Comparison of sequential versus concurrent chemoradiation regimens in non-metastatic muscle-invasive bladder cancer

PURPOSE

The treatment approach for non-metastatic bladder cancer is guided by an invasion of the muscular layer of the bladder wall. Radical cystectomy is the recommended treatment for muscle-invasive disease. However, it has considerable morbidity and mortality and is not suited for many patients. Trimodality therapy consisting of chemoradiation after transurethral resection of bladder tumor offers a definitive approach with bladder-sparing potential. However, there is a lack of research defining the optimal combination of chemotherapy and radiation in this setting.

MATERIALS AND METHODS

We extracted patient data from the National Cancer Database to compare survival outcomes and demographic factors in 2,227 non-metastatic bladder cancer patients who were treated with chemotherapy sequential to or concurrently with radiation. Sequential treatment was defined as chemotherapy beginning >14 days before radiation, and concurrent was defined as beginning within 14 days of the first radiation.

RESULTS

The sequential treatment group patients were younger (mean age, 74 vs. 78 years; p < 0.001) with more advanced disease. We found no difference in overall survival between patients who received chemotherapy sequential to radiation and those who received concurrent chemoradiation only (p = 0.533).

CONCLUSION

Our data are concordant with a previous prospective study, and support that chemotherapy prior to radiation does not decrease survival outcomes relative to patients receiving only concurrent chemoradiation. Given that the sequential group had an overall higher stage but no difference in survival, downstaging chemotherapy prior to radiation may be helpful in these patients. Further studies including a larger, multi-institutional clinical trial are indicated to support clinical decision-making.

Phase Ib trial of inhaled iloprost for the prevention of lung cancer with predictive and response biomarker assessment

Introduction

Iloprost, a prostacyclin analog, has lung cancerpreventive activity in preclinical models and improved dysplasia in former smokers in a phase IIb trial. Oral iloprost is currently unavailable. We performed a phase Ib trial of inhaled iloprost in former smokers to assess tolerance and compliance.

Methods

Participants self-administered nebulized iloprost (5ug) or placebo four (QID) or two (BID) times daily. As QID dose was well tolerated and due to expiration of the placebo, the BID dosing and placebo were eliminated early on in the trial. Bronchoscopy with biopsyat six standard sites was performed at treatment initiation and two months post-iloprost, with exploratory histological analysis. Bulk RNA sequencing, single cell RNA sequencing and an in vitro assay of epithelial progenitor cell iloprost response were performed on a subset of biopsies in an exploratory investigation of response mechanisms and predictive biomarkers.

Results and discussion

Thirty-four of a planned 48 participants were recruited to the trial.Inhaled iloprost was well tolerated with no adverse events > grade 2. Compliance was 67% in the QID group. The trial was not powered to detect histologic response and none was found. Bulk RNA sequencing of biopsies pre/post iloprost suggest that iloprost is immunomodulatory and downregulates cell proliferation pathways. Single cell RNA sequencing showed an increase in CD8-positive T cells with upregulation of genes in interferon γ signaling. In vitro iloprost response by epithelial progenitor cells correlated with histologic response with kappa coefficient of 0.81 (95% CI 0.47, 1.0). Inhaled iloprost was well tolerated with suboptimal compliance. Molecular analysis suggested that iloprosthas immunomodulatory and antiproliferative effects.The progenitor cell iloprost response assay may be a promising avenue to develop predictive biomarkers.

Clinical trial registration

https://clinicaltrials.gov/study/NCT02237183, identifier NCT02237183.

Cancer Associated Macrophage-like Cells Are Prognostic for Highly Aggressive Prostate Cancer in Both the Non-Metastatic and Metastatic Settings

Despite advancements in the early-stage detection and expansion of treatments for prostate cancer (PCa), patient mortality rates remain high in patients with aggressive disease and the overtreatment of indolent disease remains a major issue. Prostate-specific antigen (PSA), a standard PCa blood biomarker, is limited in its ability to differentiate disease subtypes resulting in the overtreatment of non-aggressive indolent disease. Here we assess engorged cancer-associated macrophage-like cells (CAMLs), a ≥50 µm, cancer-specific, polynucleated circulating cell type found in the blood of patients with PCa as a potential companion biomarker to PSA for patient risk stratification. We found that rising PSA is positively correlated with increasing CAML size (r = 0.307, p = 0.004) and number of CAMLs in circulation (r = 0.399, p < 0.001). Over a 2-year period, the presence of a single engorged CAML was associated with 20.9 times increased likelihood of progression (p = 0.016) in non-metastatic PCa, and 2.4 times likelihood of progression (p = 0.031) with 5.4 times likelihood of death (p < 0.001) in metastatic PCa. These preliminary data suggest that CAML cell monitoring, in combination with PSA, may aid in differentiating non-aggressive from aggressive PCas by adding biological information that complements traditional clinical biomarkers, thereby helping guide treatment strategies.

Abstract LB010: SMMART Program: A multi-omics tumor board with a focus on breast cancer

Many of the current approaches to personalized medicine rely on sequencing DNA to identify actionable mutations. However, growing evidence suggests that a multi-omic approach to more broadly assess biology is needed to improve patient outcomes. We have implemented a workflow for tissue acquisition, multi-omic clinical testing, and correlated computational biology analysis, within the Serial Measurements of Molecular and Architectural Responses to Therapy (SMMART) Program (Mitri et al, J Transl Med 2018). We report biopsy metrics, CLIA analytics utilized, the operation of a multi-omics tumor board, and clinical outcomes in metastatic breast cancer patients. A detailed clinical history of each patient was obtained, including demographics, tumor type, treatment and response to prior therapies, imaging, and blood tumor biomarkers. A comprehensive set of clinical assays was performed on newly obtained tumor biopsies, including immunohistochemistry (ER, PR, HER2, AR, BCL-2, and PD-L1), a targeted next-generation sequencing panel covering 225 genes (GeneTrails® Comprehensive Solid Tumor Panel), whole exome sequencing (Tempus xE), whole transcriptomic sequencing (Illumina TruSeq RNA exome), and a multiplex protein analysis of 22 key cancer proteins and phosphoproteins on the Nanostring platform (NanoString Vantage 3D™ Solid Tumor Panel). The integrated clinical and analytical information was made available to the multidisciplinary SMMART Clinical Tumor Board that provided treatment recommendations; the final treatment plan was at the discretion of the treating physician. Between 1/1/2017-1/1/2020, 53 breast cancer patients were consented. Seven screen-failed due to a lack of sites amenable to biopsy and 8 were actively co-consented to other clinical trials. The remaining 38 patients are included in this preliminary report. A total of 63 biopsies were collected from lymph node, liver, bone, soft tissue, lung, skin, breast, and brain. Serial biopsies (≥2) were obtained for 15 patients. Analytics were generated in 93.7% of biopsies. Tumor boards were held for 15 patients (17 total sessions). The experience and information gathered thus far have yielded the following unique cases: (1) single patient analysis of omics, imaging, and response over 42 months, (2) identification of an ERBB3 mutation with downstream pathway activation that responded to HER2-targeted therapy, and (3) clinically significant variation in hormonal and HER2 receptor status over time. We will provide an analysis across the 38 patients of treatment outcomes, analytics information content, biological changes observed through serial biopsies, and tumor board interventions. We demonstrate the feasibility of implementing a deep, real-time analytics platform for metastatic breast cancer patients that can provide new insight into therapeutic opportunities. The observed clinical responses support further use and investigation of this approach.

Citation Format: Ben L. Kong, Brett E. Johnson, Jamie M. Keck, Souraya Mitri, Patrick Leyshock, Jayne M. Stommel, Kiara Siex, Marlana Klinger, Christina L. Zheng, Rochelle Williams-Belizaire, Shannon McWeeney, Jeremy Goecks, Annette Kolodzie, Alexander R. Guimaraes, George V. Thomas, Christopher L. Corless, Zahi I. Mitri, Joe W. Gray, Gordon B. Mills, Raymond C. Bergan. SMMART Program: A multi-omics tumor board with a focus on breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB010.

