Abstract P1-02-02: FASN inhibition by TVB-3166 associates with breast cancer subtype

Fatty acid synthase (FASN) is overexpressed in numerous tumor types, including breast carcinomas, and promotes changes in the genetic program controlling lipid biosynthesis. While inhibiting FASN appears to be an attractive therapeutic approach under development, the success of this approach may depend on the identification of tumor subtypes with specific metabolic requirements. Applying a comprehensive profile of circulating tumor cells (CTC) using canonical pathway gene sets, we identified a correlation of metabolic subtypes with breast tumor subtype. A lipogenic subtype is strongly associated with Luminal A subtype, whereas the glycolytic subtype associated with Luminal B tumors. The triple negative subtype was more heterogeneous and had the expression of both sets of gene. Such a difference in the metabolic profile may dictate differential sensitivity to inhibitors targeting de novo lipid synthesis, including FASN. This was supported by in vitro studies using selective FASN inhibitor, TVB-3166. Exposure to TVB-3166 over 14 days incubation in Advanced MEM with 1% charcoal-stripped FBS selectively inhibited growth and viability of Luminal A breast cancer cells, but had no effect on Luminal B subtype. This was further confirmed in short-term patient derived cultures. Mechanistic studies suggest that TVB-3166 quickly disrupts FA synthesis leading to the disruption of the lipid raft architecture and tumor cell death through an apoptotic mechanism. In conclusion, our findings highlight that success of targeting cancer metabolism directly may depend on identification of tumor subtypes with specific metabolic requirements.

Citation Format: Gruslova AB, Chen C-L, Wang C-M, Elledge RM, Kaklamani VG, Lathrop K, Huang TH, Brenner A. FASN inhibition by TVB-3166 associates with breast cancer subtype [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-02-02.

EGFR expression in breast cancer: Association with biologic phenotype, prognosis, and resistance to adjuvant therapy

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Background: Expression of the epidermal growth factor receptor (EGFR) in preclinical models of breast cancer is associated with increased proliferation and resistance to apoptosis. In clinical studies, EGFR has been inconsistently linked to poor outcome. We hypothesized that EGFR expression, when objectively and uniformly assessed, is associated with an aggressive biologic phenotype and resistance to systemic adjuvant therapy. Methods: In a database of 54,865 patients with breast cancer, EGFR status was known on 2,567. EGFR levels were measured centrally by ligand binding assay performed on frozen tissue. Tumors with ≥10 fmol/mg of cytosol protein were prospectively deemed positive. Clinical and biological features of EGFR positive and negative tumors were compared. Disease-free survival (DFS) and overall survival (OS) were assessed in systemically untreated patients (untreated patients, n=1068) and those who received hormonal and/or chemotherapy (treated patients, n=1256). Results: 475 out of 2,567 tumors (18.5%) were EGFR positive. Compared to EGFR negative tumors, EGFR positive tumors were more common in younger (<50 years, 40% vs 24% p<0.0001), premenopausal (20% vs 10%, p<0.0001), and black women (10% vs 6% p=0.005). EGFR expression was associated with larger tumors (64% vs 46%, p<0.0001), aneuploidy (68% vs 46%, p<0.0001), high S-phase fraction (53% vs 22%, p<0.0001), and nodal involvement (43% vs 37%, p=0.009). Co-expression of other biomarkers was also studied. EGFR positive tumors were more likely to be HER2 positive (26% vs 16%, p<0.0001), but less likely to be ER positive (60% vs 88%, p<0.0001), and PR positive (26% vs 65%, p<0.0001). In a multivariate analysis, EGFR expression independently correlated with worse DFS (HR=1.6, 95%CI=1.2–2.2, p=0.001) and OS (HR=1.7, 95% CI=1.2–2.4, p=0.001) in treated patients, but not in untreated patients. Conclusions: EGFR expression is more common in breast tumors in young and black women. It is associated with lower hormone receptor levels, higher proliferation, genomic instability, nodal involvement, and HER2 over-expression. It is correlated with significant resistance to adjuvant hormonal and chemotherapy. Blocking EGFR activity may help overcome this resistance in selected patients.

No significant financial relationships to disclose.

Idoxifene versus tamoxifen: a randomized comparison in postmenopausal patients with metastatic breast cancer

BACKGROUND

More efficacious and safer hormonal agents are needed for breast cancer treatment and prevention. Idoxifene is a novel selective estrogen receptor modulator (SERM) that, in preclinical models, has greater antiestrogenic but lower estrogenic activity than tamoxifen.

PATIENTS AND METHODS

Three hundred and twenty-one postmenopausal patients with hormone receptor-positive or -unknown metastatic breast cancer were randomized to receive either tamoxifen or idoxifene as initial endocrine therapy for advanced disease. Data were analyzed based on intention to treat and all the responses were subject to independent review.

RESULTS

At the time of a second planned interim analysis, the trial was stopped for economic considerations, not for reasons related to safety or efficacy. Complete data for the 219 patients included in the second interim analysis are fully available and reported here. Median age was 59.1 years for idoxifene patients and 59.9 years for tamoxifen patients. Complete response (CR) plus partial response (PR) rates were as follows: tamoxifen, 9%; idoxifene, 13% (P = 0.39). Clinical benefit rate [CR + PR + stable disease (SD) >or=6 months] was 34.3% for idoxifene and 38.7% for tamoxifen (P = 0.31). Median time to progression and duration of response were 140 days and 151.5 days, respectively, for tamoxifen compared with 166 days and 218 days for idoxifene. None of these endpoints was significantly different for the two drugs, nor was survival. Adverse events (lethal, serious but not lethal and important but not life threatening) were similar in the two arms.

CONCLUSIONS

Idoxifene was both active and well tolerated in postmenopausal women with metastatic breast cancer. Idoxifene had similar efficacy and toxicity to tamoxifen in this randomized comparison.

Ductal lavage for detection of cellular atypia in women at high risk for breast cancer

BACKGROUND

Breast cancer originates in breast epithelium and is associated with progressive molecular and morphologic changes. Women with atypical breast ductal epithelial cells have an increased relative risk of breast cancer. In this study, ductal lavage, a new procedure for collecting ductal cells with a microcatheter, was compared with nipple aspiration with regard to safety, tolerability, and the ability to detect abnormal breast epithelial cells.

