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Antibodies used in the study.

Supplementary Table 1 a and b: Characteristics of PCs from patients.

The second-generation antiandrogen, enzalutamide, is approved for castrate-resistant prostate cancer (CRPC) and targets androgen receptor (AR) activity in CRPC. Despite initial clinical activity, acquired resistance to enzalutamide arises rapidly and most patients develop terminal disease. Previous work has established Stat5 as a potent inducer of prostate cancer growth. Here, we investigated the significance of Jak2–Stat5 signaling in resistance of prostate cancer to enzalutamide. The levels of Jak2 and Stat5 mRNA, proteins and activation were evaluated in prostate cancer cells, xenograft tumors, and clinical prostate cancers before and after enzalutamide therapy. Jak2 and Stat5 were suppressed by genetic knockdown using lentiviral shRNA or pharmacologic inhibitors. Responsiveness of primary and enzalutamide-resistant prostate cancer to pharmacologic inhibitors of Jak2–Stat5 signaling was assessed in vivo in mice bearing prostate cancer xenograft tumors. Patient-derived prostate cancers were tested for responsiveness to Stat5 blockade as second-line treatment after enzalutamide ex vivo in tumor explant cultures. Enzalutamide-liganded AR induces sustained Jak2–Stat5 phosphorylation in prostate cancer leading to the formation of a positive feed-forward loop, where activated Stat5, in turn, induces Jak2 mRNA and protein levels contributing to further Jak2 activation. Mechanistically, enzalutamide-liganded AR induced Jak2 phosphorylation through a process involving Jak2-specific phosphatases. Stat5 promoted prostate cancer growth during enzalutamide treatment. Jak2–Stat5 inhibition induced death of prostate cancer cells and patient-derived prostate cancers surviving enzalutamide treatment and blocked enzalutamide-resistant tumor growth in mice. This work introduces a novel concept of a pivotal role of hyperactivated Jak2–Stat5 signaling in enzalutamide-resistant prostate cancer, which is readily targetable by Jak2 inhibitors in clinical development.

Characteristics of patient-derived PCs tested ex vivo in 3D tumor explant cultures for responsiveness to Stat5-inhibitor IST5 in combination with ENZ as a second-line treatment after ENZ.

Supplementary Table 4: Genes down-regulated (> 2-fold) by Stat5-shRNA and IST5-002 in K562

Supplementary Methods. Supplementary Figure 1. Chemical structures of the small molecule IST5-002 analogs. Supplementary Figure 2. IST5-002 inhibits phosphorylation of Stat5 in mouse and human breast cancer cells. Supplementary Figure 3. IST5-002 does not have significant inhibitory activity against 50 kinases tested. Supplementary Figure 4. IST5-002 does not affect phosphorylation of Pak1/2. Supplementary Figure 5. IST5-002 inhibits expression of Stat5 target genes in PC cells and in CML cells. Supplementary Figure 6. IST5-002 is not generally cytotoxic as determined by lack of cell death induction in cancer cell lines established from other organs. Supplementary Figure 7. CWR22Rv1 PC cells were inoculated subcutaneously into the flanks of castrated athymic nude mice supplied with sustained-release 5alpha-dihydrotestosterone (DHT)-pellets (n=10/group, 1 tumor/mouse, 1.5 ??107 CWR22Rv1 cells per site, 1 DHT pellet/mouse). Supplementary Figure 8. IST5-0-02 induces apoptosis in CWR22Rv1 tumors grown in nude mice and in clinical PCs cultured ex vivo in organ explant cultures. Supplementary Figure 9. IST5-002 induces extensive apoptotic death of imatinib-sensitive and -resistant CML cells.

Metastatic prostate cancer is lethal and lacks effective strategies for prevention or treatment, requiring novel therapeutic approaches. Interleukin-6 (IL-6) is a cytokine that has been linked with prostate cancer pathogenesis by multiple studies. However, the direct functional roles of IL-6 in prostate cancer growth and progression have been unclear. In the present study, we show that IL-6 is produced in distant metastases of clinical prostate cancers. IL-6–activated signaling pathways in prostate cancer cells induced a robust 7-fold increase in metastases formation in nude mice. We further show that IL-6 promoted migratory prostate cancer cell phenotype, including increased prostate cancer cell migration, microtubule reorganization, and heterotypic adhesion of prostate cancer cells to endothelial cells. IL-6–driven metastasis was predominantly mediated by Stat3 and to lesser extent by ERK1/2. Most importantly, pharmacologic inhibition of Jak1/2 by AZD1480 suppressed IL-6–induced signaling, migratory prostate cancer cell phenotypes, and metastatic dissemination of prostate cancer in vivo in nude mice. In conclusion, we demonstrate that the cytokine IL-6 directly promotes prostate cancer metastasis in vitro and in vivo via Jak–Stat3 signaling pathway, and that IL-6–driven metastasis can be effectively suppressed by pharmacologic targeting of Jak1/2 using Jak1/2 inhibitor AZD1480. Our results therefore provide a strong rationale for further development of Jak1/2 inhibitors as therapy for metastatic prostate cancer. Mol Cancer Ther; 13(5); 1246–58. ©2014 AACR.

PDF - 295K, Suppl. Fig. 1. Autocrine IL-6 induces metastatic colonization of CWR22Rv1 human PC cells in the livers of mice in an experimental metastases assay. Figure 2. IL-6 induces a migratory phenotype in CWR22Rv1 PC cells. Suppl. Fig. 3. Pharmacological Jak1/2 inhibitor AZD1480 suppresses IL-6-activated Stat3 signaling in CWR22Rv1 PC cells and IL-6-induced migratory PC cell phenotype.

Supplementary Table 3: Genes up-regulated (> 2-fold) by Stat5-shRNA and IST5-002 in K562

Supplementary Table 5: IST5-002 regulation of known Stat5 target genes in K562 cells.

ENZ-induced activated Stat5 is capable of nuclear translocation in PC cells.

Supplementary Table 2: Genes regulated by both Stat5-shRNA and IST5-002 in K562 cells, corresponding to the heatmap in Figure 2g.

Supplementary Material and Methods

Levels of nuclear Stat5 in xenograft tumors.

