Michelle Dean

Enhanced cytotoxicity of PARP inhibition in mantle cell lymphoma harbouring mutations in both ATM and p53

Poly‐ADP ribose polymerase (PARP) inhibitors have shown promise in the treatment of human malignancies characterized by deficiencies in the DNA damage repair proteins BRCA1 and BRCA2 and preclinical studies have demonstrated the potential effectiveness of PARP inhibitors in targeting ataxia‐telangiectasia mutated (ATM)‐deficient tumours. Here, we show that mantle cell lymphoma (MCL) cells deficient in both ATM and p53 are more sensitive to the PARP inhibitor olaparib than cells lacking ATM function alone. In ATM‐deficient MCL cells, olaparib induced DNA‐PK‐dependent phosphorylation and stabilization of p53 as well as expression of p53‐responsive cell cycle checkpoint regulators, and inhibition of DNA‐PK reduced the toxicity of olaparib in ATM‐deficient MCL cells. Thus, both DNA‐PK and p53 regulate the response of ATM‐deficient MCL cells to olaparib. In addition, small molecule inhibition of both ATM and PARP was cytotoxic in normal human fibroblasts with disruption of p53, implying that the combination of ATM and PARP inhibitors may have utility in targeting p53‐deficient malignancies.

High stromal carbonic anhydrase IX expression is associated with nodal metastasis and decreased survival in patients with surgically-treated oral cavity squamous cell carcinoma

Every year, approximately 25,000 patients are diagnosed with oral cavity squamous cell carcinoma (OCSCC) in the USA. The 5-year survival rate for OCSCC is approximately 40%. Intratumoral hypoxia confers poor prognosis and treatment failure but direct tumor oxygen measurement is challenging. Carbonic anhydrase IX (CAIX) is a marker of tissue hypoxia and we have recently shown that stromal CAIX is associated with reduced survival in patients with HPV-negative head and neck cancer. We examined the importance of this observation in OCSCC patients. We identified patients diagnosed and treated with OCSCC in Calgary (Alberta, Canada) between 1998 and 2005. Clinical and pathologic data were obtained from the Alberta Cancer Registry and chart review. Tissue microarrays (TMAs) were assembled from triplicate cores of archived tumor tissue. Stromal CAIX expression was assessed by quantitative immunohistochemistry (AQUA-HistoRx). The primary endpoint was disease-specific survival. We identified 102 patients with OCSCC; 87 patients had surgery as their primary treatment and adequate tumor tissue for TMA construction was available for all patients. CAIX expression was evaluable for 61 patients. High (top quartile) stromal CAIX expression was associated with significantly reduced 5-year disease-specific survival compared to low stromal CAIX expression (p<0.006). This study confirms our previously reported association between high stromal CAIX expression and significantly reduced overall survival in an independent, predominantly p16-negative, cohort of surgically treated OCSCC. Assessment of stromal CAIX expression could identify patients with the least favorable prognosis and inform therapeutic strategies in OCSCC.

Quantification of ER/PR expression in ovarian low-grade serous carcinoma

OBJECTIVE Case reports suggest that hormonal therapy may be a useful treatment option for low-grade serous carcinomas (LGSC) but the clinical value remains uncertain. We hypothesized that LGSCs show a constitutive high hormone receptor expression and that type diagnosis may be sufficient to initiate hormonal therapy. METHODS We assessed ER and PR expression on 27 LGSC, 69 high-grade serous carcinomas (HGSC), 36 serous borderline tumors (SBOT), and five normal fallopian tubes using three different platforms/antibodies on tissue microarrays. Staining from the Leica Bond Max and DAKO PharmDx platforms was evaluated using the Allred score. Quantitative fluorescence immunohistochemistry was performed using the HistoRx AQUAnalysis platform. A second cohort of 12 LGSC and 183 HGSC was assessed using the HistoRx AQUAnalysis platform. Welch ANOVA or Fishers Exact Test was used to compare differences in the histological types for each platform. Nonparametric bivariate density plots were used to graphically demonstrate the relationship between ER and PR for the various histological types. RESULTS LGSC have higher ER and PR expression compared to HGSC but significantly less than FT and SBOT. Nonparametric bivariate density revealed two populations of LGSC: one fifth of LGSC are ER high/PR high expressers similar to SBOT but the majority show low ER/PR expression more like HGSC. CONCLUSIONS Quantitative assessment of ER/PR expression using the HistoRx AQUAnalysis platform may be useful as a predictive diagnostic for hormonal therapy in LGSC, assuming that only the fraction of double high expressers benefit from hormonal treatment.

