Measurement of S-phase fraction and ploidy in sequential fine-needle aspirates from primary human breast tumours treated with tamoxifen

Breast Cancer Chemoprevention Phase I Evaluation of Biomarker Modulation by Arzoxifene, a Third Generation Selective Estrogen Receptor Modulator

PURPOSE

Arzoxifene, a new selective estrogen receptor modulator with strong breast antiestrogen activity and absence of uterine agonist activity, was explored as a potential chemoprevention agent. We performed a multi-institutional evaluation of arzoxifene in women with newly diagnosed ductal carcinoma in situ or T1/T2 invasive cancer.

EXPERIMENTAL DESIGN

In a Phase IA trial, 50 pre- or postmenopausal women were randomized to 10, 20, or 50 mg of arzoxifene daily in the interval between biopsy and re-excision or were enrolled as no-treatment controls. In a Phase IB trial, 76 postmenopausal women were randomized to 20 mg of arzoxifene versus matched placebo. Serum specimens collected at entry and at re-excision were assayed for various hormones and growth factors. Tissue from biopsies (estrogen receptor + and/or progesterone receptor +) and re-excision specimens was evaluated immunohistochemically for proliferation (Ki-67 by MIB-1 and proliferating cell nuclear antigen) and other biomarkers.

RESULTS

In both trials, increases in serum sex hormone binding globulin were noted, as were decreases in insulin-like growth factor (IGF)-I and the IGF-I:IGF binding protein-3 ratio (P < 0.007 versus control/placebo). For 45 evaluable women in Phase IA, decreases in proliferation indices were more prevalent for arzoxifene (particularly 20 mg) than for controls. For 58 evaluable women in Phase IB, a decrease in estrogen receptor expression for arzoxifene was observed compared with no change with placebo (P = 0.0068). However, decreases in proliferation indices for arzoxifene were not statistically different from placebo, perhaps due to a confounding effect of stopping hormone replacement therapy before entry.

CONCLUSION

Given the favorable side effect profile and the biomarker modulations reported here, arzoxifene remains a reasonable candidate for additional study as a breast cancer chemoprevention agent.

MUC1 expression in primary breast cancer: the effect of tamoxifen treatment

This was a non-randomised single institution retrospective study. Forty-six banked frozen tumour specimens were obtained from a group of patients who had undergone 3 weeks of neoadjuvant treatment with tamoxifen between biopsy and surgery. Fifty-one comparison specimens were randomly selected from a group of concomitantly treated primary breast cancer patients who did not receive neoadjuvant tamoxifen. Specimen selection was not based on prognostic factors: hormone receptor status, patient age, or menopausal status. MUC1 expression and cell cycle distribution were assessed by flow cytometry. S-phase fraction of MUC1 positive and MUC1 negative cells were compared. A lower percentage of cells expressed MUC1 following 3-week tamoxifen treatment 18.2% versus 28.5% (p = 0.03, Mann-Whitney) and lower levels of MUC1 expression were seen following tamoxifen treatment 31,519 molecules/cell versus 39,387 (p = 0.04, Mann-Whitney). MUC1 positive cells, irrespective of treatment group, had a greater proportion of cells in S-phase of the cell cycle 27.9% versus 16.8% (p = 0.0004, Mann-Whitney) and demonstrated more cases of aneuploidy 80.65% versus 42.6% (p < 0.0001). MUC1 levels in primary tumours treated neoadjunctively with 3 weeks of tamoxifen were lower than a comparison group which did not receive tamoxifen. MUC1 should be explored further as an intermediate biomarker for assessment of treatment and prognosis.

Endocrine response and resistance in breast cancer: a role for the transcription factor Fos

We have previously demonstrated that elevated Fos expression may be important in de novo endocrine resistance in breast cancer. However, changes in Fos expression during endocrine response and subsequently on acquisition of resistance are unknown. This study immunocytochemically monitors Fos protein within sequential biopsies from primary human breast cancer patients obtained pre-treatment (T1), during tamoxifen therapy (T2, T3) and on disease progression (T5), examining in parallel proliferation [i.e., MIBI (Ki67) immunostaining, mitotic activity], cellularity and endocrine response. Significantly diminished Fos, proliferation and cellularity were observed after 6 weeks of therapy in patients exhibiting a better quality and/or duration of response, while modest Fos increases and a maintained proliferation and cellularity were seen in poorer responders. Decreases in Fos, proliferation and cellularity at 6 months similarly hallmarked better responders. We confirmed a significant association between de novo resistance and elevated Fos and proliferation. Additionally, however, these parameters increased at the time of disease relapse over pre-treatment and "on therapy" values. Our data indicate that tamoxifen response involves a reduction in both tumor cell proliferation and cell survival, potentially entailing diminished Fos protein expression in better-responding patients. Our data are also supportive of elevated Fos expression being involved in the departure from endocrine control inherent in both primary and acquired resistance.

