Novel Stably Transplantable Xenograft Models of Human Breast Cancer for Evaluation of Experimental Therapeutics

In translational breast cancer research, our ability to evaluate clinical responses of human tumors to new therapeutic agents is severely limited experimentally. For example, it is not possible to evaluate the response of a single tumor to multiple candidate therapeutic agents. Conversely, the limited number of well-characterized in vivo preclinical human tumor models currently available precludes evaluation of multiple clinically relevant tumors with candidate therapeutic agents. These limitations severely impinge on our ability to develop and test novel therapeutic agents, particularly those that may target tumor-initiating “cancer stem cells”, which are relatively resistant to chemotherapy and radiation and may be responsible for disease recurrence and metastases.Historically, in vivo experimental therapeutic research has relied on either genetically engineered animal models, or “xenograft” transplantation models in which established human cancer cell lines are transplanted into immunocompromised host mice. However, each type of model has significant limitations. We sought to circumvent some of these limitations by propagating a cohort of human tumors as stably transplantable xenograft tissue lines grown in the absence of engineered or immortalized fibroblasts by transplanting clinical biopsies directly into the mammary fat pad of SCID/Beige immunocompromised mice (lacking B-cell, T-cell, and NK cell function) without intervening culture in vitro.Thus far, we have established 13 independent stably transplantable xenograft lines representing nine “triple-negative” (ER-PR-HER2-), two HER2+, and two ER+ breast cancers. Established xenograft lines show phenotypic similarity to the primary tumor with respect to histology and gene expression. Xenografts are being characterized genetically by whole genome sequencing as well as for the diversity of tumor-initiating cell types present. These models are proving useful for the evaluation of experimental therapeutics for their ability to inhibit tumor growth, and for their ability to target the subset cancer cells capable of regenerating tumors upon transplantation, with the goals of overcoming chemoresistance, preventing disease recurrence, and eliminating metastases.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1159.

A BRCA1-Like, 25-Gene Assay Predicts for Anthracycline-Chemosensitivity in Sporadic Triple-Negative Breast Cancer

Background Studies have shown higher chemosensitivity to anthracyclines in BRCA1-associated breast cancer (BABC) when compared to sporadic triple-negative breast cancers (TNBC), possibly due to differences in DNA repair function. We hypothesized that a subset of TNBC with acquired BRCA1 deficiency and defective DNA repair function will benefit most from DNA-damaging agents, such as anthracyclines. Methods We applied a previously published BRCA1 gene expression signature that differentiates BABC from sporadic TNBC to three datasets of sporadic TNBC from Baylor College of Medicine (BCM, n=68), GSE2034 (n=49), and the Netherlands Cancer Institute (NKI2, n=40). The signature separated the sporadic TNBC samples into those with a gene expression profile similar to BABC, or BRCA1-like, versus those with an expression pattern similar to sporadic TNBC, nonBRCA1-like. A list of 92 genes was obtained from the overlap of the most differentially expressed genes between the BRCA1-like samples and nonBRCA1-like samples in each of the three datasets. We then confirmed a subset of the 25 most differentially expressed genes by quantitative RTPCR. We validated the predictive value of this BRCA1-based, 25-gene assay in anthracycline response in three neoadjuvant studies of fluorouracil, epirubicin, and cyclophosphamide (FEC 6 cycles, n=53), doxorubicin and cyclophosphamide (AC 4 cycles, n=12), and T-FAC (paclitaxel-FAC, n=16). Results We determined gene expression of the 92 candidate genes by RT-PCR on 30 available samples of the BCM database. 25 genes were found to have the highest correlation between the microarray and RTQPCR gene expression. Gene expression profile using these 25-gene assay was obtained for three databases which included neoadjuvant anthracycline response data. The 25-gene assay predicted for anthracycline response in sporadic triple-negative breast cancers. In a neoadjuvant FEC study, this assay predicted for pathologic complete response (pCR) in 14/25 patients with BRCA1-like pattern, vs. 7/25 with sporadic-like pattern, p<0.05. In the AC study, 6/9 patients in the BRCA1-like group achieved pCR, vs. 0/3 in nonBRCA1-like group, p<0.05. Finally, in the T-FAC study, 5/7 patients in the BRCA1-like group achieved pCR vs. 3/9 patients in the nonBRCA1-like group, p=0.15. Analysis of the microarray data of triple negative breast cancer revealed higher PARP1 expression levels in the BRCA1-like group when compared to nonBRCA1-like group. Conclusion We present a promising BRCA1-based 25-gene assay that can be used on formalin-fixed paraffin-embedded tissue that may guide therapy in triple- negative breast cancer. The assay differentiates TNBC that are very sensitive to anthracyclines, and it should now be tested and validated prospectively in clinical trials with anthracyclines, other DNA-damaging agents, and PARP1 inhibitors.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 110.

