Multigene model for predicting metastatic prostate cancer using circulating tumor cells by microfluidic magnetophoresis

Microfluidic Applications in Prostate Cancer Research

Prostate cancer is a disease in which cells in the prostate, a gland in the male reproductive system below the bladder, grow out of control and, among men, it is the second-most frequently diagnosed cancer (other than skin cancer). In recent years, prostate cancer death rate has stabilized and, currently, it is the second-most frequent cause of cancer death in men (after lung cancer). Most deaths occur due to metastasis, as cancer cells from the original tumor establish secondary tumors in distant organs. For a long time, classical cell cultures and animal models have been utilized in basic and applied scientific research, including clinical applications for many diseases, such as prostate cancer, since no better alternatives were available. Although helpful in dissecting cellular mechanisms, these models are poor predictors of physiological behavior mainly because of the lack of appropriate microenvironments. Microfluidics has emerged in the last two decades as a technology that could lead to a paradigm shift in life sciences and, in particular, controlling cancer. Microfluidic systems, such as organ-on-chips, have been assembled to mimic the critical functions of human organs. These microphysiological systems enable the long-term maintenance of cellular co-cultures in vitro to reconstitute in vivo tissue-level microenvironments, bridging the gap between traditional cell cultures and animal models. Several reviews on microfluidics for prostate cancer studies have been published focusing on technology advancement and disease progression. As metastatic castration-resistant prostate cancer remains a clinically challenging late-stage cancer, with no curative treatments, we expanded this review to cover recent microfluidic applications related to prostate cancer research. The review includes discussions of the roles of microfluidics in modeling the human prostate, prostate cancer initiation and development, as well as prostate cancer detection and therapy, highlighting potentially major contributions of microfluidics in the continuous march toward eradicating prostate cancer.

Impact of Circulating Tumor Cell-Expressed Prostate-Specific Membrane Antigen and Prostate-Specific Antigen Transcripts in Different Stages of Prostate Cancer

PURPOSE

Prostate-specific membrane antigen (PSMA)-based images, which visually quantify PSMA expression, are used to determine prostate cancer micrometastases. This study evaluated whether a circulating tumor cell (CTC)-based transcript platform, including PSMA mRNA, could help identify potential prognostic markers in prostate cancer.

EXPERIMENTAL DESIGN

We prospectively enrolled 21 healthy individuals and 247 patients with prostate cancer [localized prostate cancer (LPCa), n = 94; metastatic hormone-sensitive prostate cancer (mHSPC), n = 44; and metastatic castration-resistant prostate cancer (mCRPC), n = 109]. The mRNA expression of six transcripts [PSMA, prostate-specific antigen (PSA), AR, AR-V7, EpCAM, and KRT 19] from CTCs was measured, and their relationship with biochemical recurrence (BCR) in LPCa and mCRPC progression-free survival (PFS) rate in mHSPC was assessed. PSA-PFS and radiological-PFS were also calculated to identify potential biomarkers for predicting androgen receptor signaling inhibitor (ARSI) and taxane-based chemotherapy resistance in mCRPC.

RESULTS

CTC detection rates were 75.5%, 95.3%, and 98.0% for LPCa, mHSPC, and mCRPC, respectively. In LPCa, PSMA [hazard ratio (HR), 3.35; P = 0.028) and PSA mRNA (HR, 1.42; P = 0.047] expressions were associated with BCR. Patients with mHSPC with high PSMA (HR, 4.26; P = 0.020) and PSA mRNA (HR, 3.52; P = 0.042) expressions showed significantly worse mCRPC-PFS rates than those with low expression. Increased PSA and PSMA mRNA expressions were significantly associated with shorter PSA-PFS and radiological PFS in mCPRC, indicating an association with drug resistance.

CONCLUSIONS

PSMA and PSA mRNA expressions are associated with BCR in LPCa. In advanced prostate cancer, PSMA and PSA mRNA can also predict rapid progression from mHSPC to mCRPC and ARSI or taxane-based chemotherapy resistance.

