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Predictability of adjuvant trastuzumab benefit in N9831 patients using the ASCO/CAP HER2-positivity criteria.

ABSTRACT: The 2007 American Society of Clinical Oncology and College of American Pathologists (ASCO/CAP) joint guidelines defined criteria for HER2 positivity of tumors that modified those of the US Food and Drug Administration (FDA), causing some confusion and uncertainty among clinicians. Using data from the HER2-positive breast cancer adjuvant trial N9831, we compared eligibility for patients who met both criteria, and disease-free survival (DFS) was assessed by Cox proportional hazards regression. The number of patients in the N9831 trial retrospectively eligible for trastuzumab therapy was decreased when ASCO/CAP criteria vs FDA criteria were applied to immunohistochemistry and/or fluorescence in situ hybridization results (107 [3.7%] of 2904 patients with immunohistochemistry results, 37 [1.3%] of 2809 patients with fluorescence in situ hybridization results, and 47 [1.7%] of 2809 patients with both results). Improvement in DFS was similar among patients treated with trastuzumab under either set of criteria (concurrent trastuzumab and chemotherapy compared with chemotherapy alone: by ASCO/CAP criteria, hazard ratio of DFS = 0.59, 95% confidence interval = 0.48 to 0.73; by FDA criteria but not ASCO/CAP criteria, hazard ratio = 0.60, 95% confidence interval = 0.12 to 3.13; number needed to treat to prevent one additional DFS event at 5 years: 10 and 11.2 patients, respectively). Following the 2007 ASCO/CAP criteria for HER2 positivity would negate the option of potentially life-saving trastuzumab therapy for a small but meaningful group of patients. We recommend using FDA-approved HER2 criteria for therapeutic decision making.

SUBMITTER: Perez EA

PROVIDER: S-EPMC3260130 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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Predictability of adjuvant trastuzumab benefit in N9831 patients using the ASCO/CAP HER2-positivity criteria.

Perez Edith A EA Dueck Amylou C AC McCullough Ann E AE Reinholz Monica M MM Tenner Kathleen S KS Davidson Nancy E NE Gralow Julie J Harris Lyndsay N LN Kutteh Leila A LA Hillman David W DW Jenkins Robert B RB Chen Beiyun B

Journal of the National Cancer Institute 20111202 2

The 2007 American Society of Clinical Oncology and College of American Pathologists (ASCO/CAP) joint guidelines defined criteria for HER2 positivity of tumors that modified those of the US Food and Drug Administration (FDA), causing some confusion and uncertainty among clinicians. Using data from the HER2-positive breast cancer adjuvant trial N9831, we compared eligibility for patients who met both criteria, and disease-free survival (DFS) was assessed by Cox proportional hazards regression. The ...[more]

PMID: 22138096

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Project description:BackgroundTrastuzumab improves survival in the adjuvant treatment of HER-positive breast cancer, although combined therapy with anthracycline-based regimens has been associated with cardiac toxicity. We wanted to evaluate the efficacy and safety of a new nonanthracycline regimen with trastuzumab.MethodsWe randomly assigned 3222 women with HER2-positive early-stage breast cancer to receive doxorubicin and cyclophosphamide followed by docetaxel every 3 weeks (AC-T), the same regimen plus 52 weeks of trastuzumab (AC-T plus trastuzumab), or docetaxel and carboplatin plus 52 weeks of trastuzumab (TCH). The primary study end point was disease-free survival. Secondary end points were overall survival and safety.ResultsAt a median follow-up of 65 months, 656 events triggered this protocol-specified analysis. The estimated disease-free survival rates at 5 years were 75% among patients receiving AC-T, 84% among those receiving AC-T plus trastuzumab, and 81% among those receiving TCH. Estimated rates of overall survival were 87%, 92%, and 91%, respectively. No significant differences in efficacy (disease-free or overall survival) were found between the two trastuzumab regimens, whereas both were superior to AC-T. The rates of congestive heart failure and cardiac dysfunction were significantly higher in the group receiving AC-T plus trastuzumab than in the TCH group (P<0.001). Eight cases of acute leukemia were reported: seven in the groups receiving the anthracycline-based regimens and one in the TCH group subsequent to receiving an anthracycline outside the study.ConclusionsThe addition of 1 year of adjuvant trastuzumab significantly improved disease-free and overall survival among women with HER2-positive breast cancer. The risk-benefit ratio favored the nonanthracycline TCH regimen over AC-T plus trastuzumab, given its similar efficacy, fewer acute toxic effects, and lower risks of cardiotoxicity and leukemia. (Funded by Sanofi-Aventis and Genentech; BCIRG-006 ClinicalTrials.gov number, NCT00021255.).