Hyper engorged cancer associated macrophage-like cells in circulation predict for multi-organ metastatic disease in solid tumors

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Background: Patients with multiple organ metastases have poorer prognoses than those with a single organ metastasis, are frequently associated with drug resistance, and have higher tumor burden. Engorged (≥50um) Cancer Associated Macrophage-Like Cells (CAMLs) are a circulating stromal cell subtype detected in the blood of patients with solid tumors at high risk for recurrence or progression. While numerous studies have shown that ≥50um CAMLs predict poor clinical outcomes, meta-analysis of these studies have also suggested that hyper engorged CAMLs ≥100um (heCAMLs) may be associated with multifocal metastatic disease and even worse outcomes. In this prospective study, we evaluated the presence of heCAMLs in patients with metastatic disease and demonstrated a strong relationship with multi organ spread, which also correlated with shorter Progression Free Survival (PFS) and Overall Survival (OS). Methods: We prospectively recruited 151 patients with metastatic (m) mbreast (n = 58), mlung (n = 34), mprostate (n = 39), and mrenal (n = 20) cancers. Peripheral blood was collected prior to the induction of new treatment for metastatic cancer. Cells were isolated following standard CellSieve techniques, then imaged and measured in ZenBlue. Multi organ metastasis was defined as spread to ≥2 distant organ sites, or any spread to the brain. Single factor ANOVA was conducted to compare heCAML presence in multi organ metastatic patients versus patients with single organ site metastasis. Univariate and multivariate analysis was run to evaluate for PFS and OS against heCAMLs, and all known clinical parameters. Results: 150 viable samples (excluding 1 failed sample) were obtained. Multi organ metastases were present in 55% (n = 83/150) of patients. heCAMLs were found in 59% (n = 49/83) of the multi organ metastatic population, but only in 16% (n = 11/67) of the single site metastatic cohort (p < 0.001). heCAML presence appeared to differentiate multi organ vs single organ metastases in mbreast (85% vs. 52%, p = 0.006), mlung (71% vs. 26%, p = 0.025), mprostate (75% vs. 37%, p = 0.029), and mRCC (88% vs. 36%, p = 0.025). Further, in all n = 150 patients, heCAML presence predicted a significantly shorter median PFS of 4.5 versus 7.2 months, 24 month PFS (HR = 1.67, 95%CI = 1.13-2.45, p = 0.013), and significantly shorter median OS of 13.1 versus 20.4 months, 24 month OS (HR = 2.05, 95%CI = 1.24-3.39, p = 0.008). Conclusions: We examined a non-invasive prognostic blood based assay to determine its relationship to multi organ metastatic spread as well as its prognostic value in several solid cancers. These results showed patients with heCAMLs had higher rates of multi organ metastases, and appear to predict for shorter PFS and OS. Studies of larger cohorts are needed for prospective validation of these initial findings.

Clinical trial design: Past, present, and future in the context of big data and precision medicine

Clinical trials are fundamental for advances in cancer treatment. The traditional framework of phase 1 to 3 trials is designed for incremental advances between regimens. However, our ability to understand and treat cancer has evolved with the increase in drugs targeting an expanding array of therapeutic targets, the development of progressively comprehensive data sets, and emerging computational analytics, all of which are reshaping our treatment strategies. A more robust linkage between drugs and underlying cancer biology is blurring historical lines that define trials on the basis of cancer type. The complexity of the molecular basis of cancer, coupled with manifold variations in clinical status, is driving the individually tailored use of combinations of precision targeted drugs. This approach is spawning a new era of clinical trial types. Although most care is delivered in a community setting, large centers support real‐time multi‐omic analytics and their integrated interpretation by using machine learning in the context of real‐world data sets. Coupling the analytic capabilities of large centers to the tailored delivery of therapy in the community is forging a paradigm that is optimizing service for patients. Understanding the importance of these evolving trends across the health care spectrum will affect our treatment of cancer in the future and is the focus of this review.

With advances in cancer biology, precision therapeutics, and big data, clinical trial designs are evolving. They are transforming cancer care and research across the biomedical enterprise.

A phase II single-arm study of pembrolizumab with enzalutamide in men with metastatic castration-resistant prostate cancer progressing on enzalutamide alone

BACKGROUND

Checkpoint inhibitors can induce profound anticancer responses, but programmed cell death protein-1 (PD-1) inhibition monotherapy has shown minimal activity in prostate cancer. A published report showed that men with prostate cancer who were resistant to the second-generation androgen receptor inhibitor enzalutamide had increased programmed death-ligand 1 (PD-L1) expression on circulating antigen-presenting cells. We hypothesized that the addition of PD-1 inhibition in these patients could induce a meaningful cancer response.

METHODS

We evaluated enzalutamide plus the PD-1 inhibitor pembrolizumab in a single-arm phase II study of 28 men with metastatic castration-resistant prostate cancer (mprogressing on enzalutamide alone. Pembrolizumab 200 mg intravenous was given every 3 weeks for four doses with enzalutamide. The primary endpoint was prostate-specific antigen (PSA) decline of ≥50%. Secondary endpoints were objective response, PSA progression-free survival (PFS), time to subsequent treatment, and time to death. Baseline tumor biopsies were obtained when feasible, and samples were sequenced and evaluated for the expression of PD-L1, microsatellite instability (MSI), mutational and neoepitope burdens.

RESULTS

Five (18%) of 28 patients had a PSA decline of ≥50%. Three (25%) of 12 patients with measurable disease at baseline achieved an objective response. Of the five responders, two continue with PSA and radiographic response after 39.3 and 37.8 months. For the entire cohort, median follow-up was 37 months, and median PSA PFS time was 3.8 months (95% CI: 2.8 to 9.9 months). Time to subsequent treatment was 7.21 months (95% CI: 5.1 to 11.1 months). Median overall survival for all patients was 21.9 months (95% CI: 14.7 to 28 .4 months), versus 41.7 months (95% CI: 22.16 to not reached (NR)) in the responders. Of the three responders with baseline biopsies, one had MSI high disease with mutations consistent with DNA-repair defects. None had detectable PD-L1 expression.

CONCLUSIONS

Pembrolizumab has activity in mCRPC when added to enzalutamide. Responses were deep and durable and did not require tumor PD-L1 expression or DNA-repair defects.

TRIAL REGISTRATION NUMBER

clinicaltrials.gov (NCT02312557).

Circulating stromal cells as a potential blood-based biomarker for screening invasive solid tumors

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Background: Peripheral blood allows for a simple non-invasive method for isolating various cancer associated circulating stromal cells (CStCs) which may predict for cancer presence. Cancer Associated Macrophage-Like cells (CAMLs), a specific CStC, are phagocytic myeloid cells that derive from an immunological response to cancer and emanate from primary tumors. Using a filtration platform we screened the peripheral blood of untreated newly diagnosed cancer patients (n = 308) for CAMLs. In parallel, we screened patients with newly diagnosed non-malignant diseases, i.e. lupus, benign cysts, etc. (n = 39), and healthy control samples (n = 76). We found that CAMLs are highly prevalent (87%) in the blood of cancer patients, but uncommon in non-malignant conditions (20%) & absent in healthy individuals (0%). Methods: Anonymized peripheral blood were taken from 308 cancer patients after confirmation of invasive malignancy [stage I (n = 76), stage II (n = 73), stage III (n = 72), stage IV (n = 65) and unstaged non-metastatic (n = 22)] with pathologically confirmed lung (n = 65), pancreas (n = 53), breast (n = 52), prostate (n = 40), esophageal (n = 30), renal cell (n = 18), hepatocellular (n = 15), neuroblastoma (n = 10), melanoma (n = 8), and other (n = 17). Further, anonymized blood was taken from patients with untreated non-malignant conditions including benign breast masses (n = 19), lupus (n = 11), liver cirrhosis (n = 5), benign prostatic hyperplasia (BPH) (n = 3), and viral infection (n = 1); or from healthy control volunteers (n = 76). CAMLs were isolated from whole peripheral blood by the CellSieve™ microfiltration technique and defined as enlarged, multinuclear cells with cytokeratin and/or CD45/CD14 positive. Results: CAMLs were found in 87% of all cancer patients regardless of stage, ~5.4 CAMLs/7.5mL blood. Specifically, CAMLs were found in 80% of Stage I, 90% Stage II, 89% Stage III, and 97% Stage IV patients. No CAMLs were found in any healthy controls, but were found in 26% of benign breast masses, 18% of lupus, 0% of BPH and 0% of cirrhosis. In total, CAML sensitivity in cancer vs healthy was 87% (CI95% 82-90%), specificity = 100% (CI95% 95-100%), PPV = 100% (CI95% 100%), NPV = 67% (CI95% 58-71%). CAML sensitivity in cancer vs benign was 87% (CI95% 82-90%), specificity = 80% (CI95% 64-91%), PPV = 97% (CI95% 95-98%), NPV = 43% (CI95% 35-51%). Conclusions: CAMLs, a Circulating Stromal Cell subtype, is a sensitive blood based biomarker found in all stages of cancer that is rare in non-malignant conditions and absent in healthy individuals.

