Predicting Anthracycline Benefit: TOP2A and CEP17Not Only but Also

Predicting Anthracycline Benefit: TOP2A and CEP17NotOnly but AlsoJOURNAL OF CLINICAL ONCOLOGYVOLUME 33 NUMBER 15 MAY 20 2015John M.S. Bartlett et al.Ontario Institute forCancer Research

INTRODUCTIONclinical utility of predictive biomarkers of anthracycline activity is weakrecent meta-analysis failed to provide strong evidence for either HER2 or TOP2A (topoisomerase 2-alpha)duplication of chromosome 17 pericentromeric alpha satellite as measured with a centromere enumeration probe (CEP17) predicted sensitivity to anthracyclinesThis is an individual patientlevel pooled analysis of data from five trials comparing anthracycline based chemotherapy with CMF (cyclophosphamide, methotrexate, and fluorouracil) as adjuvant chemotherapy for early breast cancerPatients and MethodsFluorescent in situ hybridization for CEP17, HER2, and TOP2A was performed in three laboratories3,846 of 4,864 eligible patients from five trials evaluating anthracycline containing chemotherapy versus CMF1.BR9601- (Scottish Cancer Therapy Network)2.NEAT -(The National Epirubicin Adjuvant Trial)3. Belgian trial4.DBCG89D -(Danish Breast Cancer Cooperative Group-89D)and 5.the MA.5 trial -(NCIC Clinical Trials Group)

Methodologic differences did not affect HER2-to-CEP17ratios but necessitated different definitions for CEP17 duplication: 1.86 observed copies per cellfor BR9601, NEAT, Belgian, and DBCG89D trials and 2.25 for the MA.5 trial4*Data from each trial were centralized at Edinburgh University*HER2 amplification was defined as HER2-to-CEP17 ratio>2.0, *TOP2A amplification as TOP2A-to-CEP17 ratio> 2.0, and *TOP2A deletion asTOP2A-to-CEP17 ratio< 0.8.RESULTSdata retrieved from 4,864 eligible patients; tissue was available for 3,846 patient cases (79.1%)Fluorescent in situ hybridization data were available in*89.3% (HER2) *83.9% (CEP17) *80.6% (TOP2A) of 3,846 patient cases with available tissue

The impact of each biologic marker evaluated in this study was first tested with respect to RFS and OSHER2gene amplification,TOP2A deletion, and CEP17 duplication -were associated with worse outcome for both RFS and OSboth amplification and deletion of TOP2A were combined as a single variable

Predictive Significance of BiomarkersNo statistically significant interaction between treatment with epirubicin and TOP2A (amplification or deletion) was detected

However, significant interactions were observed between HER2 and treatment combined TOP2A abnormalities and treatment

Cox regression analyses of treatment-by marker interactions (HER2, TOP2A abnormalities, and CEP17, respectively),the interaction term for HER2 was not significant for either RFS or OS

a single Cox regression model was performed to test effects of TOP2A and CEP17 interactions with treatment simultaneously after adjustment for confounding factorsCEP17 duplication and anthracycline therapy remained significant for RFS (P.01) and was of borderline significance for OS (P.06).The TOP2A treatment-by-marker interaction remained significant for RFS (P.03) and OS (P.03

Patients whose tumors exhibited CEP17 and TOP2A abnormalities exhibited a 38% reduction in risk of relapse when treated with anthracycline-containing chemotherapy relative to those treated with CMF alone,

a benefit not found for those women whose tumors were normal for CEP17 and TOP2A

DISCUSSIONevidence for a potentially clinically useful predictive biomarker identifying patients who derive benefit from anthracycline-based polychemotherapy in the adjuvant treatment of early breast cancer.duplication of CEP17 and/or alteration of TOP2A were independent predictive markers of anthracycline sensitivity, with consistent results across five trials

3.notably HER2, were not strongly predictive of anthracycline benefit, as shown previously by a similar meta-analysis4. combination of CEP17 and TOP2A almost entirely eliminated the heterogeneity across trials observed when either was used as a single marker5. role for TOP2A in predicting anthracycline benefit is only when both deletions and amplifications of this gene were combined in clinical studies that the predictive effect was observed6. CEP17 duplication, identified by FISH analysis, did not identify a potential mechanism underlying anthracycline sensitivity7. CEP17 duplication reflects chromosomalinstability and spindle assembly checkpoint disregulation, which are linked in vitro to anthracycline sensitivity and could explain the observed clinical effect, linking TOP2A abnormalities (deletions and amplifications) and CEP178. No evidence for HER2 as a predictive biomarker for anthracycline benefit9. In contrast, the combination of CEP17 duplication and TOP2A amplification or deletion provided a unifying biomarker for anthracycline benefit across multiple trials10. Given the numerous possible effects of anthracyclines, it suggests that there may not be a single gene or pathway that identifies anthracycline-sensitive cancers11. In patients whose tumors were amplified for both HER2 and TOP2A, no superiority of any regimen( trastuzumab or anthracyclines) was demonstrated12. It may suggest that in HER2- or TOP2A-amplified breast cancers, TOP2A amplification is required for benefit from anthracyclines; equally, it may suggest that TOP2A amplification is a marker of trastuzumab resistance, because patients whose tumors had amplification of both HER2 and TOP2A did not benefit significantly from the addition of tratuzumabstudy cannot fully address whether the patients who benefit from anthracyclines also benefit from the further addition of taxanesOf interest, the N9831 adjuvant trastuzumab trial suggested prolonged RFS in patients with CEP17 duplication treated with doxorubicin plus cyclophosphamide and sequential paclitaxel compared with patients without duplication. In trastuzumab-treated patients, this effect was lost

CONCLUSIONPatients whose tumors harbor either CEP17 duplication or TOP2A aberrations, but not HER2 amplification, benefit from adjuvant anthracycline chemotherapyBoth CEP17and TOP2A treatment-by-marker interactions remained significant in adjusted analyses for recurrence-free and overall survival, whereas HER2 did not.

combined CEP17 and TOP2Aadjusted model predicted anthracycline benefit across all five trials for both RFS (HR, 0.64; 95% CI, 0.51 to 0.82; P