METHODS

Women at high risk for breast cancer who had nonsuspicious mammograms and clinical breast examinations underwent nipple aspiration followed by lavage of fluid-yielding ducts. All statistical tests were two-sided.

RESULTS

The 507 women enrolled included 291 (57%) with a history of breast cancer and 199 (39%) with a 5-year Gail risk for breast cancer of 1.7% or more. Nipple aspirate fluid (NAF) samples were evaluated cytologically for 417 women, and ductal lavage samples were evaluated for 383 women. Adequate samples for diagnosis were collected from 111 (27%) and 299 (78%) women, respectively. A median of 13,500 epithelial cells per duct (range, 43-492,000 cells) was collected by ductal lavage compared with a median of 120 epithelial cells per breast (range, 10-74,300) collected by nipple aspiration. For ductal lavage, 92 (24%) subjects had abnormal cells that were mildly (17%) or markedly (6%) atypical or malignant (<1%). For NAF, corresponding percentages were 6%, 3%, and fewer than 1%. Ductal lavage detected abnormal intraductal breast cells 3.2 times more often than nipple aspiration (79 versus 25 breasts; McNemar's test, P<.001). No serious procedure-related adverse events were reported.

CONCLUSIONS

Large numbers of ductal cells can be collected by ductal lavage to detect atypical cellular changes within the breast. Ductal lavage is a safe and well-tolerated procedure and is a more sensitive method of detecting cellular atypia than nipple aspiration.

Clinical management of women with genomic BRCA1 and BRCA2 mutations

PURPOSE

There is increasing evidence that BRCA1 and BRCA2 associated tumors may differ from sporadic cancers. The purpose of this report is to review the current state of knowledge of BRCA1 and BRCA2, the biology of associated tumors, and possible risk reduction strategies in women with these deleterious mutations.

DESIGN AND METHODS

We conducted an extensive literature search of all published articles (including Medline) on preclinical data on the function of BRCA1 and BRCA2, associated tumor pathology, and the clinical management for both unaffected carriers and affected patients.

RESULTS

BRCA1 and BRCA2 are likely to act as tumor suppressor genes, and together with RAD51 operate in a common DNA damage response pathway implicated in double-strand repair. Breast cancers associated with BRCA1 are frequently of a higher grade, steroid hormone receptor negative, and appear to have a higher proportion of atypical or typical medullary subtype. Conversely, BRCA2 associated breast cancers do not differ significantly from sporadic cancers. No special tumor phenotype has been ascribed to BRCA1 or BRCA2 associated ovarian cancers. Guidelines for risk reduction strategies for the high risk unaffected carrier have been recommended by expert panels in the USA and Europe. Lifestyle changes, multi-modality screening, chemoprevention, and prophylactic oophorectomy and mastectomy, with their possible benefits and attendant risks are described. Finally, locoregional and systemic treatment in breast and ovarian cancers associated with these mutations, and differences between these and sporadic cancers are discussed.

CONCLUSIONS

Although the incidence of breast or ovarian cancers that can be attributed to BRCAI or BRCA2 mutations account for less than 5% of all cancers, these cancers may differ from sporadic cases in terms of tumor biology and phenotype. These differences may impact directly on clinical management of breast and ovarian cancer patients, and their relatives. Further recommendations of these patients are constantly changing as new information emerges on the clinical behavior of these cancers.

Prognostic value of p53 for local failure in mastectomy-treated breast cancer patients

PURPOSE

The loss of p53 function is a recognized adverse prognostic factor in invasive breast cancer. Several studies have shown a relationship between the nuclear accumulation of p53 protein (a surrogate marker of p53 inactivation) and poor disease-free and overall survival. In general, however, these studies did not report the prognostic value of p53 for local failure, which we have therefore assessed retrospectively here.

MATERIALS AND METHODS

Accumulation of p53 protein was evaluated by immunohistochemistry in 1,530 mastectomy-treated breast cancer patients (259 radiation therapy [RT]- and 1,271 mastectomy only [No RT]-treated patients). Statistical comparisons were made between p53 protein accumulation, estrogen/progesterone receptors, nodal status, tumor size, and local failure rate (LFR). Local failure was defined as tumor recurrence involving the chest wall and/or the ipsilateral supraclavicular/axillary lymph nodes. The median follow-up period was 62 months.

RESULTS

In the No RT group, the LFR was 9.1% and 16. 5% in p53-negative and p53-positive patients, respectively (P<.001). Multivariate analysis revealed that p53 protein accumulation was significantly associated with an increased risk of local relapse (relative risk [RR], 1.7; 95% confidence interval [CI], 1.2 to 2.4). Nodal status and tumor size were also significant factors. In the RT group, the LFR was 9.3% and 21.5% in p53-negative and p53-positive patients, respectively (P = .009). Multivariate analysis revealed that p53 protein accumulation was significantly associated with an increased risk of local relapse (RR, 2.5; 95% CI, 1.1 to 5.7), as was nodal status.

CONCLUSION

Nuclear accumulation of p53 protein is independently associated with a significantly increased local failure rate in breast cancer patients treated with mastectomy, with or without radiation.