The master observational trial–a novel method to unify precision oncology data collection

e19313

Background: The Master Observational Trial (MOT) was recently created as a new master protocol that hybridizes the power of master interventional trials with the richness of real-world data (Cell, 2020). The MOT can be described as a series of prospective observational studies that are tied together through a common protocol, infrastructure, and organization. The MOT has broad application in many disease states but is particularly powerful in oncology. We herein expand our prior work to describe key details regarding how the MOT concept can fill multiple unmet needs in oncology. Methods: Through published information, white papers, and expert opinions we identified key unmet needs of oncology stakeholders. We reviewed the publicly available information of structure, organization, and data availability of the five largest genomic-outcome real-world data efforts. Common concerns included variability and reliability of biomarkers, the scientific rigor in real-world data, data silos, patient consent, and duplicated or disparate activities. We then determined how a specific application of the MOT in oncology could answer stakeholder concerns, integrate with current efforts, and also how to provide a model that would be equally valuable to academic and community clinics. Results: We identified significant scientific challenges with many of the current oncology real-world datasets in answering key concerns of stakeholders. We developed the Master Registry of Oncology Outcomes Associated with Testing and Treatment (ROOT) as the first national implementation of an oncology-centric MOT. We modeled how ROOT could fill scientific gaps in current data efforts and integrate with interventional and real-world efforts and help answer key concerns of stakeholders. We also identified solutions that would allow community and academic groups to participate in the same effort. Conclusions: An oncology-centric MOT has the potential to improve the quality of RWD in oncology and advance precision oncology in ways that are not fully addressed by current retrospective efforts. Reference Dickson DJ, Johnson J, Owens R, Bergan R, Subbiah V, Kurzrock R. (2020). The Master Observational Trial: A New Class of Master Protocol to Advance Precision Medicine. Cell 180, 9-14. Clinical trial information: NCT04028479 .

Feasibility of real-time serial comprehensive tumor analytics: Pilot study of olaparib and durvalumab in metastatic triple negative breast cancer (mTNBC)

e13092

Background: Longitudinal analysis of serial tumor biopsies is an under-utilized approach to studying adaptive mechanisms of resistance. We have established a comprehensive analytic platform to evaluate real-time trial sample analysis to inform precision oncology combinations in mTNBC. The primary endpoint of the study is feasibility of completing all CLIA assays within 28 days of biopsy. Methods: Following a pre-treatment biopsy and 4 weeks of olaparib monotherapy mTNBC patients underwent an on-treatment (tx) biopsy and durvalumab was added to their therapy. Pre- and on-tx biopsies underwent comparative analysis using CLIA assays (immunohistochemistry-IHC, whole exome seq, RNAseq and phospho-proteomics) as well as research assays (multiplex IHC-mIHC, cyclic immunofluorescence-IF, and reverse phase protein array-RPPA). Results: Serial biopsies were obtained from all 3 enrolled patients, and the primary endpoint was achieved for all patients (Table). Treatment was well tolerated, and 2 patients achieved clinical benefit > 6 months. In one patient with a prolonged CR ( > 18 months), the on-tx sample exhibited dramatic changes in protein network rewiring by protein data analysis (RPPA, cyclic-IF), and an increase in immune infiltrate by mIHC. Conclusions: This pilot confirmed the feasibility of rapid real-time analysis to inform treatment decisions. This led to the development and initiation of biomarker driven olaparib combination trials in mTNBC at our institution. Clinical trial information: NCT03544125 . [Table: see text]

Abstract 4929: Leveraging multi-omics tumor boards for precision medicine in the OHSU SMMART Treatments Program

Comprehensive characterization of an individual’s cancer using multi-omic analyses and an expanding list of targeted therapies is providing an opportunity to uncover therapeutic vulnerabilities and rationally target multiple driving alterations in the tumor. To leverage this opportunity, a multi-disciplinary team is required to unravel the complexity of tumor behavior and genomic variant information, integrate data from multi-omic assays, and exploit potential synergies from combination therapy while avoiding toxicity, all of which occurs within the context of the patient’s clinical history and comorbidities. We report the preliminary experience of OHSU Knight Cancer Institute’s SMMART (Serial Measurements of Molecular and Architectural Responses to Therapy) Treatments Program Multi-omics Tumor Board (MTB). The role of the SMMART MTB, to date, has been to develop and optimize procedures in a feasibility protocol for future application in the clinical setting where we will provide personalized combinatorial treatment suggestions. Here we report our preliminary experience over the last 15 months with multi-disciplinary tumor boards for metastatic breast cancer. A deep analysis of data, in many cases from serial biopsies, enabled identification of personalized, multi-targeted therapy. Clinical and laboratory data are explored individually and collectively by oncologists, oncology pharmacists, molecular pathologists, cancer biologists, and computational biologists. Data from CLIA-certified analytics include, but are not limited to, a 124 gene targeted panel, whole exome sequencing, MSI, gene-fusion, RNAseq, and clinical IHC assays that provide status information about receptors (ER/PR/AR/HER2), proliferation rate, and tumor immunogenicity along with reflexive assays for expression of relevant proteins such as p16, RB, and PTEN. A customized LabKey® system allows for visual display of a patient’s clinical timeline with information about diagnoses, treatments, biopsies events, radiographic changes, and blood biomarkers; thereby providing MTB participants with a holistic view of the patient’s case summary. Our experience with several example breast cancer case scenarios identified therapeutic vulnerabilities that would not have been considered by a standard clinical tumor board with genomic data alone. Recent cases have included observations such as HER2 status switching, a rare pathogenic germline mutation, high PD-L1 expression, and gained expression of the androgen receptor. These cases further emphasize the value and importance of MTB discussions to oncologists for interpreting and analyzing complex multi-omic data and uncovering therapeutic options for patients. This experience will be utilized in the future for employing SMMART MTBs in a clinical setting as a platform to triage patients into different multi-targeted combinatorial treatment options.

Citation Format: Jamie M. Keck, Swapnil Parmar, Ben Kong, Zahi Mitri, Christopher Corless, Annette Kolodzie, Allison Creason, Jeremy Goecks, Patrick Leyshock, Kiara Siex, Brett E. Johnson, Janice Patterson, Laura Heiser, Anastasiya Olson, Matt Viehdorfer, Georgia Mayfield, Jennifer Laverdure, Joe W. Gray, Gordon B. Mills, Raymond C. Bergan. Leveraging multi-omics tumor boards for precision medicine in the OHSU SMMART Treatments Program [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4929.

A Phase II Study of 5-AZA-2'Deoxycytidine (Decitabine) in Hormone Independent Metastatic (D2) Prostate Cancer

Aims and Background

Decitabine (5-aza-2′-deoxycytidine) is an S-phase-specific pyrimidine analog with hypomethylation properties. In laboratory models of prostate cancer (PC-3 and DU-145), decitabine induces cellular differentiation and enhanced expression of genes involved in tumor suppression, immunogenicity, and programmed cell death.

Methods

We conducted a phase II study of decitabine in 14 men with progressive, metastatic prostate cancer recurrent after total androgen blockade and flutamide withdrawal. Decitabine was administered at a dose of 75 mg/m2/dose IV as a 1 hour infusion every 8 hours for three doses. Cycles of therapy were repeated every 5 to 8 weeks to allow for resolution of toxicity.

Results

Two of 12 patients evaluable for response had stable disease with a time to progression of more than 10 weeks. This activity was seen in 2 of 3 African-American patients. Toxicity was similar to previously reported experience. No significant changes in urinary concentrations of the angiogenic factor bFGF, a potential biomarker of tumor activity, were identified over time in 7 unselected patients with progressive disease.

Conclusions

We conclude that decitabine is a well tolerated regimen with modest clinical activity against hormone-independent prostate cancer. Further investigations in patients of African-American origin may be warranted.

Early evidence of anti-PD-1 activity in enzalutamide-resistant prostate cancer

While programmed cell death 1 (PD-1) inhibitors have shown clear anti-tumor efficacy in several solid tumors, prior results in men with metastatic castration resistant prostate cancer (mCRPC) showed no evidence of activity. Here we report unexpected antitumor activity seen in mCRPC patients treated with the anti-PD-1 antibody pembrolizumab. Patients with evidence of progression on enzalutamide were treated with pembrolizumab 200 mg IV every 3 weeks for 4 doses; pembrolizumab was added to standard dose enzalutamide. Three of the first ten patients enrolled in this ongoing phase II trial experienced rapid prostate specific antigen (PSA) reductions to ≤ 0.2 ng/ml. Two of these three patients had measurable disease upon study entry; both achieved a partial response. There were three patients with significant immune-related adverse events. One had grade 2 myositis, one had grade 3 hypothyroidism, and one had grade 2 hypothyroidism. None of these patients had a response. Two of the three responders had a baseline tumor biopsy. Immunohistochemistry from those biopsies showed the presence of CD3⁺, CD8⁺, and CD163⁺ leukocyte infiltrates and PD-L1 expression. Genetic analysis of the two responders revealed markers of microsatellite instability in one. The surprising and robust responses seen in this study should lead to re-examination of PD-1 inhibition in prostate cancer.

