Identification of a Predictive Genomic Biomarker for Prostate-directed Therapy in Synchronous Low-volume Metastatic Castration-sensitive Prostate Cancer

BACKGROUND

Standard of care management for synchronous metastatic castration-sensitive prostate cancer (mCSPC) includes androgen deprivation therapy with a second-generation antiandrogen therapy and/or docetaxel. Recently, randomized data have demonstrated that prostate-directed therapy (PDT) is associated with an improvement in overall survival (OS) among patients with low-volume metastatic disease. Tumor genomics represents an additional dimension to define the clinical trajectory of patients with mCSPC.

OBJECTIVE

To evaluate a high-risk (HiRi) genomic signature to predict the benefit from PDT.

DESIGN, SETTING, AND PARTICIPANTS

We performed a single-institution retrospective review of men with synchronous low-volume mCSPC who underwent DNA panel sequencing of their tumor. Patients were classified according to the presence of HiRi mutation including pathogenic mutations in TP53, ATM, BRCA1, BRCA2, or Rb1.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary endpoint was to determine the effect of PDT on OS in patients with and without a HiRi mutation. A survival analysis was performed with the Kaplan-Meier method compared with log-rank test and multivariable Cox regression. The interaction between HiRi mutation and PDT was evaluated.

RESULTS AND LIMITATIONS

A total of 101 patients with synchronous low-volume CSPC were included with a median follow-up of 44 mo. Approximately half of patients were found to have a HiRi pathogenic mutation (49%). Patients with HiRi mutations demonstrated median OS of 73 versus 66.8 mo (p = 0.3) for no PDT versus PDT. Conversely, patients without a HiRi mutation demonstrated a significant improvement in OS of 60 versus 105.3 mo (p < 0.001) for no PDT versus PDT. The p value for interaction for OS between PDT and HiRi mutation was statistically significant (p < 0.001). Limitations include the retrospective nature of the study.

CONCLUSIONS

Here, we have identified a HiRi genomic biomarker that appears predictive for the lack of benefit from PDT in men with synchronous low-volume mCSPC. Further work validating these results is warranted.

PATIENT SUMMARY

In this report, we evaluated a high-risk genomic biomarker to predict the benefit from prostate-directed therapy for men with synchronous low-volume metastatic castration-sensitive prostate cancer. We found that men without a high-risk mutation appear to experience a greater clinical benefit from prostate-directed therapy than those with a high-risk mutation.

Clinical and Genomic Differences Between Advanced Molecular Imaging-detected and Conventional Imaging-detected Metachronous Oligometastatic Castration-sensitive Prostate Cancer

In metastatic castration-sensitive prostate cancer (mCSPC), disease volume plays an integral role in guiding treatment recommendations, including selection of docetaxel therapy, metastasis-directed therapy, and radiation to the prostate. Although there are multiple definitions of disease volume, they have commonly been studied in the context of metastases detected via conventional imaging (CIM). One such numeric definition of disease volume, termed oligometastasis, is heavily dependent on the sensitivity of the imaging modality. We performed an international multi-institutional retrospective review of men with metachronous oligometastatic CSPC (omCSPC), detected via either advanced molecular imaging alone (AMIM) or CIM. Patients were compared with respect to clinical and genomic features using the Mann-Whitney U test, Pearson's χ2 test, and Kaplan-Meier overall survival (OS) analyses with a log-rank test. A total of 295 patients were included for analysis. Patients with CIM-omCSPC had significantly higher Gleason grade group (p = 0.032), higher prostate-specific antigen at omCSPC diagnosis (8.0 vs 1.7 ng/ml; p < 0.001), more frequent pathogenic TP53 mutations (28% vs 17%; p = 0.030), and worse 10-yr OS (85% vs 100%; p < 0.001). This is the first report of clinical and biological differences between AMIM-detected and CIM-detected omCSPC. Our findings are particularly important for ongoing and planned clinical trials in omCSPC. PATIENT SUMMARY: Metastatic prostate cancer with just a few metastases only detected via newer scanning methods (called molecular imaging) is associated with fewer high-risk DNA mutations and better survival in comparison to metastatic cancer detected via conventional scan methods.

Prospective Characterization of Circulating Tumor Cells in Hormone Sensitive Oligometastatic Prostate Cancer Patients on a Metastasis-Directed Therapy Trial

PURPOSE/OBJECTIVE(S)

Prospective data have shown that metastasis-directed therapy (MDT) can alter the natural history of oligometastatic disease. In hormone-sensitive prostate cancer (HSPC), the clinical effect of MDT has been validated by STOMP, ORIOLE and SABR-COMET phase II trials. Circulating tumor cells (CTCs) are likely the source for the formation of macroscopic metastases. CTCs may provide an approach for identifying subgroups of patients with oligometastatic HSPC (oligoHSPC) that would benefit most from MDT. Our main goal was to evaluate the feasibility of CTC detection and subtypes in oligoHSPC patients that may benefit from MDT.

MATERIALS/METHODS

ORIOLE randomized men with recurrent HSPC with 1-3 metastases to observation (Obs) vs. stereotactic ablative radiotherapy (SABR) MDT. Blood samples were prospectively collected at baseline (D0) and 6-mos (D180) and shipped for analysis on Epic Sciences liquid biopsy platform (Epic Sciences, San Diego, CA). Machine learning algorithms identified CTCs and characterized androgen receptor (AR) and PSMA expression. Association with clinical factors and outcomes were examined. Biochemical failure-free survival (BFFS) event was a PSA rise of at least 2 ng/mL and 25% above nadir. Progression-free survival (PFS) was a composite endpoint including BFFS event, radiologic progression (RECIST v1.1); symptomatic progression; initiation of ADT; or death. Comparisons of patient and tumor characteristics performed by two-sample t-tests. Survival curves were generated by the Kaplan-Meier method and evaluated by the log-rank test. Effect of SABR on post-SABR on CTC levels were calculated by McNemar test.

RESULTS

A total of 82 samples were collected in ORIOLE: 70 SABR (35 D0 and 35 D180) and 12 Obs (7 D0 and 5 D180). 30/42 men had CTCs detected on D0 (71%; AR+ = 7, PSMA+ = 13) and in 26/40 on D180 (65%; AR+ = 9, PSMA+ = 8). Median follow-up was 41.7-mos. There was no association between CTC presence or subtypes (AR+ or PSMA+) with Gleason score or PSA. PFS was significantly lower in the patients with AR+ vs. AR- CTCs on D0 in the SABR arm (p = 0.011, median PFS: AR+ = 9.3- vs. AR+ = 27.1-mos). The median BFFS trended towards a difference for AR+ = 12.9- vs. AR- = 29.2-mos (D180, p = 0.058). SABR had no effect on the presence or subtypes of CTC at D180.