Basal Ki67 expression measured by digital image analysis is optimal for prognostication in oral squamous cell carcinoma

AIM The prognostic significance of Ki67 expression in cancers, including oral squamous cell carcinoma (OSCC), is unclear. This may be partly attributed to the lack of consensus surrounding the optimal approach for measuring tumour Ki67 expression. The aim of this study was to evaluate the association between different measures of Ki67 expression and disease-specific survival (DSS) in OSCC. METHODS Tissue microarrays (TMAs) were assembled from triplicate cores of formalin-fixed paraffin embedded (FFPE) pre-treatment tumour tissue obtained from 121 OSCC patients diagnosed between 1998 and 2006. Ki67 expression was quantified using fluorescence immunohistochemistry (IHC) and AQUAnalysis® in normal oral cavity squamous epithelium (OCSE) and OSCC tumour samples. Intensity and percentage-based approaches for Ki67 scoring were tested for their association with survival. RESULTS Ki67 scores obtained from intensity and percentage-based approaches had similar associations with prognosis. We also found that high basal (lowest observed in triplicate cores) Ki67 expression was more strongly associated with improved 5-year disease-specific survival than hot-spot and average Ki67 measurements. The association of high basal Ki67 expression with improved prognosis was most pronounced in patients who received postoperative radiation. Cox proportional hazards analysis showed that the basal Ki67 expression is an independent prognostic marker in our OSCC cohort when adjusted for pathological T-stage, nodal status and treatment. CONCLUSIONS Our study provides a framework for reaching a consensus on the optimal approach for measuring Ki67 expression in cancers. Our results suggest that rigorous comparisons of measurement approaches should be applied in a tumour-type and treatment-specific manner to enhance the clinical application of Ki67 assessment.

Low ATM protein expression in malignant tumor as well as cancer-associated stroma are independent prognostic factors in a retrospective study of early-stage hormone-negative breast cancer

IntroductionThe serine/threonine protein kinase ataxia telangiectasia mutated (ATM) is critical in maintaining genomic integrity. Upon DNA double-strand breaks, ATM phosphorylates key downstream proteins including p53 and BRCA1/2, thereby orchestrating complex signaling pathways involved in cell cycle arrest, DNA repair, senescence and apoptosis. Although sporadic mutation of ATM occurs rarely in breast cancer, the status of its protein expression and its clinical significance in breast cancer remain not well established. Our study was designed to investigate the influence of ATM protein in both tumor and cancer-associated stroma on clinical outcome in hormone-positive (HPBC) and hormone-negative (HNBC) early-stage breast cancer (EBC).MethodsTissue microarrays (TMAs), containing formalin-fixed, paraffin-embedded resected tumors from two cohorts of patients (HPBC cohort: n = 130; HNBC cohort: n = 168) diagnosed at the Tom Baker Cancer Centre, Calgary, Canada, were analyzed for ATM protein expression using fluorescence immunohistochemistry (IHC) and automated quantitative analysis (AQUA). ATM expression levels were measured within the tumor as a whole (tATM) as indicated by pan-cytokeratin expression, tumor nuclear compartment (nATM) as indicated by both DAPI and pan-cytokeratin-positive results, and cancer-associated stroma (csATM) as indicated by vimentin-positive and pan-cytokeratin-negative results. ATM expression levels within these compartments were correlated with clinical outcome.ResultsWhile tATM and nATM were significantly lower in tumors compared to normal breast epithelial tissues, csATM was significantly higher than the corresponding normal tissue compartment. In addition, the median expression level of both tATM and nATM were two- to threefold lower (P <0.001) in HNBC than in HPBC. In both HNBC and HPBC cohorts, patients with low tATM, nATM and csATM tumors had significantly poorer survival outcomes than those with a high tATM, nATM and csATM, but this effect was more pronounced in HNBC. A multivariate analysis demonstrates that these biomarkers predict survival independent of tumor size and lymph node status, but only in the HNBC cohort (P <0.001).ConclusionsLow ATM protein expression in both malignant tumor and stromal compartments likely contributes to the aggressive nature of breast cancer and is an independent prognostic factor associated with worse survival in HNBC patients.