Microfluidics-Based Technologies for the Assessment of Castration-Resistant Prostate Cancer

Castration-resistant prostate cancer remains a significant clinical challenge, wherein patients display no response to existing hormone therapies. The standard of care often includes aggressive treatment options using chemotherapy, radiation therapy and various drugs to curb the growth of additional metastases. As such, there is a dire need for the development of innovative technologies for both its diagnosis and its management. Traditionally, scientific exploration of prostate cancer and its treatment options has been heavily reliant on animal models and two-dimensional (2D) in vitro technologies. However, both laboratory tools often fail to recapitulate the dynamic tumor microenvironment, which can lead to discrepancies in drug efficacy and side effects in a clinical setting. In light of the limitations of traditional animal models and 2D in vitro technologies, the emergence of microfluidics as a tool for prostate cancer research shows tremendous promise. Namely, microfluidics-based technologies have emerged as powerful tools for assessing prostate cancer cells, isolating circulating tumor cells, and examining their behaviour using tumor-on-a-chip models. As such, this review aims to highlight recent advancements in microfluidics-based technologies for the assessment of castration-resistant prostate cancer and its potential to advance current understanding and to improve therapeutic outcomes.

Molecular biomarkers in prostate cancer tumorigenesis and clinical relevance

Prostate cancer (PCa) is the second most frequent type of cancer in men and assessing circulating tumor cells (CTCs) by liquid biopsy is a promising tool to help in cancer early detection, staging, risk of recurrence evaluation, treatment prediction and monitoring. Blood-based liquid biopsy approaches enable the enrichment, detection and characterization of CTCs by biomarker analysis. Hence, comprehending the molecular markers, their role on each stage of cancer development and progression is essential to provide information that can help in future implementation of these biomarkers in clinical assistance. In this review, we studied the molecular markers most associated with PCa CTCs to better understand their function on tumorigenesis and metastatic cascade, the methodologies utilized to analyze these biomarkers and their clinical significance, in order to summarize the available information to guide researchers in their investigations, new hypothesis formulation and target choice for the development of new diagnostic and treatment tools.

Systematic review and integrated analysis of prognostic gene signatures for prostate cancer patients

Prostate cancer (PC) is one of the most common cancers in men and becoming the second leading cause of cancer fatalities. At present, the lack of effective strategies for prognosis of PC patients is still a problem to be solved. Therefore, it is significant to identify potential gene signatures for PC patients' prognosis. Here, we summarized 71 different prognostic gene signatures for PC and concluded 3 strategies for signature construction after extensive investigation. In addition, 14 genes frequently appeared in 71 different gene signatures, which enriched in mitotic and cell cycle. This review provides extensive understanding and integrated analysis of current prognostic signatures of PC, which may help researchers to construct gene signatures of PC and guide future clinical treatment.

Microfluidic-Assisted CTC Isolation and In Situ Monitoring Using Smart Magnetic Microgels

Capturing rare disease-associated biomarkers from body fluids can offer an early-stage diagnosis of different cancers. Circulating tumor cells (CTCs) are one of the major cancer biomarkers that provide insightful information about the cancer metastasis prognosis and disease progression. The most common clinical solutions for quantifying CTCs rely on the immunomagnetic separation of cells in whole blood. Microfluidic systems that perform magnetic particle separation have reported promising outcomes in this context, however, most of them suffer from limited efficiency due to the low magnetic force generated which is insufficient to trap cells in a defined position within microchannels. In this work, a novel method for making soft micromagnet patterns with optimized geometry and magnetic material is introduced. This technology is integrated into a bilayer microfluidic chip to localize an external magnetic field, consequently enhancing the capture efficiency (CE) of cancer cells labeled with the magnetic nano/hybrid microgels that are developed in the previous work. A combined numerical-experimental strategy is implemented to design the microfluidic device and optimize the capturing efficiency and to maximize the throughput. The proposed design enables high CE and purity of target cells and real-time time on-chip monitoring of their behavior. The strategy introduced in this paper offers a simple and low-cost yet robust opportunity for early-stage diagnosis and monitoring of cancer-associated biomarkers.