CONCLUSION

Baseline and dynamic CTC levels and their subtypes in oligoHSPC from the ORIOLE randomized trial of MDT was examined. AR+ CTCs at baseline and 6-mos were correlated with clinical outcomes following SABR. Longer follow-up, further analysis and a greater number of patients are needed for a more comprehensive conclusion.

Identification of a Predictive Genomic Biomarker for Prostate Directed Therapy in Synchronous Low-Volume Metastatic Castration Sensitive Prostate Cancer

PURPOSE/OBJECTIVE(S)

Standard of care management for metastatic castration sensitive prostate cancer (mCSPC) includes androgen deprivation therapy (ADT) with docetaxel or second-generation anti-androgen therapy. Recently, randomized data has demonstrated radiotherapy to the prostate is associated with an improvement in overall survival among patients with low-volume metastatic disease. Tumor genomics represents an additional dimension to understand the clinical trajectory of patients with mCSPC. Herein we aim to evaluate a high-risk genomic signature for its ability to predict response to prostate directed therapy (PDT).

MATERIALS/METHODS

We performed a single institution retrospective review of men with low-volume mCSPC who underwent next-generation sequencing of their tumor. Patients were classified according to the presence of high-risk (HiRi) mutation including pathogenic mutations in either TP53, ATM, BRCA1/2, or Rb1. Our primary endpoint was to determine the effect of PDT on overall survival (OS) in patients with and without a HiRi mutation. Survival analysis was performed with the Kaplan-Meier method compared with log-rank test and multivariable cox regression. Interaction between HiRi mutation and PDT was evaluated.

RESULTS

A total of 101 patients with synchronous low-volume CSPC were included in our analysis with a median follow-up of 44 months. Approximately half of patients were found to have a HiRi pathogenic mutation (48.5%) with TP53 mutations accounting for 75.5% of HiRi mutations. On multivariable cox regression PDT was associated with improvement in OS (HR = 0.37, 95% CI 0.16-0.88; p = 0.03). When stratified by presence of HiRi mutation, PDT was not associated with any clinical outcome. Patients with HiRi mutations demonstrated a median OS of 73 vs 66.8 months (p = 0.28) for no PDT and PDT, respectively. Conversely, patients without a HiRi mutation demonstrated a significant improvement in median OS of 60 vs 105.3 months (p<0.01) for no PDT and PDT, respectively. The p-value for interaction for OS between PDT and HiRi mutation was statistically significant (p<0.01).

CONCLUSION

Here we have identified a high-risk genomic biomarker that appears predictive for response to PDT in men with synchronous low-volume mCSPC. Further work validating these results with prospective randomized data is warranted.

Transcriptomic and clinical heterogeneity of metastatic disease timing within metastatic castration-sensitive prostate cancer

BACKGROUND

Metastatic castration-sensitive prostate cancer (mCSPC) is commonly classified into high- and low-volume subgroups which have demonstrated differential biology, prognosis, and response to therapy. Timing of metastasis has similarly demonstrated differences in clinical outcomes; however, less is known about any underlying biologic differences between these disease states. Herein, we aim to compare transcriptomic differences between synchronous and metachronous mCSPC and identify any differential responses to therapy.

PATIENTS AND METHODS

We performed an international multi-institutional retrospective review of men with mCSPC who completed RNA expression profiling evaluation of their primary tumor. Patients were stratified according to disease timing (synchronous versus metachronous). The primary endpoint was to identify differences in transcriptomic profiles between disease timing. The median transcriptomic scores between groups were compared with the Mann-Whitney U test. Secondary analyses included determining clinical and transcriptomic variables associated with overall survival (OS) from the time of metastasis. Survival analysis was carried out with the Kaplan-Meier method and multivariable Cox regression.

RESULTS

A total of 252 patients were included with a median follow-up of 39.6 months. Patients with synchronous disease experienced worse 5-year OS (39% versus 79%; P < 0.01) and demonstrated lower median androgen receptor (AR) activity (11.78 versus 12.64; P < 0.01) and hallmark androgen response (HAR; 3.15 versus 3.32; P < 0.01). Multivariable Cox regression identified only high-volume disease [hazard ratio (HR) = 4.97, 95% confidence interval (CI) 2.71-9.10; P < 0.01] and HAR score (HR = 0.51, 95% CI 0.28-0.88; P = 0.02) significantly associated with OS. Finally, patients with synchronous (HR = 0.47, 95% CI 0.30-0.72; P < 0.01) but not metachronous (HR = 1.37, 95% CI 0.50-3.92; P = 0.56) disease were found to have better OS with AR and non-AR combination therapy as compared with monotherapy (P value for interaction = 0.05).

CONCLUSIONS

We have demonstrated a potential biologic difference between metastatic timing of mCSPC. Specifically, for patients with low-volume disease, those with metachronous low-volume disease have a more hormone-dependent transcriptional profile and exhibit a better prognosis than synchronous low-volume disease.

Abstract 5988: A non-canonical CDK9 complex mediates endocycling in polyaneuploid cancer cell (PACC) state

Once prostate cancer has spread from its primary site, treatment is limited to systemically administered therapy. While tumors initially respond to these therapies, eventually, all therapies fail, and the tumor recurs. Ours and others' recent studies have shown the presence of a universal mechanism of resistance: accession of the polyaneuploid cancer cell (PACC) state. The PolyAneuploid Transition (PAT) is initiated when a cancer cell is subjected to external stress, including therapy (we have tested three classes of chemotherapy and radiation), and accesses an alternative non-mitotic cell cycle known as endocycling, resulting in a greater-than-G2 polyploidization of the aneuploid genome (polyaneuploidy). While in this pro-survival PACC state, we have shown that cells are resistant to all forms of cytotoxic therapy. Initial RNA sequencing of cells that have accessed the PACC state in response to multiple classes of chemotherapy, including docetaxel and cisplatin, demonstrate a remodeled transcriptional profile that is distinct from control cultures. We hypothesize that accession of the resistance-mediating PACC state requires transcriptional remodeling. Our data show that cells in the PACC state had increased overall transcriptional activity. The multi protein complex pTEFB (positive transcription elongation factor) is a critical driver of RNA Polymerase II function and is composed of multiple subunits, including CDK9, a cyclin regulatory subunit, and a transcription factor. CDK9 phosphorylation was significantly elevated during accession and persistence in the PACC state. Genetic inhibitionof CDK9 by siRNA led to decreased expression of cyclin A which plays a role in S phase, both in the mitoticcycle and in the PACC endocycle. Interestingly, despite increased CDK9 levels, known CDK9 pTEFb complex members cyclin T1 and BRD4 were both decreased in cells in the PACC state. We treated cancer cells induced to enter the PACC state upon exposure to cisplatin with pharmaceutical inhibitors of CDK9, Flavopiridol and Fadraciclib. Combination of CDK9 inhibition with chemotherapy showed a suppressive effect on the PACC population. Our findings therefore suggest that a non-canonical CDK9 complex could be critical role for the endocycling to access and maintain the PACC state and represents a therapeutic candidate to eliminate the resistance-mediating PACC state.

