Application of a telomerase-based circulating tumor cell (CTC) assay in bladder cancer patients receiving postoperative radiation therapy: a case study

PD-L1+ CD49f+ CD133+ Circulating tumor cells predict outcome of patients with vulvar or cervical cancer after radio- and chemoradiotherapy

BACKGROUND

Monitoring individual therapy responses of patients with cancer represents a major clinical challenge providing the basis to early identify metastases and cancer relapse. We previously demonstrated that radio- or chemoradiotherapy affects the systemic cellular milieu of patients with vulvar or cervical cancer and creates individual post-therapeutic environments associated with cancer relapse. Circulating tumor cells (CTCs) in the systemic milieu are related to metastases and relapse; however, their quantitative and phenotypic characteristics during therapy of patients with vulvar and cervical cancer are still unknown.

METHODS

In this prospective, longitudinal study, we verified the presence of CTCs via immunofluorescence and systemically characterized CTCs by flow cytometry from the blood of 40 patients with vulvar and 115 patients with cervical cancer receiving surgery, adjuvant radiotherapy (aRT), chemoradiotherapy (aCRT) or primary chemoradiotherapy (pCRT) and linked the presence of different CTC subpopulations with individual outcome of disease.

RESULTS

Pre-therapeutic cytokeratin+ CD45- CTC numbers significantly correlated with tumor FIGO stages, lymph node metastases and relapse. While surgery only did not significantly alter CTC occurrence, aRT and aCRT as well as pCRT differentially decreased or increased CTCs in patients with both tumor entities compared to baseline levels. Therapy-mediated increased CTC numbers were directly linked with subsequent cancer recurrence on follow-up. Phenotypic characterization of CTCs revealed enhanced expression of the stem cell marker CD133 as well as the integrin α6 (CD49f) after aRT, aCRT and pCRT. Furthermore, the aRT, aCRT and pCRT cohorts exhibited increased proportions of Programmed Cell Death Protein Ligand (PD-L1) expressing cells among post-therapeutic CTCs. Notably, post-therapeutic PD-L1+ CD49f+ CD133+ numbers ≥ 5/ml in patients with vulvar cancer and ≥ 2/ml in patients with cervical cancer were associated with reduced recurrence-free survival on follow-up.

CONCLUSION

Our study unravels individual therapy-induced changes in CTC phenotypic characteristics and occurrence in the patients' blood and their association with cancer relapse. Our results may help to explain differences in the individual courses of disease of patients with vulvar and cervical cancer and suggest PD-L1, CD49f and CD133 as targets for immunotherapy in vulvar and cervical cancer.

Modernizing Neuro-Oncology: The Impact of Imaging, Liquid Biopsies, and AI on Diagnosis and Treatment

Advances in neuro-oncology have transformed the diagnosis and management of brain tumors, which are among the most challenging malignancies due to their high mortality rates and complex neurological effects. Despite advancements in surgery and chemoradiotherapy, the prognosis for glioblastoma multiforme (GBM) and brain metastases remains poor, underscoring the need for innovative diagnostic strategies. This review highlights recent advancements in imaging techniques, liquid biopsies, and artificial intelligence (AI) applications addressing current diagnostic challenges. Advanced imaging techniques, including diffusion tensor imaging (DTI) and magnetic resonance spectroscopy (MRS), improve the differentiation of tumor progression from treatment-related changes. Additionally, novel positron emission tomography (PET) radiotracers, such as 18F-fluoropivalate, 18F-fluoroethyltyrosine, and 18F-fluluciclovine, facilitate metabolic profiling of high-grade gliomas. Liquid biopsy, a minimally invasive technique, enables real-time monitoring of biomarkers such as circulating tumor DNA (ctDNA), extracellular vesicles (EVs), circulating tumor cells (CTCs), and tumor-educated platelets (TEPs), enhancing diagnostic precision. AI-driven algorithms, such as convolutional neural networks, integrate diagnostic tools to improve accuracy, reduce interobserver variability, and accelerate clinical decision-making. These innovations advance personalized neuro-oncological care, offering new opportunities to improve outcomes for patients with central nervous system tumors. We advocate for future research integrating these tools into clinical workflows, addressing accessibility challenges, and standardizing methodologies to ensure broad applicability in neuro-oncology.