Comparative Analysis of Breast Cancer (BrCa) Mortality Reduction among Regions of Canada between 1950 – 2004: Impact of Systemic and Diagnostic Guidelines after 1977, with Model Definition of Number of Potentially Avoided Annual Deaths (N-PAAD)

BACKGROUNDWe reported in the past the BrCa mortality trends in three Provinces of Canada with different Levels of Provincial Diagnostic and Therapy Guideline (ProvDgThGuide) implementation, reflecting access to optimum cancer care (LEVEL I, most uniform: British Columbia (B.C.); LEVEL II, medium: Ontario(ON); LEVEL III, least uniform (Atlantic Provinces AP), and have shown best outcomes in B.C. (Cancer Res 2009 69[S] 2:383).OBJECTIVETo estimate the number of BrCa deaths that potentially could have been avoided during the period 1978 – 2004 if the ProvDgThGuide Level I (i.e. of B.C.) had been implemented in Canada, Ontario and Atlantic Provinces, respectively.METHODSData were obtained from Statistics Canada.i. For each region, we calculated the average annual age-standardized mortality rate / 100,000 (aveASR) for the periods 1950-1977 (R1) and 1978-2004 (R2).ii. Subsequently, calculated was the Relative Change (RC, expressed in %) in mortality rate between the two time periods (RC = (R2-R1)/R1).iii. And for each region, the 1978 – 2004 expected rates (RE) based on RC from B.C. [i.e. calculated as "-13.8%" [(RE = 1- 0138) x R1].iv. These steps permitted estimates of Number of potentially avoided [annual] deaths (N-PAAD), based on the difference in observed mortality during the 1978-2004 period and the mortality that would have occurred if the regions had experienced the same relative change in mortality rate as observed in B.C. (R2-RE x # at risk).RESULTS R1(aveASR 1950-1977)R2(aveASR 1978-2004)RCREN-PAAD(N-AveAnnDeaths)BC30.025.8-13.8%----Ontario30.929.2-5.3%26.6137Atlantic27.528.8+4.7%23.760Canadaexcluding BC30.729.0-5.5%26.5315CONCLUSIONThis study confirms in most but not all regions of Canada a substantial mortality reduction after 1977, suggestive that implementation of optimum levels of Provincial Diagnostic and Therapy Guidelines (optimum access to cancer care) may affect mortality, and that their delay may prevent materialization of survival gains.Once the average annual rates of B.C. was applied to the rates of rest of Canada, the newly developed "Potentially Avoided Annual Deaths" model estimates over 8,000 avoided BrCa deaths in Canada (without B.C.) during the period 1978 – 2004 (26 [years] x 315).The model estimates over 3,500 (26 x 137) and 1500 (26 x 60) avoided deaths, respectively, for Ontario and Atlantic Provinces.These data are relevant to all world regions with differing access to optimum cancer care.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2063.

Results of an exercise to estimate the costs of interpersonal violence in Jamaica

This report describes the application of a draft version of the World Health Organization (WHO)/ United States Centers for Disease Control and Prevention (CDC) Manual for estimating the economic costs of injuries due to interpersonal and self-directed violence to measure costs of injuries from interpersonal violence.

METHODS

Fatal incidence data was obtained from the Jamaica Constabulary Force. The incidence of nonfatal violence-related injuries that required hospitalization was estimated using data obtained from patients treated at and/or admitted to three Type A government hospitals in 2006.

RESULTS

During 2006, direct medical cost (J$2.1 billion) of injuries due to interpersonal violence accounted for about 12% of Jamaica's total health budget while productivity losses due to violence-related injuries accounted for approximately J$27.5 billion or 160% of Jamaica's total health expenditure and 4% of Jamaica's Gross Domestic Product.