Citation Format: Cheng-fan Lee, Michael Loycano, Luke LOFTUS, Laurie Kostecka, Melvin Li, Sarah Amend, Kenneth Pienta. A non-canonical CDK9 complex mediates endocycling in polyaneuploid cancer cell (PACC) state. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5988.

Pathological Effects of Apalutamide in Lower-risk Prostate Cancer: Results From a Phase II Clinical Trial

PURPOSE

Active surveillance is a safe and effective strategy for men with lower-risk prostate cancer who want to avoid local therapy; however, many patients on active surveillance progress to active treatment (eg, prostatectomy or radiation). We hypothesized that apalutamide would decrease active surveillance attrition rates through downstaging low-grade tumors.

MATERIALS AND METHODS

This was an open-label, single-arm, phase II study testing 90 days of oral apalutamide 240 mg daily in men with low- to intermediate-risk prostate cancer on active surveillance. The primary objective was to determine the percentage of patients with a negative biopsy immediately following treatment. Secondary objectives were to assess long-term clinical outcomes, quality of life, safety, and biomarkers of response/resistance.

RESULTS

Twenty-three patients enrolled and 22 completed 90 days of apalutamide with post-treatment biopsy. Fifteen (65%) had Grade Group 1 disease, and all others had Grade Group 2 disease. Seven (30%) had favorable- to intermediate-risk disease. Of 22 evaluable patients, 13 (59%) had no residual cancer on post-treatment biopsy. The median time to first positive biopsy was 364 days (95% CI: 91-742 days). The impact of apalutamide on quality of life was minimal and transient. Decipher risk classifier revealed a greater number of negative post-treatment biopsies in those with higher baseline genomic risk score (P = .01).

CONCLUSIONS

The negative repeat biopsy rate following 90 days of apalutamide was high in men with prostate cancer followed on active surveillance. Apalutamide was safe, well tolerated, and had minimal impact on quality of life. Randomized studies evaluating the effects of apalutamide in men enrolled on active surveillance are warranted.

Abstract 140: Polyaneuploid prostate cancer cells induced via chemotherapy have predominantly large, single nuclei

While localized prostate cancer (PCa) has a high treatment success rate, over 30,000 individuals in the United States and 350,000 men globally die each year from therapy resistant, metastatic PCa. A thorough understanding of the factors contributing to PCa recurrence following development of therapy resistance is acutely needed in order to develop efficacious treatments and disease-management strategies.Our group and others have identified a unique minority population of physically enlarged cancer cells with polyaneuploid genomes, termed polyaneuploid cancer cells (PACCs), in the tumors of patients with metastatic prostate cancer and in other tumor types. PACCs are the result of a polyaneuploid transition that occurs when aneuploid cancer cells experience environmental or therapeutic stress. These aneuploid cancer cells then pause their cell cycle after whole genome doubling to survive the environmental insult. Cancer cells in the PACC state appear to be quiescent and have an increased capacity for invasion/motility, an ability to endure in stressful or novel environments, and a propensity to undergo depolyploidization to re-establish the cancer cell population. We hypothesize that PACCs are critical players in prostate cancer therapy resistance and recurrence. We seek to better understand the life cycle of the PACC state in PCa in order to inform the design of new therapeutic strategies that prevent disease recurrence.One important part of understanding how cells enter and exit that PACC state is to characterize the features of the PACC nuclei compared to “typical” PCa cells. Examining the distribution of DNA content and the size of individual nuclei allows us to infer the underlying mechanisms PCa cells use to enter the PACC state, such as cell fusion, endomitosis, endocycling, or mitotic slippage. Nuclear structure can further indicate what types of depolyploidization are possible, including neosis, polyploid mitosis, or uneven cell division. Thus, we developed a robust method to isolate nuclei from PACCs and used flow cytometry and immunofluorescence imaging to ascertain the nuclear content and size from whole PACC cells as well as the isolated nuclei. Analysis of nuclear features from both whole cells and isolated nuclei is necessary to resolve truly multinucleated cells from those that contain a single polylobulated nucleus.Our preliminary data suggests that PCa cells in the PACC state tend to have a large polyploid single nucleus more frequently than multiple smaller, single nuclei, though both were observed. This is in contrast with the opinion of many in the field, who believe that PACCs (and other variations of giant polyploid cancer cells) only exist in a multinucleated state. Continuation of these studies in various cancer cell lines and at sequential timepoints in the PACC state will deepen our understanding of how cancer cells evade systemic treatment and cause disease recurrence.

Citation Format: Anna Gonye, Chi-Ju Kim, Kenneth Pienta, Sarah Amend. Polyaneuploid prostate cancer cells induced via chemotherapy have predominantly large, single nuclei [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 140.

720 CUE-102 selectively activates and expands WT1-specific T cells for the treatment of patients with WT1+ malignancies

Background

Wilms' Tumor 1 (WT1) was ranked as the highest priority antigen for therapeutic targeting in an effort by the National Cancer Institute. Development of novel modalities targeting WT1 provide a significant opportunity to address high unmet medical need in WT1-positive malignancies, including AML, ovarian, endometrial, breast, lung, colorectal and pancreatic cancer. Leveraging the Immuno-STAT platform of targeted IL-2 therapies, and the ongoing development of CUE-101, CUE-102 is being developed as a novel therapeutic fusion protein to selectively activate tumor antigen-specific T cells to treat WT1-expressing cancers. CUE-102 consists of two human leukocyte antigen (HLA) molecules presenting a WT1 peptide, four affinity-attenuated human interleukin-2 (IL-2) molecules, and an effector attenuated human immunoglobulin G (IgG1) Fc domain.