High-Fidelity Sensitive Tracing Circulating Tumor Cell Telomerase Activity

Dynamic tracing of intracellular telomerase activity plays a crucial role in cancer cell recognition and correspondingly in earlier cancer diagnosis and personalized precision therapy. However, due to the complexity of the required reaction system and insufficient loading of reaction components into cells, achieving a high-fidelity determination of telomerase activity is still a challenge. Herein, an Aptamer-Liposome mediated Telomerase activated poly-Molecular beacon Arborescent Nanoassembly(ALTMAN) approach was described for direct high-fidelity visualization of telomerase activity. Briefly, intracellular telomerase activates molecular beacons, causing their hairpin structures to unfold and produce fluorescent signals. Furthermore, multiple molecular beacons can self-assemble, forming arborescent nanostructures and leading to exponential amplification of fluorescent signals. Integrating the enzyme-free isothermal signal amplification successfully increased the sensitivity and reduced interference by leveraging the skillful design of the molecular beacon and the extension of the telomerase-activated TTAGGG repeat sequence. The proposed approach enabled ultrasensitive visualization of activated telomerase exclusively with a prominent detection limit of 2 cells·μL-1 and realized real-time imaging of telomerase activity in living cancer cells including blood samples from breast cancer patients and urine samples from bladder cancer patients. This approach opens an avenue for establishing a telomerase activity determination and in situ monitoring technique that can facilitate both telomerase fundamental biological studies and cancer diagnostics.

Immune determinants of the pre-metastatic niche

Primary tumors actively and specifically prime pre-metastatic niches (PMNs), the future sites of organotropic metastasis, preparing these distant microenvironments for disseminated tumor cell arrival. While initial studies of the PMN focused on extracellular matrix alterations and stromal reprogramming, it is increasingly clear that the far-reaching effects of tumors are in great part achieved through systemic and local PMN immunosuppression. Here, we discuss recent advances in our understanding of the tumor immune microenvironment and provide a comprehensive overview of the immune determinants of the PMN's spatiotemporal evolution. Moreover, we depict the PMN immune landscape, based on functional pre-clinical studies as well as mounting clinical evidence, and the dynamic, reciprocal crosstalk with systemic changes imposed by cancer progression. Finally, we outline emerging therapeutic approaches that alter the dynamics of the interactions driving PMN formation and reverse immunosuppression programs in the PMN ensuring early anti-tumor immune responses.

A Novel Liquid Biopsy Strategy to Detect Small Amounts of Cancer Cells Using Cancer-Specific Replication Adenoviruses

Circulating tumor cells (CTCs) are a promising source of clinical and biological cancer information and can be a material for liquid biopsy. However, detecting and capturing these cells remains a challenge. Various biological factors (e.g., cell surface proteins, cell size, deformability, or dielectrophoresis) have been applied to detect CTCs. Cancer cells dramatically change their characteristics during tumorigenesis and metastasis. Hence, defining a cell as malignant using such a parameter is difficult. Moreover, immortality is an essential characteristic of cancer cells. Telomerase elongates telomeres and plays a critical role in cellular immortality and is specifically activated in cancer cells. Thus, the activation of telomerase can be a good fingerprint for cancer cells. Telomerase cannot be recognized by antibodies in living cells because it is a nuclear enzyme. Therefore, telomerase-specific replication adenovirus, which expresses the green fluorescent protein, has been applied to detect CTCs. This review explores the overview of this novel technology and its application in gynecological cancers.

Circulating Tumor Cells Are Associated with Recurrent Disease in Patients with Early-Stage Non-Small Cell Lung Cancer Treated with Stereotactic Body Radiotherapy

PURPOSE

Although stereotactic body radiotherapy (SBRT) is effective in early-stage non-small cell lung cancer (NSCLC), approximately 10%-15% of patients will fail regionally and 20%-25% distantly. We evaluate a novel circulating tumor cell (CTC) assay as a prognostic marker for increased risk of recurrence following SBRT.

EXPERIMENTAL DESIGN

Ninety-two subjects (median age, 71 years) with T1a (64%), T1b (23%), or T2a (13%) stage I NSCLC treated with SBRT were prospectively enrolled. CTCs were enumerated by utilizing a GFP-expressing adenoviral probe that detects elevated telomerase activity in cancer cells. Samples were obtained before, during, and serially up to 24 months after treatment. SBRT was delivered to a median dose of 50 Gy (range, 40-60 Gy), mostly commonly in four to five fractions (92%).

