Simone Detre

Molecular Changes in Tamoxifen-Resistant Breast Cancer: Relationship Between Estrogen Receptor, HER-2, and p38 Mitogen-Activated Protein Kinase

PURPOSE To evaluate growth factor receptor cross talk with the estrogen receptor (ER) in paired clinical breast cancer specimens and in a xenograft model before tamoxifen and at tumor progression as a possible mechanism for tamoxifen resistance. METHODS Specimen pairs from 39 patients were tissue arrayed and stained for ER, progesterone receptor (PgR), Bcl-2, c-ErbB2 (HER-2), and phosphorylated (p) p38 mitogen-activated protein kinase (MAPK), p-ERK1/2 MAPK, and p-Akt. Xenograft MCF-7 tumors before and after tamoxifen resistance were assessed for levels of p-p38. RESULTS Pretreatment, there were strong correlations between ER, PgR, and Bcl-2, and an inverse correlation between ER and HER-2. These correlations were lost in the tamoxifen- resistant tumors and replaced by strong correlations between ER and p-p38 and p-ERK. ER expression was lost in 17% of resistant tumors. Three (11%) of the 26 tumors originally negative for HER-2 became amplified and/or overexpressed at resistance. All ER-positive tumors that overexpressed HER-2 originally or at resistance expressed high levels of p-p38. In the pretreatment and tamoxifen-resistant specimens, there were strong correlations between p-p38 and p-ERK. In the tamoxifen-resistant xenograft tumors, like the clinical samples, there was a striking increase in p-p38. CONCLUSION The molecular pathways driving tumor growth can change as the tumor progresses. Crosstalk between ER, HER-2, p38, and ERK may contribute to tamoxifen resistance and may provide molecular targets to overcome this resistance.

Biomarker Changes During Neoadjuvant Anastrozole, Tamoxifen, or the Combination: Influence of Hormonal Status and HER-2 in Breast Cancer—A Study from the IMPACT Trialists

PURPOSE To investigate the relationships between biomarker changes in breast cancer during neoadjuvant (preoperative) endocrine therapy. PATIENTS AND METHODS The IMPACT trial compared the preoperative use of tamoxifen with anastrozole alone or in combination in postmenopausal women (n = 330) with primary breast cancer. Biomarkers were measured in tumor biopsy specimens taken at baseline, and after 2 and 12 weeks of treatment. RESULTS 52 (93%) of 56, 46 (85%) of 54, and 37 (84%) of 44 patients in the anastrozole, tamoxifen, and combination groups, respectively. There was a significantly greater suppression of Ki67 in the anastrozole-treated group than in the tamoxifen- or combination-treated groups, which is parallel to the greater efficacy seen for anastrozole over these two treatments in the Arimidex, Tamoxifen, Alone or in Combination adjuvant trial. A positive relationship was noted between estrogen-receptor level and Ki67 suppression in all patients. Ki67 was reduced to a greater extent in progesterone receptor-positive tumors compared with progesterone receptor-negative tumors. HER-2-negative tumors tended to show a greater reduction in Ki67 compared with HER-2-positive tumors, but the difference was only significant in the tamoxifen group after 2 weeks, and in the anastrozole group after 12 weeks. CONCLUSION These results confirm the value of Ki67 as a molecular marker, and provide information regarding the relationships between treatment-induced changes in Ki67 and other important biomarkers. Studies such as this should help integrate agents targeted at growth factor signaling with endocrine agents in breast cancer.

A phase II placebo-controlled trial of neoadjuvant anastrozole alone or with gefitinib in early breast cancer.