Cancer-associated macrophage-like cells as prognostic indicators of overall survival in a variety of solid malignancies

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Background: Cancer Associated Macrophage-Like cells (CAMLs) are a recently described circulating stromal cell subtype commonly found in the peripheral blood of patients in all stages of solid malignancies and in a variety of cancer subtypes. However, while their biological association to cancer is being studied, their clinical utilization as it relates to cancer prognosis has not been evaluated. Methods: A two year prospective study was undertaken to evaluate the relationship of CAMLs and overall survival (OS) in 6 solid tumor types. The single blind multi-institutional study consisted of 269 stage I-IV patients; breast (n = 57), esophageal (n = 21), prostate (n = 43), pancreatic (n = 59), lung (n = 54), and renal cell (n = 35), in treatment (n = 134) and untreated baseline (n = 135). 7.5mL of whole blood was filtered by CellSieve microfiltration assay and CAMLs enumerated, as previously described. Patients were grouped by CAML number ( < 6 or ≥6) and by size ( < 49 or ≥50 µm) to evaluate hazard ratios (HR) by censored univariate & multivariate analysis. Results: CAMLs were identified in 93% of samples, averaging 8.2 CAMLs/7.5mL blood sample, and found in all 6 cancers at baseline and during treatment. Average CAML number was associated with disease stage and CAML positivity was 4.4 & 80% (Stage I), 4.7 & 93% (Stage II), 9.3 & 98% (Stage 3), 12.1 & 97% (Stage IV). Univariate analysis of patients (n = 269) stratified by ≥6 CAMLs had reduced OS (HR = 1.8, 95%CI 1.1-2.9, p = 0.03). Further, CAML size also had reduced OS in patients with ≥50 µm CAMLs (HR = 2.7, 95%CI 1.8-4.0, p < 0.0001). Conclusions: Our data suggests that in solid malignancies, CAML number and size appear to clinically correlate with OS in early and late stage disease. Given these results relating CAMLs with OS, further analysis is warranted to determine if CAMLs can serve as a clinically-relevant blood-based marker.

Spectral biomarkers for chemoprevention of colonic neoplasia: a placebo-controlled double-blinded trial with aspirin

OBJECTIVE

A major impediment to translating chemoprevention to clinical practice has been lack of intermediate biomarkers. We previously reported that rectal interrogation with low-coherence enhanced backscattering spectroscopy (LEBS) detected microarchitectural manifestations of field carcinogenesis. We now wanted to ascertain if reversion of two LEBS markers spectral slope (SPEC) and fractal dimension (FRAC) could serve as a marker for chemopreventive efficacy.

DESIGN

We conducted a multicentre, prospective, randomised, double-blind placebo-controlled, clinical trial in subjects with a history of colonic neoplasia who manifested altered SPEC/FRAC in histologically normal colonic mucosa. Subjects (n=79) were randomised to 325 mg aspirin or placebo. The primary endpoint changed in FRAC and SPEC spectral markers after 3 months. Mucosal levels of prostaglandin E2 (PGE2) and UDP-glucuronosyltransferase (UGT)1A6 genotypes were planned secondary endpoints.

RESULTS

At 3 months, the aspirin group manifested alterations in SPEC (48.9%, p=0.055) and FRAC (55.4%, p=0.200) with the direction towards non-neoplastic status. As a measure of aspirin's pharmacological efficacy, we assessed changes in rectal PGE2 levels and noted that it correlated with SPEC and FRAC alterations (R=-0.55, p=0.01 and R=0.57, p=0.009, respectively) whereas there was no significant correlation in placebo specimens. While UGT1A6 subgroup analysis did not achieve statistical significance, the changes in SPEC and FRAC to a less neoplastic direction occurred only in the variant consonant with epidemiological evidence of chemoprevention.

CONCLUSIONS

We provide the first proof of concept, albeit somewhat underpowered, that spectral markers reversion mirrors antineoplastic efficacy providing a potential modality for titration of agent type/dose to optimise chemopreventive strategies in clinical practice.

TRIAL NUMBER

NCT00468910.

Genistein suppresses FLT4 and inhibits human colorectal cancer metastasis

Dietary consumption of genistein, found in soy, has been associated with a potentially protective role in colorectal cancer (CRC) development and progression. Herein we demonstrate that genistein will inhibit human CRC cell invasion and migration, that it does so at non-cytotoxic concentrations and we demonstrate this in multiple human CRC cell lines. After orthotopic implantation of human CRC tumors into mice, oral genistein did not inhibit tumor growth, but did inhibit distant metastasis formation, and was non-toxic to mice. Using a qPCR array, we screened for genistein-induced changes in gene expression, followed by Western blot confirmation, demonstrating that genistein downregulated matrix metalloproteinase 2 and Fms-Related Tyrosine Kinase 4 (FLT4; vascular endothelial growth factor receptor 3). After demonstrating that genistein suppressed neo-angiogenesis in mouse tumors, we examined FLT4 expression in primary CRC and adjacent normal colonic tissue from 60 human subjects, demonstrating that increased FLT4 significantly correlates with increased stage and decreased survival. In summary, we demonstrate for the first time that genistein inhibits human CRC metastasis at dietary, non-toxic, doses. FLT4 is identified as a marker of metastatic disease, and as a response marker for small molecule therapeutics that inhibit CRC metastasis.

Heat shock protein 27 regulates human prostate cancer cell motility and metastatic progression

Prostate cancer (PCa) is the most common form of cancer in American men. Mortality from PCa is caused by the movement of cancer cells from the primary organ to form metastatic tumors at distant sites. Heat shock protein 27 (HSP27) is known to increase human PCa cell invasion and its overexpression is associated with metastatic disease. The role of HSP27 in driving PCa cell movement from the prostate to distant metastatic sites is unknown. Increased HSP27 expression increased metastasis as well as primary tumor mass. In vitro studies further examined the mechanism of HSP27-induced metastatic behavior. HSP27 did not affect cell detachment, adhesion, or migration, but did increase cell invasion. Cell invasion was dependent upon matrix metalloproteinase 2 (MMP-2), whose expression was increased by HSP27. In vivo, HSP27 induced commensurate changes in MMP-2 expression in tumors. These findings demonstrate that HSP27 drives metastatic spread of cancer cells from the prostate to distant sites, does so across a continuum of expression levels, and identifies HSP27-driven increases in MMP-2 expression as functionally relevant. These findings add to prior studies demonstrating that HSP27 increases PCa cell motility, growth and survival. Together, they demonstrate that HSP27 plays an important role in PCa progression.

Abstract 5394: A high-throughput screening platform for the identification of small molecule inhibitors of MAP2K4

Prostate cancer (PCa) is the second highest cause of cancer death in United States males. If the metastatic movement of PCa cells could be inhibited, then mortality from PCa could be greatly reduced. Mitogen-activated protein kinase kinase 4 (MAP2K4) has previously been shown to activate pro-invasion signaling pathways in human PCa. Recognizing that MAP2K4 represents a novel and validated therapeutic target, we sought to develop and characterize an efficient process for the identification of small molecules that target MAP2K4. Using a fluorescence-based thermal shift assay (FTS) assay, we first evaluated an 80 compound library of known kinase inhibitors, thereby identifying 8 hits that thermally stabilized MAP2K4 in a concentration dependent manner. We then developed two in vitro MAP2K4 kinase assays to evaluate kinase inhibitory function, one a western-blot based assay employing the biologically relevant downstream substrates, JNK1 and p38 MAPK, and the other an Alphascreen based activity assay. In this manner, we validated the performance of our initial FTS screen. Finally, by coupling our structure-activity relationship data to MAP2K4's crystal structure, we constructed a model for inhibitor binding. It predicted binding of our identified inhibitors to MAP2K4's ATP pocket. We next applied this approach in a high-throughput fashion to over 2200 chemically diverse compounds and identified new inhibitors of MAP2K4. Herein we report the creation of a robust inhibitor-screening platform with the ability to inform the discovery and design of new and potent MAP2K4 inhibitors.