Estrogen receptor (ER) and progesterone receptor (PgR), by ligand-binding assay compared with ER, PgR and pS2, by immuno-histochemistry in predicting response to tamoxifen in metastatic breast cancer: a Southwest Oncology Group Study

Results of estrogen receptor (ER) and progesterone receptor (PgR) ligand-binding assays (LBAs) are strongly correlated with ER and PgR by immuno-histochemistry (IHC). To investigate whether ER and PgR by IHC are also strongly correlated with tamoxifen response, time to treatment failure (TTF) and overall survival (OS), the results of the 2 methods were directly compared in 205 patients with ER(+) metastatic breast cancer treated with daily tamoxifen (Southwest Oncology Group protocol 8228) with 9 years median follow-up. pS2, another estrogen-regulated molecule, was also analyzed. Tumors were scored for IHC from 0 to 5, according to the proportion of positively stained cells. These IHC scores for both ER and PgR were significantly associated with LBA levels (p < 0.001). There was a significant direct relationship between higher IHC ER, PgR and pS2 and increasing response to tamoxifen. TTF and OS were also significantly longer for patients with higher ER or PgR, but not pS2, IHC scores. Low, intermediate and high ER or PgR categories showed similar differences in response rates whether defined by LBA or IHC. In logistic regression models which included ER, PgR and pS2 by IHC; ER and PgR by LBA; and menopausal status, only ER (IHC) and pS2 (IHC) retained significance for predicting tamoxifen response (p = 0. 02 and p = 0.005, respectively), along with menopausal status (for PgR by IHC, p = 0.09). Increasing ER and PgR by IHC, as by LBA, are thus significantly associated with a progressively better response and longer survival in ER(+) metastatic breast cancer. pS2 is also predictive in this setting.

Tumor characteristics and clinical outcome of elderly women with breast cancer

BACKGROUND

The number of elderly patients with breast cancer is increasing. Limited age-related information available about this disease prompted this study.

PATIENTS AND METHODS

The study population was derived from 50828 and 256287 patients with invasive breast cancer in San Antonio breast cancer databases and the Surveillance, Epidemiology, and End Results (SEER) registry, respectively. Tumor biologic and clinical characteristics, local and systemic therapies, and survival according to the patient's age were analyzed. Survival was also compared with that of age-matched women from the general population.

RESULTS

In patients 55 years old or older, there was an association between increasing age at diagnosis and the presence of more favorable biologic characteristics of the tumor, including more tumors that express steroid receptors, lower proliferative rates, diploidy, normal p53, and absence of the expression of epidermal growth factor receptor and c-erbB2. In older patients with lymph node-negative disease and/or small tumors, the observed and expected survivals were almost identical. In the SEER registry, the 8-year survival of lymph node-negative patients relative to the expected survival of age-matched women from the general population was 1.01 (95% confidence interval [CI] = 0.98-1. 04) for patients 70-74 years old, 1.06 (95% CI = 1.01-1.11) for patients 75-79 years old, and 1.09 (95% CI = 0.98-1.20) for patients 80-84 years old.

CONCLUSION

In women 55 years old or older, advancing age is associated with more favorable tumor biology, and breast cancer survival in older women is similar to survival in the general population irrespective of disease status. This favorable outcome should be considered when making clinical decisions in older patients.

Tumor characteristics and clinical outcome of tubular and mucinous breast carcinomas

PURPOSE

To comprehensively characterize the clinical and biologic features of tubular and mucinous carcinomas in a large cohort of patients and to relate this to clinical outcome and management.

PATIENTS AND METHODS

The clinical and biologic features of 444 patients with tubular and 1,221 patients with mucinous carcinomas were compared with those of 43,587 patients with infiltrating ductal carcinoma, not otherwise specified (NOS). Disease-free survival (DFS) and overall survival (OS) for patients with tubular and mucinous carcinomas were compared with those of patients with NOS carcinomas and with age-matched sets from the general population.

RESULTS

Tubular and mucinous carcinomas were more likely to occur in older patients, be smaller in size (tubular only), have substantially less nodal involvement, be estrogen receptor- and progesterone receptor-positive, have a lower S-phase fraction, be diploid, and be c-erbB-2- and epidermal growth factor receptor-negative compared with NOS carcinomas. Axillary node involvement was a poor prognostic feature in mucinous but not tubular carcinomas. Mucinous carcinomas < or = 1 cm had a < or = 5% incidence of node involvement. The 5-year DFS and OS were 94% and 88% for tubular, 90% and 80% for mucinous, and 80% and 77% for NOS carcinoma, respectively (P < .001 for differences among all three types for both DFS and OS). The 5-year OS of females from the general population age-matched to the patients with tubular and mucinous carcinomas was 89% and 82%, respectively, which is not different from the OS of patients with tubular or mucinous carcinomas.

CONCLUSION

The biologic phenotype of tubular and mucinous carcinomas is quite favorable. Consistent with this observation, the survival of patients with tubular and mucinous carcinomas is similar to that of the general population. Systemic adjuvant therapy and node dissection may be avoided in many patients with these special types of carcinoma.

Prognostic and predictive value of p53 and p21 in breast cancer

The prognostic and predictive value of p53 has been extensively studied in breast cancer. p53 serves a multifunctional role as a transcriptional regulator, genomic stabilizer, inhibitor of cell cycle progression, facilitator of apoptosis, and also perhaps an inhibitor of angiogenesis. Abrogation of its function should therefore lead to a more aggressive breast cancer phenotype and a worse clinical outcome, and indeed the preponderance of studies confirm this, with the risk of recurrence and death increasing by 50% or more if p53 is abnormal. Lack of unanimity of results may be due to differences in technique, study design, or population, as well as the subjectivity inherent in some approaches; however, the complexity and random nature of genomic change present in cancer cells may well also contribute to the lack of unanimity. Because many anticancer agents may exert a therapeutic effect through genomic damage and subsequent triggering of apoptosis, and because p53 can respond to genomic damage and facilitate apoptosis, it can be hypothesized that an intact p53 would predict sensitivity to therapy. Present data in breast cancer, however, does not clearly indicate that this is the case. There are several potential explanations. Study designs to accurately test the predictive value of a molecular marker are more exacting and difficult to achieve than prognostic studies. There may also be multiple alternative pathways, not involving p53, that play a part in determining the therapeutic effect of a treatment. The prognostic value of a downstream effector of p53 has also been assessed, though less extensively. p21 is transcriptionally upregulated by p53 and is an inhibitor of cyclin-dependent kinases and thus of cell cycle progression. Higher levels of p21 might indicate a more indolent type of breast cancer. However, data from a number of clinical studies is very conflicting, and at present p21 is not a promising prognostic factor in breast cancer.