Methods

Human PBMCs were tested to demonstrate cellular activity and specificity of CUE-102, while in vivo activity of CUE-102 was assessed in HLA-A2 transgenic mice. HLA-A2/WT1-specific TCRs were validated and expressed in primary human CD8 T cells. Tetramer staining and flow cytometry identified cell populations and activation markers.

Results

Multiple in vitro assessments demonstrate that CUE-102 selectively activates and expands WT1-specific CD8+ T cells from PBMC of healthy and cancer bearing donors. These CUE-102-expanded CD8+ T cells exhibit polyfunctional and cytotoxic responses upon challenge with WT1-presenting target cells. In addition, significant functional attenuation of the IL-2 components of CUE-102 was shown, similar to preclinical results obtained with CUE-101. In vivo studies in HLA-A2 transgenic mice confirm that CUE-102 elicits and expands polyfunctional WT1-specific CD8+ T cells from naïve and previously immunized mice without significantly altering the frequencies of other immune lineages. The WT1-specific CD8+ T cells expanded in vivo exhibit polyfunctionality in response to peptide-loaded target cells, and selectively kill WT1-presenting target cells in vivo.

Conclusions

CUE-102 elicits selective expansion of a WT1-specific population of cytotoxic CD8+ T cells both in vitro and in vivo. These results, together with its similarity to CUE-101, support its anticipated tolerability profile and potential for clinical efficacy in a Phase 1 trial planned to initiate in 2022.

Ethics Approval

All animal studies followed guidance from the SmartLabs Institutional Animal Care and Use Committee protocol MIL-100 and were performed in compliance with federal guidelines.

438 A phase 1 trial of CUE-101, a novel HPV16 E7-pHLA-IL2-Fc fusion protein, alone and in combination with pembrolizumab in patients with recurrent/metastatic HPV16+ head and neck cancer

Background

Immuno-STATsTM are novel, modular fusion proteins designed to selectively activate tumor-antigen-specific CD8+ T cells. CUE-101 is comprised of a human leukocyte antigen (HLA) complex, HLA-A*0201, a peptide epitope derived from the HPV16 E7 protein, and 4 molecules of a reduced affinity human interleukin-2 (IL-2) and is designed to bind and activate HPV16-specific T cells for treatment of HPV16-driven cancers. In preclinical studies CUE-101 demonstrated selective binding, activation, and expansion of HPV16 E7-specific CD8+ T cells, and a murine surrogate activated anti-tumor immunity.1

Methods

CUE-101-01 is a first-in-human study in HLA-A*0201 positive patients with HPV16+ recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC). Safety of escalating monotherapy and combination doses was evaluated to establish the recommended phase 2 dose (RP2D) for expanded enrollment. Patients with R/M HNSCC refractory to 1 or more prior platinum or pembrolizumab based systemic treatments received CUE-101 monotherapy, and patients with R/M HNSCC and PD-L1 tumor expression received combination CUE-101 and 200 mg pembrolizumab as first line treatment. Study treatment was administered intravenously every 3 weeks until progression or toxicity. Objectives included evaluation of safety, pharmacokinetics (PK), pharmacodynamics (PD), and antitumor activity.

Results

As of June 30, 2021, 39 patients have received CUE-101 monotherapy ranging from 0.06 to 8 mg/kg. The maximum tolerated dose (MTD) was not identified. Based on PK, PD and clinical data, a monotherapy RP2D of 4 mg/kg was selected. The combination cohort of 1 mg/kg CUE-101 and pembrolizumab has been tested and dose escalation is ongoing. Adverse events have included CTCAE grade 2 or less fatigue (41%), anemia (31%), lymphopenia (24%), chills (21%), decreased appetite (19%) and dyspnea (17%). CUE-101 PK data demonstrate dose-dependent increases in drug exposure that are sustained upon repeat dosing. PD data demonstrate dose-dependent expansion of HPV-16 E711-20-specific CD8+ T cells, sustained increase in natural killer cells and transient increase in Treg cells. An increase in CD3+ GZMB+ tumor infiltrating T cells was observed in tissue following treatment with CUE-101 in one patient with available pre- and post-treatment biopsies. One patient at the CUE-101 monotherapy RP2D has an ongoing partial response and 8 of 33 patients have experienced stable disease ≥ 12 weeks based on RECIST 1.1 criteria.

Conclusions

CUE-101 is a novel immunotherapeutic demonstrating acceptable safety and tolerability with encouraging PD signals, supporting selective activation of tumor-specific T cells, and promising antitumor activity. Enrollment continues in both monotherapy and combination cohorts.

Acknowledgements

The authors would like to thank all the patients who are participating in this study. The study is sponsored by Cue Biopharma.

Trial Registration

ClinicalTrials.

gov NCT03978689

References

Quayle SN, Girgis N, Thapa DR, et al. CUE-101, a Novel HPV16 E7-pHLA-IL-2-Fc fusion protein, enhances tumor antigen specific T cell activation for the treatment of HPV16-driven malignancies. Clin Cancer Res 2020;26:1953–64.

Ethics Approval

This study was approved by Ethics and Institutional Review Boards (IRBs) at all study sites. IRB reference numbers: Advarra Pro00037736 (Moffitt Cancer Center), IRB 52744 (Stanford University School of Medicine), IRB 191714 (Vanderbilt University Medical Center Vanderbilt-Ingram Cancer Center), HRPO# 201905108 (Washington University School of Medicine), 2019–087 Karmanos Cancer Institute, DF/HCC IRB# 19-374 (Massachusetts General Hospital), WIRB 2000026098 (Yale Cancer Center), WIRB 1908869642 (University of Arizona Cancer Center), WIRB STUDY00008948 (University of Washington, Seattle), IRB(IRBMED) HUM00165746 (University of Michigan Comprehensive Cancer Center), WIRB IRB00112341(Winship Cancer Institute/Emory University), 2019–0578 (The University of Texas MD Anderson Cancer Center), IRB 20-073 (Memorial Sloan Kettering Cancer Center), IRB00255391 (Johns Hopkins University School of Medicine).

Abstract 5365: Profiling circulating tumor cell RNA from a large blood screening volume: A pilot study using diagnostic leukapheresis followed by the NanoString low RNA input nCounter assay

Introduction and objective: The presence of circulating tumor cells (CTC) is associated with poor prognosis in metastatic prostate cancer (mPCa) patients. The aim of this study is to evaluate the feasibility of using diagnostic leukapheresis (LP) followed by gene profiling using the NanoString low RNA input nCounter assay to achieve reliable CTC gene profiling.