Citation Format: Sankar Narayan Krishna, Chi-Hao Luan, Matthew R. Clutter, Rama K. Mishra, Karl A. Scheidt, Wayne F. Anderson, Raymond C. Bergan. A high-throughput screening platform for the identification of small molecule inhibitors of MAP2K4. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5394. doi:10.1158/1538-7445.AM2014-5394

Mitogen-activated protein kinase kinase 4 (MAP2K4) promotes human prostate cancer metastasis

Prostate cancer (PCa) is the second leading cause of cancer death in the US. Death from PCa primarily results from metastasis. Mitogen-activated protein kinase kinase 4 (MAP2K4) is overexpressed in invasive PCa lesions in humans, and can be inhibited by small molecule therapeutics that demonstrate favorable activity in phase II studies. However, MAP2K4's role in regulating metastatic behavior is controversial and unknown. To investigate, we engineered human PCa cell lines which overexpress either wild type or constitutive active MAP2K4. Orthotopic implantation into mice demonstrated MAP2K4 increases formation of distant metastasis. Constitutive active MAP2K4, though not wild type, increases tumor size and circulating tumor cells in the blood and bone marrow. Complementary in vitro studies establish stable MAP2K4 overexpression promotes cell invasion, but does not affect cell growth or migration. MAP2K4 overexpression increases the expression of heat shock protein 27 (HSP27) protein and protease production, with the largest effect upon matrix metalloproteinase 2 (MMP-2), both in vitro and in mouse tumor samples. Further, MAP2K4-mediated increases in cell invasion are dependent upon heat shock protein 27 (HSP27) and MMP-2, but not upon MAP2K4's immediate downstream targets, p38 MAPK or JNK. We demonstrate that MAP2K4 increases human PCa metastasis, and prolonged over expression induces long term changes in cell signaling pathways leading to independence from p38 MAPK and JNK. These findings provide a mechanistic explanation for human studies linking increases in HSP27 and MMP-2 to progression to metastatic disease. MAP2K4 is validated as an important therapeutic target for inhibiting human PCa metastasis.

Circulating tumor cells exhibit a biologically aggressive cancer phenotype accompanied by selective resistance to chemotherapy

With prostate cancer (PCa), circulating tumor cells (CTCs) and disseminated tumor cells (DTCs) portend a poor clinical prognosis. Their unknown biology precludes rational therapeutic design. We demonstrate that CTC and DTC cell lines, established from mice bearing human PCa orthotopic implants, exhibit increased cellular invasion in vitro, increased metastasis in mice, and express increased epithelial to mesenchymal transition biomarkers. Further, they are selectively resistant to growth inhibition by mitoxantrone-like agents. These findings demonstrate that CTC formation is accompanied by phenotypic progression without obligate reversion. Their increased metastatic potential, selective therapeutic resistance, and differential expression of potential therapeutic targets provide a rational basis to test further interventions.

Genistein inhibits human prostate cancer cell detachment, invasion, and metastasis

Prostate cancer (PCa) is the most commonly diagnosed cancer in men in the United States and the second leading cause of cancer death. Death is not caused by the primary tumor but rather by the formation of distinct metastatic tumors. Therefore, prevention of metastasis is of utmost importance. The natural product genistein, found in high amounts in soy products, has been implicated in preventing PCa formation and metastasis in men who consume high amounts of soy. In vitro studies and in vivo rodent models that used human PCa cells, as well as prospective human clinical trials, provide a mechanistic explanation directly supporting genistein as an antimetastatic agent. Specifically, our group showed that genistein inhibits cell detachment, protease production, cell invasion, and human PCa metastasis at concentrations achieved in humans with dietary intake. Finally, phase I and phase II clinical trials conducted by us and others showed that concentrations of genistein associated with antimetastatic efficacy in preclinical models are achievable in humans, and treatment with genistein inhibits pathways that regulate metastatic transformation in human prostate tissue.

Diminished expression of h2-calponin in prostate cancer cells promotes cell proliferation, migration and the dependence of cell adhesion on substrate stiffness

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Calponin is an actin filament-associated protein and its h2 isoform inhibits cell motility.

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H2-calponin expression is strong in prostate epithelial cells and diminished in cancerous cells.

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Low h2-calponin metastatic prostate cancer cells had faster rates of cell proliferation and migration.

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Low h2-calponin metastatic prostate cancer cells showed reduced substrate adhesion.

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Low h2-calponin prostate cancer cells had a higher dependence on substrate stiffness.

Calponin is an actin filament-associated protein and its h2 isoform inhibits cell motility. Here we report significant expression of h2-calponin in prostate epithelial cells, which is diminished in cancerous cells. Comparison between a prostate cancer cell line PC3 and its metastatic derivative PC3-M showed lower levels of h2-calponin in PC3-M, corresponding to faster rates of cell proliferation and migration. Substrate adhesion of PC3 and PC3-M cells was positively correlated to the level of h2-calponin and the adhesion of PC3-M exhibited a higher dependence on substrate stiffness. Such effects of h2-calponin on cell proliferation, migration and substrate adhesion were also seen in normal versus cancerous primary prostate cells. Further supporting the role of h2-calponin in inhibiting cell motility, fibroblasts isolated from h2-calponin knockout mice proliferated and migrated faster than that of wild type fibroblasts. Transfective over-expression of h2-calponin in PC3-M cells effectively inhibited cell proliferation and migration. The results suggest that the diminished expression of h2-calponin in prostate cancer cells increases cell motility, decreases substrate adhesion, and promotes adhesion on high stiffness substrates.

A fluorescence-based thermal shift assay identifies inhibitors of mitogen activated protein kinase kinase 4

Prostate cancer (PCa) is the second highest cause of cancer death in United States males. If the metastatic movement of PCa cells could be inhibited, then mortality from PCa could be greatly reduced. Mitogen-activated protein kinase kinase 4 (MAP2K4) has previously been shown to activate pro-invasion signaling pathways in human PCa. Recognizing that MAP2K4 represents a novel and validated therapeutic target, we sought to develop and characterize an efficient process for the identification of small molecules that target MAP2K4. Using a fluorescence-based thermal shift assay (FTS) assay, we first evaluated an 80 compound library of known kinase inhibitors, thereby identifying 8 hits that thermally stabilized MAP2K4 in a concentration dependent manner. We then developed an in vitro MAP2K4 kinase assay employing the biologically relevant downstream substrates, JNK1 and p38 MAPK, to evaluate kinase inhibitory function. In this manner, we validated the performance of our initial FTS screen. We next applied this approach to a 2000 compound chemically diverse library, identified 7 hits, and confirmed them in the in vitro kinase assay. Finally, by coupling our structure-activity relationship data to MAP2K4's crystal structure, we constructed a model for ligand binding. It predicts binding of our identified inhibitory compounds to the ATP binding pocket. Herein we report the creation of a robust inhibitor-screening platform with the ability to inform the discovery and design of new and potent MAP2K4 inhibitors.

An orthotopic murine model of human prostate cancer metastasis

Our laboratory has developed a novel orthotopic implantation model of human prostate cancer (PCa). As PCa death is not due to the primary tumor, but rather the formation of distinct metastasis, the ability to effectively model this progression pre-clinically is of high value. In this model, cells are directly implanted into the ventral lobe of the prostate in Balb/c athymic mice, and allowed to progress for 4-6 weeks. At experiment termination, several distinct endpoints can be measured, such as size and molecular characterization of the primary tumor, the presence and quantification of circulating tumor cells in the blood and bone marrow, and formation of metastasis to the lung. In addition to a variety of endpoints, this model provides a picture of a cells ability to invade and escape the primary organ, enter and survive in the circulatory system, and implant and grow in a secondary site. This model has been used effectively to measure metastatic response to both changes in protein expression as well as to response to small molecule therapeutics, in a short turnaround time.

Endoglin-mediated suppression of prostate cancer invasion is regulated by activin and bone morphogenetic protein type II receptors

Mortality from prostate cancer (PCa) is due to the formation of metastatic disease. Understanding how that process is regulated is therefore critical. We previously demonstrated that endoglin, a type III transforming growth factor β (TGFβ) superfamily receptor, suppresses human PCa cell invasion and metastasis. Endoglin-mediated suppression of invasion was also shown by us to be dependent upon the type I TGFβ receptor, activin receptor-like kinase 2 (ALK2), and the downstream effector, Smad1. In this study we demonstrate for the first time that two type II TGFβ receptors are required for endoglin-mediated suppression of invasion: activin A receptor type IIA (ActRIIA) and bone morphogenetic protein receptor type II (BMPRII). Downstream signaling through these receptors is predominantly mediated by Smad1. ActRIIA stimulates Smad1 activation in a kinase-dependent manner, and this is required for suppression of invasion. In contrast BMPRII regulates Smad1 in a biphasic manner, promoting Smad1 signaling through its kinase domain but suppressing it through its cytoplasmic tail. BMPRII’s Smad1-regulatory effects are dependent upon its expression level. Further, its ability to suppress invasion is independent of either kinase function or tail domain. We demonstrate that ActRIIA and BMPRII physically interact, and that each also interacts with endoglin. The current findings demonstrate that both BMPRII and ActRIIA are necessary for endoglin-mediated suppression of human PCa cell invasion, that they have differential effects on Smad1 signaling, that they make separate contributions to regulation of invasion, and that they functionally and physically interact.