Supplemental Table 1: Structure-Activity-Relationship analysis.

Primary human Ph+ ALL samples

Combining standard cytotoxic chemotherapy with BCR-ABL1 tyrosine kinase inhibitors (TKI) has greatly improved the upfront treatment of patients with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). However, due to the development of drug resistance through both BCR-ABL1–dependent and -independent mechanisms, prognosis remains poor. The STAT5 transcription factor is activated by BCR-ABL1 and by JAK2-dependent cytokine signaling; therefore, inhibiting its activity could address both mechanisms of resistance in Ph+ ALL. We show here that genetic and pharmacologic inhibition of STAT5 activity suppresses cell growth, induces apoptosis, and inhibits leukemogenesis of Ph+ cell lines and patient-derived newly diagnosed and relapsed/TKI-resistant Ph+ ALL cells ex vivo and in mouse models. STAT5 silencing decreased expression of the growth-promoting PIM-1 kinase, the apoptosis inhibitors MCL1 and BCL2, and increased expression of proapoptotic BIM protein. The resulting apoptosis of STAT5-silenced Ph+ BV173 cells was rescued by silencing of BIM or restoration of BCL2 expression. Treatment of Ph+ ALL cells, including samples from relapsed/refractory patients, with the PIM kinase inhibitor AZD1208 and/or the BCL2 family antagonist Sabutoclax markedly suppressed cell growth and leukemogenesis ex vivo and in mice. Together, these studies indicate that targeting STAT5 or STAT5-regulated pathways may provide a new approach for therapy development in Ph+ ALL, especially the relapsed/TKI-resistant disease.Significance:Suppression of STAT5 by BCL2 and PIM kinase inhibitors reduces leukemia burden in mice and constitutes a new potential therapeutic approach against Ph+ ALL, especially in tyrosine kinase inhibitor-resistant disease. Cancer Res; 78(20); 5793–807. ©2018 AACR.

Purpose: The standard treatment for organ-confined prostate cancer is surgery or radiation, and locally advanced prostate cancer is typically treated with radiotherapy alone or in combination with androgen deprivation therapy. Here, we investigated whether Stat5a/b participates in regulation of double-strand DNA break repair in prostate cancer, and whether Stat5 inhibition may provide a novel strategy to sensitize prostate cancer to radiotherapy.Experimental Design: Stat5a/b regulation of DNA repair in prostate cancer was evaluated by comet and clonogenic survival assays, followed by assays specific to homologous recombination (HR) DNA repair and nonhomologous end joining (NHEJ) DNA repair. For HR DNA repair, Stat5a/b regulation of Rad51 and the mechanisms underlying the regulation were investigated in prostate cancer cells, xenograft tumors, and patient-derived prostate cancers ex vivo in 3D explant cultures. Stat5a/b induction of Rad51 and HR DNA repair and responsiveness to radiation were evaluated in vivo in mice bearing prostate cancer xenograft tumors.Results: Stat5a/b is critical for Rad51 expression in prostate cancer via Jak2-dependent mechanisms by inducing Rad51 mRNA levels. Consistent with this, genetic knockdown of Stat5a/b suppressed HR DNA repair while not affecting NHEJ DNA repair. Pharmacologic Stat5a/b inhibition potently sensitized prostate cancer cell lines and prostate cancer tumors to radiation, while not inducing radiation sensitivity in the neighboring tissues.Conclusions: This work introduces a novel concept of a pivotal role of Jak2–Stat5a/b signaling for Rad51 expression and HR DNA repair in prostate cancer. Inhibition of Jak2–Stat5a/b signaling sensitizes prostate cancer to radiation and, therefore, may provide an adjuvant therapy for radiation to reduce radiation-induced damage to the neighboring tissues. Clin Cancer Res; 24(8); 1917–31. ©2018 AACR.

Supplementary Materials & Methods

PDF file, 966K, Supplementary Figure 1. The growth of CWR22Pc cells is down-regulated by bicalutamide. ; Supplementary Figure 2. Stat5a/b, but not Stat3, is persistently activated in CWR22Rv1 and CWR22Pc cells. Supplementary Figure 3. Inhibition of Stat5a/b, but not Stat3, significantly decreases the fraction of viable CWR22Rv1 and CWR22Pc cells. ; Supplementary Figure 4. AZD1480 induces caspase-3 activity to the same extent as genetic knockdown of Jak2 or Stat5 by shRNA. ; Supplementary Figure 5. AZD1480-treated mice maintain higher body weights than docetaxeltreated mice. ; Supplementary Figure 6. AZD1480 does not affect levels of nuclear Stat3 in CWR22Pc tumors. Supplementary Figure 7. AZD1480 induces apoptotic cell death in CWR22Pc xenograft tumors. ; Supplementary Figure 8. AZD1480 down-regulates Stat5-target gene Bcl-Xl expression in CWR22Rv1 cells in culture. ; Supplementary Figure 9. AZD1480 regulates the expression of Stat5 target genes Bcl-Xl and Ecadherin in CWR22Pc xenograft tumors.

Purpose: Progression of prostate cancer to the lethal castrate-resistant stage coincides with loss of responsiveness to androgen deprivation and requires development of novel therapies. We previously provided proof-of-concept that Stat5a/b is a therapeutic target protein for prostate cancer. Here, we show that pharmacologic targeting of Jak2-dependent Stat5a/b signaling by the Jak2 inhibitor AZD1480 blocks castrate-resistant growth of prostate cancer.Experimental Design: Efficacy of AZD1480 in disrupting Jak2–Stat5a/b signaling and decreasing prostate cancer cell viability was evaluated in prostate cancer cells. A unique prostate cancer xenograft mouse model (CWR22Pc), which mimics prostate cancer clinical progression in patients, was used to assess in vivo responsiveness of primary and castrate-resistant prostate cancer (CRPC) to AZD1480. Patient-derived clinical prostate cancers, grown ex vivo in organ explant cultures, were tested for responsiveness to AZD1480.Results: AZD1480 robustly inhibited Stat5a/b phosphorylation, dimerization, nuclear translocation, DNA binding, and transcriptional activity in prostate cancer cells. AZD1480 reduced prostate cancer cell viability sustained by Jak2–Stat5a/b signaling through induction of apoptosis, which was rescued by constitutively active Stat5a/b. In mice, pharmacologic targeting of Stat5a/b by AZD1480 potently blocked growth of primary androgen-dependent as well as recurrent castrate-resistant CWR22Pc xenograft tumors, and prolonged survival of tumor-bearing mice versus vehicle or docetaxel-treated mice. Finally, nine of 12 clinical prostate cancers responded to AZD1480 by extensive apoptotic epithelial cell loss, concurrent with reduced levels of nuclear Stat5a/b.Conclusions: We report the first evidence for efficacy of pharmacologic targeting of Stat5a/b as a strategy to inhibit castrate-resistant growth of prostate cancer, supporting further clinical development of Stat5a/b inhibitors as therapy for advanced prostate cancer. Clin Cancer Res; 19(20); 5658–74. ©2013 AACR.