PURPOSE Increased epidermal growth factor receptor (EGFR) expression may promote breast cancer resistance to endocrine therapy. We have therefore investigated whether neoadjuvant gefitinib, an EGFR inhibitor, might overcome biologic and clinical resistance to neoadjuvant anastrozole in a phase II placebo-controlled trial. PATIENTS AND METHODS Postmenopausal women with stage I to IIIB hormone receptor-positive early breast cancer received anastrozole 1 mg daily for 16 weeks and were randomly assigned at a ratio of 2:5:5 to receive, in addition, gefitinib 250 mg/d orally for 16 weeks: placebo 1 tablet/d orally for 2 weeks and then gefitinib for 14 weeks or placebo for 16 weeks. The primary end point was biologic change in proliferation as measured by Ki67 at 2 and 16 weeks; the main secondary end point was overall objective response (OR). RESULTS Two hundred six women were randomly assigned. Mean changes in Ki67 with anastrozole and gefitinib versus anastrozole alone were -77.4% and -83.6%, respectively, between baseline and 16 weeks (geometric mean ratio = 1.37; 95% CI, 0.79 to 2.39; P = .26), -80.1% and -71.3% between baseline and 2 weeks (geometric mean ratio = 0.70; 95% CI, 0.39 to 1.25; P = .22) and -19.3% and -43% (geometric mean ratio = 1.42; 95% CI, 0.86 to 2.35; P = .16) between 2 and 16 weeks. ORs in the combination and anastrozole alone groups were 48% and 61% (estimated difference = -13.1%; 95% CI, -27.3% to 1.2%), respectively, with a nonsignificant trend against the combination (P = .08) and 48% versus 72% (estimated difference = -24.1%; 95% CI, -45.3% to -2.9%) in the progesterone-receptor-positive subgroup, which was significant (P = .03) and consistent with Ki67 changes. Common treatment-related adverse events included diarrhea, rash, alopecia, dry skin, and nausea. There was no evidence of a pharmacokinetic interaction. CONCLUSION Addition of gefitinib to neoadjuvant anastrozole had no additional clinical or biologic effect, failing to support our original hypothesis.

Reduced apoptosis and proliferation and increased Bcl-2 in residual breast cancer following preoperative chemotherapy.

Experimental laboratory data suggest that tumour growth is a balance between apoptosis and proliferation and that suppression of drug-induced apoptosis by oncogenes such as bcl-2 may be an important cause of intrinsic chemoresistance. The aims of this study were to assess the in vivo relationship of apoptosis to proliferation and Bcl-2 protein in human breast tumours both prior to chemotherapy and in the residual resistant cell population at the completion of treatment. We examined apoptotic index (AI), Ki67 and Bcl-2 protein expression in the tissue of 40 patients with operable breast cancer immediately before ECF preoperative chemotherapy, and in 20 of these patients with residual tumour, at the completion of treatment. There was a significant positive association between AI and Ki67 both before and after chemotherapy, and in their percentage change with treatment. In the residual specimens AI and Ki67 were significantly reduced compared with pre-treatment biopsies, while Bcl-2 expression showed a significant increase. No differences were seen in the pre-treatment levels of any of the variables measured between patients obtaining pathological complete response and those who did not, although numbers were small. These data suggest that apoptosis and proliferation are closely related in vivo. It is possible that the phenotype of reduced apoptosis and proliferation, and increased Bcl-2 may be associated with breast cancer cells resistant to cytotoxic chemotherapy, although this can only be proven by assessing larger numbers of patients in relation to pathological response.

INDUCTION OF APOPTOSIS BY TAMOXIFEN AND ICI 182780 IN PRIMARY BREAST CANCER

Hormonal breast cancer therapies have traditionally been considered cytostatic, but recent pre‐clinical data suggest that anti‐oestrogens can induce apoptosis. The aim of this study was to assess whether tamoxifen (TAM) and ICI 182780 (ICI) could induce apoptosis in human breast cancer, and whether this was related to oestrogen receptor status. We measured apoptosis in primary breast cancer patients before and after pre‐surgical treatment with 20 mg/day TAM (study 1) or 6 or 18 mg/day ICI (study 2). In each study there was a randomised non‐treatment (NT) control group. TAM significantly increased apoptotic index (AI) in ER+ but not in ER− tumours. There was a significant increase in AI following treatment with ICI. Insufficient pairs of samples were available to determine whether this change was confined to ER+ tumours, but in a cross‐sectional analysis AI was significantly higher in excision biopsies for ICI‐treated than NT patients for ER+ but not ER− tumours. Our results provide clinical evidence that apoptosis may be induced in ER+ primary breast cancer by both non‐steroidal and steroidal anti‐oestrogens. Int. J. Cancer 72:608–613, 1997.