A phase I trial of aminolevulinic acid-photodynamic therapy for treatment of oral leukoplakia

BACKGROUND

Photodynamic therapy with aminolevulinic acid (ALA PDT) for oral leukoplakia has shown promising effects in regression of oral leukoplakia. Although ALA has been extensively studied and is an ideal photosensitizer, the optimal light dose for treatment of oral leukoplakia has not been determined. We conducted a phase I study to determine MTD and DLT of PDT in patients treated with ALA for leukoplakia.

METHODS

Patients with histologically confirmed oral leukoplakia received a single treatment of ALA PDT in cohorts with escalating doses of light (585nm). Clinical, histologic, and biologic markers were assessed.

RESULTS

Analysis of 11 participants is reported. No significant toxicity from ALA PDT was observed in patients who received ALA with a light dose of up to 4J/cm(2). One participant experienced transient grade 3 transaminase elevation due to ALA. One participant had a partial clinical response 3months after treatment. Biologic mucosal risk markers showed no significant associations. Determination of MTD could not be accomplished within a feasible timeframe for completion of the study.

CONCLUSIONS

ALA PDT could be safely administered with a light dose up to 4J/cm(2) and demonstrated activity. Larger studies are needed to fully elucidate the MTD and efficacy of ALA-PDT.

Abstract 1448: Identifying and subtyping circulating tumor cells from breast, prostate, and pancreatic cancer patients based on distinct morphology

Background: Isolation of circulating tumor cells (CTCs) from peripheral blood based on size exclusion is rapid and straight-forward using precision microfilters. We describe the use of CellSieveTM microfilters to isolate CTCs from the peripheral blood of breast, prostate, and pancreatic cancer patients. It is accepted that CTCs isolated from patient samples represent a highly heterogeneous population with varying degrees of epithelial mesenchymal differentiation. We hypothesized that the CTCs from three different epithelial malignancies can be identified and grouped into distinct subtypes by morphological characterization.

Methods: Prostate, breast, and pancreatic patient blood samples were provided by Northwestern University, Fox Chase Cancer Center, University of Maryland, and Medical College of Wisconsin and analyzed by Creatv MicroTech. The CellSieveTM microfilters have 8 micron diameter pores in a uniform array, with 160,000 pores in a 9 mm diameter area. 7.5 mL of whole blood was diluted in fixative and drawn through a microfilter. CTCs collected by this size exclusion technique were post-fixed, permeabilized, and stained with DAPI, cytokeratin 8, 18 and 19 (FITC), EpCAM (PE), PSMA (Texas Red), and CD45 (Cy5). CTCs were CD45 negative cells identified by their morphology, nuclear profile, and expression of cytokeratin, PSMA, and EpCAM.

Results: Each patient sample was found to have a number of phenotypic CTC subtypes. Distinct morphological patterns emerged in the three malignancies. CTCs from breast cancer patients demonstrated high expression of cytokeratin signal with web-like cytokeratin filamentation. Prostate cancer CTCs had less defined filamentation, but intense PSMA and cytokeratin signal and mottled cytokeratin morphology. Pancreatic CTCs had extremely fine filamentation, with spindle-like morphology and little or no EpCAM expression. Within each cancer, CTCs could be grouped into distinct subtypes. Additional markers, such as vimentin (PE), are used to further analyze the cells after bleaching the original PE.

Conclusions: In addition to enumeration and identification, the phenotypic analysis of CTCs provides new information that can be used to characterize disease status for personalized treatment of cancer patients. We have shown that CTCs can have multiple distinct phenotypes. These phenotypic morphologies may implicate definable traits which can be exploited while tracking site directed treatment of metastatic cancer patients.

Citation Format: Daniel Adams, R. Katherine Alpaugh, Massimo Cristofanilli, Stuart Martin, Saranya Chumsri, Monica Charpentier, Raymond C. Bergan, Irene May Ogden, Susan Tsai, Peixuan Zhu, Olga V. Makarova, Shuhong Li, Platte T. Amstutz, Cha-Mei Tang. Identifying and subtyping circulating tumor cells from breast, prostate, and pancreatic cancer patients based on distinct morphology. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1448. doi:10.1158/1538-7445.AM2013-1448

Androgen receptor-independent function of FoxA1 in prostate cancer metastasis

FoxA1 (FOXA1) is a pioneering transcription factor of the androgen receptor (AR) that is indispensible for the lineage-specific gene expression of the prostate. To date, there have been conflicting reports on the role of FoxA1 in prostate cancer progression and prognosis. With recent discoveries of recurrent FoxA1 mutations in human prostate tumors, comprehensive understanding of FoxA1 function has become very important. Here, through genomic analysis, we reveal that FoxA1 regulates two distinct oncogenic processes via disparate mechanisms. FoxA1 induces cell growth requiring the AR pathway. On the other hand, FoxA1 inhibits cell motility and epithelial-to-mesenchymal transition (EMT) through AR-independent mechanism directly opposing the action of AR signaling. Using orthotopic mouse models, we further show that FoxA1 inhibits prostate tumor metastasis in vivo. Concordant with these contradictory effects on tumor progression, FoxA1 expression is slightly upregulated in localized prostate cancer wherein cell proliferation is the main feature, but is remarkably downregulated when the disease progresses to metastatic stage for which cell motility and EMT are essential. Importantly, recently identified FoxA1 mutants have drastically attenuated ability in suppressing cell motility. Taken together, our findings illustrate an AR-independent function of FoxA1 as a metastasis inhibitor and provide a mechanism by which recurrent FoxA1 mutations contribute to prostate cancer progression.

Abstract 4752: Selective inhibition of cancer metastasis with a novel small therapeutic molecule

Prostate cancer (PCa) is the second most common cause of cancer death in US males. Death is typically caused by metastasis. Naturally occurring isoflavanones have been reported to be a class of compounds that effectively inhibit PCa motility and metastasis. This led us to use these compounds as a synthetic scaffold starting point. By integrating fragment-based diversification synthesis with chemi-driven biological selection, we discovered novel small molecule therapeutics with increased selectivity and potent efficacy. We thereby efficiently synthesized a new class of bioactive compounds that inhibit cell motility in vitro and inhibit human PCa metastasis in a murine model at low nanomolar concentrations. Extensive investigations indicate high specificity at the molecular and cellular levels, and failed to identify toxicity, even at high doses administered over extended periods. Importantly, efficacy against several cancer types was also demonstrated. Target validation studies used our lead as a chemical probe, and point to inhibition of ATM/ATR interaction with specific substrate proteins as important. Together, these studies indicate that we have successfully discovered a novel compound, acting upon a novel pharmacologic target, which selectively inhibits human PCa metastasis. Taken with our favorable preclinical toxicological data, these findings support movement of our lead compound into early phase human trials.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4752. doi:1538-7445.AM2012-4752

Abstract 491: Endoglin suppresses prostate cancer invasion through two distinct type II TGF-β receptors

Prostate cancer (PCa) is the most common cancer of American men and the second leading cause of cancer-related death. Death from PCa results from the development of metastatic disease, yet the processes underlying progression from localized to invasive and ultimately metastatic disease remain poorly understood. Our group has previously shown that endoglin, an auxiliary TGF-β superfamily receptor, is lost with PCa progression. Restoration of endoglin expression inhibits PCa cell migration, invasion, and metastasis in pre-clinical models. Endoglin-mediated suppression of PCa invasion (EMSI) is mediated through the type I TGF-β receptor ALK2 and the downstream effector Smad1. Given that TGF-β signaling minimally requires both a type I and a type II TGF-β receptor (RII), we sought to determine the RII(s) involved in EMSI. We now show that silencing of either the type IIA activin receptor (ActRII) or the type II bone morphogenic protein receptor (BMPRII) abrogates endoglin's invasion suppressive effects. Surprisingly, ActRII and BMPR2 have opposite effects on downstream Smad1 signaling: ActRII promotes basal and endoglin-mediated Smad1 transcriptional activity dependent on its kinase domain, while BMPR2 suppresses Smad1 transcriptional activity independent of its kinase domain but dependent on its cytoplasmic tail. Moreover, we show that engagement of distinct BMP-responsive R-Smads (i.e. Smad1, Smad5, & Smad8) does not account for differential signaling and confirm that Smad1 is the main mediator downstream of endoglin. We posit the existence of two parallel pathways that are required for EMSI: an ActRII / ALK2 / Smad1 pathway and a second, as-yet-uncharacterized pathway involving BMPR2.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 491. doi:1538-7445.AM2012-491

Abstract 615: Apigenin regulates prostate cancer matrix composition and cell attachment through an integrin alpha 1 dependent pathway

