biomarker assays Oncotype DX, EndoPredict, PAM50, Breast Cancer Index, and urokinase plasminogen activator and plasminogen activator inhibitor type 1 in specific subgroups of breast cancer. No biomarker except for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 was found to guide choices of specific treatment regimens. Treatment decisions should also consider disease stage, comorbidities, and patient preferences.

A phase II study of Epirubicin in oxaliplatin-resistant patients with metastatic colorectal cancer and TOP2A gene amplification

ᅟ

The overall purpose of this study is to provide proof of concept for introducing the anthracycline epirubicin as an effective, biomarker-guided treatment for metastatic colorectal cancer (mCRC) patients who are refractory to treatment with oxaliplatin-based chemotherapy and have TOP2A gene amplification in their tumor cells.

Background

Epirubicin is an anthracycline that targets DNA topoisomerase 2-α enzyme encoded by the TOP2A gene. It is used for treatment of several malignancies, but currently not in CRC. TOP2A gene amplifications predict improved efficacy of epirubicin in patients with breast cancer and thus could be an alternative option for patients with CRC and amplified TOP2A gene. We have previously analysed the frequency of TOP2A gene aberrations in CRC and found that 46.6 % of these tumors had TOP2A copy gain and 2.0 % had loss of TOP2A when compared to adjacent normal tissue. The TOP2A gene is located on chromosome 17 and when the TOP2A/CEN-17 ratio was applied to identify tumors with gene loss or amplifications, 10.5 % had a ratio ≥ 1.5 consistent with gene amplification and 2.6 % had a ratio ≤ 0.8 suggesting gene deletions. Based on these observations and the knowledge gained from treatment of breast cancer patients, we have initiated a prospective clinical, phase II protocol using epirubicin (90 mg/m2 iv q 3 weeks) in mCRC patients, who are refractory to treatment with oxaliplatin.

Methods/Design

The study is an open label, single arm, phase II study, investigating the efficacy of epirubicin in patients with oxaliplatin refractory mCRC and with a cancer cell TOP2A/CEN-17 ratio ≥ 1.5. TOP2A gene amplification measured by fluorescence in situ hybridization. A total of 25 evaluable patients (15 + 10 in two steps) will be included (Simon’s two-stage minimax design). Every nine weeks, response is measured by computed tomography imaging and evaluated according to RECIST 1.1. The primary end-point of the study is progression-free survival.

Trial registration

Eudract no. 2013-001648-79.

Triple-negative breast cancer exhibits a favorable response to neoadjuvant chemotherapy independent of the expression of topoisomerase IIα

The present study retrospectively analyzed the utility of topoisomerase IIα expression as a prognostic marker to predict the neoadjuvant chemotherapeutic response and survival among different breast cancer subtypes. The patients were subtyped and the expression of topoisomerase IIα was determined using immunohistochemistry. All patients (n=147) received an anthracycline-containing regimen preoperatively, and 139 (95%) patients also received docetaxel. Of the 147 patients, 25 (17%) were triple-negative and 20 (17%) were human epidermal growth factor receptor 2 (HER2)-positive. Among these subtypes, a significantly higher a rate (P<0.0001) and higher incidence of topoisomerase IIα expression (P=0.036) were observed compared with that in the hormone receptor-positive and HER2-negative breast cancer types. However, the expression of topoisomerase IIα revealed no correlation with the treatment response or survival in any of the subtypes. Therefore, these results indicated that the favorable response to anthracycline-containing chemotherapy among triple-negative and HER2-positive breast cancer was independent of the expression of topoisomerase IIα.

Topoisomerase-1 and -2A gene copy numbers are elevated in mismatch repair-proficient colorectal cancers

INTRODUCTION

Topoisomerase 1 (TOP1) and 2A (TOP2A) are potential predictive biomarkers for irinotecan and anthracycline treatment, respectively, in colorectal cancer (CRC), and we have recently reported a high frequency of gene gain of the TOP1 and TOP2A genes in CRC. Furthermore, Mismatch Repair (MMR) subtypes of CRC have been associated with benefit from adjuvant chemotherapy of primary CRC. Given the involvement of the topoisomerase enzymes in DNA replication and repair, we raised the hypothesis that an association may exist between TOP gene copy numbers and MMR proficiency/deficiency in CRC.