Models for early chemoprevention trials in breast cancer

Several models are being explored for use in the phase I and phase II evaluation of breast cancer chemoprevention agents. The short-term DCIS/small invasive cancer model is probably best used in late phase I trials in conjunction with agents likely to have activity in the progression phase of neoplastic development in addition to activity in earlier phases. The core biopsy or FNA hyperplasia models may be best used with drugs that are likely to have activity primarily in the promotion phase of neoplastic development and that are suitable for longer duration trials lasting several months to years. Morphology currently is the key surrogate endpoint biomarker for assessing efficacy in phase II trials. Other biomarkers that may undergo modulation will have to be validated, in that modulation will have to be shown to be directly related to decreased cancer risk in subsequent phase III trials. Only then can they be considered as validated surrogate endpoint biomarkers and used as stand-alone efficacy markers in phase II trials. Despite accrual challenges and technologic hurdles, interest in phase I and phase II chemoprevention trials is high.

Heat shock proteins hsp27 and hsp70: lack of correlation with response to tamoxifen and clinical course of disease in estrogen receptor-positive metastatic breast cancer (a Southwest Oncology Group Study)

In this study, we tested the hypothesis that heat shock proteins (hsps) 27 and 70 are associated with clinical resistance to tamoxifen. hsp27 is, like progesterone receptor, an estrogen-regulated protein. hsp70 is also of interest because of its interaction with estrogen receptors and because hsp70 is a component of the molecular chaperone machinery functioning in the assembly and trafficking of steroid receptors. In addition, hsps in general help protect cells against noxious stimuli and stress, and their expression has been linked to drug resistance. The study involved 205 tumors from estrogen receptor-positive tamoxifen-treated breast cancer patients with metastatic disease. All patients received daily tamoxifen as initial therapy for metastatic disease. The study began in 1982, and follow-up is now 9 years. hsp27 and hsp70 were detected by immunohistochemistry and scored according to the nuclear and/or cytoplasmic content. Expression of hsp27 or hsp70 was unrelated to estrogen receptor content, progesterone receptor content, menopausal status, age, and presence of visceral disease. Cytoplasmic and nuclear hsp27 positivities were weakly and inversely related to each other (P = 0.05). There was a significant association between cytoplasmic hsp27 and cytoplasmic hsp70 content (P < 0.001), as well as between nuclear hsp70 and nuclear hsp27 content (P = 0.001). Cytoplasmic and nuclear hsp70 were also associated (P = 0.02). However, increased hsp27 and hsp70 expression (nuclear or cytoplasmic) was not significantly associated with response to tamoxifen, time to treatment failure, or survival. Thus, this study clarifies the lack of clinical utility of hsp27 and hsp70 in predicting the response to tamoxifen in an estrogen receptor-positive breast cancer population.

Radiation therapy and survival in breast cancer patients with 10 or more positive axillary lymph nodes treated with mastectomy

PURPOSE

Adjuvant loco-regional radiation (XRT) frequently is recommended after mastectomy and adjuvant systemic therapy in patients with 10 or more positive axillary lymph nodes (ALN) to reduce the high loco-regional failure rate observed in this subset. In this study, we explored the possibility that adjuvant loco-regional radiation therapy (LR-XRT) also could decrease distant failure and improve overall survival (OS) in this subset of poor-prognosis patients.

PATIENTS AND METHODS

Retrospectively, 618 breast patients with 10 or more positive ALN were studied. The median follow-up time was 7.5 years. All patients received systemic adjuvant therapy and 35% also received adjuvant radiation therapy. Loco-regional failure, distant failure, and OS analyses were adjusted for age, tumor size, number of positive ALN, and estrogen receptor (ER) status using Cox regression model.

RESULTS

As expected, patients had a very high risk of loco-regional and distant failure. At 5 years, 30% of patients had loco-regional failure as a first event and 54% had distant failure. Radiation dramatically reduced loco-regional failure (hazards rate ratios [RR]=0.29; 95% confidence interval [CI], 0.19 to 0.45). The adjusted 5-year loco-regional failure rate was 13% with radiation and 38% without radiation (P=.0001). Radiation also was associated with improved distant control (RR=0.75; 95% CI, 0.58 to 0.96). The adjusted 5-year distant failure rate was 48% with radiation and 58% without radiation (P=.02). OS also improved with radiation (RR=0.68; 95% CI, 0.53 to 0.85). The adjusted 5-year OS was 56% with radiation and 42% without radiation (P=.001).

CONCLUSION

In this cohort of high-risk breast cancer patients, XRT was associated with less loco-regional and distant failure and improved OS. This suggests that improved loco-regional control might decrease secondary systemic spread and improve survival.

bcl-2 and apoptosis in lymph node positive breast carcinoma

BACKGROUND

Because bcl-2 can block apoptosis in vitro, and because lower levels of apoptosis might lead to malignant cell accumulation and therefore to a more aggressive clinical course, the authors tested the hypothesis that high bcl-2 and low apoptosis would result in a worse prognosis for breast carcinoma patients.

METHODS

Primary breast tumor specimens from 979 patients with positive axillary lymph nodes were evaluated for bcl-2 protein expression by immunohistochemistry (IHC). Apoptosis was evaluated by using IHC to detect 3' DNA fragments end-labeled with biotinylated uridine. Results were analyzed with respect to patient characteristics, prognostic factors, and clinical outcome. Median follow-up was 61 months.

RESULTS

High bcl-2 expression was significantly associated with a number of favorable prognostic factors, including a lower number of positive lymph nodes, absence of p53 protein accumulation, estrogen receptor (ER) and progesterone receptor (PR) positivity, diploidy, and a lower proliferative rate. However, although bcl-2 is generally considered a negative regulator of apoptosis, in these tumors there was no significant association between bcl-2 and apoptosis. Patients with high bcl-2 expression had significantly improved disease free survival (DFS) (P < 0.0001) and overall survival (OS) (P < 0.0001). In a multivariate analysis, bcl-2 expression was independently associated with better DFS (P = 0.004). Regarding apoptosis, the presence of > or = 1% apoptotic cells was significantly associated with a greater number of positive lymph nodes, p53 protein expression, ER and PR negativity, aneuploidy, and a higher proliferation rate, although there was no significant association with a worse clinical outcome when this dichotomized cutoff was used.