Prostate cancer (PCa) mortality is primarily attributed to metastatic rather than primary, organ-confined disease. Acquiring a motile and invasive phenotype is an important step in the development of metastasis. This step involves remodeling of the extracellular matrix (ECM) and of cell-matrix interactions, cell movement mediated by the actin cytoskeleton, and activation of focal adhesion kinase (FAK)/Src signaling. Epidemiologic studies suggest that the metastatic behavior of PCa may be an ideal target for chemoprevention. The natural flavone apigenin is known to have chemopreventive properties against many cancers, including PCa. Building upon our previous findings showing that apigenin inhibits cell motility and invasion of PCa cells through the FAK/Src signaling pathway, here we study the effect of apigenin on integrin receptors, cell attachment, and ECM composition. By using an alpha/beta integrin-mediated cell adhesion array, we found that integrin alpha 1 (ITGA1) was the only integrin subunit to be down-regulated by apigenin in PC3-M cells. ITGA1, whose only binding partner is integrin beta 1, is a receptor for collagen and laminin. Integrin α1α1 gives cells the ability to attach to collagenous substrata. As collagen and laminin are important regulators of PCa cell survival, growth and metastasis to bone, we next elucidated the effect of apigenin on PC3-M cell attachment to laminin 1 and collagen IV. We found that apigenin decreases cell attachment to both of these ECM molecules, suggesting a potential anti-tumorigenic mechanism. It has been shown that integrin α1α1 can regulate the synthesis of collagen. So we next tested whether apigenin can alter the ECM deposited by PC3-M cells. We first tested whether ECM deposited by apigenin-treated cells provided the same adhesive support to PCa cells as the ECM deposited by the untreated cells. Interestingly, even cells not treated with apigenin did not attach and spread well on the ECM deposited by apigenin-treated cells, indicating that apigenin treatment changes the composition of the ECM. Using Western blot to evaluate differences in the composition of matrix deposited by control cells and apigenin-treated cells, we found that apigenin-treated cells produce much less collagen I and IV, thus correlating with the decrease in adhesion and spreading. These results demonstrate that the chemopreventive bioflavonoid apigenin may inhibit PCa cell adhesion through a combined effect on integrin α1α1 cell surface expression and ECM deposition.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 615. doi:1538-7445.AM2012-615

Soy isoflavone supplementation for breast cancer risk reduction: a randomized phase II trial

Soy isoflavone consumption may protect against breast cancer development. We conducted a phase IIB trial of soy isoflavone supplementation to examine its effect on breast epithelial proliferation and other biomarkers in the healthy high-risk breast. One hundred and twenty-six consented women underwent a random fine-needle aspiration (rFNA); those with 4,000 or more epithelial cells were randomized to a double-blind 6-month intervention of mixed soy isoflavones (PTIG-2535) or placebo, followed by repeat rFNA. Cells were examined for Ki-67 labeling index and atypia. Expression of 28 genes related to proliferation, apoptosis, and estrogenic effect was measured using quantitative reverse transcriptase PCR. Hormone and protein levels were measured in nipple aspirate fluid (NAF). All statistical tests were two-sided. Ninety-eight women were evaluable for Ki-67 labeling index. In 49 treated women, the median Ki-67 labeling index was 1.18 at entry and 1.12 post intervention, whereas in 49 placebo subjects, it was 0.97 and 0.92 (P for between-group change: 0.32). Menopausal stratification yielded similar results between groups, but within premenopausal soy-treated women, Ki-67 labeling index increased from 1.71 to 2.18 (P = 0.04). We saw no treatment effect on cytologic atypia or NAF parameters. There were significant increases in the expression of 14 of 28 genes within the soy, but not the control group, without significant between-group differences. Plasma genistein values showed excellent compliance. A 6-month intervention of mixed soy isoflavones in healthy, high-risk adult Western women did not reduce breast epithelial proliferation, suggesting a lack of efficacy for breast cancer prevention and a possible adverse effect in premenopausal women.

Abstract C177: Chemical-driven biological probing: Discovery of a novel antimetastatic drug

Chemicals constitute richly informative probes, have high resolving potential and are able to uncover complex biological processes. Harnessing this potential provides an avenue for the discovery of new therapeutics that act via novel mechanisms. We focused these principles upon an intractable problem: cancer metastasis. We started with a chemical scaffold with broad bioactivity, with desirable drug-like properties and that would support synthetic diversification. Initially focusing upon human prostate cancer (PCa) we then coupled fragment-diversification and novel synthetic routes to upfront positive selection screens (inhibition of cell motility) and negative selection screens (cell toxicity) in an iterative fashion. We thereby efficiently synthesized a new class of bioactive compounds that inhibits systemic PCa metastasis at low nanomolar concentrations. Efficacy against other cancer types was demonstrated. Extensive investigations indicate high specificity and no toxicity. Target validation studies point to inhibition of protein-protein interaction motifs. Together, these studies support the notion that this approach is powerful, can be broadly applied across biological systems, and constitutes a paradigm. Specifically, they have led to the discovery of a novel acting drug that inhibits human cancer metastasis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr C177.

The Ninth Annual American Association of cancer research international conference on frontiers in cancer prevention research

The Ninth Annual AACR Frontiers in Cancer PREVENTION Research conference was held in Philadelphia in November 7-10, 2010. Its thematic focus was "

PREVENTION

From Basic Science to Public Health Benefit." Telomere plasticity, the microenvironment, inflammation, transformation to the metastatic phenotype, and pathways to obesity were highlighted as important elements of carcinogenesis amenable to intervention. The integration of information from novel technologies related to physical biology, molecular and genetic profiles, and imaging along with behavioral and clinical parameters have advanced risk stratification and early detection. Cancer prevention represents a powerful testing ground for the development of individually tailored intervention and for increasing the efficiency of drug discovery. Advances in clinical trials relate to more efficient design strategies, have shown first-in-human targeting capabilities, and have developed powerful strategies to overcome accrual barriers. Tailored intervention strategies now show high efficacy on large cohorts across several cancer types. These successes are expected to increase.

Abstract 1407: Mitogen-activated protein kinase kinase 4 (MEK4) is a key regulator of prostate cancer progression

Mitogen-activated protein kinase kinase 4 (MEK4) is a dual-specificity kinase that has been implicated in cancer progression in multiple cancer types, including prostate cancer (PCa). MEK4 is upregulated in invasive PCa lesions in human tissue. We hypothesize that increased MEK4 promotes PCa invasion and metastasis. Our group has created PC3-M cells stably transfected with either constitutively-active or increased levels of wild-type MEK4. In a Matrigel Boyden chamber assay, constitutively-active or wild-type MEK4 was shown to increase PCa invasion. Cancer cell invasion requires the coupling of cell migration with increased production of proteases. We hypothesized that MEK4 promoted invasion via production of proteases, but not via cell migration. Using an uncoated boyden chamber, MEK4 was shown not to affect migration. Using quantitative real time polymerase chain reaction (qRT/PCR), we went on to demonstrate that MEK4 increased MMP-2 and MMP-9 transcript expression, but did not affect MMP-10 expression. In addition to these studies, we have also looked at the effect of increased or constitutively-active MEK4 on an orthotopic mouse model of PCa. In this model, PCa cells are injected into the prostates of nude mice and tumor size, circulating tumor cells, and lung metastasis are quantified. Preliminary data shows that constitutively-active MEK4 causes an increase in primary tumor size as well as an increase in circulating tumor cells in both the blood and the bone marrow. In summary, we demonstrated that chronic high expression of MEK4 increases human PCa invasion, that this is not due to increased migration, but is associated with increases in MMP-2 and MMP-9. Further, constitutively-active MEK4 appears to have different biological effects than high levels of wild type MEK4 in vivo. Ongoing studies are evaluating the effect of wild type MEK4 and of constitutively-active MEK4 on the formation of distant soft tissue metastasis in the above murine model. In related studies we are seeking to identify downstream proteins critical for MEK4's effects on cell invasion and metastasis both in vitro and in vivo. We are also seeking to examine the effects of sustained MEK4 knockdown on PCa invasion and metastasis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1407. doi:10.1158/1538-7445.AM2011-1407

Endoglin regulates cancer-stromal cell interactions in prostate tumors

Endoglin is an accessory receptor for TGF-β that has been implicated in prostate cancer cell detachment, migration, and invasiveness. However, the pathophysiologic significance of endoglin with respect to prostate tumorigenesis has yet to be fully established. In this study, we addressed this question by investigation of endoglin-dependent prostate cancer progression in a TRAMP (transgenic adenocarcinoma mouse prostate) mouse model where endoglin was genetically deleted. In this model, endoglin was haploinsufficient such that its allelic deletion slightly increased the frequency of tumorigenesis, yet produced smaller, less vascularized, and less metastatic tumors than TRAMP control tumors. Most strikingly, TRAMP:eng(+/-)-derived tumors lacked the pronounced infiltration of carcinoma-associated fibroblasts (CAF) that characterize TRAMP prostate tumors. Studies in human primary prostate-derived stromal cells (PrSC) confirmed that suppressing endoglin expression decreased cell proliferation, the ability to recruit endothelial cells, and the ability to migrate in response to tumor cell-conditioned medium. We found increased levels of secreted insulin-like growth factor-binding proteins (IGFBP) in the conditioned medium from endoglin-deficient PrSCs and that endoglin-dependent regulation of IGFBP-4 secretion was crucial for stromal cell-conditioned media to stimulate prostate tumor cell growth. Together, our results firmly establish the pathophysiologic involvement of endoglin in prostate cancer progression; furthermore, they show how endoglin acts to support the viability of tumor-infiltrating CAFs in the tumor microenvironment to promote neovascularization and growth.