Prospective assessment of AR splice variant and multi-biomarker expression on circulating tumor cells of mCRPC patients undergoing androgen receptor targeted agents: interim analysis of PRIMERA trial (NCT04188275)

Circulating tumor cells detection and ARV7 expression are associated with worse clinical outcomes in metastatic Castration-Resistant Prostate Cancer (mCRPC) undergoing Androgen Receptor Targeted Agents. ARFL, PSMA and PSA may help to refine prognostic models. In our institution, a prospective observational trial testing CTC detection in mCPRC undergoing I line ARTA therapy terminated the planned enrollment in 2020. Here, we present a pre-planned interim analysis with 18 months of median follow-up. RT-qPCR was used to determine the CTC expression of PSA, PSMA, AR and ARV7 before starting ARTA. PSA-drop, Progression-Free and Overall Survival (PFS and OS) and their correlation with CTC detection were reported. Forty-four patients were included. CTC were detected in 43.2% of patients, of whom 8.94% expressed PSA, 15.78% showed ARV7, 63.15% and 73.68% displayed ARFL and PSMA, respectively. Biochemical response was significantly improved in CTC + vs CTC- patients, with median PSA-drop of 18.5 vs 2.5 ng/ml (p = 0.03). After a median follow-up of 18 months, 50% of patients progressed. PFS was significantly longer in CTC- patients (NR vs 16 months). Eight (18.2%) patients died, a non-significant trend in terms of OS was detected in favor of CTC- patients (NR vs 29 months, p = 0.05). AR, PSA and PSMA expression in CTC + had no significant impact on PSA-drop, PFS or OS. PRIMERA-trial confirmed the CTC detection predictive importance in mCRPC patients.

Clinical Applications of Liquid Biopsy in Prostate Cancer: From Screening to Predictive Biomarker

Prostate cancer (PC) remains the most common malignancy and the second most common cause of cancer death in men. As a result of highly variable biological behavior and development of resistance to available agents under therapeutic pressure, optimal management is often unclear. Traditional surgical biopsies, even when augmented by genomic studies, may fail to provide adequate guidance for clinical decisions as these can only provide a snapshot of a dynamic process. Additionally, surgical biopsies are cumbersome to perform repeatedly and often involve risk. Liquid biopsies (LB) are defined as the analysis of either corpuscular (circulating tumor cells, extracellular vesicles) or molecular (circulating DNA or RNA) tumor-derived material. LB could more precisely identify clinically relevant alterations that characterize the metastatic potential of tumors, predict response to specific treatments or actively monitor for the emergence of resistance. These tests can potentially be repeated as often as deemed necessary and can detect real-time response to treatment with minimal inconvenience to the patient. In the current review, we consider common clinical scenarios to describe available LB assays in PC as a platform to explore existing evidence for their use in guiding decision making and to discuss current limitations to their adoption in the clinic.

Circulating tumor cell gene expression and plasma AR gene copy number as biomarkers for castration-resistant prostate cancer patients treated with cabazitaxel

BACKGROUND

Cabazitaxel improves overall survival (OS) in metastatic castration-resistant prostate cancer (mCRPC) patients progressing after docetaxel. In this prospective study, we evaluated the prognostic role of CTC gene expression on cabazitaxel-treated patients and its association with plasma androgen receptor (AR) copy number (CN).

METHODS

Patients receiving cabazitaxel 20 or 25 mg/sqm for mCRPC were enrolled. Digital PCR was performed to assess plasma AR CN status. CTC enrichment was assessed using the AdnaTest EMT-2/StemCell kit. CTC expression analyses were performed for 17 genes. Data are expressed as hazard ratio (HR) or odds ratio (OR) and 95% CI.

RESULTS

Seventy-four patients were fully evaluable. CTC expression of AR-V7 (HR=2.52, 1.24-5.12, p=0.011), AKR1C3 (HR=2.01, 1.06-3.81, p=0.031), AR (HR=2.70, 1.46-5.01, p=0.002), EPCAM (HR=3.75, 2.10-6.71, p< 0.0001), PSMA (HR=2.09, 1.19-3.66, p=0.01), MDK (HR=3.35, 1.83-6.13, p< 0.0001), and HPRT1 (HR=2.46, 1.44-4.18, p=0.0009) was significantly associated with OS. ALDH1 (OR=5.50, 0.97-31.22, p=0.05), AR (OR=8.71, 2.32-32.25, p=0.001), EPCAM (OR=7.26, 1.47-35.73, p=0.015), PSMA (OR=3.86, 1.10-13.50, p=0.035), MDK (OR=6.84, 1.87-24.98, p=0.004), and HPRT1 (OR=7.41, 1.82-30.19, p=0.005) expression was associated with early PD. AR CN status was significantly correlated with AR-V7 (p=0.05), EPCAM (p=0.02), and MDK (p=0.002) expression. In multivariable model, EPCAM and HPRT1 CTC expression, plasma AR CN gain, ECOG PS=2, and liver metastases and PSA were independently associated with poorer OS. In patients treated with cabazitaxel 20 mg/sqm, median OS was shorter in AR-V7 positive than negative patients (6.6 versus 14 months, HR=3.46, 1.47-8.17], p=0.004).