Methods: Blood samples were collected from 4 mPCa patients and 3 healthy donors. In the LP procedure, different blood elements were separated based on density. The mononuclear cell layer (presumed to contain any CTCs) was collected. The Alere™ CTC AdnaTest (AdnaGen, Langenhagen, Germany), an EpCAM positive selection method for isolation of EpCAM+ CTCs, followed by RT-qPCR for PSA, PSMA, and HOXB13 was used to detect CTCs from LP. The Ct value thresholds for positive CTC signal by RT-qPCR were set based on healthy donor LP subjected to AdnaTest as a negative control (PSA 36.3, PSMA 36.82, HOXB13 40). The cDNA of cells captured by EpCAM+ selection (including putative CTCs) and of the EpCAM+ depleted white blood cells (WBC) were assayed by the nCounter PanCancer Progression Panel to determine expression of 770 selected mRNAs. The NanoString nCounter Low RNA Input Kit with the multiplex 770-gene primer pool was used for the pre-amplification of cDNA and overnight hybridization with the PanCancer Progression panel. To validate the assay, healthy donor LPs were spiked with known numbers of PCa cell line LN95 cells.

Results: For mPCa patients, the LP procedure took 136.2±10.6 min, with a screening volume of 10L of peripheral blood. The mean volume of mPCa LP product was 123.64±12.23 ml. The WBC concentration was 69.75±28.2×109/L. All samples were subjected to AdnaTest in triplicate and CTCs were identified in 3 out of 4 patients. The positive Ct values of PSA were 33.86±0.81, 32.14±0.31 and 33.09±0.34; PSMA were 35.55±1.02, 33.55±0.83 and 35.30±0.65; HOXB13 were 36.25±0.34, 37.15±0.22 and 37.09±0.33. To assess profiling of CTCs isolated from LP using the nCounter platform, 100, 500, and 1000 LN95 cells were spiked in healthy LPs and were analyzed with the AdnaTest. Within each spiking group, pre-spiking WBC, captured CTC, post-capture WBC, and LN95 cells in PBS alone were subjected to the Nanostring assay. Eisen Cluster analysis separated pre- and post- WBCs, captured CTCs, LN95 cells into three groups. The gene expression of captured CTCs correlated with those of LN95 cells, and the correlation increased with the spiking cancer cell number (R2=0.45, 0.57, and 0.70, respectively). The gene expression of pre-spiked WBCs were highly correlated with those of post-capture WBCs regardless of spiking cancer cell number (R2=0.83, 0.84 and 0.85).

Conclusions: Analyzing CTCs in LP samples by AdnaTest is feasible and offers a promising method for liquid biopsy of mPCa patients. The NanoString low RNA input nCounter assay can provide reliable gene expression profiling of CTC.

Citation Format: Liang Dong, Chung-Ying Huang, Changxue Lu, Diane Reyes, Sarah R. Amend, Jun Luo, Kenneth Pienta. Profiling circulating tumor cell RNA from a large blood screening volume: A pilot study using diagnostic leukapheresis followed by the NanoString low RNA input nCounter assay [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5365.

Game Theory Cancer Models of Cancer Cell-Stromal Cell Dynamics using Interacting Particle Systems

We describe an evolutionary game theory model that has been used to predict the population dynamics of interacting cancer and stromal cells. We first consider the mean field case assuming homogeneous and nondiscrete populations. Interacting Particle Systems (IPS) are then presented as a discrete and spatial alternative to the mean field approach. Finally, we discuss cases where IPS gives results different from the mean field approach.

Abstract B11: O-GlcNAcylation is required for mutant KRAS-induced lung tumorigenesis

Mutant KRAS drives glycolytic flux in lung cancer, potentially impacting aberrant protein glycosylation. Recent evidence suggests aberrant KRAS drives flux of glucose into the hexosamine biosynthetic pathway (HBP). HBP is required for various glycosylation processes, such as protein N- or O-glycosylation and glycolipid synthesis. However, its function during tumorigenesis is poorly understood. One contributor and proposed target of KRAS-driven cancers is a developmentally conserved epithelial plasticity program called epithelial-mesenchymal transition (EMT). Here we showed in novel autochthonous mouse models that EMT accelerated KrasG12D lung tumorigenesis by upregulating expression of key enzymes of the HBP pathway. We demonstrated that HBP was required for suppressing KrasG12D-induced senescence, and targeting HBP significantly delayed KrasG12D lung tumorigenesis. To explore the mechanism, we investigated protein glycosylation downstream of HBP and found elevated levels of O-linked β-N-acetylglucosamine (O-GlcNAcylation) post-translational modification on intracellular proteins. O-GlcNAcylation suppressed KrasG12D oncogene-induced senescence (OIS) and accelerated lung tumorigenesis. Conversely, loss of O-GlcNAcylation delayed lung tumorigenesis. O-GlcNAcylation of proteins SNAI1 and c-MYC correlated with the EMT-HBP axis and accelerated lung tumorigenesis. Our results demonstrated for the first time that O-GlcNAcylation was sufficient and required to accelerate KrasG12D lung tumorigenesis in vivo, which was reinforced by epithelial plasticity programs.

Citation Format: Takumi Shiraishi, Phuoc T. Tran, Reem Malek, Audrey Lafargue, Mustafa Barbhuiya, Xing Wang, Brian Simons, Matthew Ballew, Katriana Nugent, Jennifer Groves, Russell Williams, Hailun Wang, James Verdone, Gokben Yildirir, Roger Henry, Bin Zhang, John Wong, Ken Wang, Barry Nelkin, Kenneth Pienta, Dean Felsher, Natasha Zachara, Kekoa Taparra. O-GlcNAcylation is required for mutant KRAS-induced lung tumorigenesis [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr B11.

Abstract 4597: Bladder cancer patients experience circulating tumor cell number surge during intramedullary nailing procedures intended for treating pathological fractures

Introduction and Objective: The goal of this study is to evaluate if intramedullary nailing procedure of completed or impending pathologic fractures in long bones secondary to metastatic bladder cancer affects the circulating tumor cell (CTC) number.