MATERIAL AND METHODS

Test cohort: FISH analysis with an in-house TOP1/CEN20 probe mix and a commercially available TOP2A/CEN17 (Dako, Glostrup, Denmark) probe mix was performed on archival formalin fixed paraffin embedded (FFPE) tissue samples from 18 patients with proficient MMR (pMMR) CRC and 18 patients with deficient MMR (dMMR) CRC. TOP1 and TOP2A gene copy numbers and their ratios per nucleus were correlated with MMR status using the Mann-Whitney test. Validation cohort: FFPE samples from 154 patients with primary stage III CRC (originally included in the RANX05 study) were classified according to MMR status by immunohistochemical analysis using validated antibodies for MLH1, MLH2, MSH6 and PMS2, and information on TOP1, CEN20, TOP2A and CEN17 status was previously published for this cohort.

RESULTS

The observed TOP1 gene copy numbers in the 36 CRC test cohort were significantly greater (p < 0.01) in the pMMR subgroup (mean: 3.84, SD: 2.03) than in the dMMR subgroup (mean: 1.50, SD: 0.12). Similarly, the TOP2A copy numbers were significantly greater (p < 0.01) in the pMMR subgroup (mean: 1.99, SD: 0.52) than in the dMMR subgroup (mean: 1.52, SD: 0.10). These findings were confirmed in the validation cohort, where in the pMMR subgroup 51% had ≥2 extra TOP1 copies per cell, while all tumors classified as dMMR had diploid TOP1 status and mean TOP2A copy numbers were 2.30 (SD: 1.36) and 1.80 (SD: 0.31) (p = 0.01) in the pMMR subgroup vs. dMMR subgroup, respectively.

DISCUSSION AND CONCLUSION

Our results show that TOP1 and TOP2A gene copy numbers are increased in the pMMR subgroup. We propose that this preference may reflect a selective pressure to gain and/or maintain the gained extra copies of topoisomerase genes whose products are required to cope with high replication stress present in the pMMR tumors, thereby providing a survival advantage selectively in pMMR tumors. Future studies should test this concept and explore potential differences between pMMR and dMMR tumors in response to Top1 and Top2 inhibitors.

Topoisomerase II alpha and TLE3 as predictive markers of response to anthracycline and taxane-containing regimens for neoadjuvant chemotherapy in breast cancer

Purpose

Anthracyclines and taxanes are considered the standard for neoadjuvant chemotherapy of breast cancer, although they are often associated with serious side effects and wide variability of individual response. In this study, we analyzed the value of topoisomerase II alpha (TOP2A) and transducin-like enhancer of split 3 (TLE3) as predictive markers of response to therapy with anthracyclines and taxanes.

Materials and methods

TOP2A and TLE3 protein expressions were evaluated using immunohistochemistry on 28 samples, obtained by core needle biopsy in patients with locally advanced breast carcinoma, subsequently subjected to epirubicin- and paclitaxel-based neoadjuvant chemotherapy. The immunohistochemical staining was correlated with the clinical response measured by the tumor size reduction evaluated by breast magnetic resonance imaging, prior and after chemotherapy, and by pathologic evaluation of the surgical specimen.

Results

Neoadjuvant chemotherapy achieved a size reduction in 26/28 tumors (92.9%), with an average percentage decrease of 45.6%. A downstaging was achieved in 71.4% of the cases of locally advanced carcinoma. TOP2A positivity was correlated with a greater reduction in tumor diameter (P=0.06); negative staining for TLE3 was predictive of a better response to neoadjuvant chemotherapy (P=0.07). A higher reduction in tumor diameter (P=0.03) was also found for tumors that were concurrently TLE3-negative and TOP2A-positive.

Conclusion

TOP2A and TLE3 showed a correlation with response to neoadjuvant chemotherapy. While TOP2A is a well-known marker of response to anthracyclines-based chemotherapy, TLE3 is a new putative predictor of response to taxanes. Data from the current study suggest that TOP2A and TLE3 warrant further investigation in a larger series as predictors of response to neoadjuvant chemotherapy for locally advanced breast carcinoma.

