Infiltrating immune cells in prostate cancer tissue after androgen deprivation and radiotherapy

OBJECTIVES

Androgen deprivation therapy (ADT) has long been a cornerstone in treatment of advanced prostate cancer (PCa), and is known to improve the results of radiotherapy (RT) for high-risk disease. The purpose of our study was to use a multiplexed immunohistochemical (mIHC) approach to investigate the infiltration of immune cells in PCa tissue after eight weeks of ADT and/or RT with 10 Gy.

METHODS

From a cohort of 48 patients divided into two treatment arms, we obtained biopsies before and after treatment and used a mIHC method with multispectral imaging to analyze the infiltration of immune cells in tumor stroma and tumor epithelium, focusing on areas with high infiltration.

RESULTS

Tumor stroma showed a significantly higher infiltration of immune cells compared to tumor epithelium. The most prominent immune cells were CD20⁺ B-lymphocytes, followed by CD68⁺ macrophages, CD8⁺ cytotoxic T-cells, FOXP3⁺ regulatory T-cells (Tregs), and T-bet⁺ Th1-cells. Neoadjuvant ADT followed by RT significantly increased the infiltration of all five immune cells. Numbers of Th1-cells and Tregs significantly increased after single treatment with ADT or RT. In addition, ADT alone increased the number of cytotoxic T-cells and RT increased the number of B-cells.

CONCLUSIONS

Neoadjuvant ADT in combination with RT results in a higher inflammatory response compared to RT or ADT alone. The mIHC method may be a useful tool for investigating infiltrating immune cells in PCa biopsies to understand how immunotherapeutic approaches can be combined with current PCa therapies.

Correlation of integrated ERG/PTEN assessment with biochemical recurrence in prostate cancer

INTRODUCTION

Prostate cancer is a heterogeneous disease, with a complex molecular landscape that evolves throughout disease progression. Common alterations in genes such as ERG and PTEN have been attributed to worse prognosis. This study aimed to further examine the clinical relevance of PTEN and ERG expression in a cohort of patients with prostate cancer post radical prostatectomy.

METHODS

Tissue microarrays were constructed from 132 patients with prostate cancer from the Irish Prostate Cancer Research Consortium and University Hospital of Orebro, Sweden. Patients were divided into three groups - Group 1: biochemical recurrence, Group 2: no biochemical recurrence and Group 3: immediate progression after surgery. PTEN and ERG immunohistochemical analysis was performed and the association between expression levels and clinical parameters were compared.

RESULTS

Pathological stage pT3 tumours were more common at borderline significantly higher levels amongst patients who biochemically recurred when compared to patients who did not recur after radical prostatectomy (p = 0.05). ERG and PTEN expression levels were compared separately and concurrently across all three patient groups. Lack of ERG expression was strongly associated with immediate progression after surgery (p = 0.029). Loss of/low PTEN trended towards an association with immediate progression, however this was not statistically significant (p = 0.066).

CONCLUSION

In this study, negative ERG expression was strongly associated with immediate biochemical progression after radical prostatectomy. Moreover, a trend towards a relationship between aberrant PTEN expression and progression was observed. Additional studies with long-term follow up data may provide further clinical insight into the genomic heterogeneity in this population.

TRIM24 as an independent prognostic biomarker for prostate cancer

INTRODUCTION

Simply applicable biomarkers for prostate cancer patients predicting the clinical course are urgently needed. Recently, TRIM24 has been identified to promote androgen receptor signaling and to correlate with an aggressive prostate cancer phenotype. Based on these data, we proofed TRIM24 as a prognostic biomarker for risk stratification.

MATERIALS AND METHODS

We performed TRIM24 immunohistochemistry on 2 independent cohorts including a total of 806 primary tumors, 26 locally advanced/recurrent tumors, 30 lymph node metastases, 30 distant metastases, and 129 benign prostatic samples from 497 patients as well as on 246 prostate needle biopsies. Expression data were correlated with clinic-pathological data including biochemical recurrence-free survival (bRFS) as endpoint.