CONCLUSIONS

For lymph node positive breast carcinoma patients, high bcl-2 expression is associated with a number of good prognostic factors and is independently associated with better clinical outcome. Apoptosis is associated with a number of poor prognostic factors but not with a significantly worse outcome.

HER-2 expression and response to tamoxifen in estrogen receptor-positive breast cancer: a Southwest Oncology Group Study

HER-2/neu is a growth factor receptor, the expression of which has been associated with a more aggressive breast tumor biology and resistance to some types of chemotherapy. Preliminary laboratory and clinical data have led to claims that HER-2/neu expression is also associated with resistance to tamoxifen. Therefore, to test the hypothesis that HER-2/neu expression is associated with a poorer response to tamoxifen, a shorter time to treatment failure (TTF), and worse survival in estrogen receptor (ER)-positive metastatic breast cancer, we examined 205 paraffin-embedded blocks of tumors from patients enrolled on Southwest Oncology Group 8228 for HER-2/neu expression. Tumors were ER positive (ER level > 3 fmol/mg cytosolic protein in either primary tumors or metastases), and patients had not received any prior therapy for metastatic disease. All patients were treated with daily tamoxifen. The study began in 1982, and median follow-up of patients who are still alive is now 9 years. Membrane staining for HER-2/neu was evaluated by immunohistochemistry using antibody TAB 250 and was scored according to the proportion of cells staining positive; tumors were deemed positive if > 1% of the cells stained for HER-2/neu. HER-2/neu positivity was associated with lower ER values (P = 0.04) and low bcl-2 (P = 0.01). HER-2/neu positivity was not significantly associated with response rate (negative versus positive, 57 versus 54%; P = 0.67), TTF (median, 8 versus 6 months; P = 0.15), or survival (median, 31 versus 29 months; P = 0.36). There was also no significant evidence of a progressive relationship between an increasing proportion of cells expressing HER-2/neu and a shorter TTF or survival. HER-2/neu expression in ER-positive metastatic breast cancer is not significantly associated with a poorer response to tamoxifen or a more aggressive clinical course. Earlier suggestions to the contrary may have been due to failure to rigorously exclude ER-negative tumors, which are much less likely to respond to tamoxifen and more likely to have high HER-2/neu levels.

bcl-2, p53, and response to tamoxifen in estrogen receptor-positive metastatic breast cancer: a Southwest Oncology Group study

PURPOSE

To test the hypothesis that high bcl-2 expression and accumulation of p53 protein, both of which should inhibit apoptosis, are associated with a poorer tamoxifen response and a more aggressive clinical course in estrogen receptor (ER)-positive metastatic breast cancer.

METHODS

A total of 205 paraffin-embedded tumor blocks were evaluated for nuclear p53 (a marker of p53 inactivation) and cytoplasmic bcl-2 by immunohistochemistry (IHC). All patients received tamoxifen as initial therapy for metastatic disease. The study began in 1982 and follow-up duration of the 24 patients last known alive is 8 years.

RESULTS

Response to tamoxifen and time to treatment failure (TTF) were not significantly associated with p53 status, although patients with higher p53 had a worse survival (P = .008; median, 36 v 20 months). Higher bcl-2 expression was associated with higher levels of ER (P = .02), better response to tamoxifen (62% v 49%; P = .07), longer TTF (median, 9 v 5 months; P = .002), and better survival (median, 40 months v 25 months; P = .009). In multivariate analyses, including ER, progesterone receptor (PgR), and p53, high bcl-2 remained significantly associated with a longer TTF (P = .007) and survival (P = .07). p53 status was a significant factor for shorter survival (P = .05), but not for TTF (P = .61).

CONCLUSION

p53 status, as determined by IHC is not significantly associated with response to tamoxifen, although tumors with altered p53 protein are inherently more aggressive. Contrary to expectation, high bcl-2 identifies a relatively indolent phenotype of ER-positive metastatic breast cancer, in which patients experience a better clinical response to tamoxifen and a longer survival.

WAF1/CIP1 protein expression in human breast tumors

WAF1/CIP1 is a cyclin-dependent kinase inhibitor which is directly induced by p53 and negatively controls cell proliferation. To test the hypothesis that increased levels of WAF1 would be associated with a lower S-phase fraction and better prognosis, WAF1 protein was assessed by immunohistochemistry (IHC) in 115 node-negative human breast tumors, and results were correlated with established prognostic factors and clinical outcome. Nuclear staining was observed in malignant cells in 43% of tumors. In most (90%) of the positive tumors, the proportion of cells staining for WAF1 was low (< 10%). WAF1 was not detected in the cytoplasm, or in non-malignant epithelium. Contrary to expectations, the accumulation of p53 protein, a surrogate marker of p53 inactivation, was weakly but positively associated with WAF1 expression (p = 0.05). Surprisingly, there was no significant correlation with S-phase fraction, ER or PgR status, tumor size, age, ploidy, nuclear grade, or survival.

CONCLUSION

WAF1 expression is found in the nuclei of a small fraction of cells in human breast tumors. WAF1 status is not significantly associated with cell proliferation, other established prognostic factors, or clinical outcome.