Underpinning the repurposing of anthracyclines towards colorectal cancer: assessment of topoisomerase II alpha gene copy number alterations in colorectal cancer

OBJECTIVE. We propose a repurposing strategy where anthracyclines are reintroduced to a subgroup of patients with metastatic colorectal cancer with the highest likelihood of response. In breast cancer, DNA topoisomerase II alpha gene (TOP2A) alterations predict incremental benefit of anthracyclines, but this association has not been investigated in colorectal cancer. Frequency analysis of TOP2A gene alterations in colorectal cancer and the association with prognosis are evaluated and the challenges of using a TOP2A/CEN-17 FISH probe combination are addressed. MATERIAL AND METHODS. Formalin-fixed, paraffin-embedded material from 154 stage III colorectal cancer patients included in the RANX05 clinical trial was retrospectively assessed for TOP2A gene alterations using FISH. The TOP2A/CEN-17 ratio as well as the TOP2A gene copy number alone was used to define gene alterations and associations between gene status and outcomes were analyzed. RESULTS. TOP2A gene gain was a frequent finding with 9.8 % having a total of ≥4 TOP2A copies per cell. According to the TOP2A/CEN-17 ratio, 10.5 % had TOP2A gene gain. Polysomy or gain of the centromere region of chromosome-17 was not as frequent as reported in breast cancer. No prognostic characteristic of TOP2A was identified. CONCLUSION. TOP2A gene gain is present in numbers relevant to identify a subgroup of patients who may benefit from anthracycline therapy. Based on the present findings, we will initiate a prospective clinical trial designed to evaluate this hypothesis in patients with metastatic colorectal cancer who have failed 5-fluorouracil and oxaliplatin chemotherapy.

Predictive factors determining neoadjuvant chemotherapy outcomes in breast cancer - a single center experience

From January 1, 2008 to March 31, 2010, 101 patients with stage II-III breast cancer were enrolled in this study and subjected to an anthracycline-based neoadjuvant chemotherapy regimen with or without docetaxel. Surgery was performed after 2-6 cycles of chemotherapy, and the clinical response was determined by pathological and histochemical assessments. The clinical response rate, as indicated by complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD), were 6.9, 52.5, 36.6, and 4.0%, respectively. A multivariable correlation analysis indicated that the overall clinical response rate correlated with the number of metastatic lymph nodes, number of chemotherapy cycles, and vessel invasion status. Importantly, the CR rate was only associated with the number of chemotherapy cycles. Nonparametric tests failed to detect a correlation between HER2 or Topo IIα status and clinical response to neoadjuvant chemotherapy in these patients. When they were stratified by HER2 or HR status, for HER2-positive patients the CR rate was associated with vessel invasion and Topo IIα status. Based on our findings, we propose that HR, HER-2 and Topo IIα are not putative predictive biomarkers of chemotherapy outcome for breast cancer patients. Topo IIα expression level was only inversely correlated with CR rate among HR-positive patients. Importantly, the achievement of CR was largely related to the number of chemotherapy cycles.

Mechanisms regulating resistance to inhibitors of topoisomerase II

Inhibitors of topoisomerase II (topo II) are clinically effective in the management of hematological malignancies and solid tumors. The efficacy of anti-tumor drugs targeting topo II is often limited by resistance and studies with in vitro cell culture models have provided several insights on potential mechanisms. Multidrug transporters that are involved in the efflux and consequently reduced cytotoxicity of diverse anti-tumor agents suggest that they play an important role in resistance to clinically active drugs. However, in clinical trials, modulating the multidrug-resistant phenotype with agents that inhibit the efflux pump has not had an impact. Since reduced drug accumulation per se is insufficient to explain tumor cell resistance to topo II inhibitors several studies have focused on characterizing mechanisms that impact on DNA damage mediated by drugs that target the enzyme. Mammalian topo IIα and topo IIβ isozymes exhibit similar catalytic, but different biologic, activities. Whereas topo IIα is associated with cell division, topo IIβ is involved in differentiation. In addition to site specific mutations that can affect drug-induced topo II-mediated DNA damage, post-translation modification of topo II primarily by phosphorylation can potentially affect enzyme-mediated DNA damage and the downstream cytotoxic response of drugs targeting topo II. Signaling pathways that can affect phosphorylation and changes in intracellular calcium levels/calcium dependent signaling that can regulate site-specific phosphorylation of topoisomerase have an impact on downstream cytotoxic effects of topo II inhibitors. Overall, tumor cell resistance to inhibitors of topo II is a complex process that is orchestrated not only by cellular pharmacokinetics but more importantly by enzymatic alterations that govern the intrinsic drug sensitivity.