Supplementary Fig. S1. Effect of Doxycycline on shScramble (shSCR)-transduced Ph+ ALL cell lines. Supplementary Fig. S2. Effect of STAT5 inhibitor IST5-002 on Ph+ leukemia lines. Supplementary Fig. S3. Effect of treatment with IST5-002 in Ph like leukemia cells. Supplementary Fig. S4. Effect of IST5-002 on G-CSF-mobilized peripheral blood normal CD34+ hematopoietic cells. Supplementary Fig. S5. Effect of BIM silencing on apoptosis of STAT5-silenced Ph+ ALL cells. Supplementary Fig. S6. qPCR analysis of STAT5-regulated genes in untreated and Doxy-treated shScramble- or shSTAT5-BV173 cells. Supplementary Fig. S7. Levels of PIM1-s in STAT5-silenced Ph+ ALL lines and correlation with STAT5 expression in primary Ph+ ALL cells. Supplementary Fig. S8. Ectopic expression of PIM-1 does not rescue the apoptosis of STAT5-silenced BV173 cells. Supplementary Fig. S9. Effect of AZD1208 and Sabutoclax on cell growth and survival of Ph+ leukemia cell lines. Supplementary Fig. S10. Effects of the AZD1208- Sabutoclax combination on the growth of Ph+ leukemia cell lines. Supplementary Fig. S11. Effects of the AZD1208, Sabutoclax, or the drug combination on colony formation of Ph-like cell lines.

Supplementary Figure 1 from Transcription Factor Stat5 Synergizes with Androgen Receptor in Prostate Cancer Cells

The molecular mechanisms underlying progression of prostate cancer to the hormone-independent state are poorly understood. Signal transducer and activator of transcription 5a and 5b (Stat5a/b) is critical for the viability of human prostate cancer cells. We have previously shown that Stat5a/b is constitutively active in high-grade human prostate cancer, but not in normal prostate epithelium. Furthermore, activation of Stat5a/b in primary human prostate cancer predicted early disease recurrence. We show here that transcription factor Stat5a/b is active in 95% of clinical hormone-refractory human prostate cancers. We show for the first time that Stat5a/b synergizes with androgen receptor (AR) in prostate cancer cells. Specifically, active Stat5a/b increases transcriptional activity of AR, and AR, in turn, increases transcriptional activity of Stat5a/b. Liganded AR and active Stat5a/b physically interact in prostate cancer cells and, importantly, enhance nuclear localization of each other. The work presented here provides the first evidence of synergy between AR and the prolactin signaling protein Stat5a/b in human prostate cancer cells. [Cancer Res 2008;68(1):236–48]

PURPOSE T-cell–mediated cytotoxicity is suppressed when programmed cell death-1 (PD-1) is bound by PD-1 ligand-1 (PD-L1) or PD-L2. Although PD-1 inhibitors have been approved for triple-negative breast cancer, the lower response rates of 25%-30% in estrogen receptor–positive (ER+) breast cancer will require markers to identify likely responders. The focus of this study was to evaluate whether PD-L2, which has higher affinity than PD-L1 for PD-1, is a predictor of early recurrence in ER+ breast cancer. METHODS PD-L2 protein levels in cancer cells and stromal cells of therapy-naive, localized or locoregional ER+ breast cancers were measured retrospectively by quantitative immunofluorescence histocytometry and correlated with progression-free survival (PFS) in the main study cohort (n = 684) and in an independent validation cohort (n = 273). All patients subsequently received standard-of-care adjuvant therapy without immune checkpoint inhibitors. RESULTS Univariate analysis of the main cohort revealed that high PD-L2 expression in cancer cells was associated with shorter PFS (hazard ratio [HR], 1.8; 95% CI, 1.3 to 2.6; P = .001), which was validated in an independent cohort (HR, 2.3; 95% CI, 1.1 to 4.8; P = .026) and remained independently predictive after multivariable adjustment for common clinicopathological variables (HR, 2.0; 95% CI, 1.4 to 2.9; P < .001). Subanalysis of the ER+ breast cancer patients treated with adjuvant chemotherapy (n = 197) revealed that high PD-L2 levels in cancer cells associated with short PFS in univariate (HR, 2.5; 95% CI, 1.4 to 4.4; P = .003) and multivariable analyses (HR, 3.4; 95% CI, 1.9 to 6.2; P < .001). CONCLUSION Up to one third of treatment-naive ER+ breast tumors expressed high PD-L2 levels, which independently predicted poor clinical outcome, with evidence of further elevated risk of progression in patients who received adjuvant chemotherapy. Collectively, these data warrant studies to gain a deeper understanding of PD-L2 in the progression of ER+ breast cancer and may provide rationale for immune checkpoint blockade for this patient group.