Methods: Bladder cancer patients who presented with completed or impending pathologic fracture due to metastatic disease and underwent fracture fixation were recruited in this study. During nailing procedures performed by orthopedic oncologists, blood samples were collected from peripheral vein, peripheral artery and central vein at four time points (TP). TP1 was at the time of incision; TP2 was during the passage of the first reamer; TP3 was during wound closure; and TP4 was 24 hours post-operatively. Two CTC capture technologies were used: The FAST disk is a size-selective, clog-free rare cancer cell isolation platform (Clinomics, Ulsan, South Korea). CTCs were captured by a filter and stained with immunofluorescent antibodies. The filter was then scanned using the Metafer5 (MetaSystems, V3.11.8) automated scanning system to enumerate CTCs. The second platform was the AccuCyte-CyteFinder system (RareCyte, Inc., Seattle, WA), a selection-free method to enumerate and characterize CTCs from peripheral blood samples (PB) via immunofluorescent staining and scanning. The criteria for defining a CTC is DAPI positive, CK/EpCAM positive, and CD45 negative.

Results: Three nailing cases from two patients were enrolled in this study (one patient had 2 affected limbs). The surgical sites were the right humerus (2 cases) and the right femur (3rd case). The AccuCyte-CyteFinder system was used for all three cases. FAST was used for the second and the third case. With the AccuCyte-CyteFinder system (TP1/TP2/TP3/TP4), the CTC counts were: 8/3314/7/2 for the first case; 259/3616/322/548 for the second case; 755/2507/917 CTCs for the third case (no TP4 sample). With FAST disk (TP1/TP2/TP3/TP4), the CTC counts were: 5/964/28/9 CTCs for the second case; 27/523/27/13 for the third case. Many CTC clusters were seen for TP2 venous samples, but rarely seen for the other samples.

Conclusions: A surge in CTC number during the nailing procedure was observed in all cases by both methods. Our data suggest that the palliative nailing procedure may contribute to further CTC dissemination. Whether the surge of CTCs results in clinical relevant disease warrants further investigation.

Citation Format: Zhongyuan Zhang, Liang Dong, Stephanie Glavaris, Emily Caruso, Kenneth Pienta, Carol Morris. Bladder cancer patients experience circulating tumor cell number surge during intramedullary nailing procedures intended for treating pathological fractures [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 4597.

Abstract B070: Epithelial-marker absent and disease-marker specific circulating and disseminated tumor cells are rarely detected in men with localized prostate cancer

Introduction and Objectives: Epithelial-marker negative circulating tumor cells (CTCs) have recently been discovered in metastatic prostate cancer (PCa). Many popular CTC detection methods, including the AdnaTest, utilize a selection-based first step of bead pull down against an epithelial marker such as EpCAM. It has previously been shown that disseminated tumor cells (DTCs) are rare at the time of localized PCa using the AdnaTest. Here we queried the matched epithelial-marker depleted buffy coat (DBC) fraction of the AdnaTest for the presence of DTCs and CTCs in a cohort of localized patients undergoing radical prostatectomy (RP).

Methods: 8 mL of bone marrow (BM) were collected from 28 patients (5 controls, 2 metastatic, and 21 localized) along with 8 mL of matched peripheral blood (PB) from 11 patients (3 controls, 2 metastatic, 6 localized). 5 mL of BM and PB were evaluated with the AdnaTest ProstateCancer Select kit (Qiagen) to enrich for EpCAM positive cells using immunomagnetic beads. The DBCs having the remaining cells after AdnaTest enrichment were isolated and queried for the presence of DTCs and CTCs. Cells were lysed and reverse transcribed into cDNA followed by real-time qPCR for the expression of the prostate-specific markers, NKX3.1, androgen receptor (AR), prostate specific antigen (PSA), and HOXB13, as well as the epithelial marker EpCAM. The buffy coats from the remaining 3 mL of nonenriched BM and PB were isolated and stored in -80°C for future evaluation.

Results: EpCAM, NKX3.1, and AR were expressed in localized, control, and metastatic BM and PB and thus were nonspecific to identifying prostate CTCs and DTCs. PSA and HOXB13 positive cells were only identified in the metastatic setting. With the AdnaTest, PSA and HOXB13 positive DTCs were detected in 0/21 (0%) localized patients, but were identified in 2/2 (100%) metastatic samples. Positive PSA and HOXB13 matched in all cases. No controls expressed PSA or HOXB13. The DBC fraction was contaminated with EpCAM positive cells in 27/28 (96%) BM samples in addition to 8/11 (73%) PB specimens. PSA or HOXB13 expression were not detected in any DBC, demonstrating the absence of epithelial-marker negative DTCs. In two instances, EpCAM was detected in the PB depleted fraction but not with the AdnaTest.

Conclusion: EpCAM, NKX3.1, and AR are nonspecific, while PSA and HOXB13 are prostate-specific markers in the PB and BM. PSA and HOXB13 positive prostate CTCs and DTCs are rarely identified in localized men undergoing RP. Epithelial-marker negative DTCs and CTCs were not detected in localized men. The AdnaTest bead selection step did not capture all epithelial cells, and ongoing investigation into a selection-free CTC/DTC detection platform is necessary.

Citation Format: Stephanie Glavaris, Heather Chalfin, Changxue Lu, Yan Chen, Emily Caruso, Kenneth Valkenburg, Jun Luo, Kenneth Pienta. Epithelial-marker absent and disease-marker specific circulating and disseminated tumor cells are rarely detected in men with localized prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr B070.

Cancer dormancy and criticality from a game theory perspective

BACKGROUND

The physics of cancer dormancy, the time between initial cancer treatment and re-emergence after a protracted period, is a puzzle. Cancer cells interact with host cells via complex, non-linear population dynamics, which can lead to very non-intuitive but perhaps deterministic and understandable progression dynamics of cancer and dormancy.

RESULTS

We explore here the dynamics of host-cancer cell populations in the presence of (1) payoffs gradients and (2) perturbations due to cell migration.

CONCLUSIONS

We determine to what extent the time-dependence of the populations can be quantitively understood in spite of the underlying complexity of the individual agents and model the phenomena of dormancy.

Androgen Receptor Pathway-Independent Prostate Cancer Is Sustained through FGF Signaling

Androgen receptor (AR) signaling is a distinctive feature of prostate carcinoma (PC) and represents the major therapeutic target for treating metastatic prostate cancer (mPC). Though highly effective, AR antagonism can produce tumors that bypass a functional requirement for AR, often through neuroendocrine (NE) transdifferentiation. Through the molecular assessment of mPCs over two decades, we find a phenotypic shift has occurred in mPC with the emergence of an AR-null NE-null phenotype. These "double-negative" PCs are notable for elevated FGF and MAPK pathway activity, which can bypass AR dependence. Pharmacological inhibitors of MAPK or FGFR repressed the growth of double-negative PCs in vitro and in vivo. Our results indicate that FGF/MAPK blockade may be particularly efficacious against mPCs with an AR-null phenotype.