The predictive role of phosphatase and tensin homolog (PTEN) loss, phosphoinositol-3 (PI3) kinase (PIK3CA) mutation, and PI3K pathway activation in sensitivity to trastuzumab in HER2-positive breast cancer: a meta-analysis

OBJECTIVE

Phosphatase and tensin homolog (PTEN) loss or activating mutations of phosphoinositol-3 (PI3) kinase (PIK3CA) may be related to trastuzumab resistance in in vitro studies; however, this issue in clinical studies is controversial. Therefore, we conducted a meta-analysis to assess the association between PTEN loss, PIK3CA mutation and the efficacy of trastuzumab-based treatment in HER2-positive breast cancer patients.

METHODS

A computerized search was performed through the PubMed database, the online proceedings of the American Society of Clinical Oncology Annual Meetings, the San Antonio Breast Cancer Symposium and the International St. Gallen Breast Cancer Conference. Ten eligible studies including 1889 cases were identified.

RESULTS

In HER2-positive locally advanced breast cancer patients, neither PTEN loss, PIK3CA mutation nor PI3K activation was associated with the response rate of trastuzumab-based neoadjuvant treatment (PTEN loss: RR = 0.687, 95% CI: 0.439-1.074, P = 0.099; PIK3CA mutation: RR = 1.114, 95% CI: 0.453-2.735, P = 0.814; PI3K activation: RR = 0.787, 95% CI: 0.417-1.484, P = 0.459; RR = 0.772, 95% CI: 0.387-1.539, P = 0.462). In HER2-positive early stage breast cancer patients, PTEN loss was not associated with the disease-free survival (DFS) rate of trastuzumab-based adjuvant treatment (HR = 1.096, 95% CI: 0.706-1.700, P = 0.684). In HER2-positive recurrent or metastatic breast cancer patients, PTEN loss was significantly correlated with poorer efficacy of trastuzumab-based salvage treatment (RR = 0.682, 95% CI: 0.550-0.846, P = 0.000).

CONCLUSIONS

In HER2-positive recurrent or metastatic breast cancer patients PTEN loss might indicate resistance to trastuzumab-based salvage treatment. Due to the small sample size and the considerable heterogeneity in the chemotherapy treatment regimens, further research is needed to clarify the association between PTEN loss, PIK3CA mutation and the efficacy of trastuzumab-based treatment in neoadjuvant and adjuvant settings.

The HER2 amplicon in breast cancer: Topoisomerase IIA and beyond

HER2 gene amplification is observed in about 15% of breast cancers. The subgroup of HER2-positive breast cancers appears to be heterogeneous and presents complex patterns of gene amplification at the locus on chromosome 17q12-21. The molecular variations within the chromosome 17q amplicon and their clinical implications remain largely unknown. Besides the well-known TOP2A gene encoding Topoisomerase IIA, other genes might also be amplified and could play functional roles in breast cancer development and progression. This review will focus on the current knowledge concerning the HER2 amplicon heterogeneity, its clinical and biological impact and the pitfalls associated with the evaluation of gene amplifications at this locus, with particular attention to TOP2A and the link between TOP2A and anthracycline benefit. In addition it will discuss the clinical and biological implications of the amplification of ten other genes at this locus (MED1, STARD3, GRB7, THRA, RARA, IGFPB4, CCR7, KRT20, KRT19 and GAST) in breast cancer.