CONCLUSIONS

The availability of accurate and reliable data of the highest quality from health-related information systems is critical for providing useful data on the burden of violence and injury to decision-makers. As Ministries of Health take a leading role in violence and injury prevention, data collection and information systems must have a central role. This study describes the results of one approach to examining the economic burden of interpersonal violence in developing countries where the burden of violence is heaviest. The WHO-CDC manual also tested in Thailand and Brazil is a first step towards generating a reference point for resource allocation, priority setting and prevention advocacy.

Concurrent hypofractionated chemoradiation (CRT) for head and neck squamous cancer with weekly cisplatin: A Lancashire experience

e17052

Background: Concurrent chemoradiation with intravenous cisplatin is the standard treatment for locally advanced head and neck cancer. We evaluated the use of hypofractionated radiotherapy and weekly concomitant cisplatin in our center. Methods: We retrospectively analysed 37 patients treated at our centre from August 2005 to November 2007. They received weekly concurrent chemoradiation with cisplatin 30 mg/m2 with radiotherapy 65Gy in 30 fractions. We analysed tumour sites, changes in weight as an indirect measure of nutritional status, calculated creatinine clearance to assess nephrotoxicity, sites of recurrence, progression free survival and overall survival. The minimum follow up was 6 months. Results: Our study population comprised of 61% of T4 disease while 25% of our patients had T3 disease. Nearly a third of our patients underwent radical neck dissection prior to concurrent chemoradiation. We found that 80% of our patients had completed the full course of concurrent chemoradiation. More than 50% of patients had oropharyngeal cancer while 25% hypopharyngeal cancer. Majority of patients lost weight during treatment. The mean weight loss was 3.56 kilograms, despite 90% having had prophylactic enteral feeding tubes. Eleven patients maintained their weight while on treatment. There were 11 recurrences: 5 were at the primary site, 4 had distant metastasis, 1 had combination of primary site and nodal drainage and 1 patient had only nodal relapse. Lung was the most common site of distant metastasis amongst the 4 patients. While a proportion of patients had a fall in creatinine clearance, the values did not drop below the accepted 50 mL/min.Two-year progression free survival was 68% and overall survival at 24 months was 68.7%. Conclusions: Weekly intravenous cisplatin when combined with radiotherapy 65Gy in 30 fractions was effective in treating head and neck cancer. The nephrotoxicity was within acceptable limits. Many patients lost weight with this treatment despite having prophylactic enteral feeding tubes. Our survival figures were encouraging and similar to other reports in the literature.

No significant financial relationships to disclose.

Phase I clinical experience of a targeted TCR-IL2 fusion protein in patients with metastatic malignancies

3040

Background: ALT-801 is recombinant human interleukin-2 (IL-2) genetically fused to a single-chain T-cell receptor specific to a peptide antigen of human p53 presented in the context of HLA-A2 positivity. In tumor xenografts in animal models, this fusion protein demonstrated potent and targeted antitumor activity. Methods: A phase I/IIa multicenter clinical study was initiated to assess safety and clinical response of ALT-801 in patients with various metastatic malignancies. Patients screened positively for HLA-A2 and tumors expressed p53 peptide/HLA-A2 complex. In this dose escalation trial, patients received ALT-801 as a daily intravenous infusion for 4 days followed by a 10-day rest period and 4 additional daily doses. Results: Data from three dosing cohorts (0.015, 0.04, and 0.08 mg/kg/dose) indicate that ALT-801 is well-tolerated up to 0.04 mg/kg/dose. The half-life of ALT-801 is 2.5–4 hours per pharmacokinetic analysis, depending on the dose. Even at the 0.015 mg/kg level, there were sufficient concentrations of ALT-801 in the patients’ serum to fully activate cell lytic activity in vitro. Treatment with ALT-801 also led to immune activation in patients as demonstrated by elevated serum IFN-γ levels as well as an increase in IFN-γ-producing immune cells in patients’ blood. Interestingly, serum TNF-α, a major inducer of hypotension in patients receiving high-dose IL-2 treatment, was not induced in patients receiving ALT-801. Evidence of antitumor activity (i.e., stable disease, tumor shrinkage) was observed in some patients after one or two courses of ALT-801. Conclusions: At a dose of 0.04 mg/kg, ALT-801 is a well-tolerated agent that generated a vigorous immune response and demonstrated clinical efficacy in a group of patients with various metastatic malignancies. An expansion cohort of patients is in progress at 0.04 mg/kg.