Simple Summary A majority of breast cancer deaths are caused by aggressive molecular subtypes that are at high risk of progression. Patients with high-risk breast cancer commonly receive first-line systemic chemotherapy. Chemotherapy exerts direct cytotoxic effects on proliferating cancer cells. In addition, significant effects of chemotherapy are mediated through immune-boosting anti-cancer mechanisms that counteract immunosuppressive tumor-associated macrophages (TAMs). The aim of our study was to evaluate the potential prognostic value of the prevalence and the spatial localization of CD163+ TAMs in tumor tissue from breast cancer patients treated with chemotherapy after surgery. We developed a novel algorithm that identifies CD163+ TAMs in an objective manner and quantifies spatial interactions between CD163+ TAMs and cancer cells using distance-based metrics. Our results demonstrate that close spatial proximity of CD163+ TAMs to cancer cells and the average number of CD163+ cells either directly adjacent to or within communicating distance of each cancer cell are independent predictors of unfavorable prognosis in breast cancer. Abstract Tumor-associated macrophages (TAMs) promote progression of breast cancer and other solid malignancies via immunosuppressive, pro-angiogenic and pro-metastatic effects. Tumor-promoting TAMs tend to express M2-like macrophage markers, including CD163. Histopathological assessments suggest that the density of CD163-positive TAMs within the tumor microenvironment is associated with reduced efficacy of chemotherapy and unfavorable prognosis. However, previous analyses have required research-oriented pathologists to visually enumerate CD163+ TAMs, which is both laborious and subjective and hampers clinical implementation. Objective, operator-independent image analysis methods to quantify TAM-associated information are needed. In addition, since M2-like TAMs exert local effects on cancer cells through direct juxtacrine cell-to-cell interactions, paracrine signaling, and metabolic factors, we hypothesized that spatial metrics of adjacency of M2-like TAMs to breast cancer cells will have further information value. Immunofluorescence histo-cytometry of CD163+ TAMs was performed retrospectively on tumor microarrays of 443 cases of invasive breast cancer from patients who subsequently received adjuvant chemotherapy. An objective and automated algorithm was developed to phenotype CD163+ TAMs and calculate their density within the tumor stroma and derive several spatial metrics of interaction with cancer cells. Shorter progression-free survival was associated with a high density of CD163+ TAMs, shorter median cancer-to-CD163+ nearest neighbor distance, and a high number of either directly adjacent CD163+ TAMs (within juxtacrine proximity

BACKGROUND Diffusion-weighted imaging (DWI) is commonly used to detect prostate cancer, and a major clinical challenge is differentiating aggressive from indolent disease. PURPOSE To compare 14 site-specific parametric fitting implementations applied to the same dataset of whole-mount pathologically validated DWI to test the hypothesis that cancer differentiation varies with different fitting algorithms. STUDY TYPE Prospective. POPULATION Thirty-three patients prospectively imaged prior to prostatectomy. FIELD STRENGTH/SEQUENCE 3 T, field-of-view optimized and constrained undistorted single-shot DWI sequence. ASSESSMENT Datasets, including a noise-free digital reference object (DRO), were distributed to the 14 teams, where locally implemented DWI parameter maps were calculated, including mono-exponential apparent diffusion coefficient (MEADC), kurtosis (K), diffusion kurtosis (DK), bi-exponential diffusion (BID), pseudo-diffusion (BID*), and perfusion fraction (F). The resulting parametric maps were centrally analyzed, where differentiation of benign from cancerous tissue was compared between DWI parameters and the fitting algorithms with a receiver operating characteristic area under the curve (ROC AUC). STATISTICAL TEST Levene's test, P

Simple Summary Prostate Cancer (PC) is currently estimated to affect 1 in 9 men and is the second leading cause of cancer in men in the US. While androgen deprivation therapy, which targets the androgen receptor, is one of the front-line therapies for advanced PC and for recurrence of organ-confined PC treated with surgery, lethal castrate-resistant PC develops consistently in patients. PC is a multi-focal cancer with different grade carcinoma areas presenting simultaneously. Jak2-Stat5 signaling pathway has emerged as a potentially highly effective molecular target in PCs with positive areas for activated Stat5 protein. Activated Jak2-Stat5 signaling can be readily targeted by the second-generation Jak2-inhibitors that have been developed for myeloproliferative and autoimmune disorders and hematological malignancies. In this review, we analyze and summarize the Jak2 inhibitors that are currently in preclinical and clinical development. Abstract Androgen deprivation therapy (ADT) for metastatic and high-risk prostate cancer (PC) inhibits growth pathways driven by the androgen receptor (AR). Over time, ADT leads to the emergence of lethal castrate-resistant PC (CRPC), which is consistently caused by an acquired ability of tumors to re-activate AR. This has led to the development of second-generation anti-androgens that more effectively antagonize AR, such as enzalutamide (ENZ). However, the resistance of CRPC to ENZ develops rapidly. Studies utilizing preclinical models of PC have established that inhibition of the Jak2-Stat5 signaling leads to extensive PC cell apoptosis and decreased tumor growth. In large clinical cohorts, Jak2-Stat5 activity predicts PC progression and recurrence. Recently, Jak2-Stat5 signaling was demonstrated to induce ENZ-resistant PC growth in preclinical PC models, further emphasizing the importance of Jak2-Stat5 for therapeutic targeting for advanced PC. The discovery of the Jak2V617F somatic mutation in myeloproliferative disorders triggered the rapid development of Jak1/2-specific inhibitors for a variety of myeloproliferative and auto-immune disorders as well as hematological malignancies. Here, we review Jak2 inhibitors targeting the mutated Jak2V617F vs. wild type (WT)-Jak2 that are currently in the development pipeline. Among these 35 compounds with documented Jak2 inhibitory activity, those with potency against WT-Jak2 hold strong potential for advanced PC therapy.

Most breast cancer deaths are caused by estrogen receptor-α–positive (ER+) disease. Preclinical progress is hampered by a shortage of therapy-naive ER+ tumor models that recapitulate metastatic pro...

Pancreatic adenocarcinoma (PDAC) is a devastating malignancy. There have been few advances that have substantially improved overall survival in the past several years. On its current trajectory, the deaths from PDAC are expected to cross that from all gastrointestinal cancers combined by 2030. Radiation therapy is a technically very complex modality that bridges multiple different treatment strategies. It represents a hybrid amongst advanced diagnostic imaging, local (often ablative) intervention, heterogenous biological mechanisms contributing to normal and oncologic cell kill. In this article we bring an overview of the several promising strategies that are currently being investigated to improve outcomes using radiation therapy for patients with pancreatic adenocarcinoma.

