No significant predictive value of c-erbB-2 or p53 expression regarding sensitivity to primary chemotherapy or radiotherapy in breast cancer

ERBB2 overexpression in breast carcinomas: no positive correlation with complete pathological response to preoperative high-dose anthracycline-based chemotherapy

The predictive value of ERBB2 amplification/expression to doxorubicin use is controversial. Preoperative chemotherapy, followed by the pathological assessment of tumour response to treatment provide optimal conditions for the evaluation of the predictive value of biological parameters. We report here data on the predictive value of ERBB2 in a series of 54 cases of breast cancer treated by preoperative high-dose anthracycline-based chemotherapy. Our series consisted of 26 women presenting an inflammatory breast cancer (IBC) and of 28 women with poor prognosis primary cancer (PPPC). Patients received a total of four cycles with doxorubicin (75 mg/m(2) for IBC or 70 mg/m(2) for PPPC) and cyclophosphamide (6 g/m(2) for IBC or 1400 mg/m(2) for PPPC), every 21 days. ERBB2 expression was determined by immunohistochemistry (clone CB11) performed on a tumour biopsy taken before chemotherapy. All patients underwent surgery as a second step of treatment, and the tumour response was assessed on pathological specimens. A complete pathological response was observed in 24 of the 54 cases (44%) (95% confidence interval (CI), 31-57). Pathological complete response was positively correlated with high histological grade (P=0. 02) and with the absence of oestrogen (P=0.003) or progesterone (P=0. 02) receptor expression. ERBB2 overexpression was found in 18 of the 54 cases (33%). A complete pathological response was observed in 33% of these cases (6/18). This figure was not significantly different from the 50% rate of complete response observed for tumours with no detectable ERBB2 expression (18/36). In this small series, ERBB2 overexpression was not a significant predictive marker of the pathological response to high-dose doxorubicin-based chemotherapy.

Prognostic and predictive implications of HER2 status for breast cancer patients

Women diagnosed with breast cancer face many emotional and psychological challenges, which are often related to how they perceive their chances of survival. A number of factors are known to be indicators of breast cancer prognosis, including tumour type, size and grade, and lymph node status. These factors can be used alone or in combination to make management decisions based on a broad assessment of tumour aggression. However, identifying an independent marker of prognosis has proved more difficult. The human epidermal growth factor receptor-2 (HER2) is amplified/overexpressed in 25-30% of breast tumours. This event has been shown to be associated with poor prognosis in breast cancer patients. Initial observations indicated that median survival duration is reduced by at least 50% in patients who overexpress HER2 compared with those who do not overexpress the receptor. This finding has been supported by many subsequent studies and data are accumulating to indicate that the relationship holds for both node-negative and node-positive patients. This could be particularly important for identifying the 30% of node-negative patients who will progress despite therapy. HER2 status may also be able to predict the outcome of therapy. It appears likely that HER2 overexpression predicts for resistance to tamoxifen and other hormonal therapies. It is also possible that HER2-overexpressing patients may respond better to dose-intense anthracycline therapy and worse to cyclophosphamide/methotrexate/5-fluorouracil than non-overexpressing patients. Explaining these associations to patients may empower them to deal with the psychological effects of a diagnosis of breast cancer while providing hope for the future.