Life and death by p53

p53 is a multifunctional protein which plays a role in modulating gene transcription, policing cell cycle checkpoints, activating apoptosis, controlling DNA replication and repair, maintaining genomic stability and responding to genetic insults. Mutation of the p53 gene confers the single greatest known selective advantage favoring cancer formation. Point mutations result not only in the loss of tumor suppressor functions, but also in the gain of tumor promotion functions. These dual circumstances may be unique to p53 and, in part, could explain the relatively powerful force behind this selection pressure. General mechanisms of gain of function by mutated p53 may include alteration in transcriptional modulation and newly acquired targets for transcriptional regulation and protein binding. Despite the direct significance of p53 mutations, loss of the remaining wild-type allele is usually required for the formation of tumors in the natural setting. Novel applications of the basic scientific knowledge of p53 could lead to an improvement in cancer treatment, hopefully in the not so distant future.

p53 mutation and tamoxifen resistance in breast cancer

A substantial portion of patients with estrogen receptor-positive breast cancer fail to respond to estrogen depletion or to the antiestrogen tamoxifen. The molecular changes that lead to tamoxifen resistance and estrogen-independent growth are unknown. To test the hypothesis that a p53 mutation could result in tamoxifen resistance and estrogen-independent growth, the MCF-7 cell line was transfected with p53 cDNA which was mutated at codon 179 (histidine to glutamine). MCF-7 is an estrogen receptor-positive, estrogen-dependent, tamoxifen-sensitive cell line with only wild-type p53. The presence of transfected mutant p53 cDNA was verified by the PCR, and overexpression of p53 protein was assessed by Western blotting. Five separate mutant-transfected clones were selected and tested in subsequent growth experiments. In monolayer culture, there was no consistent evidence of estrogen-independent growth or tamoxifen resistance in the mutant transfectants compared with vector-only controls or the parental cell line. In soft agar growth experiments, four of five mutant transfectants remained sensitive to tamoxifen in a dose-dependent manner. In the presence of wild-type p53, mutant 179 p53 protein does not result in estrogen-independent growth or tamoxifen resistance. These results do not exclude the possibility that other p53 mutational types could result in tamoxifen resistance, or that loss of the remaining wild-type allele may be necessary to result in this phenotype.

Rapid in vitro assay for predicting response to fluorouracil in patients with metastatic breast cancer

PURPOSE

To determine if a rapid 3H-uridine uptake assay using breast tumor cells from biopsy specimens could predict clinical response to fluorouracil (5FU) in patients with metastatic breast cancer.

PATIENTS AND METHODS

A double-blind prospective study was conducted of 60 patients with measurable, metastatic breast cancer who had failed to respond to at least one prior chemotherapy regimen. Patients received 5FU 300 mg/m2/d by continuous infusion and were monitored for response. Tumor cells from biopsy specimens were grown in microwells and exposed for 3 days to 0.1, 1.0, 10.0, and 100.00 micrograms/mL of 5FU on strips coated with drug and extracellular matrix. Cells were pulsed with 3H-uridine overnight. Incorporated radioactivity was compared for wells with and without drug. Results were available 4 days from specimen submission.

RESULTS

Of 45 eligible patients, 11 (24%) were not assessable in vitro. Nine patients were assessable in vitro, but not clinically. Of the remaining 25 patients, who were assessable both clinically and in vitro, there was one complete response (CR), five partial responses (PRs), five cases of stable disease, and 14 cases of progressive disease, for an objective response rate of 24%. Response in vitro was significantly correlated with clinical response (P = .002). Of six clinical responders, five also responded in vitro, for an assay sensitivity of 83%. Of 19 nonresponders, 17 were nonresponders in vitro, for a specificity of 89%. The positive predictive value of the test was 71% (five of seven), and the negative predictive value was 94% (17 of 18).

CONCLUSION

Results of an in vitro assay were significantly correlated with clinical response in patients with metastatic breast cancer treated with continuous infusion 5FU.

Rising levels of estrogen receptor in breast cancer over 2 decades

BACKGROUND

The incidence of estrogen receptor (ER)-positive breast cancer apparently is increasing. It remains unclear whether this increase is due to an improvement in receptor assay sensitivity, a change in patient characteristics, or a change in tumor biology.

METHODS

The distribution of ER, tumor size, and patient age for 11,195 tumor specimens gathered from patients nationwide from 1973 to 1992 were analyzed. All assays were performed in a single laboratory. A single-label, dextran-coated charcoal (DCC) method was used from 1973 to 1984, and a dual-label, DCC method, which allows the determination of both ER and progesterone receptor levels in the same assay, was used from 1985 to 1992.

RESULTS

The median level of ER has increased steadily from 14 fmol per milligram of protein in 1973 to 58 fmol per milligram of protein in 1992 (P < 0.0001). The percentage of ER-positive tumors also rose from 73-78% during the same period (P = 0.008). When the assay method was modified from single to dual label, no abrupt or stepwise increase occurred. Tumor size decreased over the same period (P < 0.0001). From 1973 to 1977, 48% of tumors were larger than 2 cm, and 15% were larger than 5 cm, compared to 60% and 9%, respectively, from 1988 to 1992. The percentage of women older than 50 years of age remained relatively constant over time. After adjusting for tumor size, age, number of positive lymph nodes, and change in assay method, a sustained rise in ER level remained. In a multivariate analysis that included age, age group, year of biopsy, tumor size, and number of positive nodes, the year of biopsy still was independently predictive of ER level (P < 0.0001).

CONCLUSION

The measured level of ER in primary breast cancers has increased during the last 2 decades. It is unlikely that technical improvements or changes in tumor size, age, or nodal status fully explain this increase. The rising level of ER may reflect a change in breast cancer biology and in hormonal events that influence breast cancer genesis and growth.

p53 protein accumulation detected by five different antibodies: relationship to prognosis and heat shock protein 70 in breast cancer

Nuclear accumulation of p53 protein is associated with a poorer clinical outcome in breast cancer patients. Heat shock protein 70 (hsp70) is a chaperone that binds to mutant p53 and consequently could regulate its accumulation or localization. The aims of this study were to determine if the prognostic significance of p53 accumulation was dependent on the type of antibody used for detection and whether hsp70 was associated with this accumulation. Node-negative breast tumors (n = 169) were examined by immunohistochemistry for nuclear p53, cytoplasmic or nuclear hsp70, and for p53 gene alteration by single-strand conformation polymorphism analysis. Frozen sections of pulverized breast tumors were stained with five p53 antibodies (240, 1801, 421, BP53-12, and CM1), a cocktail of both 240 and 1801, and the hsp70 antibody C92. Protein level was expressed as the sum of a proportion and intensity score (total 0, 2-8) with > or = 2 defined as positive staining. The cocktail 240/1801 gave the highest rate of positive staining (45%), followed by BP53-12 (35%), 1801 (27%), 240 (25%), CM1 (24%), and 421 (18%), with a high correlation between antibodies. Positive staining with each individual antibody or the cocktail was significantly associated with estrogen receptor and progesterone receptor negativity, age < 50, and high S-phase fraction. Only staining detected by the 240/1801 cocktail was associated with significantly worse overall survival; 85 versus 70% at 5 years for p53-negative compared to p53-positive tumors, respectively (P = 0.02). There was no association between nuclear or cytoplasmic hsp70 staining and accumulation of p53. Patients that were p53-negative/cytoplasmic hsp70-positive had a better overall survival than those that were p53-negative/cytoplasmic hsp70-negative. No other combination of p53 and hsp70 status could further define subsets of patients with a significantly different prognosis compared to p53 status alone. Tumors without a detectable p53 gene alteration by single-strand conformation polymorphism but with accumulated p53 protein did not have relatively increased levels of hsp70. We conclude that in node-negative breast cancer, the cocktail of two antibodies, 240/1801, resulted in the highest rate of positive staining and was most strongly associated with overall survival compared with either antibody alone or with the other individual antibodies. By immunohistochemistry, nuclear accumulation of p53 was not associated with cytoplasmic or nuclear hsp70 levels.