Abstract 3918: Identification of disseminated prostate tumor cells in bone marrow during radical prostatectomy from patients with localized prostate cancer

INTRODUCTION AND OBJECTIVES In prostate cancer, disseminated tumor cells (DTC) can escape the primary lesion and enter the bone marrow (BM) niche, representing an initial step towards conventionally detectable metastasis. The frequency of occurrence is elusive in clinically localized prostate cancer. We detected and characterized these cells by measuring gene expression of prostate-specific markers from BM samples collected at the time of radical prostatectomy (RP).

METHODS 5 mL of BM were harvested at RP for 36 clinically localized patients. A whole cell extract was assayed with the AdnaTest ProstateCancerSelect kit (Qiagen). Reverse transcription (SensiScript RT kit, Qiagen) and real-time qPCR quantified expression of RPL13A (control, ribosomal protein), EPCAM (epithelial), NKX3.1 and HOXB13 (prostate-specific), and AR-FL (androgen receptor full length). Prostate markers known to be less sensitive or specific were also assayed in a subset of patients (TMPRSS2-ERG, AR-V7, PSA, and PSMA). DTC detection was defined as prostate-specific marker expression in the BM. Quality control was performed with Sanger sequencing. The associations of PSA and Gleason score (GS) with DTC detection were evaluated with the Mann-Whitney U Test and Fisher’s exact test respectively.

RESULTS DTC were detected via NKX3.1 expression in 30/36 patients (83%). 100% of patients were EPCAM+, consistent with the known non-specific expression of EPCAM in the BM. HOXB13, AR-V7, and TMPRSS2-ERG were not detected in any sample. AR-FL was also non-specifically expressed in 67% of NKX3.1+ and 83% of NKX3.1- patients. There was a pattern with DTC detection and higher PSA and GS, with 100% of NKX3.1- patients having low-risk PSA less than 10, and only one with primary GS greater than 3 (17%, 1/6). Conversely 47% (14/30) of NKX3.1+ patients had primary GS greater than or equal to 4, and 27% (8/30) had PSA greater than 10. Yet, this was not statistically significant (GS p=0.367, PSA p=0.302), and DTC were detected across all Gleason scores.

CONCLUSIONS DTC were detected based on NKX3.1 positivity in a large portion of clinically localized prostate cancer patients at all Gleason scores. Ongoing investigation with healthy patient BM will clarify whether NKX3.1 is truly prostate-specific, and if its expression associates with clinico-pathologic outcomes.

Citation Format: Stephanie A. Glavaris, Emma E. van der Toom, Michael Gorin, James Verdone, Changxue Lu, Jun Luo, Kenneth Pienta, Heather Chalfin. Identification of disseminated prostate tumor cells in bone marrow during radical prostatectomy from patients with localized prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3918. doi:10.1158/1538-7445.AM2017-3918

Biomanufacturing Seamless Tubular and Hollow Collagen Scaffolds with Unique Design Features and Biomechanical Properties

A versatile process to develop designer collagen scaffolds for hollow and tubular tissue engineering applications is presented. This process creates seamless and biomechanically tunable scaffolds ranging from ureter-like microsized tubings to structures with highly customized lumens that resemble intestinal villi, fluid bladders, and alveolar sacs that together with stem cells can potentially be used in preclinical and clinical settings.

Abstract 1564: Reactive endosteum in prostate cancer bone metastases: role of tenascin-C in regulating cancer cell adhesion and proliferation

The objective of this study is to assess the regulatory roles of reactive endosteum associated with foci of bone metastatic prostate cancer cells. Previous studies evaluated tissue arrays of human prostate cancer bone metastases and we identified a “reactive endosteum” spatially associated with foci of prostate cancer cells on trabecular bone. Reactive endosteum was characterized by elevated expression of tenascin-C, a glycoprotein deposited in the extracellular matrix of reactive stroma at sites of wound repair and in the primary tumor microenvironment in adult tissues. In general, tenascin-C is stromal derived in adult tissues. Of interest, tenascin-C is also deposited at sites of fracture repair and at sites of Brodie abscess osteomyelitis-associated inflammation in human bone. Tenascin-C has many diverse functions: it regulates cell adhesion, migration and proliferation in different pathological states while playing an important role in neuropatterning and osteogenesis during development. Moreover, tenascin-C has been shown to regulate several signal transduction pathways.

To evaluate prostate cancer-bone interactions, we developed an in vitro, 3D, osteogenic organoid model composed of human mesenchymal stem cells induced to osteogenesis that were combined with human prostate VCaP cells in organ culture. In this model, foci of VCaP cells associated preferentially to regions of high tenascin-C deposition. VCaP cells also preferentially bound to purified human tenascin-C deposited on culture plates in a dose-dependent manner. VCaP cells also exhibited an elevated growth rate on osteo-mimetic plates coated with human tenascin-C as compared to control. Moreover, VCaP cells preferentially bound to human tenascin-C coated bovine trabecular bone cubes in vitro and initiated colony formation. Evaluation of potential mediators identified integrin alpha 9 beta 1 as the key mediator of attachment to human tenascin-C. Neutralization of this integrin inhibited adhesion. Evaluation of potential signaling pathways have implicated activation of EGF receptor (EGFR), Wnk1, and STAT6 pathways. Human tenascin-C exhibits EGF-like repeats and fibronectin type III domains that may mediate activation of these pathways. Of interest, adhesion and growth of VCaP cells on tenascin-C also induced elevated tenascin-C expression in these cells, a novel finding. Additional 3D organoid and in vivo xenograft studies with other cell types support the finding of induced expression of tenascin-C in epithelial cells associated with reactive stroma or matrix.

In summary, our studies characterize elevated tenascin-C at sites of a reactive endosteum associated with metastatic prostate cancer foci. Data suggests that tenascin-C mediates adhesion and proliferation of cancer cells via activation of several pathways. These data may aid in developing novel therapeutic approaches to treat metastatic disease.

Citation Format: Rebeca San Martin, Kenneth Pienta, David R. Rowley. Reactive endosteum in prostate cancer bone metastases: role of tenascin-C in regulating cancer cell adhesion and proliferation. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1564.