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Decreased TGFβ signaling and increased COX2 expression in high risk women with increased mammographic breast density

Abstract #1107

Background
 High mammographic density is associated with up to a 6-fold increased risk of breast cancer. Pathways responsible for this increased density are unknown. We hypothesize that specific molecular pathways exist that are associated with increased mammographic density and breast cancer risk, and may therefore be used to identify potential targets for chemoprevention.
 Methods
 Histologically confirmed normal breast tissue was collected from women undergoing breast surgery who had available demographic data and mammograms for review. Breast parenchymal density was classified according to the American College of Radiology's Breast Imaging – Reporting and Data System reporting system. Quantitative classification of mammographic parenchyma was performed using thresholding method and percent density. Women with low (less than 50%) versus high (greater than 50%) breast density were compared. Double-stranded cDNA was synthesized from the normal breast tissue using an oligo-dT primer containing a T7 RNA polymerase promoter, followed by in vitro transcription with biotinylated ribonucleotides. The labeled cRNA was hybridized to Affymetrix HG U133Plus2 chips which comprise ∼28,600 genes to determine gene expression patterns. Immunohistochemical analysis (IHC) of estrogen receptor, progesterone receptor, proliferation (Ki67) and COX2 expression was performed.
 Results
 Sixty-two women were identified, 26 (42%) had high, and 36 (58%) had low mammographic density. Neither age, menopausal nor hormone receptor status influenced the gene expression pattern. Seventy-three genes had differential expression between normal breast tissue with high and low mammographic density (p<0.001, fold change>1.5) and had a low false discovery rate (<10%). Of these 73 differentially expressed genes, network and canonical pathway analysis demonstrate decreased TGFβ signaling (TGFBR2, SOS, SMAD3 and CD44 expression) in dense breast relative to non-dense breast. By IHC, Ki67 (stroma) and COX2 expression were significantly higher in dense breasts (p<0.05) on univariate analysis, and only COX2 expression in the stroma was statistically significant at (p<0.01) on multivariate analysis.
 Conclusion
 TGFβ ligands are currently the only growth factors known to prevent mammary epithelial cell proliferation. TGFβ has been reported to influence COX-2 expression, and these molecules are highly differentially expressed in individuals at high risk of developing breast cancer. These results suggest that COX2 inhibition should be further investigated for breast cancer prevention despite possible increase in cardiovascular risk.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1107.

BRCA1 gene expression signature predicts for anthracycline-chemosensitivity in triple-negative breast cancer