RESULTS

Benign samples show no or low TRIM24 expression in 94%, while tumor tissues demonstrate significant higher levels. Strongest expression is observed in advanced and metastatic tumors. In multivariate analyses, TRIM24 up-regulation on radical prostatectomy specimens correlates with shorter bRFS independent of other prognostic parameters. 5-(10-) year bRFS rates for TRIM24 negative, low, medium and high expressing tumors are 93.1(93.1)%, 75.4(68.5)%, 54.9(47.5)% and 43.1(32.3)%, respectively. Of interest, tumors diagnosed as indolent disease, TRIM24 expression stratifies patients into specific risk groups. Increased TRIM24 expression associates with higher grade group, positive nodal status and extraprostatic tumor growth. TRIM24 assessment on prostate needle biopsies taken prior to treatment decision at time of initial diagnosis significantly correlates with recurrence after surgery.

CONCLUSION

Using 2 large independent radical prostatectomy specimen cohorts, we found that TRIM24 expression predicts patients' risk to develop disease recurrence with high accuracy and independent from other established biomarkers. Further, this is the first study exploring TRIM24 expression on prostate needle biopsies which represents the clinically relevant tissue type on which biomarkers guide treatment decisions. Thus, we strongly suggest introducing TRIM24 evaluation in prostate needle biopsies in clinical routine as an inexpensive and simple immunohistochemical test.

ProBio II: An adaptive and randomized multi-arm biomarker driven phase 2 study in men with castrate resistant prostate cancer (CRPC)

TPS397

Background: Castrate-resistant prostate cancer (CRPC) affects around 3,000 men in Sweden every year. New drugs are available but they have moderate effect, low response rates, are expensive, and lack predictive treatment markers. This will lead to an unsustainable situation for prostate cancer care. Our hypothesis is that treatment decisions based on molecular profiling will significantly increase the response rate at 3 months compared to current clinical care, translating into improved progression free and overall survival. The vast majority of CRPC metastasize to the bone, with low success rate in obtaining sufficient material. Therefore, we will sequence circulating tumor DNA (ctDNA) being present at high levels in plasma. Methods: ProBio-II is an adaptive, multi-arm, open-label, multiple assignment randomized biomarker driven phase 2 trial in men with CRPC . Men (n=750) will be randomized to receive either standard of care (following Swedish national guidelines) or treatment with Enzalutamide, Abiraterone, PARP inhibitors, RA-223, Cabazitaxel, or immune modulators based on molecular subtypes. The molecular subtypes are defined as tumor properties or mutations in certain genes/pathways including: Microsatellite instability; Androgen receptor alterations; DNA-repair deficiency; TP53 inactivation; PTEN inactivation etc. The molecular subtypes will be identified by ctDNA profiling. A specially designed ctDNA profile for CRPC has been developed by our group to detect: mutations, amplifications and genomic rearrangements in the androgen receptor (AR); mutations, genomic rearrangements and amplifications/deletions in 300 key genes involved in prostate cancer; and microsatellite instable and hypermutated cancers. ProBio-II’s design is novel and inspired by successful studies as I-SPY (breast cancer) and the NCI-MATCH trial (metastatic cancer). Novel aspects of the study design includes using prior probability of treatment response; re-randomization of non-responders; and adaptive design. The ProBio II study will start recruiting patients in Sweden in Q1 2018 and recruit patients during a 18 month period. All major oncology departments in Sweden will participate.

FOXP3+ regulatory T cells in normal prostate tissue, postatrophic hyperplasia, prostatic intraepithelial neoplasia, and tumor histological lesions in men with and without prostate cancer

BACKGROUND

The tumor promoting or counteracting effects of the immune response to cancer development are thought to be mediated to some extent by the infiltration of regulatory T cells (T_regs ). In the present study we evaluated the prevalence of T_reg populations in stromal and epithelial compartments of normal, post atrophic hyperplasia (PAH), prostatic intraepithelial neoplasia (PIN), and tumor lesions in men with and without prostate cancer.

METHODS

Study subjects were 102 men consecutively diagnosed with localized prostate cancer undergoing radical prostatectomy and 38 men diagnosed with bladder cancer undergoing cystoprostatectomy without prostate cancer at the pathological examination. Whole mount sections from all patients were evaluated for the epithelial and stromal expression of CD4⁺ T_regs and CD8⁺ T_regs in normal, PAH, PIN, and tumor lesions. A Friedmańs test was used to investigate differences in the mean number of T_regs across histological lesions. Logistic regression was used to estimate crude and adjusted odds ratios (OR) for prostate cancer for each histological area.