Expression of PD-L1 and presence of CD8-positive T cells in pre-treatment specimens of locally advanced cervical cancer

Several of the cancer immunotherapies under investigation or in clinical use target the programmed death-ligand 1/programmed death-1 (PD-L1/PD-1) signaling axis. PD-L1 expression in tumor samples has been used as a predictive marker for response to these therapeutics, and may also have independent prognostic utility when assessed along with immune cell markers. Our objectives were to assess the expression of PD-L1 in tumor specimens from a uniformly treated patient cohort with locally advanced cervical cancer, and to determine its prognostic significance along with the density of tumor-infiltrating T cells. We identified 120 patients with locally advanced cervical cancer treated with radical chemoradiotherapy, and built tissue microarrays from their formalin-fixed, paraffin-embedded pre-treatment biopsies. We used conventional brightfield and fluorescence immunohistochemistry to detect PD-L1, and quantified protein expression using both manual pathologist scoring and automated software analysis. We also evaluated the effect of PD-L1 expression in tumors, along with the presence and density of intra-tumoral CD8+ T cells, on patient survival outcomes. Approximately 96% of the tumor samples expressed PD-L1, as determined using quantitative software analysis. Neither expression of PD-L1 nor density of CD8+ T cells was associated with progression-free or overall survival. However, there was a trend towards worse progression-free survival in patients whose tumors expressed PD-L1 but lacked CD8+ T cells (hazard ratio=0.43 (0.18–1.01), P=0.053). Nevertheless, the high percentage of cervical cancer tumor samples expressing PD-L1 suggests that anti-PD-L1 or anti-PD-1 therapies are potential treatment options for this patient population.

Cav3.1 overexpression is associated with negative characteristics and prognosis in non-small cell lung cancer

Introduction Voltage-gated calcium channels (VGCC) have been found to be differentially expressed in several different tumor types, but their role in tumor growth, malignant invasion, metastases and impact on clinical outcomes has not been clarified. Materials and Methods From a cohort database of 193 patients with early-stage NSCLC, 163 formalin-fixed paraffin-embedded specimens were available for analysis to construct tissue microarrays. Cav3.1 protein expression was detected using fluorescence immunohistochemistry, and quantified using automated image acquisition and analysis. Results Among the cohort of 193 NSCLC patients, adenocarcinoma (53.9%) and squamous cell carcinoma (SCC) (30.1%) were the most common histologies. There was no difference between SCC and non-SCC subtypes in overall survival (OS) or relapse-free survival (RFS); 74.2 vs 90.1 months (p = 0.543) and 48.8 vs 52.6 months (p = 0.766), respectively. T-type VGCC 3.1 (Cav3.1) overexpression was assessed by tissue microarray immunohistochemistry analysis from 163 available patient samples. Eighteen (11.0%) NSCLC primaries were found to have Cav3.1 overexpression levels, and were significantly associated with SCC histology (p < 0.001), larger tumor size (p < 0.001) and later stage disease at diagnosis (p = 0.019). Median OS was 48.6 vs 106.7 months for Cav3.1 overexpressing and non-overexpressing patients, respectively (p = 0.032). Regression analysis revealed a significantly negative effect for Cav3.1 overexpression on RFS (Hazard ratio [HR] = 2.02, p = 0.048). Conclusions Cav3.1 overexpression is a potential biomarker for poorer patient outcomes. These results bring supportive evidence for calcium channels inducing an aggressive phenotype in NSCLC and potentially may serve as a therapeutic target in overexpressing tumors.

An international multicenter study to evaluate reproducibility of automated scoring for assessment of Ki67 in breast cancer