Quantitative changes in cytological molecular markers during primary medical treatment of breast cancer: a pilot study

AIM

To quantify the changes in biological molecular markers during primary medical treatment in patients with operable breast cancer and to assess their possible relationship with response to treatment.

METHODS

The treatment group consisted of 31 patients with operable breast carcinomas, median age 57 years (range 41-67), treated with four 3-weekly cycles of chemotherapy with Mitoxantrone, methotrexate (+/- mitomycin C), and tamoxifen before surgery. Fine needle aspiration (FNA) was used to obtain samples from patients prior to and at 10 or 21 days post-treatment. The following molecular markers were assessed: estrogen receptor (ER), progesterone receptor (PgR), p53, Bcl-2, and Ki67 measured by immunocytochemistry, and ploidy and S-phase fraction (SPF) by flow cytometry. To evaluate the reproducibility of the technique, repeat FNA was performed in a separate non-treatment control group of 20 patients and the same molecular markers assessed, two weeks after the first sample with no intervening treatment.

RESULTS

The non-treatment control group showed a high reproducibility for the measurement of molecular markers from repeat FNA. In the treatment group there was a non-significant reduction in SPF and a significant reduction (p = 0.005) in Ki67. Patients who responded to neoadjuvant therapy were more likely to have a reduction in these two markers than those who failed to respond. Similarly, a reduction in ER scores was observed between the first and second samples (p = 0.04). For PgR, the change between the first and second samples was not significant although there was a significant difference between responders and non-responders (p = 0.03). All nine patients with an increase in PgR were responders. No significant changes in p53 or Bcl-2 were observed during treatment.

CONCLUSION

Molecular markers can be adequately measured from FNA samples prior to and during neoadjuvant therapy. Changes in cellular proliferation and hormone receptors have been shown that may be related to tumour response. These relationships should be assessed in a larger cohort of patients.

Iododeoxyuridine labelling of S-phase fraction in fine needle aspirates from breast carcinomas

The suitability of measuring the S-phase fraction in human breast cancer by labelling tumour cells from fine needle aspirates (FNAs) in vitro with iododeoxyuridine (IdU) was studied in 11 patients. The S-phase fraction was measured both in preoperative FNAs labelled in vitro with IdU, and in FNAs taken from the same tumour when surgically removed after intravenous administration of IdU. Frozen sections were also immunostained for incorporated IdU. The mean S-phase fraction measured in FNAs after in vitro or in vivo labelling and in sections after in vivo labelling was 4.0, 3.6, and 3.1, respectively. Results of in vitro and in vivo labelling of FNAs with IdU were similar. However, as the S-phase fraction in breast cancer is generally low, the variation between the different measurements is too large; therefore, the S-phase fraction is not a suitable indicator of response to treatment.

Comparison of MIB-1 proliferation index with S-phase fraction in human breast carcinomas

The MIB-1 antibody has been raised against recombinant parts of the Ki-67 antigen and, unlike Ki-67, has wider application to routinely fixed specimens. The aim of this study was to compare the usefulness of MIB-1 with S-phase fraction (SPF) as a measure of proliferation. A total of 75 patients with operable breast cancer were studied, 44 (median age 56 years) before any treatment and 31 (median age 68 years) after primary medical hormonal therapy. Sections from formalin-fixed paraffin-embedded tissue were stained with the MIB-1 antibody and a percentage score of positively stained cells obtained. SPF was measured by flow cytometry in fine-needle aspiration samples taken from the same lesion in each patient. Median MIB-1 score was 9% and median SPF was 11.1%. A close correlation was found between MIB-1 score and SPF (rho=0.59, P<0.0001). There was a difference in the strength of the correlation found between the no treatment group and the treatment group, however, 95% confidence intervals for the rho values overlapped, indicating that there was no significant statistical difference. When analysed for ploidy status a correlation was found only in aneuploid tumours. MIB-1 immunostaining can be used as an effective method of assessing proliferation in human breast carcinomas. This can be done using simple, widely available technology and provides the opportunity to perform large-scale retrospective analyses of archival materials.