The Ki-67 protein: from the known and the unknown

The expression of the human Ki-67 protein is strictly associated with cell proliferation. During interphase, the antigen can be exclusively detected within the nucleus, whereas in mitosis most of the protein is relocated to the surface of the chromosomes. The fact that the Ki-67 protein is present during all active phases of the cell cycle (G(1), S, G(2), and mitosis), but is absent from resting cells (G(0)), makes it an excellent marker for determining the so-called growth fraction of a given cell population. In the first part of this study, the term proliferation marker is discussed and examples of the applications of anti-Ki-67 protein antibodies in diagnostics of human tumors are given. The fraction of Ki-67-positive tumor cells (the Ki-67 labeling index) is often correlated with the clinical course of the disease. The best-studied examples in this context are carcinomas of the prostate and the breast. For these types of tumors, the prognostic value for survival and tumor recurrence has repeatedly been proven in uni- and multivariate analysis. The preparation of new monoclonal antibodies that react with the Ki-67 equivalent protein from rodents now extends the use of the Ki-67 protein as a proliferation marker to laboratory animals that are routinely used in basic research. The second part of this review focuses on the biology of the Ki-67 protein. Our current knowledge of the Ki-67 gene and protein structure, mRNA splicing, expression, and cellular localization during the cell-division cycle is summarized and discussed. Although the Ki-67 protein is well characterized on the molecular level and extensively used as a proliferation marker, the functional significance still remains unclear. There are indications, however, that Ki-67 protein expression is an absolute requirement for progression through the cell-division cycle.

P53 autoantibodies in 1006 patients followed up for breast cancer

Serial plasma samples from 1006 patients with breast cancer revealed: (i) no correlation of p53 autoantibody status with disease status at the time of sample collection, or with menopausal status at time of primary diagnosis of breast cancer; (ii) 155 out of 1006 (15%) of patients were positive for p53 autoantibodies, and these patients tended to have a persistent autoantibody status throughout follow up, irrespective of disease behaviour; and (iii) where a negative autoantibody status was found at primary diagnosis of breast cancer, this negative status persisted throughout follow up, irrespective of later disease behaviour. We conclude that screening for p53 autoantibody status is not informative on residual tumour activity nor on therapeutic responsiveness.

Assessment of HER2 status in breast cancer: why, when and how?

Human epidermal growth factor receptor 2 (HER2) is overexpressed, usually as a result of HER2 proto-oncogene amplification, in 20-30% of breast cancers. A HER2-positive status is generally associated with more aggressive disease and a worse prognosis. Furthermore, a positive HER2 status may predict the likelihood of resistance to some conventional therapies, as well as probably being predictive of sensitivity to anthracycline dose intensification. In addition to this prognostic/predictive value, HER2 is a target for specific therapy, with anti-HER2 monoclonal antibody therapy available in the USA. This article reviews the different assays used to determine HER2 status, discussing their relative advantages/disadvantages and the need for their standardisation before integration alongside other pathological indices into the clinical management of breast cancer.

Reduced MLH1 expression in breast tumors after primary chemotherapy predicts disease-free survival

PURPOSE

Loss of function or expression of the mismatch repair protein MLH1 and the tumor suppressor protein p53 have been implicated in acquired resistance to anticancer drugs. We have compared the expression of MLH1 and p53 in tumors from women with clinically node-positive breast cancer before and after primary (neoadjuvant) chemotherapy. Further, we have assessed the value of these markers as predictors of response to therapy by correlation with disease-free survival.

PATIENTS AND METHODS

Immunohistochemistry scores of MLH1 and p53 expression were made on 36 tru-cut prechemotherapy biopsies and 29 paired postchemotherapy tumor samples. The significance of the change in scores and their correlation with disease-free survival were evaluated by the Wilcoxon signed rank sum test and Cox proportional hazards regression analysis, respectively.

RESULTS

Primary chemotherapy results in a significant reduction in the percent of cells expressing MLH1 (P =.010). This change in MLH1 expression after chemotherapy is strongly associated with poor disease-free survival (P =.0025). Expression of p53 was not significantly altered by chemotherapy. Neither MLH1 nor p53 expression before chemotherapy predicted disease-free survival or tumor response to chemotherapy. Low MLH1 expression after chemotherapy was an independent predictor of poor disease-free survival on multivariate Cox analysis when considered with other clinicopathologic prognostic factors.

CONCLUSION

Tumor cells that have reduced MLH1 expression seem to have a survival advantage during combined chemotherapy of locally advanced breast cancers, which supports the hypothesis that loss of MLH1 has a role in drug resistance. MLH1 expression after chemotherapy is an independent predictive factor for poor disease-free survival and may, therefore, define a group of patients with drug-resistant breast cancer.