RESULTS

Thirty-eight of 92 subjects (41%) had a positive CTC test prior to SBRT. A cutoff of ≥5 CTCs/mL before treatment defined favorable (n = 78) and unfavorable (n = 14) prognostic groups. Increased risk of nodal (P = 0.04) and distant (P = 0.03) failure was observed in the unfavorable group. Within 3 months following SBRT, CTCs continued to be detected in 10 of 35 (29%) subjects. Persistent detection of CTCs was associated with increased risk of distant failure (P = 0.04) and trended toward increased regional (P = 0.08) and local failure (P = 0.16).

CONCLUSIONS

Higher pretreatment CTCs and persistence of CTCs posttreatment is significantly associated with increased risk of recurrence outside the targeted treatment site. This suggests that CTC analysis may potentially identify patients at higher risk for regional or distant recurrences and who may benefit from either systemic therapy and/or timely locoregional salvage treatment.

Irradiation induces cancer lung metastasis through activation of the cGAS-STING-CCL5 pathway in mesenchymal stromal cells

Emerging evidence indicates that mesenchymal stromal cells (MSCs) have an important role in cancer metastasis. Although tumor microenvironment, which includes MSCs and immune cells, can be altered by ionizing radiation (IR), whether irradiation can promote metastasis through MSCs remains unclear. Using the lung colonization model of transplanted 4T1 breast cancer cells, we found an increased lung metastasis in mice exposed to ionizing radiation, even when the thorax was shielded during whole-body irradiation. This radiation-induced lung metastasis can be replicated using irradiated MSCs. cGAS-STING signaling pathway was found to be activated in MSCs, accompanied by upregulation of type I interferon-related genes, including chemokine CCL5. Disruption of cGAS-STING signaling in MSCs abolished their pro-metastatic effect. Deletion of CCL5 in MSCs also abrogated the pro-metastatic effect endowed by IR. Furthermore, we showed that the lung pro-metastatic effect of irradiated MSCs required the presence of macrophages. Our results indicate that radiation-induced alterations in distant mesenchymal stromal cells facilitate cancer metastasis.

Bone and Soft-Tissue Sarcoma: A New Target for Telomerase-Specific Oncolytic Virotherapy

Adenovirus serotype 5 (Ad5) is widely and frequently used as a virus vector in cancer gene therapy and oncolytic virotherapy. Oncolytic virotherapy is a novel antitumor treatment for inducing lytic cell death in tumor cells without affecting normal cells. Based on the Ad5 genome, we have generated three types of telomerase-specific replication-competent oncolytic adenoviruses: OBP-301 (Telomelysin), green fluorescent protein (GFP)-expressing OBP-401 (TelomeScan), and tumor suppressor p53-armed OBP-702. These viruses drive the expression of the adenoviral E1A and E1B genes under the control of the hTERT (human telomerase reverse transcriptase-encoding gene) promoter, providing tumor-specific virus replication. This review focuses on the therapeutic potential of three hTERT promoter-driven oncolytic adenoviruses against bone and soft-tissue sarcoma cells with telomerase activity. OBP-301 induces the antitumor effect in monotherapy or combination therapy with chemotherapeutic drugs via induction of autophagy and apoptosis. OBP-401 enables visualization of sarcoma cells within normal tissues by serving as a tumor-specific labeling reagent for fluorescence-guided surgery via induction of GFP expression. OBP-702 exhibits a profound antitumor effect in OBP-301-resistant sarcoma cells via activation of the p53 signaling pathway. Taken together, telomerase-specific oncolytic adenoviruses are promising antitumor reagents that are expected to provide novel therapeutic options for the treatment of bone and soft-tissue sarcomas.

Telomerase-specific attenuated viruses, a definitive strategy or just one more in circulating tumor cells detection anthology?

The quantification and isolation of Circulating Tumor Cells (CTC) is being the battleground during last years. There are many groups that are investing economic resources in trying to solve this jigsaw. Technological platforms based on different proofs of concept have been developed achieving in some cases excellent results despite not having been able to detect the total compute of the patient's CTC population. The handicap of this matter has been the lack of universal markers. Several years have gone so that in detection of CTC is take into account a basic characteristic that possesses the most of tumor cells, the loss of inactivation of the enzyme telomerase. Gene therapy has been combined with telomerase activity concept for develop a molecular tool that makes it possible to identify CTC: Telomerase-specific replication-selective viruses. This review includes for the first time all the scientific studies that have been published to date with this advanced technology. Furthermore, it describes the role in the diagnosis and prognosis that Telomerase-specific attenuated viruses have been playing in cancer patients study during this last decade.