Combining standard cytotoxic chemotherapy with BCR-ABL1 tyrosine kinase inhibitors (TKI) has greatly improved the upfront treatment of patients with Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). However, due to the development of drug resistance through both BCR-ABL1–dependent and -independent mechanisms, prognosis remains poor. The STAT5 transcription factor is activated by BCR-ABL1 and by JAK2-dependent cytokine signaling; therefore, inhibiting its activity could address both mechanisms of resistance in Ph+ ALL. We show here that genetic and pharmacologic inhibition of STAT5 activity suppresses cell growth, induces apoptosis, and inhibits leukemogenesis of Ph+ cell lines and patient-derived newly diagnosed and relapsed/TKI-resistant Ph+ ALL cells ex vivo and in mouse models. STAT5 silencing decreased expression of the growth-promoting PIM-1 kinase, the apoptosis inhibitors MCL1 and BCL2, and increased expression of proapoptotic BIM protein. The resulting apoptosis of STAT5-silenced Ph+ BV173 cells was rescued by silencing of BIM or restoration of BCL2 expression. Treatment of Ph+ ALL cells, including samples from relapsed/refractory patients, with the PIM kinase inhibitor AZD1208 and/or the BCL2 family antagonist Sabutoclax markedly suppressed cell growth and leukemogenesis ex vivo and in mice. Together, these studies indicate that targeting STAT5 or STAT5-regulated pathways may provide a new approach for therapy development in Ph+ ALL, especially the relapsed/TKI-resistant disease. Significance:Suppression of STAT5 by BCL2 and PIM kinase inhibitors reduces leukemia burden in mice and constitutes a new potential therapeutic approach against Ph+ ALL, especially in tyrosine kinase inhibitor-resistant disease. Cancer Res; 78(20); 5793–807. ©2018 AACR.

Purpose: This study aims to combine multiparametric magnetic resonance imaging (MRI) and digitized pathology with machine learning to generate predictive maps of histologic features for prostate cancer localization. Methods and Materials: Thirty-nine patients underwent MRI prior to prostatectomy. After surgery, tissue was sliced according to MRI orientation using patient-specific 3-dimensionally printed slicing jigs. Whole-mount sections were annotated by our pathologist and digitally contoured to differentiate the lumen and epithelium. Slides were co-registered to the T2-weighted MRI scan. A learning curve was generated to determine the number of patients required for a stable machine-learning model. Patients were randomly stratified into 2 training sets and 1 test set. Two partial least-squares regression models were trained, each capable of predicting lumen and epithelium density. Predicted density values were calculated for each patient in the test dataset, mapped into the MRI space, and compared between regions confirmed as high-grade prostate cancer. Results: The learning-curve analysis showed that a stable fit was achieved with data from 10 patients. Maps indicated that regions of increased epithelium and decreased lumen density, generated from each independent model, corresponded with pathologist-annotated regions of high-grade cancer. Conclusions: We present a radio-pathomic approach to mapping prostate cancer. We find that the maps are useful for highlighting high-grade tumors. This technique may be relevant for dose-painting strategies in prostate radiation therapy. © 2018 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)., Summary This study aims to combine whole-mount prostate pathology with multiparametric magnetic resonance imaging from 39 patients to generate predictive maps of epithelium and lumen density in magnetic resonance imaging space. We show that the new image contrasts generated stratify high-grade tumors from low-grade tumors and healthy tissue. Future studies will explore targeted radiation therapy and clinical disease staging using the radio-pathomic mapping technique.

Purpose: Prostate cancer primarily arises from the glandular epithelium. Histomophometric techniques have been used to assess the glandular epithelium in automated detection and classification pipelines; however, they are often rigid in their implementation, and their performance suffers on large datasets where variation in staining, imaging, and preparation is difficult to control. The purpose of this study is to quantify performance of a pixelwise segmentation algorithm that was trained using different combinations of weak and strong stroma, epithelium, and lumen labels in a prostate histology dataset. Approach: We have combined weakly labeled datasets generated using simple morphometric techniques and high-quality labeled datasets from human observers in prostate biopsy cores to train a convolutional neural network for use in whole mount prostate labeling pipelines. With trained networks, we characterize pixelwise segmentation of stromal, epithelium, and lumen (SEL) regions on both biopsy core and whole-mount H&E-stained tissue. Results: We provide evidence that by simply training a deep learning algorithm on weakly labeled data generated from rigid morphometric methods, we can improve the robustness of classification over the morphometric methods used to train the classifier. Conclusions: We show that not only does our approach of combining weak and strong labels for training the CNN improve qualitative SEL labeling within tissue but also the deep learning generated labels are superior for cancer classification in a higher-order algorithm over the morphometrically derived labels it was trained on.

The second-generation antiandrogen, enzalutamide, is approved for castrate-resistant prostate cancer (CRPC) and targets androgen receptor (AR) activity in CRPC. Despite initial clinical activity, acquired resistance to enzalutamide arises rapidly and most patients develop terminal disease. Previous work has established Stat5 as a potent inducer of prostate cancer growth. Here, we investigated the significance of Jak2–Stat5 signaling in resistance of prostate cancer to enzalutamide. The levels of Jak2 and Stat5 mRNA, proteins and activation were evaluated in prostate cancer cells, xenograft tumors, and clinical prostate cancers before and after enzalutamide therapy. Jak2 and Stat5 were suppressed by genetic knockdown using lentiviral shRNA or pharmacologic inhibitors. Responsiveness of primary and enzalutamide-resistant prostate cancer to pharmacologic inhibitors of Jak2–Stat5 signaling was assessed in vivo in mice bearing prostate cancer xenograft tumors. Patient-derived prostate cancers were tested for responsiveness to Stat5 blockade as second-line treatment after enzalutamide ex vivo in tumor explant cultures. Enzalutamide-liganded AR induces sustained Jak2–Stat5 phosphorylation in prostate cancer leading to the formation of a positive feed-forward loop, where activated Stat5, in turn, induces Jak2 mRNA and protein levels contributing to further Jak2 activation. Mechanistically, enzalutamide-liganded AR induced Jak2 phosphorylation through a process involving Jak2-specific phosphatases. Stat5 promoted prostate cancer growth during enzalutamide treatment. Jak2–Stat5 inhibition induced death of prostate cancer cells and patient-derived prostate cancers surviving enzalutamide treatment and blocked enzalutamide-resistant tumor growth in mice. This work introduces a novel concept of a pivotal role of hyperactivated Jak2–Stat5 signaling in enzalutamide-resistant prostate cancer, which is readily targetable by Jak2 inhibitors in clinical development.

