Publications by authors named "Ryan Dittamore"

Article Synopsis
  • - Neuroendocrine prostate cancer (NEPC) is a highly aggressive form of prostate cancer that can form directly or develop from existing prostate adenocarcinoma, often as a way to resist treatment.
  • - NEPC commonly shows the loss of key tumor suppressor genes (RB1, TP53, PTEN), which are also found in some prostate adenocarcinoma cases.
  • - The study emphasizes the importance of single-cell genomic analysis of circulating tumor cells to explore the genetic diversity and heterogeneity of tumors in patients with advanced prostate cancer.
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Purpose: Circulating tumor cells (CTC) are under investigation as a minimally invasive liquid biopsy that may improve risk stratification and treatment selection. CTCs uniquely allow for digital pathology of individual malignant cell morphology and marker expression. We compared CTC features and T-cell counts with survival endpoints in a cohort of patients with metastatic genitourinary cancer treated with combination immunotherapy.

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Chromosomal instability (CIN) increases a tumor cell's ability to acquire chromosomal alterations, a mechanism by which tumor cells evolve, adapt, and resist therapeutics. We sought to develop a biomarker of CIN in circulating tumor cells (CTC) that are more likely to reflect the genetic diversity of patient's disease than a single-site biopsy and be assessed rapidly so as to inform treatment management decisions in real time. Large-scale transitions (LST) are genomic alterations defined as chromosomal breakages that generate chromosomal gains or losses of greater than or equal to10 Mb.

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In the PURE-01 study, patients with muscle-invasive bladder cancer (MIBC) who achieved a pathological complete response (CR; ypT0N0) had tumor features suggesting that pre-existing immunity may promote response. We focused on fibroblast growth factor receptor-3 (FGFR3) genomic alterations (GAs) as potential tumor resistance features. The primary endpoint of our study was CR.

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Purpose: Aggressive variant prostate cancer (AVPC) represents a clinical subset distinguished by therapy resistance and poor prognosis, linked to combined losses of the tumor suppressor genes (TSG) , and . Circulating tumor cells (CTC) provide a minimally invasive opportunity for identification and molecular characterization of AVPC. We aimed to evaluate the incidence and clinical significance of compound (2+)TSG losses and genomic instability in prostate cancer CTC, and to expand the set genomic biomarkers relevant to AVPC.

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Background: The PURE-01 study (NCT02736266) evaluated the use of pembrolizumab before radical cystectomy (RC) in muscle-invasive bladder cancer (MIBC).

Objective: To evaluate the ability of molecular signatures to predict the pathological complete response (CR: ypT0N0) and progression-free survival (PFS) after pembrolizumab and RC.

Design, Setting, And Participants: We analyzed the expression data from patients with T2-4aN0M0 MIBC enrolled in the PURE-01 study (N=84) and from patients of a retrospective multicenter cohort treated with cisplatin-based neoadjuvant chemotherapy (NAC; N=140).

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Expression of the DNA/RNA helicase schlafen family member 11 (SLFN11) has been identified as a sensitizer of tumor cells to DNA-damaging agents including platinum chemotherapy. We assessed the impact of SLFN11 expression on response to platinum chemotherapy and outcomes in patients with metastatic castration-resistant prostate cancer (CRPC). Tumor expression of SLFN11 was assessed in 41 patients with CRPC treated with platinum chemotherapy by RNA sequencing (RNA-seq) of metastatic biopsy tissue ( = 27) and/or immunofluorescence in circulating tumor cells (CTC; = 20).

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Circulating tumor cell (CTC) and cell-free (cf) DNA-based genomic alterations are increasingly being used for clinical decision-making in oncology. However, the concordance and discordance between paired CTC and cfDNA genomic profiles remain largely unknown. We performed comparative genomic hybridization (CGH) on CTCs and cfDNA, and low-pass whole genome sequencing (lpWGS) on cfDNA to characterize genomic alterations (CNA) and tumor content in two independent prospective studies of 93 men with mCRPC treated with enzalutamide/abiraterone, or radium-223.

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Background: Proof of the clinical utility of a biomarker is when its use informs a management decision and improves patient outcomes relative to when it is not used.

Objective: To model the clinical benefit of the nuclear-localized androgen receptor splice variant 7 (AR-V7) test for men with progressing metastatic castration-resistant prostate cancer (mCRPC) at the second line of therapy or greater to inform the choice of an androgen receptor signaling inhibitor (ARSI) or a taxane.

Design, Setting, And Participants: The study population was a cross-sectional cohort of 193 unique patients with progressing mCRPC from whom 255 samples were drawn at the time of the second line or later treatment decision who then received an ARSI or taxane, with up to 3 yr of additional follow-up Circulating tumor cells (CTCs) were identified from blood samples and tested for AR-V7.

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Purpose: Approximately 15% of men with newly diagnosed prostate cancer have high risk features which increase the risk of recurrence and metastasis. Better predictive biomarkers could allow for earlier detection of biochemical recurrence and change surveillance and adjuvant treatment paradigms. Circulating tumor cells are thought to represent the earliest form of metastases.

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Histologic transformation to small cell neuroendocrine prostate cancer occurs in a subset of patients with advanced prostate cancer as a mechanism of treatment resistance. Rovalpituzumab tesirine (SC16LD6.5) is an antibody-drug conjugate that targets delta-like protein 3 (DLL3) and was initially developed for small cell lung cancer.