The Significance of Circulating Tumour Cells in the Clinic

BACKGROUND

Despite the hype about circulating tumour cells (CTCs) in the early 2000s and their potential in the diagnosis of metastasis, in recent years, the hope for personalised cancer management relies more on circulating tumour (ct)DNA that has entered the clinic in a much more efficient way. So far, approved methods for CTCs in the clinic only provide the counting of CTCs, which enables monitoring of the progression of metastatic breast, prostate, and colorectal cancer patients with therapy. Approved methods for ctDNA facilitate the analysis of specific mutations in lung cancer, thereby providing indications for potentially successful treatments. This situation inclined the balance towards molecular analysis in liquid biopsy, leveraged by new technologies and companies providing broader mutation and gene expression analysis towards the early diagnosis of cancer.

STUDY DESIGN

We conducted a search for the studies published to date that provide details about the significance of CTCs in the clinic.

RESULTS

Many studies and clinical trials have demonstrated the potential of CTCs in patient screening, early diagnosis, therapy resistance, and patient prognosis.

CONCLUSIONS

Large multi-centre studies are still needed to formally validate the clinical relevance of CTCs. Meticulous design of the clinical trials is a crucial point to achieve this long-sought objective.

The Emerging Role of Gas Plasma in Oncotherapy

Atmospheric pressure gas plasmas are emerging as a promising treatment in cancer that can supplement the existing set of treatment modalities and, when combined with other therapies, enhance their selectivity and efficacy against resistant cancers. With further optimisation in production and administration of plasma treatment, plasma-enabled therapy has a strong potential to mature as a tool for selectively curing highly resistant solid tumours. Although intense preclinical studies have been conducted to exploit the unique traits of plasma as an oncotherapy, few clinical studies are underway. This review identifies types of cancers and patient groups that most likely benefit from plasma oncotherapy, to introduce clinical practitioners to plasma therapy and accelerate the speed of translating plasma for cancer control in clinics.

Circulating Tumor Cell Assessment in Presumed Early Stage Non-Small Cell Lung Cancer Patients Treated with Stereotactic Body Radiation Therapy: A Prospective Pilot Study

PURPOSE

In patients treated with stereotactic body radiation therapy (SBRT) for presumed early stage non-small cell lung cancer (NSCLC), detection and monitoring of circulating tumor cells (CTCs) may be useful for assessing treatment response safely and noninvasively. No published reports of CTC trends in this patient population exist to date.

METHODS AND MATERIALS

Patients with clinically diagnosed stage I NSCLC treated with SBRT were eligible for this institutional review board-approved prospective clinical trial. Peripheral blood samples were assayed for CTCs via a green fluorescent protein-expressing adenoviral probe. CTC positivity was defined as 1.3 green fluorescent protein-positive cells/mL of collected blood. Samples were obtained before (pre-radiation therapy [RT]), during, and after SBRT (post-RT; months 1, 3, 6, 12, 18, and 24). SBRT was delivered in ≤5 fractions (median dose of 50 Gy in 12.5 Gy fractions) to a biological equivalent dose of ≥100 Gy in all cases.

RESULTS

Forty-eight consecutive patients (T1a [73%], T1b [21%], and T2a [6%]) were enrolled. Median follow-up was 14.2 months. Twenty patients (42%) had a positive CTC level pre-RT, with a median CTC count of 4.2 CTCs per mL (interquartile range [IQR], 2.2-18.7). Of these 20 patients, 17 had evaluable post-RT CTC evaluations showing reduced CTC counts at 1 month (median, 0.2; IQR, 0.1-0.8) and 3 months (median, 0.6; IQR, 0-1.1). Three of these 17 patients experienced disease progression at a median of 19.9 months; all 3 experienced ≥1 positive post-RT CTC test predating clinical progression by a median of 16 months (range, 2-17 months). In contrast, among patients presenting with CTC-detectable disease and for whom all post-RT CTC tests were negative, none experienced recurrence or progression.

CONCLUSIONS

CTC monitoring after SBRT for presumed early stage NSCLC may give lead-time notice of disease recurrence or progression. Conversely, negative CTC counts after treatment may provide reassurance of disease control. CTC analysis is thus potentially useful in enhancing clinical diagnosis and follow-up in this population.