Prostate cancer is the most common noncutaneous cancer in men in the United States. The current paradigm for screening and diagnosis is imperfect, with relatively low specificity, high cost, and high morbidity. This study aims to generate new image contrasts by learning a distribution of unique image signatures associated with prostate cancer. In total, 48 patients were prospectively recruited for this institutional review board–approved study. Patients underwent multiparametric magnetic resonance imaging 2 weeks before surgery. Postsurgical tissues were annotated by a pathologist and aligned to the in vivo imaging. Radiomic profiles were generated by linearly combining 4 image contrasts (T2, apparent diffusion coefficient [ADC] 0-1000, ADC 50-2000, and dynamic contrast-enhanced) segmented using global thresholds. The distribution of radiomic profiles in high-grade cancer, low-grade cancer, and normal tissues was recorded, and the generated probability values were applied to a naive test set. The resulting Gleason probability maps were stable regardless of training cohort, functioned independent of prostate zone, and outperformed conventional clinical imaging (area under the curve [AUC] = 0.79). Extensive overlap was seen in the most common image signatures associated with high- and low-grade cancer, indicating that low- and high-grade tumors present similarly on conventional imaging.

The αvβ3 integrin is known to be highly upregulated during cancer progression and promotes a migratory and metastatic phenotype in many types of tumors. We hypothesized that the αvβ3 integrin is transferred through exosomes and, upon transfer, has the ability to support functional aberrations in recipient cells. Here, for the first time, it is demonstrated that αvβ3 is present in exosomes released from metastatic PC3 and CWR22Pc prostate cancer cells. Exosomal β3 is transferred as a protein from donor to nontumorigenic and tumorigenic cells as β3 protein or mRNA levels remain unaffected upon transcription or translation inhibition in recipient cells. Furthermore, it is shown that upon exosome uptake, de novo expression of an αvβ3 increases adhesion and migration of recipient cells on an αvβ3 ligand, vitronectin. To evaluate the relevance of these findings, exosomes were purified from the blood of TRAMP mice carrying tumors where the expression of αvβ3 is found higher than in exosomes from wild-type mice. In addition, it is demonstrated that αvβ3 is coexpressed with synaptophysin, a biomarker for aggressive neuroendocrine prostate cancer. Implications: Overall this study reveals that the αvβ3 integrin is transferred from tumorigenic to nontumorigenic cells via exosomes, and its de novo expression in recipient cells promotes cell migration on its ligand. The increased expression of αvβ3 in exosomes from mice bearing tumors points to its clinical relevance and potential use as a biomarker. Mol Cancer Res; 14(11); 1136–46. ©2016 AACR.

Despite aggressive treatment for localized cancer, prostate cancer (PC) remains a leading cause of cancer-related death for American men due to a subset of patients progressing to lethal and incurable metastatic castrate-resistant prostate cancer (CRPC). Organ-confined PC is treated by surgery or radiation with or without androgen deprivation therapy (ADT), while options for locally advanced and disseminated PC include radiation combined with ADT, or systemic treatments including chemotherapy. Progression to CRPC results from failure of ADT, which targets the androgen receptor (AR) signaling axis and inhibits AR-driven proliferation and survival pathways. The exact mechanisms underlying the transition from androgen-dependent PC to CRPC remain incompletely understood. Reactivation of AR has been shown to occur in CRPC despite depletion of circulating androgens by ADT. At the same time, the presence of AR-negative cell populations in CRPC has also been identified. While AR signaling has been proposed as the primary driver of CRPC, AR-independent signaling pathways may represent additional mechanisms underlying CRPC progression. Identification of new therapeutic strategies to target both AR-positive and AR-negative PC cell populations and, thereby, AR-driven as well as non-AR-driven PC cell growth and survival mechanisms would provide a two-pronged approach to eliminate CRPC cells with potential for synthetic lethality. In this review, we provide an overview of AR-dependent and AR-independent molecular mechanisms which drive CRPC, with special emphasis on the role of the Jak2-Stat5a/b signaling pathway in promoting castrate-resistant growth of PC through both AR-dependent and AR-independent mechanisms.

A number of solid tumors are treated with radiation therapy (RT) as a curative modality. At the same time, for certain types of cancers the applicable doses of RT are not high enough to result in a successful eradication of cancer cells. This is often caused by limited pharmacological tools and strategies to selectively sensitize tumors to RT while simultaneously sparing normal tissues from RT. We present an outline of a novel strategy for RT sensitization of solid tumors utilizing Jak inhibitors. Here, recently published pre-clinical data are reviewed which demonstrate the promising role of Jak inhibition in sensitization of tumors to RT. A wide number of currently approved Jak inhibitors for non-malignant conditions are summarized including Jak inhibitors currently in clinical development. Finally, intersection between Jak/Stat and the levels of serum cytokines are presented and discussed as they relate to susceptibility to RT.