CONCLUSIONS

Baseline CTC biomarkers may be prognosticators for cabazitaxel-treated mCRPC patients. Cabazitaxel at lower (20 mg/sqm) dose was associated with poorer outcomes in AR-V7 positive patients compared to AR-V7 negative patients in a post hoc subgroup analysis.

TRIAL REGISTRATION

Clinicaltrials.gov NCT03381326 . Retrospectively registered on 18 December 2017.

Perioperative Circulating Tumor Cells (CTCs), MCTCs, and CTC-White Blood Cells Detected by a Size-Based Platform Predict Prognosis in Renal Cell Carcinoma

To explore the clinical significance of the perioperative counts of circulating tumor cells (CTCs), mesenchymal CTCs (MCTCs), and CTC- white blood cells (WBCs) in renal cell carcinoma patients. A total of 131 patients with renal cancer who underwent operation excision from our hospital were enrolled. In addition, 20 patients with benign renal diseases were recruited as a control. Blood samples were collected from the 131 patients, before operation and 3 months after surgery. Samples were also obtained simultaneously from the control group. CanPatrol CTC detection technique was used to enrich and identify CTCs, MCTCs, and CTC-WBCs. All enrolled patients were T1-3N0M0. From these, 52 patients with renal cancer underwent radical resection, while other 79 patients underwent nephron-sparing surgery. The positive rate of CTC, MCTC, and CTC-WBC before surgery were 95.4% (125/131), 61.1% (80/131), and 11.5% (15/131), respectively. Preoperative total CTCs, MCTCs, or CTC-WBCs were poorly correlated with patients' parameters. Preoperative CTC, MCTC, or CTC-WBC showed no association with progression-free survival (PFS). In contrast, postoperative total CTCs (≥6), positive MCTCs, and positive CTC-WBCs significantly correlated with recurrence and metastasis. These results remained independent indicators for worse PFS. In addition, the increased CTC and MCTC count after surgery also correlated with unfavorable PFS. The detection of six or more total CTCs, MCTC, or CTC-WBCs in peripheral blood after surgery might help to identify a subset of patients that have higher recurrent risk than the overall population of patients with at different stages of renal cancer.

Multigene model for predicting metastatic prostate cancer using circulating tumor cells by microfluidic magnetophoresis

We aimed to isolate circulating tumor cells (CTCs) using a microfluidic technique with a novel lateral magnetophoretic microseparator. Prostate cancer–specific gene expressions were evaluated using mRNA from the isolated CTCs. A CTC‐based multigene model was then developed for identifying advanced prostate cancer. Peripheral blood samples were obtained from five healthy donors and patients with localized prostate cancer (26 cases), metastatic hormone‐sensitive prostate cancer (mHSPC, 10 cases), and metastatic castration‐resistant prostate cancer (mCRPC, 28 cases). CTC recovery rate and purity (enriched CTCs/total cells) were evaluated according to cancer stage. The areas under the curves of the six gene expressions were used to evaluate whether multigene models could identify mHSPC or mCRPC. The number of CTCs and their purity increased at more advanced cancer stages. In mHSPC/mCRPC cases, the specimens had an average of 27.5 CTCs/mL blood, which was 4.2 × higher than the isolation rate for localized disease. The CTC purity increased from 2.1% for localized disease to 3.8% for mHSPC and 6.7% for mCRPC, with increased CTC expression of the genes encoding prostate‐specific antigen (PSA), prostate‐specific membrane antigen (PSMA), and cytokeratin 19 (KRT19). All disease stages exhibited expression of the genes encoding androgen receptor (AR) and epithelial cell adhesion molecule (EpCAM), although expression of the AR‐V7 variant was relatively rare. Relative to each gene alone, the multigene model had better accuracy for predicting advanced prostate cancer. Our lateral magnetophoretic microseparator can be used for identifying prostate cancer biomarkers. In addition, CTC‐based genetic signatures may guide the early diagnosis of advanced prostate cancer.