Combined cell surface carbonic anhydrase 9 and CD147 antigens enable high-efficiency capture of circulating tumor cells in clear cell renal cell carcinoma patients

Circulating tumor cells (CTCs) have emerged as promising tools for noninvasive cancer detection and prognosis. Most conventional approaches for capturing CTCs use an EpCAM-based enrichment strategy, which does not work well in cancers that show low or no expression of EpCAM, such as renal cell carcinoma (RCC). In this study, we developed a new set of cell surface markers including CA9 and CD147 as alternative CTC-capture antigens specifically designed for RCC patients. We showed that the expression of both CA9 and CD147 was prevalent in a RCC patient cohort (n=70) by immunohistochemical analysis, with both molecules in combination covering 97.1% of cases. The NanoVelcro platform combined with CA9-/CD147-capture antibodies demonstrated significantly higher efficiency for capturing both CTC-mimicking renal cancer cells and RCC CTCs in peripheral blood, compared to the conventional EpCAM-based method. Using immunofluorescence cytological validation at the single-cell level, we were able to identify bona fide CTCs in RCC patient blood following the well-accepted criteria in our CTC-capture system. We further demonstrated a significant association of CTC numbers as well as the CTC expression status of Vimentin, a mesenchymal marker, with disease progression, including pathologic features and clinical staging. These results provide new insights into developing novel, effective targets/approaches for capturing CTCs, making CTCs a valuable tool for improved cancer detection, prognosis and treatment in RCC.

The current status and clinical value of circulating tumor cells and circulating cell-free tumor DNA in bladder cancer

Urothelial carcinoma of the bladder (UCB) is a complex disease, which is associated with highly aggressive tumor biologic behavior, especially in patients with muscle-invasive and advanced tumors. Despite multimodal therapy options including surgery, radiotherapy and chemotherapy, UCB patients frequently suffer from poor clinical outcome. Indeed, the potential of diverse opportunities for modern targeted therapies is not sufficiently elucidated in UCB yet. To improve the suboptimal treatment situation in UCB, biomarkers are urgently needed that help detecting minimal residual disease (MRD), predicting therapy response and subsequently prognosis as well as enabling patient stratification for further therapies and therapy monitoring, respectively. To date, decision making regarding treatment planning is mainly based on histopathologic evaluation of biopsies predominantly derived from the primary tumors and on clinical staging. However, both methods are imperfect for sufficient outcome prediction. During disease progression, individual disseminated tumor cells and consecutively metastases can acquire characteristics that do not match those of the corresponding primary tumors, and often are only hardly assessable for further evaluation. Therefore, during recent years, strong efforts were directed to establish non-invasive biomarkers from liquid biopsies. Urine cytology and serum tumor markers have been established for diagnostic purposes, but are still insufficient as universal biomarkers for decision-making and treatment of UCB patients. To date, the clinical relevance of various newly established blood-based biomarkers comprising circulating tumor cells (CTCs), circulating cell-free nucleic acids or tumor-educated platelets is being tested in cancer patients. In this review we summarize the current state and clinical application of CTCs and circulating cell-free tumor DNA originating from blood as biomarkers in patients with different UCB stages.

Novel plasma telomerase detection method to improve cancer diagnostic assessment

Background

The activity levels of telomerase and its mRNA have been found to be more diagnostically sensitive than cytological results in many cancerous tissues and correlate well with the clinical disease stage. Currently, there are several methods of detecting telomerase in tissues and in blood. The most commonly used method is a conventional quantitative real-time polymerase chain reaction (PCR) which is time and labor exhausting.

Methods

We have developed a simple and innovative blood test method that allows us to diagnose cancer and relapsed cancer in a cost- and time -effective manner. We had evaluated our novel method in two populations: 1) in vivo in three mice with pancreatic ductal adenocarcinoma (PDAC) versus one control mouse and 2) clinically in 30 cancer patients versus 10 individuals without cancer. We compared our novel method with the old conventional method. At least one sample was obtained from each patient included in the study.

Results

The novel method substantially increased the sensitivity (from 37% to 77%, p<0.001) and negative predictive value (from 32% to 56%, p = 0.005) of the telomerase test for all cancer patients (those who were substantially treated and those who were not). There was no significant difference in telomerase activity between cancer patients and healthy volunteers using the conventional method (p = 0.13), whereas there was a significant difference using the novel method (p = 0.001).

Conclusion

Conventional method shows no significant difference in telomerase activity between cancer patients and healthy volunteers (p = 0.13), whereas there was a significant difference using the novel method (p = 0.001).