Background: A significant fraction of prostate cancer patients experience post–radical prostatectomy (RP) biochemical recurrence (BCR). New predictive markers are needed for optimizing postoperative prostate cancer management. STAT5 is an oncogene in prostate cancer that undergoes amplification in 30% of prostate cancers during progression. Methods: We evaluated the significance of a positive status for nuclear STAT5 protein expression versus STAT5 locus amplification versus combined positive status for both in predicting BCR after RP in 300 patients. Results: Combined positive STAT5 status was associated with a 45% disadvantage in BCR in Kaplan–Meier survival analysis in all Gleason grade patients. Patients with Gleason grade group (GG) 2 and 3 prostate cancers and combined positive status for STAT5 had a more pronounced disadvantage of 55% to 60% at 7 years after RP in univariate analysis. In multivariate analysis, including the Cancer of the Prostate Risk Assessment Postsurgical nomogram (CAPRA-S) variables, combined positive STAT5 status was independently associated with a shorter BCR-free survival in all Gleason GG patients (HR, 2.34; P = 0.014) and in intermediate Gleason GG 2 or 3 patients (HR, 3.62; P = 0.021). The combined positive STAT5 status improved the predictive value of the CAPRA-S nomogram in both ROC-AUC analysis and in decision curve analysis for BCR. Conclusions: Combined positive status for STAT5 was independently associated with shorter disease-free survival in univariate analysis and was an independent predictor for BCR in multivariate analysis using the CAPRA-S variables in prostate cancer. Impact: Our results highlight potential for a novel precision medicine concept based on a pivotal role of STAT5 status in improving selection of prostate cancer patients who are candidates for early adjuvant interventions to reduce the risk of recurrence.

Active Stat5a/b predicts early recurrence and disease-specific death in prostate cancer (PC), which both typically are caused by development of metastatic disease. Herein, we demonstrate that Stat5a/b induces epithelial-to-mesenchymal transition (EMT) of PC cells, as shown by Stat5a/b regulation of EMT marker expression (Twist1, E-cadherin, N-cadherin, vimentin, and fibronectin) in PC cell lines, xenograft tumors in vivo, and patient-derived PCs ex vivo using organ explant cultures. Jak2-Stat5a/b signaling induced functional end points of EMT as well, indicated by disruption of epithelial cell monolayers and increased migration and adhesion of PC cells to fibronectin. Knockdown of Twist1 suppressed Jak2-Stat5a/b-induced EMT properties of PC cells, which were rescued by re-introduction of Twist1, indicating that Twist1 mediates Stat5a/b-induced EMT in PC cells. While promoting EMT, Jak2-Stat5a/b signaling induced stem-like properties in PC cells, such as sphere formation and expression of cancer stem cell markers, including BMI1. Mechanistically, both Twist1 and BMI1 were critical for Stat5a/b induction of stem-like features, because genetic knockdown of Twist1 suppressed Stat5a/b-induced BMI1 expression and sphere formation in stem cell culture conditions, which were rescued by re-introduction of BMI1. By using human prolactin knock-in mice, we demonstrate that prolactin-Stat5a/b signaling promoted metastases formation of PC cells in vivo. In conclusion, our data support the concept that Jak2-Stat5a/b signaling promotes metastatic progression of PC by inducing EMT and stem cell properties in PC cells.

Purpose: The standard treatment for organ-confined prostate cancer is surgery or radiation, and locally advanced prostate cancer is typically treated with radiotherapy alone or in combination with androgen deprivation therapy. Here, we investigated whether Stat5a/b participates in regulation of double-strand DNA break repair in prostate cancer, and whether Stat5 inhibition may provide a novel strategy to sensitize prostate cancer to radiotherapy. Experimental Design: Stat5a/b regulation of DNA repair in prostate cancer was evaluated by comet and clonogenic survival assays, followed by assays specific to homologous recombination (HR) DNA repair and nonhomologous end joining (NHEJ) DNA repair. For HR DNA repair, Stat5a/b regulation of Rad51 and the mechanisms underlying the regulation were investigated in prostate cancer cells, xenograft tumors, and patient-derived prostate cancers ex vivo in 3D explant cultures. Stat5a/b induction of Rad51 and HR DNA repair and responsiveness to radiation were evaluated in vivo in mice bearing prostate cancer xenograft tumors. Results: Stat5a/b is critical for Rad51 expression in prostate cancer via Jak2-dependent mechanisms by inducing Rad51 mRNA levels. Consistent with this, genetic knockdown of Stat5a/b suppressed HR DNA repair while not affecting NHEJ DNA repair. Pharmacologic Stat5a/b inhibition potently sensitized prostate cancer cell lines and prostate cancer tumors to radiation, while not inducing radiation sensitivity in the neighboring tissues. Conclusions: This work introduces a novel concept of a pivotal role of Jak2–Stat5a/b signaling for Rad51 expression and HR DNA repair in prostate cancer. Inhibition of Jak2–Stat5a/b signaling sensitizes prostate cancer to radiation and, therefore, may provide an adjuvant therapy for radiation to reduce radiation-induced damage to the neighboring tissues. Clin Cancer Res; 24(8); 1917–31. ©2018 AACR.

Multiparametric magnetic resonance imaging (MP-MRI), including diffusion-weighted imaging, is commonly used to diagnose prostate cancer. This radiology–pathology study correlates prostate cancer grade and morphology with common b-value combinations for calculating apparent diffusion coefficient (ADC). Thirty-nine patients undergoing radical prostatectomy were recruited for MP-MRI prior to surgery. Diffusion imaging was collected with seven b-values, and ADC was calculated. Excised prostates were sliced in the same orientation as the MRI using 3-D printed slicing jigs. Whole-mount slides were digitized and annotated by a pathologist. Annotated samples were aligned to the MRI, and ADC values were extracted from annotated peripheral zone (PZ) regions. A receiver operating characteristic (ROC) analysis was performed to determine accuracy of tissue type discrimination and optimal ADC b-value combination. ADC significantly discriminates Gleason (G) G4-5 cancer from G3 and other prostate tissue types. The optimal b-values for discriminating high from low-grade and noncancerous tissue in the PZ are 50 and 2000, followed closely by 100 to 2000 and 0 to 2000. Optimal ADC cut-offs are presented for dichotomized discrimination of tissue types according to each b-value combination. Selection of b-values affects the sensitivity and specificity of ADC for discrimination of prostate cancer.

