P1-12-17: Fluorescent In Situ Hybridization Evaluation of HER2 Status in Tumors with Chromosome 17 Polysomy

Introduction: According to the American Society of Clinical Oncology-College of American Pathologists recommendations for HER2 testing, a positive fluorescent in situ hybridization (FISH) result is defined as >6 HER2 gene copies/nucleus (for test systems with no internal control probe [single-color]) or as HER2 gene/chromosome 17 centromere (CEP17) ratio > 2.2 (for systems with an internal control probe [dual-color]). Although an increase in CEP17 copy number (average ≥ 3.0 copies/nucleus) is commonly considered to represent polysomy of chromosome 17, it can also be a result of gains of 17q with centromere involvement, or amplification of the centromeric region. The classification of HER2−positive tumors according to the HER2/CEP17 ratio may therefore misclassify a fraction of truly amplified cases as polysomic. We prospectively evaluated tumors with chromosome 17 polysomy but no HER2 amplification to assess HER2 status using the above two FISH classifications and immunohistochemistry (IHC).

Materials and methods: Tumors were tested for gene amplification by FISH with probes to HER2/neu and CEP17 using the PathVysion HER-2 DNA Probe Kit (Vysis). Classification was based on the HER2/CEP17 ratio (amplified when > 2.2) and average HER2 gene copy number/nucleus (amplified when > 6 copies). Both polysomic and equivocal cases (HER2/CEP17 ratio 1.8 - 2.2) were further studied by IHC using the HercepTest (Dako) with 0–3 scoring system (overexpression when 3+).

Results: From March 2010 to May 2011 we evaluated 31 primary breast cancers showing chromosome 17 polysomy. Median HER2/CEP17 ratio was 1.3 (range 0.5−1.9), median HER2 copy number was 5.4 (range 2.6−13.8), and median CEP17 copy number was 4.2 (range 3.2−8.0). Thirteen (42%) had an average HER2 gene copy number > 6/nucleus (median 6.8, range 6.1−13.8) and would therefore be considered as amplified if classified according to the absolute HER2 gene copy number. Nine (75%) of these were 3+ at IHC and the remaining 4 were 2+, whereas among the 18 cases with an average HER2 gene copy number < 6/nucleus, one was 2+, ten were 1+, and 7 scored 0. Twenty-nine cases showed negative HER2/CEP17 ratios (< 1.8) and three cases equivocal HER2/CEP17 ratios (between 1.8 and 2.2). Using HER2/CEP17 ratio as first assessment and IHC only in equivocal cases, only one of the 31 “polysomic” cases would have been classified as HER2−positive. However, 8 polysomic cases with HER2/CEP17 ratio < 1.8 showed 3+ immunostaining (all with average HER2 gene copy number > 6/nucleus), while 3 other cases had an average HER2 gene copy number > 6/nucleus with 2+ immunostaining.

Conclusions: Our results show that both FISH evaluation criteria and IHC can modify the percentage of polysomic tumors classified as HER2−positive. However, the number of gene copies/nucleus appears more frequently associated with 3+ IHC than the HER2/CEP17 ratio. The predictive impact of the former method on response to anti-HER2 treatments warrants further investigation.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-12-17.

Phase I study of paclitaxel and uracil plus tegafur combination in patients with pretreated metastatic breast cancer: drug sequencing based on preclinical modelling studies

OBJECTIVE

Taxanes and fluoropyrimidines are active in metastatic breast cancer (MBC), and their combination has proven effective in anthracycline-refractory patients. We conducted a phase I study to determine the maximum tolerated dose (MTD) of uracil plus tegafur (UFT) given in combination with leucovorin (LV) and paclitaxel (Pacl) in patients with refractory MBC.

METHODS

Pacl was infused at a fixed dose of 150 mg/m2 on day 1. UFT, at doses escalated by 50 mg/m2 starting from 200 mg/m2 . day, and LV, at a fixed dose of 90 mg/day, were given orally every 8 h for 11 days (days 3-13). Cohorts of at least 3 patients were treated at each dose level, and if 1 experienced dose-limiting toxicity (DLT), a maximum of 3 additional patients were added at the same dose level. MTD was reached if 2 out of the 6 patients experienced DLT.

RESULTS

Sixteen patients were enrolled in the study. The most important toxicity observed was hematological. Nonhematological toxicities were paresthesia and myalgia, asthenia, nausea, and mucositis. DLT occurred in only 1 patient (grade 3 hepatic toxicity).

CONCLUSIONS

The recommended dose for a subsequent phase II trial is Pacl 150 mg/m2 on day 1, and UFT 300 mg/m2 and LV 90 mg on days 3-13, every 2 weeks.

Breast cancer (BC): May intra-arterial (IA) chemotherapy (CT) play a role in the treatment of locally advanced disease or liver metastases? Report of our experience

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Background: IA infusion of CT increases drug concentrations within a tumor. We investigated if it is effective in BC patients (pts) with locally advanced disease or liver metastases. Methods: Twenty-five pts were treated with IA CT using angiographic technique in the Department of Medical Oncology, Morgagni-Pierantoni Hospital in Forlì. Pts received a short IA infusion through the proper hepatic artery (liver metastases) or the internal mammary artery (locally advanced disease). Drugs were: Epirubicin (EPI) 30 mg/m2, Mitomycin-c (MMC) 7 mg/m2 and 5-fluoruracil (5FU) 1000 mg on day 1 every 21 days. EPI was not administered in anthracycline pretreated pts. Results: Median age was 54.3 years (31–75 years) and ECOG Performance Status (PS) was ≤2. Nine pts had liver metastases and 16 had locally advanced disease. Twenty-three (96%) of the 25 pts had received adjuvant treatment (21 CT, 7 endocrine therapy), 20 (80%) had had at least one treatment for metastatic disease (20 CT, 11 endocrine therapy, 8 radiotherapy), and 11 pts (40%) had received concomitant therapy (3 CT and 8 endocrine). Fifteen pts were anthracycline-naïve. A total of 88 angiographic sessions were carried out, with a median number of 3.5 cycles per patient (1–8 cycles). One transitory ischaemic attack occurred during angiographic procedure . No other serious complications were observed. The only cases of toxicity higher than grade 2 were one grade III neutropenia and one grade IV thrombocytopenia. A dose reduction was necessary in 4 pts (2 due to PS, 1 to toxicity and 1 to pre-treatment) and treatment was interrupted in 4 pts (2 due to PS, 1 to early progression and 1 to technical problems). Among the 19 pts assessable for response, 13 (68%) had a partial response, 2 (11%) showed stable disease and 4 (21%) progressed. Median time to progression and median overall survival will be given. Conclusions: Our results suggest that IA CT may play a role in the treatment of advanced pre-treated BC pts.

No significant financial relationships to disclose.