Abstract #6039

Background: We used a previously published gene expression signature that can identify tumors from BRCA1 mutation carriers to evaluate its predictive value in triple-negative breast cancer as a marker for chemosensitivity to anthracycline-based chemotherapy. We proposed that based on preclinical evidence suggesting that BRCA1-deficient breast cancer cells are sensitive to DNA damaging drugs such as cisplatin and anthracyclines this gene expression profile may identify tumors with anthracycline chemosensitivity. Two previously published studies defined a gene expression signature associated with BRCA1 germline mutation.(1,2) In these studies, sporadic tumors were misclassified as BRCA1 tumors and further analysis revealed methylation of the BRCA1 promoter region and decreased BRCA1 gene expression. This finding suggests the possibility of identifying sporadic tumors with decreased BRCA1 activity.
 Methods: We selected from our database of a locally advanced breast cancer neoadjuvant trial all cases of triple negative breast cancer that received 4 cycles of doxorubicin/cyclophosphamide(AC, 60/200 mg/m2, every 3 weeks) prior to surgery. Pathologic response to chemotherapy was disappearance of all invasive cancer or microscopic residual disease. Tumoral gene expression profile previously obtained using Affymetrix U133A Chip was analyzed for an optimal set of 100 most differentially expressed genes distinguishing BRCA1 and sporadic triple negative tumors according to the previously identified gene signature by van't Veer et al.1 We performed unsupervised clustering to determine if this signature could classify a subtype of triple-negative tumors with "BRCAness" and to test our hypothesis that BRCA1-like tumors are more sensitive to AC. We then performed a supervised analysis to determine the most differentially expressed genes that could prospectively identify triple-negative sporadic tumors with “BRCAness” and tumors from BRCA1 germline carriers that are sensitive to anthracyclines.
 Results: Of the 66 patients enrolled in our neoadjuvant trial, 12 patient's tumors were triple negative and received preoperative AC. By unsupervised clustering, the gene expression pattern associated with BRCA1 cancers subdivided these sporadic cancers in to two groups: Group A(6/7 pathologic responders), and group B(5/5 non-pathologic responders). By supervised analysis, the most differentially overexpressed gene from the BRCA1 profile for AC sensitivity was YWHAH(14-3-3 eta polypeptide), while DKK3(Inhibitor of Wnt and Notch signaling pathway) and RPL23A were most overexpressed in all cases with adriamycin-resistance(p<0.01).
 Discussion: Triple negative sporadic breast cancer displaying “BRCAness” appear to be sensitive to AC chemotherapy. YWHAH, DKK3, and RPL23A are differentially expressed in anthracycline-sensitive versus resistant tumors. These three genes can potentially identify triple-negative breast cancers that exhibit “BRCAness” and sensitivity to DNA-damaging chemotherapy such as cisplatin, anthracycline, or PARP inhibitors.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6039.

Promoter hypermethylation of FANCF and outcome in advanced ovarian cancer

The Fanconi gene family has a role in DNA repair and inactivation of FANCF has been proposed as a mechanism of sensitisation to platinum chemotherapy. This study sought to confirm this hypothesis in cell lines and a large series of ovarian cancer samples. Promoter methylation was assessed by methylation-sensitive polymerase chain reaction of FANCF in nine ovarian cancer cell lines and 74 ovarian cancer samples taken from patients entered on a trial of cisplatin-based chemotherapy. This study confirmed methylation-dependent silencing of FANCF in one out of nine ovarian cancer cell lines. Methylation of FANCF was demonstrated in 13.2% of 53 evaluable ovarian tumour samples. Progression-free survival gave an HR of 3.63 (95% CI: 1.54–8.54, P=0.0016) in favour of the unmethylated cases. There was no association with overall survival. This study does not support methylation-dependent silencing of FANCF as a mechanism of sensitisation to platinum-based chemotherapy in ovarian cancer.

High Dose Rate Brachytherapy as a Boost after Preoperative Chemoradiotherapy for More Advanced Rectal Tumours — the Clatterbridge Experience

In a systemic review of 8507 patients from 22 randomised trials, radiotherapy has been shown to reduce the risk of local recurrence and death from rectal cancer compared with surgery alone. Recent large randomised trials confirmed that chemoradiotherapy was better than radiotherapy alone. Contact radiotherapy as a boost after external beam radiotherapy (without chemotherapy) has also been shown to improve local control and sphincter preservation in the Lyon 092 trial. Brachytherapy has now been used as preoperative treatment for rectal cancer and showed similar results. The Swedish and Dutch trial results of short-course preoperative radiotherapy have shown improved local control in favour of the radiotherapy group. Similar to the Scandinavian group, investigators from McGill University in Montreal adopted a short course using brachytherapy instead of external beam radiotherapy. However, surgery was delayed for 4-8 weeks to achieve downstaging. The radiation dose was delivered directly on to the tumour and the surrounding normal tissues were spared the effects of radiation. This approach has been shown to reduce the side-effects seen with external beam short-course radiotherapy, but maintains the benefit of improved local control. The Danish group used brachytherapy as a boost after external beam chemoradiotherapy for more advanced rectal tumours and have shown improved pathological complete remission and R0 resection rates. The Mount Vernon group used a similar rectal applicator for inoperable rectal cancer patients and achieved good local and symptom control. The brachytherapy group at Clatterbridge used the same approach as the Danish group, but reduced the external beam radiotherapy dose and increased the brachytherapy dose to lower the side-effects. All 16 patients (100%) had R0 resection compared with 63% with conventional preoperative chemoradiotherapy using a bolus 5-fluorouracil regimen. Pathological complete remission was achieved in seven (44%) patients compared with 2-12% with conventional chemoradiotherapy. There was no increase in grade 3-4 toxicity from radiotherapy and no delay in wound healing or anastamotic leakage. The inclusion of high dose rate brachytherapy seems to increase the pathological complete remission rates and improves the R0 resection rates with no detriment to the side-effects as the increased dose of radiation from the high dose rate boost is confined mainly to the tumour. This treatment may be particularly suitable for elderly patients where intensive chemoradiotherapy regimens are not suitable. Several trials are planned to define the role of preoperative high dose rate brachytherapy in rectal cancer and the results are awaited with interest.