OBJECTIVES/SPECIFIC AIMS: The objective of this study is to use machine Learning techniques to generate maps of epithelium and lumen density in MRI space. METHODS/STUDY POPULATION: Methods: We prospectively recruited 39 patients undergoing prostatectomy for this institutional review board (IRB) approved study. Patients underwent MP-MRI before prostatectomy on a 3T field strength MRI scanner (General Electric, Waukesha, WI, USA) using an endorectal coil. MP-MRI included field-of-view optimized and constrained undistorted single shot (FOCUS) diffusion weighted imaging with 10 b-values (b=0, 10, 25, 50, 80, 100, 200, 500, 1000, and 2000), dynamic contrast enhanced imaging, and T2-weighted imaging. T2 weighted images were intensity normalized and apparent diffusion coefficient maps were calculated. The dynamic contrast enhanced data was used to calculate the percent change in signal intensity before and after contrast injection. All images were aligned to the T2 weighted image. Robotic prostatectomy was performed 2 weeks after image acquisition. Prostate samples were sliced using a 3D printed slicing jig matching the slice profile of the T2 weighted image. Whole mount samples at 10 μm thickness were taken, hematoxylin and eosin stained, digitized, and annotated by a board certified pathologist. A total of 210 slides were included in this study. Lumen and epithelium were automatically segmented using a custom algorithm written in MATLAB. The algorithm was validated by comparing manual to automatic segmentation on 18 samples. Slides were aligned with the T2 weighted image using a nonlinear control point warping technique. Lumen and epithelium density and the expert annotation were subsequently transformed into MRI space. Co-registration was validated by applying a known warp to tumor masks noted by the pathologist and control point warping the whole mount slide to match the transform. Overlap was measured using a DICE coefficient. A learning curve was generated to determine the optimal number of patients to train the algorithm on. A PLS algorithm was trained on 150 random permutations of patients incrementing from 1 to 29 patients. Slides were stratified such that all slides from a single patient were in the same cohort. Three cohorts were generated, with tumor burden balanced across all cohort. A PLS algorithm was trained on 2 independent training sets (cohorts 1 and 2) and applied to cohort 3. The input vector consisted of MRI values and the target variable was lumen and epithelium density. The algorithm was trained lesion-wise. Trained PiCT models were applied to the test cohort voxel-wise to generate 2 new image contrasts. Mean lesion values were compared between high grade, low grade, and healthy tissue using an ANOVA. An ROC analysis was performed lesion-wise on the test set. RESULTS/ANTICIPATED RESULTS: Results: The segmentation accuracy validation revealed R=0.99 and R=0.72 (p

221 Background: Androgen targeted therapy remains the mainstay for advanced prostate cancer (PC). Second-generation androgen receptor (AR) antagonist, enzalutamide (ENZ), re-targets persistent AR activity in castrate-resistant (CR) PC tumors, and is approved for CRPC. Despite initial clinical activity, acquired resistance to ENZ arises rapidly and most patients succumb to PC. Mechanisms underlying resistance to ENZ are incompletely understood. Prior work has established Stat5 as a potent inducer of PC growth. Here, we investigated the significance of Jak2-Stat5 signaling in ENZ-resistant growth of PC. Methods: Levels of Jak2 and Stat5 activation in PC cells, tumors and patient samples were evaluated by immunohistochemistry, 3D tumor explant cultures and western blotting. Jak2 and Stat5 were inhibited by lentiviral (expression of) shRNA or pharmacologically. Levels of mRNA were assessed by QPCR and gene expression profiling. Results: ENZ induced a robust increase in Stat5 activation in PC cells in vitro, in xenograft tumors in vivo and in patient-derived PCs during ENZ treatment. Mechanistically, ENZ activation of Stat5 involves a positive feed-forward mechanism where ENZ-liganded AR induces rapid and sustained Jak2 phosphorylation in PC cells through a process involving Jak2-specific phosphatases. This results in a formation of a positive feed-forward loop in PC where activated Stat5 induces Jak2 mRNA and protein levels in PC. We showed that active Stat5 increased viability of PC cells during ENZ treatment and, at the same time, inhibition of Stat5 as a second-line treatment induced excessive death of PC cells surviving ENZ treatment. Importantly, pharmacological Stat5 blockade inhibited CR growth of PC xenograft tumors after ENZ resistance developed. Conclusions: Collectively, this work introduces a novel concept for a pivotal role of Jak2-Stat5 signaling in mediating resistance of PC to ENZ. Pharmacological Jak2-Stat5 inhibition may provide efficacious therapy in advanced PC in combination with ENZ or after ENZ fails.

Purpose: Progression of prostate cancer to the lethal castrate-resistant stage coincides with loss of responsiveness to androgen deprivation and requires development of novel therapies. We previously provided proof-of-concept that Stat5a/b is a therapeutic target protein for prostate cancer. Here, we show that pharmacologic targeting of Jak2-dependent Stat5a/b signaling by the Jak2 inhibitor AZD1480 blocks castrate-resistant growth of prostate cancer. Experimental Design: Efficacy of AZD1480 in disrupting Jak2–Stat5a/b signaling and decreasing prostate cancer cell viability was evaluated in prostate cancer cells. A unique prostate cancer xenograft mouse model (CWR22Pc), which mimics prostate cancer clinical progression in patients, was used to assess in vivo responsiveness of primary and castrate-resistant prostate cancer (CRPC) to AZD1480. Patient-derived clinical prostate cancers, grown ex vivo in organ explant cultures, were tested for responsiveness to AZD1480. Results: AZD1480 robustly inhibited Stat5a/b phosphorylation, dimerization, nuclear translocation, DNA binding, and transcriptional activity in prostate cancer cells. AZD1480 reduced prostate cancer cell viability sustained by Jak2–Stat5a/b signaling through induction of apoptosis, which was rescued by constitutively active Stat5a/b. In mice, pharmacologic targeting of Stat5a/b by AZD1480 potently blocked growth of primary androgen-dependent as well as recurrent castrate-resistant CWR22Pc xenograft tumors, and prolonged survival of tumor-bearing mice versus vehicle or docetaxel-treated mice. Finally, nine of 12 clinical prostate cancers responded to AZD1480 by extensive apoptotic epithelial cell loss, concurrent with reduced levels of nuclear Stat5a/b. Conclusions: We report the first evidence for efficacy of pharmacologic targeting of Stat5a/b as a strategy to inhibit castrate-resistant growth of prostate cancer, supporting further clinical development of Stat5a/b inhibitors as therapy for advanced prostate cancer. Clin Cancer Res; 19(20); 5658–74. ©2013 AACR.