Inhibition of cancer cell invasion and metastasis by genistein

Genistein is a small, biologically active flavonoid that is found in high amounts in soy. This important compound possesses a wide variety of biological activities, but it is best known for its ability to inhibit cancer progression. In particular, genistein has emerged as an important inhibitor of cancer metastasis. Consumption of genistein in the diet has been linked to decreased rates of metastatic cancer in a number of population-based studies. Extensive investigations have been performed to determine the molecular mechanisms underlying genistein’s antimetastatic activity, with results indicating that this small molecule has significant inhibitory activity at nearly every step of the metastatic cascade. Reports have demonstrated that, at high concentrations, genistein can inhibit several proteins involved with primary tumor growth and apoptosis, including the cyclin class of cell cycle regulators and the Akt family of proteins. At lower concentrations that are similar to those achieved through dietary consumption, genistein can inhibit the prometastatic processes of cancer cell detachment, migration, and invasion through a variety of mechanisms, including the transforming growth factor (TGF)-β signaling pathway. Several in vitro findings have been corroborated in both in vivo animal studies and in early-phase human clinical trials, demonstrating that genistein can both inhibit human cancer metastasis and also modulate markers of metastatic potential in humans, respectively. Herein, we discuss the variety of mechanisms by which genistein regulates individual steps of the metastatic cascade and highlight the potential of this natural product as a promising therapeutic inhibitor of metastasis.

Abstract CN02-04: Phase II study of genistein in men with prostate cancer

Progression of cells to a metastatic phenotype begins in the primary organ and represents an important chemoprevention target. In preclinical studies, genistein induces reversion of human prostate cancer (PCa) cells to a less metastatic phenotype. In a phase II study, men with localized PCa were randomized between genistein treatment versus not prior to radical prostatectomy. Analysis of prostate epithelial cells within harvested organs revealed that genistein had the following effects: 1) it decreased matrix metalloproteinase 2 (MMP-2) expression; 2) it induced nuclear spreading; a surrogate marker of inhibition of cell detachment; and 3) gene expression profiling demonstrated selective modulation of genes associated with regulation of cell motility in other cell types. By engineering the expression of these genes in cell lines, we demonstrated that they were important regulators of human PCa cell invasion. Genistein increased the expression of genes that suppress invasion and decreased the expression of genes that enhance invasion. Together, this study demonstrates that genistein induces reversion of human prostate cells in man to a less metastatic phenotype. Importantly, this study demonstrates the proof-of-principal concept that the conduct of molecular screens in human chemoprevention trials has the ability to identify the mechanism of action of investigational agents.

Citation Information: Cancer Prev Res 2010;3(12 Suppl):CN02-04.

Concise syntheses of the abyssinones and discovery of new inhibitors of prostate cancer and MMP-2 expression

Hydrogen-bonding catalysis is an emerging field that facilitates rapid access to medicinally relevant enantioenriched small molecules. Here, we report the first asymmetric total syntheses of four members of the abyssinone class of natural products (I, II, III, and IV 4´-OMe) via quinine- or quinidine-derived thiourea-catalyzed intramolecular conjugate additions of β-keto ester alkylidenes. This concise strategy includes a tandem deprotection/decarboxylation final step that delivers all four natural products and their corresponding antipodes. A preliminary evaluation of all of these small molecules against a metastatic human prostate cancer cell line has identified that these compounds selectively and differentially inhibit cell growth and downregulate the expression of matrix metalloproteinase-2 (MMP-2) at non-toxic concentrations.

Endoglin suppresses human prostate cancer metastasis

Endoglin is a transmembrane receptor that suppresses human prostate cancer (PCa) cell invasion. Small molecule therapeutics now being tested in humans can activate endoglin signaling. It is not known whether endoglin can regulate metastatic behavior, PCa tumor growth, nor what signaling pathways are linked to these processes. This study sought to investigate the effect of endoglin on these parameters. We used a murine orthotopic model of human PCa metastasis, designed by us to measure effects at early steps in the metastatic cascade, and implanted PCa cells stably engineered to express differing levels of endoglin. We now extend this model to measure cancer cells circulating in the blood. Progressive endoglin loss led to progressive increases in the number of circulating PCa cells as well as to the formation of soft tissue metastases. Endoglin was known to suppress invasion by activating the Smad1 transcription factor. We now show that it selectively activates specific Smad1-responsive genes, including JUNB, STAT1, and SOX4. Increased tumor growth and increased Ki67 expression in tissue was seen only with complete endoglin loss. By showing that endoglin increased TGFβ-mediated suppression of cell growth in vitro and TGFβ-mediated signaling in tumor tissue, loss of this growth-suppressive pathway appears to be implicated at least in part for the increased size of endoglin-deficient tumors. Endoglin is shown for the first time to suppress cell movement out of primary tumor as well as the formation of distant metastasis. It is also shown to co-regulate tumor growth and metastatic behavior in human PCa.

Endoglin phosphorylation by ALK2 contributes to the regulation of prostate cancer cell migration

Endoglin, a transmembrane glycoprotein that acts as a transforming growth factor-beta (TGF-beta) coreceptor, is downregulated in PC3-M metastatic prostate cancer cells. When restored, endoglin expression in PC3-M cells inhibits cell migration in vitro and attenuates the tumorigenicity of PC3-M cells in SCID mice, though the mechanism of endoglin regulation of migration in prostate cancer cells is not known. The current study indicates that endoglin is phosphorylated on cytosolic domain threonine residues by the TGF-beta type I receptors ALK2 and ALK5 in prostate cancer cells. Importantly, in the presence of constitutively active ALK2, endoglin did not inhibit cell migration, suggesting that endoglin phosphorylation regulated PC3-M cell migration. Therefore, our results suggest that endoglin phosphorylation is a mechanism with relevant functional consequences in prostate cancer cells. These data demonstrate for the first time that TGF-beta receptor-mediated phosphorylation of endoglin is a Smad-independent mechanism involved in the regulation of prostate cancer cell migration.

MEK4 function, genistein treatment, and invasion of human prostate cancer cells

BACKGROUND

Dietary intake of genistein by patients with prostate cancer has been associated with decreased metastasis and mortality. Genistein blocks activation of p38 mitogen-activated protein kinase and thus inhibits matrix metalloproteinase-2 (MMP-2) expression and cell invasion in cultured cells and inhibits metastasis of human prostate cancer cells in mice. We investigated the target for genistein in prostate cancer cells.

METHODS

Prostate cell lines PC3-M, PC3, 1532NPTX, 1542NPTX, 1532CPTX, and 1542CPTX were used. All cell lines were transiently transfected with a constitutively active mitogen-activated protein kinase kinase 4 (MEK4) expression vector (to increase MEK4 expression), small interfering RNA against MEK4 (to decrease MEK4 expression), or corresponding control constructs. Cell invasion was assessed by a Boyden chamber assay. Gene expression was assessed by a quantitative reverse transcription-polymerase chain reaction. Protein expression was assessed by Western blot analysis. Modeller and AutoDock programs were used for modeling of the structure of MEK4 protein and ligand docking, respectively. MMP-2 transcript levels were assessed in normal prostate epithelial cells from 24 patients with prostate cancer from a phase II randomized trial comparing genistein treatment with no treatment. Statistical significance required a P value of .050 or less. All statistical tests were two-sided.

RESULTS

Overexpression of MEK4 increased MMP-2 expression and cell invasion in all six cell lines. Decreased MEK4 expression had the opposite effects. Modeling showed that genistein bound to the active site of MEK4. Genistein inhibited MEK4 kinase activity with a half maximal inhibitory concentration of 0.40 microM (95% confidence interval [CI] = 0.36 to 0.45 muM). The MMP-2 transcript level in normal prostate epithelial cells was statistically significantly higher in the untreated group (100%) than in the genistein-treated group (24%; difference = 76%, 95% CI = 38% to 115%; P = .045).

CONCLUSIONS

We identified MEK4 as a proinvasion protein in six human prostate cancer cell lines and the target for genistein. We showed, to our knowledge for the first time, that genistein treatment, compared with no treatment, was associated with decreased levels of MMP-2 transcripts in normal prostate cells from prostate cancer-containing tissue.