Tumor biologic factors and breast cancer prognosis among white, Hispanic, and black women in the United States

BACKGROUND

In the United States, prognosis and survival after the diagnosis of breast cancer is poorer among black patients and, to a lesser extent, among Hispanic patients, compared with white patients. Patients who are black or Hispanic have been reported to present with higher stage or more advanced disease. Even after adjusting for stage, however, survival rates are lower for blacks but not for Hispanics.

PURPOSE

Our purpose was to compare survival, age, tumor size, nodal status, estrogen-receptor (ER) and progesterone-receptor (PgR) status, histologic type, S-phase fraction, DNA ploidy status, HER-2/neu protein expression, and p53 protein status, along with systemic treatment, in a large group of white, black, and Hispanic U.S. women.

METHODS

From 1970 to 1991, breast tumor specimens were submitted to The University of Texas Health Science Center from 31 contributing hospitals throughout the United States for ER and PgR assay. A total of 4885 white, 1016 black, and 777 Hispanic women were eligible for this study. Median follow-up was 57 months.

RESULTS

Overall, white women were significantly more likely to be older and to have smaller tumors, have less lymph node involvement, have tumors with positive ER and PgR status, and have a lower S-phase fraction compared with Hispanic or black women. There were no clinically important differences in DNA ploidy, histologic type, HER-2/neu, and p53 expression among the three groups. Considering all stages, white women had the best overall survival (date of diagnosis to date of death) at 5 years--75% +/- 1% (means +/- SE), with a median survival of 166 months, but Hispanic women had an intermediate survival--70% +/- 2% (median survival, 156 months), and black women had the worst survival--65% +/- 2% (median survival, 117 months) (P < .0001). For node-negative patients, there was no significant difference in disease-free survival (date of diagnosis to date of first recurrence) or overall survival, although blacks tended to have a worse prognosis. For node-positive or locally advanced disease and for metastatic disease, blacks had significantly (P < .0001) worse disease-free and overall survival than did white or Hispanic women. Differences in the use of systemic therapy did not explain these outcomes.

CONCLUSION

A number of biologic factors associated with poor prognosis are found with a significantly increased frequency in breast tumors from Hispanic and, particularly, from black women. Tumors with a more aggressive biology could lead to a higher stage at diagnosis and a poorer survival for the group as a whole.

Evaluation of thymidylate synthase RNA expression by polymerase chain reaction

5-Fluorouracil (5FU), an antimetabolite often used for the treatment of breast cancer, binds to and inactivates the enzyme thymidylate synthase (TS). Measurement of TS levels may be useful in examining resistance to 5FU, but current methods involving ligand binding assays present considerable problems due to the low basal level of this enzyme in many tissues. Therefore, a semiquantitative polymerase chain reaction (PCR) technique to measure TS RNA concentration in breast tumour cell lines has been developed with potential for measuring TS RNA levels in individual breast tumours. Using less than 1 microgram of total RNA, we determined that the T47D breast cancer cell line expressed TS levels 1.3 to 4.4 times lower than those of four other breast cancer cell lines, MCF-7, MDA-MB-468, MDA-MB-231, and MDA-A1R. Using the MCF-7 cell line as a representative of relatively high TS expression, the relationship between the S-phase fraction (SPF), and TS levels in MCF-7 and T47D cells was next examined because cell cycle kinetics can also influence drug response. TS expression was directly related to SPF. MCF-7 cells had a higher SPF, corresponding to their higher TS level relative to T47D cells. Lastly, 5FU sensitivity was assayed for and it was found that MCF-7 cells were more sensitive to 5FU than T47D, despite having higher TS levels. A semiquantitative technique for assessing TS RNA expression by PCR in breast cancer cell lines has been demonstrated. In the cell lines tested, there was no direct relationship between TS level and 5FU sensitivity, though there was a direct relationship between cell proliferation and sensitivity to 5FU.

The p53 tumor suppressor gene in breast cancer

Alterations of the p53 tumor suppressor gene are the most common genetic changes found so far in breast cancer, suggesting that the gene plays a central role in the development of the disease. p53 functions as a negative regulator of cell growth, and alterations in the gene lead to loss of this negative growth regulation and more rapid cell proliferation. A number of independent groups using different methods of detection have shown that p53 alterations are associated with more aggressive tumor biologic factors and a poorer prognosis in breast cancer patients. Because of its possible role in the regulation of apoptosis and response to DNA damage, p53 status could also be a predictive marker for response to hormonal or chemotherapy.

Estrogen receptor, progesterone receptor, and HER-2/neu protein in breast cancers from pregnant patients

BACKGROUND

Because the occurrence of breast cancer during pregnancy is uncommon and because the high levels of estrogens and progestins associated with pregnancy could cause false-negative results from ligand binding assays (LBA), the actual incidence of steroid hormone receptor positivity in tumors from this subset of women is unclear.