RESULTS

In men with prostate cancer, similarly high numbers of stromal CD4⁺ T_regs were identified in PAH and tumor, but CD4⁺ T_regs were less common in PIN. Greater numbers of epithelial CD4+ T_regs in normal prostatic tissue were positively associated with both Gleason score and pT-stage. We observed a fourfold increased risk of prostate cancer in men with epithelial CD4⁺ T_regs in the normal prostatic tissue counterpart.

CONCLUSIONS

Our results may suggest a possible pathway through which PAH develops directly into prostate cancer in the presence of CD4⁺ T_regs and indicate that transformation of the anti-tumor immune response may be initiated even before the primary tumor is established.

Abstract B26: iNOS expression and lethal prostate cancer in patients with localized disease

Inducible nitric oxide synthase (iNOS) has demonstrated both tumor-promoting and tumor-inhibiting effects in prostate cancer. However, the relationship between iNOS protein expression and long-term prostate cancer outcomes is unclear. We evaluated iNOS expression in tumor epithelia and stroma in 300 men with localized tumors diagnosed incidentally by transurethral resection of the prostate (TURP) in Sweden. In this extreme case-control design, cases (N=132) died of prostate cancer and controls (N=168) survived at least 8 years following diagnosis without death from prostate cancer or a competing cause. Immunohistochemistry was undertaken with a polyclonal rabbit anti-human NOS2 antibody (Abcam) and the Ventana (Roche) semi-automated staining system. Two observers individually scored the staining according to intensity and number of positive cells from 0-3. The median value across cores in each patient were then categorized as <1, >1-<2, and >2, separately for epithelial and stromal compartments. Odds ratios for lethal prostate cancer were estimated with logistic regression controlling for the matching factors (age, calendar year of diagnosis), as well as tumor stage, Gleason score, and percent tumor. iNOS was expressed by stromal-associated M1 macrophages and fibroblasts, as well as tumor cells. Gleason score was positively associated with both stromal and epithelial iNOS staining. In the stroma, there was no statistically significant association between iNOS expression and lethal prostate cancer after adjustment for clinical covariates. However, the odds of lethal prostate cancer increased with tumor expression of iNOS in the fully adjusted model. Compared to patients with the lowest category of iNOS expression, the odds ratios for lethal prostate cancer were 2.96 (95% CI: 1.26-6.96) for patients in the second category and 3.80 (95% CI: 1.45-9.97) for patients in the top category. These results suggest that iNOS may help to identify patients with aggressive prostate cancer at the time of diagnosis, or may be a therapeutic target. Given previously reported in vitro data suggesting that iNOS promotes proliferation of androgen-independent prostate tumors, future analyses will investigate association between iNOS expression and time to castration-resistant prostate cancer in this patient population.

Citation Format: Jennifer R. Rider, Ann Erlandsson, Chirag Vyas, Sabina Davidsson, Jessica Carlsson, Swen-Olof Andersson, Ove Andren. iNOS expression and lethal prostate cancer in patients with localized disease [abstract]. In: Proceedings of the AACR International Conference: New Frontiers in Cancer Research; 2017 Jan 18-22; Cape Town, South Africa. Philadelphia (PA): AACR; Cancer Res 2017;77(22 Suppl):Abstract nr B26.

Intracellular location of BRCA2 protein expression and prostate cancer progression in the Swedish Watchful Waiting Cohort