A phase 2 trial of salvage radiation and concurrent weekly docetaxel after a rising prostate-specific antigen level after radical prostatectomy

Purpose/Objective(s)

We sought to assess the utility of docetaxel administered concurrently with salvage radiation therapy (SRT) following postprostatectomy biochemical failure (BF).

Methods and materials

Men with postprostatectomy BF were accrued on a single-arm phase 2 clinical trial. SRT doses ranged from 64.8 to 70.2 Gy and were delivered in 1.8-Gy fractions to the prostate bed alone as the clinical target volume with a +1-cm uniform planning target volume expansion. The primary endpoint was progression-free survival at 4 years compared with the Stephenson nomogram estimate. Kaplan-Meier methods were used to assess late toxicity, BF, and distant metastases. An unplanned matched-pair analysis was performed with 19 patients treated with SRT alone.

Results

Nineteen men were accrued and treated. Median follow-up was 4.8 years. Median pre-RT prostate-specific antigen level was 0.7 ng/mL (interquartile range, 0.4-1.3 ng/mL). All 8 cycles of docetaxel were completed in 17 (89%) patients. Acute grade 1-4 toxicities were observed in 79%, 50%, 58%, and 11%, respectively. A total of 68% of acute grade 1 toxicities were related to fatigue, urinary, or bowel symptoms. For grade 2 toxicities, 76% were related to neutropenia, fatigue, or urinary symptoms. Acute grade 3 and 4 toxicities were most commonly neutropenia (84% and 100%, respectively). All late toxicities were grade 1 to 2 with 89% related to bowel or urinary function. Predicted 4-year progression-free survival was 39% and observed was 42% (90% confidence interval [CI], 24-60). Matched-pair analysis demonstrated no significant improvement in BF (P = .96, hazard ratio, 0.98; 90% CI, 0.4-2.3) or distant metastases (P = .09; hazard ratio, 0.3; 90% CI, 0.07-1.2), and no difference between late bowel (P = .60) or urinary toxicity (P = .41).

Conclusions

Docetaxel can safely be administered concurrently with SRT without significantly impacting posttreatment toxicity. Neutropenia was the most significant acute toxicity. Given the small sample size, no clear clinical benefit was observed. Larger studies are needed to determine the efficacy of concurrent docetaxel in this setting.

Abstract 4985: Notch1 as a key mediator in promoting advanced castration-resistant prostate cancer

The first line of treatment for men with advanced prostate cancers is androgen deprivation therapy. However, the disease commonly relapses in its lethal metastatic form referred to as castration-resistant prostate cancer (CRPC). CRPC is the primary cause of prostate cancer specific mortality in men. Current therapies including chemotherapeutic agents improve median overall survival by only few months. The mechanisms that distinguish clinically localized indolent tumors from lethal CRPC are unclear. Here we demonstrate that ectopic expression of Notch1 promotes progression to poorly differentiated carcinoma when combined with pathways that are altered in advanced disease but are insufficient to drive aggressive prostate cancer alone. Notch1 driven tumors are resistant to androgen deprivation. Transcriptional profiling reveals that these tumors display features of epithelial to mesenchymal transition, a morphological change associated with tumor aggressiveness and metastasis. Our study provides the first functional evidence that Notch1 signaling axis is a key mediator in promoting advanced prostate cancer and may represent a new therapeutic target for the advanced disease.

Note: This abstract was not presented at the meeting.

Citation Format: Tanya Stoyanova, Claire Faltermeier, Bryan Smith, Andrew Goldstein, Xi Zhang, Justin Drake, John Lee, Sandra Orellana, Steven Blum, Donghui Cheng, Kenneth Pienta, Jiaoti Huang, Owen Witte. Notch1 as a key mediator in promoting advanced castration-resistant prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4985. doi:10.1158/1538-7445.AM2015-4985

A method to measure cellular adhesion utilizing a polymer micro-cantilever

In the present study we engineered a micro-machined polyimide cantilever with an embedded sensing element to investigate cellular adhesion, in terms of its relative ability to stick to a cross-linker, 3,3'-dithiobis[sulfosuccinimidylpropionate], coated on the cantilever surface. To achieve this objective, we investigated adhesive properties of three human prostate cancer cell lines, namely, a bone metastasis derived human prostate cancer cell line (PC3), a brain metastasis derived human prostate cancer cell line (DU145), and a subclone of PC3 (PC3-EMT14). We found that PC3-EMT14, which displays a mesenchymal phenotype, has the least adhesion compared to PC3 and DU145, which exhibit an epithelial phenotype.

New and emerging therapies for bone metastases in genitourinary cancers

CONTEXT

Bone metastases are a common feature of advanced genitourinary malignancies and a prominent cause of morbidity and mortality.

OBJECTIVE

The objective of this review is to discuss the incidence, pathophysiology, and management of bone metastases in the most prevalent genitourinary malignancies.

EVIDENCE ACQUISITION

We reviewed the relevant medical literature, with a particular emphasis on prospective randomized controlled trials. Much of the relevant clinical trial data focus on prostate cancer (PCa). We provide a nonsystematic review and our perspective on the available data.

EVIDENCE SYNTHESIS

Clinical manifestations can include pain, hypercalcemia, pathologic fractures, and spinal cord compression. Optimal systemic therapy for skeletal metastases often features a combination of disease-specific therapy and bone-targeted therapy. Some agents, such as the radiopharmaceutical radium-223, blur the line between those categories. Osteoclast inhibition is a validated strategy in the management of selected patients with bone metastases. Zoledronic acid, a bisphosphonate, is approved for the prevention of skeletal events caused by solid tumors metastatic to bone. Denosumab is a fully human monoclonal antibody that inactivates receptor activator of nuclear factor-κB ligand and is approved for the same indication. Beta-emitting radiopharmaceuticals can be effective for the palliation of pain caused by bone metastases, but their use is often limited by marrow suppression. The alpha-emitting radiopharmaceutical radium-223 has recently been shown to improve overall survival and prevent skeletal events in select men with castration-resistant PCa metastatic to bone. Multiple ongoing clinical trials are designed to examine the potential for therapeutic inhibition of additional targets such as Src and hepatocyte growth factor (MET).

CONCLUSIONS

Bone metastases cause considerable morbidity and mortality among patients with genitourinary malignancies. Optimal management requires consideration of bone-targeted therapy as well as disease-specific therapy. Further research is needed to optimize the use of existing agents and to define the therapeutic potential of novel targets.