Extreme loss of immunoreactive p-Akt and p-Erk1/2 during routine fixation of primary breast cancer

IntroductionVery few studies have investigated whether the time elapsed between surgical resection and tissue fixation or the difference between core-cut and excision biopsies impact on immunohistochemically measured biomarkers, including phosphorylated proteins in primary breast cancer. The aim of this study was to characterise the differences in immunoreactivity of common biomarkers that may occur (1) as a result of tissue handling at surgery and (2) between core-cuts and resected tumours.MethodsCore-cuts taken from surgical breast cancer specimens immediately after resection (sample A) and after routine X-ray of the excised tumour (sample B) were formalin-fixed and paraffin-embedded and compared with the routinely fixed resection specimen (sample C). The variation in immunohistochemical expression of Ki67, oestrogen receptor (ER), progesterone receptor (PgR), human epidermal growth factor 2 (HER2), p-Akt and p-Erk1/2 were investigated.ResultsTwenty-one tissue sets with adequate tumour were available. Median time between collection of core-cuts A and B was 30 minutes (range, 20 to 80 minutes). None of the markers showed significant differences between samples A and B. Similarly, Ki67, ER, PgR and HER2 did not differ significantly between core-cuts and main resection specimen, although there was a trend for lower resection values for ER (P = 0.06). However, p-Akt and p-Erk1/2 were markedly lower in resections than core-cuts (median, 27 versus 101 and 69 versus 193, respectively; both P < 0.0001 [two-sided]). This difference was significantly greater in mastectomy than in lumpectomy specimens for p-Erk1/2 (P = 0.01).ConclusionsThe delay in fixation in core-cuts taken after postoperative X-ray of resection specimens has no significant impact on expression of Ki67, ER, PgR, HER2, p-Akt or p-Erk1/2. However, extreme loss of phospho-staining can occur during routine fixation of resection specimens. These differences are likely attributable to suboptimal fixation and may have major repercussions for clinical research involving these markers.

Proliferation and Apoptosis as Markers of Benefit in Neoadjuvant Endocrine Therapy of Breast Cancer

The study of changes in proliferation as a marker of treatment benefit during presurgical endocrine treatment of breast cancer has become increasingly popular, particularly using the nuclear marker Ki67, and holds the potential for prioritizing new treatments for full clinical development. There are weakly significant relationships between Ki67 change and clinical response that differ according to data handling. In the neoadjuvant Immediate Preoperative Anastrozole, Tamoxifen, or Combined with Tamoxifen trial, suppression of Ki67 at both 2 and 12 weeks was greater with the aromatase inhibitor anastrozole than with either tamoxifen or the combination of anastrozole and tamoxifen. We report here that absolute values of Ki67 after 2 weeks were also significantly lower with anastrozole than with tamoxifen and the combination. This indicates that it may be possible to make such comparisons using surgical samples only. We argue that these changes in proliferation and concurrent changes in apoptosis may be expected to be more predictive of adjuvant benefit from endocrine therapy than clinical response.

Lapatinib Restores Hormone Sensitivity with Differential Effects on Estrogen Receptor Signaling in Cell Models of Human Epidermal Growth Factor Receptor 2–Negative Breast Cancer with Acquired Endocrine Resistance

Purpose: Acquired endocrine resistance in estrogen receptor (ER)α+/human epidermal growth factor receptor 2–negative (HER2−) breast cancer has been associated with modest adaptive increases in HER2, although exactly how aberrant HER2 signaling affects the ERα pathway is poorly understood. We investigated (a) whether the epidermal growth factor receptor/HER2 inhibitor lapatinib could restore endocrine responsiveness in cell models of acquired endocrine resistance with modest increases in HER2, and (b) the nature of ERα-HER2 cross-talk in this process. Methods: Combination growth studies, ERα transcription, immunoblot, and gene expression assays were conducted in two models of acquired resistance to (a) estrogen deprivation (long-term estrogen-deprived cells) and (b) tamoxifen (long-term tamoxifen-treated cells), and in hormone sensitive controls. Changes in ERα, PgR, and HER2 were assessed in samples from patients treated with tamoxifen. Results: Both cell models of acquired endocrine resistance showed modest adaptive upregulation in HER2, and lapatinib restored endocrine sensitivity in both. The effect of lapatinib on ERα signaling varied markedly depending on the nature of the HER2/ERα cross-talk. In long-term estrogen-deprived cells characterized by enhanced ERα function, lapatinib suppressed ERα genomic activity (as measured by pERSer118, ERα transcriptional activity, and PGR gene expression). In contrast, in long-term tamoxifen-treated cells with reduced ERα activation, lapatinib reactivated ERα genomic function. Twenty percent of tamoxifen-resistant patients relapsed with modest increases in HER2 and either suppressed or enhanced ERα/PgR expression. Conclusions: Aberrant GFR signaling can augment or suppress ERα function. Regardless, interrupting the HER2/ERα cross-talk with lapatinib can restore endocrine sensitivity and should be investigated as a therapeutic strategy in combination with endocrine therapy in ERα+/HER2− patients with acquired endocrine resistance. Clin Cancer Res; 16(5); 1486–97