Prostate cancer patients with inherited BRCA2 mutations have a survival disadvantage. However, it is unknown whether progression is associated with BRCA2 protein expression in diagnostic prostate cancer tissue, among men without inherited mutations. We conducted a nested case-control study within the Swedish Watchful Waiting cohort. The case group included all 71 patients who died from prostate cancer within 5 years from diagnosis and controls were all patients (n = 165) who lived at least 7 years after diagnosis. Tissue microarrays were stained using antibodies for C- and N-terminal domains of the BRCA2 protein. Location (nuclear, cytoplasmic and membranous) and magnitude (intensity and percentage) of expression were assessed. Logistic regression models produced odds ratios (OR) and 95% confidence intervals (CI) adjusted for age, year of diagnosis and Gleason score. Positive BRCA2 staining at the cell membrane was associated with reduced risk of death within 5 years (N-terminal: OR = 0.47, 95% CI = 0.21-1.04, P = 0.06; C-terminal: OR = 0.41, 95% CI = 0.18-0.91, P = 0.03) and low Gleason scores (P = 0.006). Positive cytoplasmic C-terminal staining was associated with higher Gleason scores and increased lethality (OR = 3.61, 95% CI = 1.61-8.07, P = 0.002). BRCA2 protein expression at the cell membrane and lack of C-terminal expression in the cytoplasm were associated with a reduced risk of rapidly fatal prostate cancer. BRCA2 protein expression in prostate cancer tissue may have independent prognostic value. The potential biological significance of BRCA2 expression at the cell membrane warrants further investigation.

MED12 overexpression is a frequent event in castration-resistant prostate cancer

In a recent effort to unravel the molecular basis of prostate cancer (PCa), Barbieri and colleagues using whole-exome sequencing identified a novel recurrently mutated gene, MED12, in 5.4% of primary PCa. MED12, encoding a subunit of the Mediator complex, is a transducer of Wnt/β-catenin signaling, linked to modulation of hedgehog signaling and to the regulation of transforming growth factor beta (TGFβ)-receptor signaling. Therefore, these studies prompted us to investigate the relevance of MED12 in PCa. Expression of MED12, SMAD3 phosphorylation, and proliferation markers was assessed by immunohistochemistry on tissue microarrays from 633 patients. siRNA-mediated knockdown of MED12 was carried out on PCa cell lines followed by cellular proliferation assays, cell cycle analysis, apoptosis assays, and treatments with recombinant TGFβ3. We found nuclear overexpression of MED12 in 40% (28/70) of distant metastatic castration-resistant prostate cancer (CRPC(MET)) and 21% (19/90) of local-recurrent CRPC (CRPC(LOC)) in comparison with frequencies of less than 11% in androgen-sensitive PCa, and no overexpression in benign prostatic tissues. MED12 expression was significantly correlated with high proliferative activity in PCa tissues, whereas knockdown of MED12 decreased proliferation, reduced G1- to S-phase transition, and increased the expression of the cell cycle inhibitor p27. TGFβ signaling activation associates with MED12 nuclear overexpression in tissues and results in a strong increase in MED12 nuclear expression in cell lines. Furthermore, MED12 knockdown reduced the expression of the TGFβ target gene vimentin. Our findings show that MED12 nuclear overexpression is a frequent event in CRPC in comparison with androgen-sensitive PCa and is directly implicated in TGFβ signaling.

Utility of multispectral imaging in automated quantitative scoring of immunohistochemistry

BACKGROUND

Automated scanning devices and image analysis software provide a means to overcome the limitations of manual semiquantitative scoring of immunohistochemistry. Common drawbacks to automated imaging systems include an inability to classify tissue type and an inability to segregate cytoplasmic and nuclear staining.

METHODS

Immunohistochemistry for the membranous marker α-catenin, the cytoplasmic marker stathmin and the nuclear marker Ki-67 was performed on tissue microarrays (TMA) of archival formalin-fixed paraffin-embedded tissue comprising 471 (α-catenin and stathmin) and 511 (Ki-67) cases of prostate adenocarcinoma. These TMA were quantitatively analysed using two commercially available automated image analysers, the Ariol SL-50 system and the Nuance system from CRi. Both systems use brightfield microscopy for automated, unbiased and standardised quantification of immunohistochemistry, while the Nuance system has spectral deconvolution capabilities.

RESULTS

Overall concordance between scores from both systems was excellent (r=0.90; 0.83-0.95). The software associated with the multispectral imager allowed accurate automated classification of tissue type into epithelial glandular structures and stroma, and a single-step segmentation of staining into cytoplasmic or nuclear compartments allowing independent evaluation of these areas. The Nuance system, however, was not able to distinguish reliably between tumour and non-tumour tissue. In addition, variance in the labour and time required for analysis between the two systems was also noted.

CONCLUSION

Despite limitations, this study suggests some beneficial role for the use of a multispectral imaging system in automated analysis of immunohistochemistry.