METHODS

Estrogen receptor (ER) and progesterone receptor (PgR) were determined using LBA methods in 15 tumors from 15 pregnant patients with breast cancer. In addition, immunohistochemistry was done for ER, PgR, pS2, heat shock protein 27 (hsp27), and HER-2/neu on 12 of the 15 tumors.

RESULTS

Five of 15 (33%) tumors were positive for ER by LBA, compared with 52% of tumors from age-matched nonpregnant patients. Six of 12 (50%) were ER-positive by immunohistochemistry. For PgR, 7 of 15 (47%) tumors were positive by LBA, compared with 42% of tumors from nonpregnant patients. Ten of 12 (83%) stained positive for PgR. By LBA, 67% of tumors studied were positive for ER or PgR or both, as opposed to 57% of tumors from the nonpregnant comparison group. Two other estrogen receptor-mediated proteins, pS2 and hsp27, were present by staining in 8 of 12 (67%) and 10 of 12 (83%) of tumors, respectively. Seven of 12 tumors (58%) had positive staining for HER-2/neu, whereas only 16% of age-matched nonpregnant patients had positive-staining tumors.

CONCLUSION

By LBA, the incidence of ER and PgR in breast tumors from pregnant women was not significantly different from that of tumors from nonpregnant age-matched patients. Some ER-negative tumors were PgR, pS2, or hsp27 positive, indicating that an intact estrogen response system was operative although ER was not detectable by standard LBA.

Prognostic factors and therapeutic decisions in axillary node-negative breast cancer

The incidence of node-negative breast cancer is increasing, and it is becoming a more commonly encountered clinical problem. Prognostic factors such as tumor size, histopathological characteristics, receptor status, proliferative markers, biochemical alterations, and gene abnormalities can be useful in assessing the risk of cancer recurrence after primary local therapy. By accurately assessing the risk of recurrence, informed decisions can be made about whether or not to treat with adjuvant systemic therapy.

William L. McGuire Memorial Symposium. The role and prognostic significance of p53 gene alterations in breast cancer

Alterations in the p53 tumor suppressor gene are the most frequent genetic changes found in breast cancer, with an incidence reported in a range of 15 to 50%. The incidence of p53 alterations is approximately 15% for in situ carcinoma, while for invasive node-positive disease it is 2 to 3 times higher. This high rate of alteration suggests that the gene plays a central role in the development of breast cancer. The p53 gene functions as a negative regulator of cell growth. Alterations in the gene lead to loss of its usual negative growth regulation and more rapid cell proliferation. Since p53 alteration can reflect a more advanced state of progression and a higher rate of proliferation, breast tumors that have a p53 alteration could have a greater probability of having micrometastasis. p53 alterations could therefore be a prognostic factor for recurrence after primary local therapy. Consistent with this hypothesis, several independent studies using different methodologies have found that breast tumors with altered p53 have a worse prognosis and are also more likely to have other poor prognostic factors.

The ER-positive/PgR-negative breast cancer phenotype is not associated with mutations within the DNA binding domain

We have used in vitro DNA binding assays as a measure of estrogen receptor (ER) function in human breast tumors. We found that the majority of ER+ (25 ER+/progesterone receptor [PgR]+, and 25 ER+/PgR-) tumors we examined were capable of binding consensus estrogen response element (ERE) oligonucleotides in this assay system. We found significant proteolytic activity in many of the tumors such that protease inhibitors were found to be essential during the preparation of tumor extracts. We next applied direct sequence analysis of the ER DNA binding domain of several of these tumors, and determined that the ER+/PgR- breast tumors did not contain mutations within the DNA binding domain which might explain their apparent discordant receptor phenotype. We did identify an alternatively spliced ER variant missing exon 3 of the DNA binding domain. This variant was unable to function as a transcriptional inducer of an estrogen-responsive reporter in a yeast assay system. Furthermore, the exon 3 ER deletion variant was expressed at equivalent levels in all of the ER+ breast tumors, so that it does not appear to be involved in the evolution of the ER+/PgR- breast cancer phenotype.

Prognostic significance of p53 gene alterations in node-negative breast cancer

Mutations in the p53 gene can play a role in the transformation of normal to malignant cells. Because these mutations are more frequently reported later in the course of transformation, their presence could reflect a greater malignant potential of the tumor and, thus, an increased probability of metastasis and recurrence after local therapy. In a pilot study using single-stranded conformation polymorphism analysis (SSCP), 200 node-negative breast tumors were examined for mutations in the region encompassing exons 5 through 9 of the p53 gene. Exons 5 through 9 were tested because they contain 80-90% of known p53 gene mutations. The tumors ranged in size from 1 to 3 cm. 28 tumors were found to have an abnormal band pattern on both initial and repeat analysis. 4 of these tumors were sequenced; 3 contained a p53 mutation and the 4th had a rare neutral polymorphism. Disease-free survival (DFS) at 5 years for women with tumors having an abnormal SSCP analysis was 57% (+/- 10%), compared to a 79% (+/- 3%) DFS for the group with a normal pattern. By the log rank test, this difference was highly significant, p < or = 0.01. The relative risk of recurrence for the group with an abnormal SSCP pattern was 2.2. In a multivariate analysis including ER, PgR, ploidy, S-phase, age, and tumor size, an abnormal p53 by SSCP analysis and patient age were the only factors that independently predicted DFS at 5 years.

CONCLUSION

Women with node-negative breast cancer who have tumors with alterations in the p53 gene, as indicated by SSCP analysis, have a significantly poorer prognosis and a higher rate of relapse at 5 years. The prognostic significance is maintained in a multivariate analysis including many established prognostic factors.

Inhibition of estrogen receptor action by a naturally occurring variant in human breast tumors

It is fairly well accepted that the presence of estrogen receptor (ER) and progesterone receptor (PgR) identifies breast cancer patients with a lower risk of relapse and better overall survival. But patients with discordant receptors, the ER+/PgR- phenotype, are often intermediate in clinical response. We focused upon this group of patients and have identified a truncated ER which is abundant in some ER+/PgR- breast tumors and which inhibits the binding of wild-type ER to its cognate response element. This variant interferes in a dominant negative manner with wild-type ER function and may represent a mechanism for modulation of estrogen responsiveness.