The nuclear proliferation biomarker Ki67 has potential prognostic, predictive, and monitoring roles in breast cancer. Unacceptable between-laboratory variability has limited its clinical value. The International Ki67 in Breast Cancer Working Group investigated whether Ki67 immunohistochemistry can be analytically validated and standardized across laboratories using automated machine-based scoring. Sets of pre-stained core-cut biopsy sections of 30 breast tumors were circulated to 14 laboratories for scanning and automated assessment of the average and maximum percentage of tumor cells positive for Ki67. Seven unique scanners and 10 software platforms were involved in this study. Pre-specified analyses included evaluation of reproducibility between all laboratories (primary) as well as among those using scanners from a single vendor (secondary). The primary reproducibility metric was intraclass correlation coefficient between laboratories, with success considered to be intraclass correlation coefficient >0.80. Intraclass correlation coefficient for automated average scores across 16 operators was 0.83 (95% credible interval: 0.73–0.91) and intraclass correlation coefficient for maximum scores across 10 operators was 0.63 (95% credible interval: 0.44–0.80). For the laboratories using scanners from a single vendor (8 score sets), intraclass correlation coefficient for average automated scores was 0.89 (95% credible interval: 0.81–0.96), which was similar to the intraclass correlation coefficient of 0.87 (95% credible interval: 0.81–0.93) achieved using these same slides in a prior visual-reading reproducibility study. Automated machine assessment of average Ki67 has the potential to achieve between-laboratory reproducibility similar to that for a rigorously standardized pathologist-based visual assessment of Ki67. The observed intraclass correlation coefficient was worse for maximum compared to average scoring methods, suggesting that maximum score methods may be suboptimal for consistent measurement of proliferation. Automated average scoring methods show promise for assessment of Ki67 scoring, but requires further standardization and subsequent clinical validation.

Expression of DNA damage response proteins in cervical cancer patients treated with radical chemoradiotherapy

OBJECTIVE The management of locally advanced cervical cancer has improved significantly with the advent of cisplatin-based chemoradiotherapy (CRT) as the primary treatment regimen. Nevertheless, a significant proportion of patients fail to respond or relapse on this treatment and have a very poor prognosis. Our goal was to determine the prognostic value of a panel of proteins involved in detection and repair of DNA damage. METHODS We performed fluorescence immunohistochemistry, and used software analysis to assess expression of DNA damage response proteins ATM, DNA-PKcs, PARP-1, Ku70 and Ku86 in 117 pre-treatment specimens from patients with locally advanced cervical cancer. We compared expression to clinicopathologic correlates to determine prognostic significance. RESULTS Five-year progression-free survival was significantly lower in the low expressors than in high expressors of ATM (35% vs. 58%, p=0.044) and PARP-1 (24% vs. 61%, p=0.003), and showed a trend to significance for DNA-PKcs (30% vs. 60%, p=0.050). Low expression of the same proteins also correlated significantly with lower overall survival. In multivariable analysis, adjusted for FIGO stage and tumor size, low ATM and PARP-1 expression was significantly associated with both poorer progression-free and overall survival. Pairwise analyses indicated that expression levels of these proteins were correlated. CONCLUSIONS Expression of DNA damage response proteins in cervical cancer is associated with outcome in patients treated with CRT. Immunohistochemical analysis of these proteins may be useful in guiding treatment decisions in such patients.

Low Ki67/high ATM protein expression in malignant tumors predicts favorable prognosis in a retrospective study of early stage hormone receptor positive breast cancer

Introduction This study was designed to investigate the combined influence of ATM and Ki67 on clinical outcome in early stage hormone receptor positive breast cancer (ES-HPBC), particularly in patients with smaller tumors (< 4 cm) and fewer than four positive lymph nodes. Methods 532 formalin-fixed paraffin-embedded specimens of resected primary breast tumors were used to construct a tissue microarray. Samples from 297 patients were suitable for final statistical analysis. We detected ATM and Ki67 proteins using fluorescence and brightfield immunohistochemistry respectively, and quantified their expression with digital image analysis. Data on expression levels were subsequently correlated with clinical outcome. Results Remarkably, ATM expression was useful to stratify the low Ki67 group into subgroups with better or poorer prognosis. Specifically, in the low Ki67 subgroup defined as having smaller tumors and no positive nodes, patients with high ATM expression showed better outcome than those with low ATM, with estimated survival rates of 96% and 89% respectively at 15 years follow up (p = 0.04). Similarly, low-Ki67 patients with smaller tumors, 1-3 positive nodes and high ATM also had significantly better outcomes than their low ATM counterparts, with estimated survival rates of 88% and 46% respectively (p = 0.03) at 15 years follow up. Multivariable analysis indicated that the combination of high ATM and low Ki67 is prognostic of improved survival, independent of tumor size, grade, and lymph node status (p = 0.02). Conclusions These data suggest that the prognostic value of Ki67 can be improved by analyzing ATM expression in ES-HPBC.