Combined Modality Treatment of Early Rectal Cancer — the UK Experience

With the introduction of colorectal screening in the UK, more patients will probably be diagnosed with early rectal cancer. The UK has an increasingly elderly population and not all patients diagnosed with early rectal cancer will be suitable for radical surgery. Therefore, a national plan is needed to develop the provision of alternative local treatment with equity of access across the country. Here we review the Clatterbridge Centre for Oncology multimodality treatment policy, which has been in clinical practice since 1993 and we discuss its rationale. Clatterbridge is the only centre in the UK offering Papillon-style contact radiotherapy. In total, 220 patients have been treated over 14 years, most of whom were referred from other centres. One hundred and twenty-four patients received Papillon (contact radiotherapy) as part of their multimodality management. The guidelines of the Association of Coloproctology of Great Britain and Ireland recommend local treatment for T1 tumours<3 cm in diameter, but this refers to treatment by surgery alone. There are no published national guidelines for radiotherapy. We plan each treatment in stages and achieve excellent local control (93% at 3 years) with low morbidity. We conclude that radical local treatment for cure can be offered safely to carefully selected elderly patients. Close follow-up is necessary so that effective salvage treatment can be offered. Because of a lack of randomised trial evidence, at present local radiotherapy is not yet accepted as an alternative option to the gold standard surgical treatment. Even with international collaboration, a randomised trial will be difficult to complete as the number of cases requiring local radiotherapy is small due to the highly selective nature of the treatment involved. However, an observational phase II trial is planned. In addition, the Transanal Endoscopic Microsurgery Users Group is also planning a phase II trial using preoperative radiotherapy. These studies will provide evidence to help establish the true role of radiotherapy in early rectal cancer.

High affinity IL-2 receptor (CD25) expression among Chronic Lymphocytic leukemia (CLL) patients is independent of mutational status and ZAP-70 positivitys

Background: Recent studies have suggested promising roles for immunotherapy through CD40 ligand /IL-2 signaling pathway in CLL patients. Differential expression of the IL-2 receptor (IL-2 R) has been reported in CLL and other B-cell malignancies. Because CLL is divided into two distinct prognostic groups (based on the level of somatic hypermutation or alternatively on the presence or absence of ZAP-70), it is important to determine the correlation of IL-2 R expression with mutational status and/or ZAP-70 positivity in CLL for better patient group stratification in clinical trials. Methods: In this study, 132 pts (82 M/50F; M: F 1.6) with an age range of 33-91 yrs (median 66 yrs) were included. Of these, 67/132 (51%) were found to be CD25+, 44/132 (33%) CD25- and 16% were CD25 dim (not further analyzed). In terms of ZAP positivity, 19/132 (14%) pts were ZAP-70+ and 113 (86%) were ZAP-70-. Results: Mutational data (n=93) revealed 60/93 (65%) patients with SHM and 33/ 93 (35%) without. Correlation between ZAP-70+ and absence of SHM was highly significant (p< 0.0001), however, no statistically significant correlation was noted between CD25 expression and SHM (p= 0.331) or ZAP positivity (p= 0.785). Conclusions: This data suggests that IL-2 R expression, although noted among a significant proportion of patients with B-CLL, is independent of somatic hypermutation or ZAP-70 expression. This observation will be important in evaluation of clinical efficacy of immunotherapy among CLL patients, and points to the existence of another mechanism for the presence of IL-2 R in these patients. Abbreviations: B-CLL (B-cell Chronic Lymphocytic Leukemia), SHM (Somatic Hypermutation)