Evaluation of Ki-67 proliferation and apoptotic index before, during and after neoadjuvant chemotherapy for primary breast cancer

IntroductionBiological markers that reliably predict clinical or pathological response to primary systemic therapy early during a course of chemotherapy may have considerable clinical potential. This study evaluated changes in Ki-67 labeling index and apoptotic index (AI) before, during, and after neoadjuvant anthracycline chemotherapy.MethodsTwenty-seven patients receiving neoadjuvant FEC (5-fluorouracil, epirubicin, and cyclophosphamide) chemotherapy for operable breast cancer underwent repeat core biopsy after 21 days of treatment. Tissue from pre-treatment biopsy, day 21 and surgery was analysed for Ki-67 index and AI.ResultsThe objective clinical response rate was 56%. Eight patients (31%) achieved a pathological response by histological criteria; two patients had a near-complete pathological response. A reduction in Ki-67 index was observed in 68% of patients at day 21 and 72% at surgery; Ki-67 index increased between day 21 and surgery in 54%. AI decreased in 50% of tumours by day 21, increased in 45% and was unchanged in one patient; 56% demonstrated rebound increases in AI by the time of surgery. Neither pre-treatment nor post-chemotherapy median Ki-67 index nor median AI at all three time points or relative changes at day 21 and surgery differed significantly between clinical or pathological responders and non-responders. Clinical responders had lower median Ki-67 indices at day 21 (11.4% versus 27.0%, p = 0.02) and significantly greater percentage reductions in Ki-67 at day 21 than did non-responders (-50.6% versus -5.3%, p = 0.04). The median day-21 Ki-67 was higher in pathological responders (30.3% versus 14.1%, p = 0.046). A trend toward increased AI at day 21 in pathological responders was observed (5.30 versus 1.68, p = 0.12). Increased day-21 AI was a statistically significant predictor of pathological response (p = 0.049). A strong trend for predicting pathological response was seen with higher Ki-67 indices at day 21 and AI at surgery (p = 0.06 and 0.06, respectively).ConclusionThe clinical utility of early changes in biological marker expression during chemotherapy remains unclear. Until further prospectively validated evidence confirming the reliability of predictive markers is available, clinical decision-making should not be based upon individual biological tumour marker profiles.

Changes in breast cancer biomarkers in the IGF1R/PI3K pathway in recurrent breast cancer after tamoxifen treatment

Development of resistance to the antioestrogen tamoxifen occurs in a large proportion of patients with oestrogen receptor-positive (ER+) breast cancer and is an important clinical challenge. While loss of ER occurs in c.20% of tamoxifen-resistant tumours, this cannot be the sole explanation for tamoxifen treatment failure. PI3K pathway activation, including by insulin-like growth factor receptor 1 (IGF1R), has been implicated in some resistance models. The primary aim was to determine whether evidence exists in clinical breast cancer for a role of IGF1R and/or the PI3K pathway, in acquisition of resistance to tamoxifen. Invasive primary and recurrent tamoxifen-resistant tumours from the same patient (n=77) were assessed for changes in ER, progesterone receptor (PgR), human epidermal growth factor receptor 2 (HER2), IGF1R, stathmin, PTEN expression and PIK3CA mutations where possible. ER and PgR levels were significantly reduced at recurrence with 22 and 45%, respectively, showing negative status at this time. Acquisition of HER2 overexpression occurred in 6% of cases. IGF1R expression was significantly reduced in both ER+ and ER- recurrences and stathmin levels increased. A positive association between stathmin and IGF1R emerged in recurrent samples, despite their opposing relationships with ER, suggesting some coalescence of their activities may be acquired. The data confirm loss of ER and PgR and gain of HER2 in some tamoxifen-resistant tumours. There is no evidence for IGF1R gain in tamoxifen resistance; increases in stathmin levels suggest that activation of the PI3K pathway may have contributed, but PTEN loss and PIK3CA hotspot mutations were relatively rare.