Project description:Importance:The 2013/2014 American Society of Clinical Oncology and College of American Pathologists (ASCO-CAP) guidelines for HER2 testing by fluorescence in situ hybridization (FISH) designated an "equivocal" category (average HER2 copies per tumor cell ?4-6 with HER2/CEP17 ratio <2.0) to be resolved as negative or positive by assessments with alternative control probes. Approximately 4% to 12% of all invasive breast cancers are characterized as HER2-equivocal based on FISH. Objective:To evaluate the following hypotheses: (1) genetic loci used as alternative controls are heterozygously deleted in a substantial proportion of breast cancers; (2) use of these loci for assessment of HER2 by FISH leads to false-positive assessments; and (3) these HER2 false-positive breast cancer patients have outcomes that do not differ from clinical outcomes for patients with HER2-negative breast cancer. Design, Setting, and Participants:We retrospectively assessed the use of chromosome 17 p-arm and q-arm alternative control genomic sites (TP53, D17S122, SMS, RARA, TOP2A), as recommended by the 2013/2014 ASCO-CAP guidelines for HER2 testing, in patients whose data were available through Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) and whose tissues were available through the Breast Cancer International Research Group clinical trials. We used data from an international cohort database of invasive breast cancers (1980 participants) and international clinical trial of adjuvant chemotherapy in invasive, node-positive breast cancer patients. Main Outcomes and Measures:The primary objectives were to (1) assess frequency of heterozygous deletions in chromosome 17 genomic sites used as FISH internal controls for evaluation of HER2 status among HER2-equivocal cancers; (2) characterize impact of using deleted sites for determination of HER2-to-internal-control-gene ratios; (3) assess HER2 protein expression in each subgroup; and (4) compare clinical outcomes for each subgroup. Results:Of the 1980 patients in METABRIC,1915 patients were fully evaluated. In addition, 100 HER2-equivocal breast cancers by FISH and 100 comparator FISH-negative breast cancers from the BCIRG-005 trial were analyzed. Heterozygous deletions, particularly in specific p-arm sites, were common in both HER2-amplified and HER2-not-amplified breast cancers. Use of alternative control probes from these regions to assess HER2 by FISH in HER2-equivocal as well as HER2-not-amplified breast cancers resulted in high rates of false-positive ratios (HER2-to-alternative control ratio ?2.0) owing to heterozygous deletions of control p-arm genomic sites used in ratio denominators. Misclassification of HER2 status was observed not only in breast cancers with ASCO-CAP equivocal status but also in breast cancers with an average of fewer than 4.0 HER2 copies per tumor cell when using alternative control probes. Conclusions and Relevance:The indiscriminate use of alternative control probes to calculate HER2 FISH ratios in HER2-equivocal breast cancers may lead to false-positive interpretations of HER2 status resulting from unrecognized heterozygous deletions in 1 or more of these alternative control genomic sites and incorrect HER2 ratio determinations.

Project description:Findings from the human epidermal growth factor receptor 2 (HER2) -positive National Surgical Adjuvant Breast and Bowel Project (NSABP) B31 trial suggested that MYC/HER2 coamplification (> 5.0 copies/nucleus) was associated with additional benefit from adjuvant trastuzumab in patients with early-stage breast cancer. To further explore this relationship, we investigated associations between MYC amplification and disease-free survival (DFS) in a similar adjuvant trastuzumab HER2-positive breast cancer trial-North Central Cancer Treatment Group (NCCTG) N9831.This analysis included 799 patients randomly assigned to receive chemotherapy alone or with concurrent trastuzumab on N9831. Fluorescence in situ hybridization (FISH) was performed by using a dual-probe mixture for MYC and centromere 8 (MYC:CEP8) on tissue microarrays. MYC amplification was prespecified as MYC:CEP8 ratio > 2.2 or average MYC copies/nucleus > 5.0. Exploratory variables included polysomy 8.In comparing DFS (median follow-up, 4.0 years) between treatments, patients with MYC:CEP8 ratio ? 2.2 (n = 618; 77%) and > 2.2 (n = 181; 23%) had hazard ratios (HRs) of 0.46 (P < .001) and 0.67 (P = .33), respectively (interaction P = .38). Patients with MYC copies/nucleus ? 5.0 (n = 534; 67%) and > 5.0 (n = 265; 33%) had HRs of 0.52 (P = .002) and 0.48 (P = .02), respectively (interaction P = .94). Patients with MYC:CEP8 ratio < 1.3 with normal chromosome 8 copy number (n = 141; 18%) and ? 1.3 or < 1.3 with polysomy 8 (n = 658; 82%) had HRs of 0.66 (P = .28) and 0.44 (P < .001), respectively (interaction P = .23). Patients with MYC copies/nucleus < 2.5 (n = 130; 16%) and ? 2.5 (n = 669; 84%) had HRs of 1.07 (P = .87) and 0.42 (P < .001), respectively (interaction P = .05).We did not confirm the B31 association between MYC amplification and additional trastuzumab benefit. Exploratory analyses revealed potential associations between alternative MYC/chromosome 8 copy number alterations and differential benefit of adjuvant trastuzumab.

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Predictability of adjuvant trastuzumab benefit in N9831 patients using the ASCO/CAP HER2-positivity criteria.

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Predictability of adjuvant trastuzumab benefit in N9831 patients using the ASCO/CAP HER2-positivity criteria.

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