Biological markers as indicators of response to primary and adjuvant chemotherapy in breast cancer

Interest in translational studies on breast cancer is presently devoted to identify biological predictors of treatment response. In patients with operable breast cancer, subjected to primary and adjuvant chemotherapy, we analyzed the predictivity on objective clinical response and relapse-free survival of biological markers related to different cellular aspects and functions. Tumour proliferative rate (evaluated as the (3)H-thymidine-labelling index, TLI), oestrogen and progesterone receptors (ER and PgR, evaluated by the dextran-coated-charcoal method), nuclear DNA ploidy and the immunocytochemical expression of p53, bcl-2 and bax proteins were determined before primary treatment, at the time of diagnosis, and after primary chemotherapy, at surgery. Objective clinical response was significantly related only to pre-treatment p53 expression or PgR status, with a higher rate for tumours not expressing than for those expressing p53 (94% vs. 72%), as well as for PgR-negative (PgR(-)) than for PgR-positive (PgR(+)) tumours (86% vs. 68%). In the overall series, 8-year clinical outcome was significantly related only to post-treatment steroid receptors. In particular, higher 8-year relapse-free survival rate was observed for patients with ER(-) or PgR(-) than for those with ER(+) (64% vs. 38%) or PgR(+) (53% vs. 37%) tumours. Such findings held true even within the sub-set of patients who received adjuvant post-operative chemotherapy, i.e., those with node-positive (N(+)) or ER(-)/node-negative (N(-)) tumours, among whom also rapid proliferation or the presence of apoptosis-favouring markers (bcl-2(-) or bax(+), singly and in association) on surgical specimens identified a sub-set of women who benefited from systemic treatment. The different biological markers were variously indicative of clinical outcome, with a predictivity on tumour shrinkage for p53 and PgR, detected before primary chemotherapy, and on long-term follow-up for ER, PgR and, to a lesser extent, TLI and apoptosis-modulating markers. Int. J. Cancer (Pred. Oncol.) 84:580-586, 1999.

Quantitative PCR analysis of c-erb B-2 (HER2/neu) gene amplification and comparison with p185(HER2/neu) protein expression in breast cancer drill biopsies

A PCR assay using capillary electrophoresis was designed for the detection of c-erbB-2 gene amplification in alcohol-formalin-acetic acid (AFA)-fixed, paraffin-embedded biopsies from 81 consecutive breast tumors. c-erbB-2 expression was analyzed in the same samples using immuno-histochemistry (IHC). In the competitive PCR assay, a single pTag plasmid containing a 4-nucleotide (nt)-deleted copy of a 124-nt sequence of c-erbB-2 and a 4-nt-deleted copy of a 120-nt sequence of GAPDH was co-amplified with genomic DNA extracted from 3 10-micrometer-thick tissue sections of the tumor biopsy. The percentage of tumor cells in the biopsy specimen and the percentage of tumor cells stained with the membrane anti-c-erbB-2 monoclonal antibody CB11 were recorded by a single pathologist on 2 consecutive sections. Among 81 consecutive tumor biopsies assayed by PCR, 21 (26%) displayed unequivocal c-erbB-2 amplification (actual gene copy number, AGCN > 4), 47 (58%) displayed no c-erbB-2 amplification (AGCN </= 2) and 7 (9%) could not be analyzed due to an insufficient amount of DNA. Six samples (7%) were considered inconclusive since the percentage of tumor cells was <20%. Analysis of c-erbB-2 expression by IHC showed that among the 21 amplified specimens 15 displayed strong staining, while all non-amplified samples (47) displayed no or only weak staining. The concordance of the 2 techniques was 91%. We conclude that c-erbB-2 gene amplification can be accurately quantitated by competitive PCR performed on small, fixed and embedded tumor samples.