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Purpose: Androgen receptor splice variant 7 (AR-V7) results in a truncated receptor, which leads to ligand-independent constitutive activation that is not inhibited by anti-androgen therapies, including abiraterone or enzalutamide. Given that previous reports suggested that circulating tumor cell (CTC) AR-V7 detection is a poor prognostic indicator for the clinical efficacy of secondary hormone therapies, we conducted a prospective multicenter validation study.

Patients And Methods: PROPHECY ( ClinicalTrials.

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Purpose: Using nonenrichment-based, potentially more sensitive Epic Sciences circulating tumor cell (CTC) platform, we sought to detect and characterize CTCs in untreated, high-risk localized prostate cancer and to evaluate their clinical implication.

Methods: Between 2012 and 2015, blood samples were prospectively collected from patients with National Comprehensive Cancer Network high-risk localized prostate cancer undergoing either radiotherapy (XRT) plus androgen deprivation therapy or radical prostatectomy (RP) with curative intent. Samples were analyzed with the Epic Sciences platform with 4,6-diamidino-2-phenylindole, CD45, cytokeratin (CK), and androgen receptor (AR) -terminal staining.

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Background: Checkpoint inhibitors have not been effective for prostate cancer as single agents. Durvalumab is a human IgG1-K monoclonal antibody that targets programmed death ligand 1 and is approved by the U.S.

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AR-V7-expressing metastatic prostate cancer is an aggressive phenotype with poor progression-free survival (PFS) and overall survival (OS). Preliminary evidence suggests that AR-V7-positive tumors may be enriched for DNA-repair defects, perhaps rendering them more sensitive to immune-checkpoint blockade. We enrolled 15 metastatic prostate cancer patients with AR-V7-expressing circulating tumor cells into a prospective phase-2 trial.

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Importance: Preferential delivery of docetaxel to tumors by prostate-specific membrane antigen (PSMA)-targeted nanoparticles is clinically effective, and the selective reduction of PSMA-positive circulating tumor cells (CTCs) after treatment has implications for patient selection and disease monitoring.

Objective: To determine the safety and efficacy of BIND-014, a PSMA-directed docetaxel-containing nanoparticle, in patients with metastatic castration-resistant prostate cancer (mCRPC).

Design, Setting, And Participants: A multicenter open-label, phase 2 clinical trial of 42 chemotherapy-naive patients with progressing mCRPC after treatment with abiraterone acetate and/or enzalutamide was conducted from June 24, 2013, to June 10, 2016.

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Importance: A blood test to determine whether to treat patients with metastatic castration-resistant prostate cancer (mCRPC) with an androgen receptor signaling (ARS) inhibitor or taxane is an unmet medical need.

Objective: To determine whether a validated assay for the nuclear-localized androgen receptor splice variant 7 (AR-V7) protein in circulating tumor cells can determine differential overall survival among patients with mCRPC treated with taxanes vs ARS inhibitors.

Design, Setting, And Participants: This blinded correlative study conducted from December 31, 2012, to September 1, 2016, included 142 patients with histologically confirmed mCRPC and who were treated at Memorial Sloan Kettering Cancer Center, The Royal Marsden, or the London Health Sciences Centre.

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Purpose: Androgen receptor (AR) is frequently detected in breast cancers, and AR-targeted therapies are showing activity in AR-positive (AR+) breast cancer. However, the role of AR in breast cancers is still not fully elucidated and the biology of AR in breast cancer remains incompletely understood. Circulating tumor cells (CTCs) can serve as prognostic and diagnostic tools, prompting us to measure AR protein expression and conduct genomic analyses on CTCs in patients with metastatic breast cancer.

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The heterogeneity of an individual patient's tumor has been linked to treatment resistance, but quantitative biomarkers to rapidly and reproducibly evaluate heterogeneity in a clinical setting are currently lacking. Using established tools available in a College of American Pathologists-accredited and Clinical Laboratory Improvement Amendments-certified clinical laboratory, we quantified digital pathology features on 9,225 individual circulating tumor cells (CTC) from 179 unique metastatic castration-resistant prostate cancer (mCRPC) patients to define phenotypically distinct cell types. Heterogeneity was quantified on the basis of the diversity of cell types in individual patient samples using the Shannon index and associated with overall survival (OS) in the 145 specimens collected prior to initiation of the second or later lines of therapy.

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Background: Abiraterone acetate (AA) inhibits androgen biosynthesis and prolongs survival in men with metastatic castration-resistant prostate cancer (mCRPC) when combined with prednisone (P). Resistance to therapy remains incompletely understood. In this open-label, single-arm, multicenter phase II study we investigated the clinical benefit of increasing the dose of AA at the time of resistance to standard-dose therapy.

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Lung cancer treatment has become increasingly dependent upon invasive biopsies to profile tumors for personalized therapy. Recently, tumor expression of programmed death-ligand 1 (PD-L1) has gained interest as a potential predictor of response to immunotherapy. Circulating biomarkers present an opportunity for tumor profiling without the risks of invasive procedures.

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Background: Circulating tumor cells (CTCs) expressing AR-V7 protein localized to the nucleus (nuclear-specific) identify metastatic castration-resistant prostate cancer (mCRPC) patients with improved overall survival (OS) on taxane therapy relative to the androgen receptor signaling inhibitors (ARSi) abiraterone acetate, enzalutamide, and apalutamide.

Objective: To evaluate if expanding the positivity criteria to include both nuclear and cytoplasmic AR-V7 localization ("nuclear-agnostic") identifies more patients who would benefit from a taxane over an ARSi.

Design, Setting, And Participants: The study used a cross-sectional cohort.

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