Effects of radiation on metastasis and tumor cell migration

It is well known that tumor cells migrate from the primary lesion to distant sites to form metastases and that these lesions limit patient outcome in a majority of cases. However, the extent to which radiation influences this process and to which migration in turn alters radiation response remains controversial. There are preclinical and clinical reports showing that focal radiotherapy can both increase the development of distant metastasis, as well as that it can induce the regression of established metastases through the abscopal effect. More recently, preclinical studies have suggested that radiation can attract migrating tumor cells and may, thereby, facilitate tumor recurrence. In this review, we summarize these phenomena and their potential mechanisms of action, and evaluate their significance for modern radiation therapy strategies.

Circulating Tumor Cells, DNA, and mRNA: Potential for Clinical Utility in Patients With Melanoma

: Circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), and messenger RNA (mRNA), collectively termed circulating tumor products (CTPs), represent areas of immense interest from scientists' and clinicians' perspectives. In melanoma, CTP analysis may have clinical utility in many areas, from screening and diagnosis to clinical decision-making aids, as surveillance biomarkers or sources of real-time genetic or molecular characterization. In addition, CTP analysis can be useful in the discovery of new biomarkers, patterns of treatment resistance, and mechanisms of metastasis development. Here, we compare and contrast CTCs, ctDNA, and mRNA, review the extent of translational evidence to date, and discuss how future studies involving both scientists and clinicians can help to further develop this tool for the benefit of melanoma patients.

IMPLICATIONS FOR PRACTICE

Scientific advancement has enabled the rapid development of tools to analyze circulating tumor cells, tumor DNA, and messenger RNA, collectively termed circulating tumor products (CTPs). A variety of techniques have emerged to detect and characterize melanoma CTPs; however, only a fraction has been applied to human subjects. This review summarizes the available human data that investigate clinical utility of CTP in cancer screening, melanoma diagnosis, prognosis, prediction, and genetic or molecular characterization. It provides a rationale for how CTPs may be useful for future research and discusses how clinicians can be involved in developing this exciting new technology.

Targeting Artificial Tumor Stromal Targets for Molecular Imaging of Tumor Vascular Hypoxia

Developed and tested for many years, a variety of tumor hypoxia detection methods have been inconsistent in their ability to predict treatment outcomes or monitor treatment efficacy, limiting their present prognostic capability. These variable results might stem from the fact that these approaches are based on inherently wide-ranging global tumor oxygenation levels based on uncertain influences of necrotic regions present in most solid tumors. Here, we have developed a novel non-invasive and specific method for tumor vessel hypoxia detection, as hypoxemia (vascular hypoxia) has been implicated as a key driver of malignant progression, therapy resistance and metastasis. This method is based on high-frequency ultrasound imaging of α-pimonidazole targeted-microbubbles to the exogenously administered hypoxia marker pimonidazole. The degree of tumor vessel hypoxia was assessed in three mouse models of mammary gland carcinoma (4T1, SCK and MMTV-Wnt-1) and amassed up to 20% of the tumor vasculature. In the 4T1 mammary gland carcinoma model, the signal strength of α-pimonidazole targeted-microbubbles was on average 8-fold fold higher in tumors of pimonidazole-injected mice than in non-pimonidazole injected tumor bearing mice or non-targeted microbubbles in pimonidazole-injected tumor bearing mice. Overall, this provides proof of principle for generating and targeting artificial antigens able to be ‘created’ on-demand under tumor specific microenvironmental conditions, providing translational diagnostic, therapeutic and treatment planning potential in cancer and other hypoxia-associated diseases or conditions.

A novel approach for the detection and genetic analysis of live melanoma circulating tumor cells

Background

Circulating tumor cell (CTC) detection and genetic analysis may complement currently available disease assessments in patients with melanoma to improve risk stratification and monitoring. We therefore sought to establish the feasibility of a telomerase-based assay for detecting and isolating live melanoma CTCs.

Methods

The telomerase-based CTC assay utilizes an adenoviral vector that, in the presence of elevated human telomerase activity, drives the amplification of green fluorescent protein. Tumor cells are then identified via an image processing system. The protocol was tested on melanoma cells in culture or spiked into control blood, and on samples from patients with metastatic melanoma. Genetic analysis of the isolated melanoma CTCs was then performed for BRAF mutation status.

Results

The adenoviral vector was effective for all melanoma cell lines tested with sensitivity of 88.7% (95%CI 85.6-90.4%) and specificity of 99.9% (95%CI 99.8-99.9%). In a pilot trial of patients with metastatic disease, CTCs were identified in 9 of 10 patients, with a mean of 6.0 CTCs/mL. At a cutoff of 1.1 CTCs/mL, the telomerase-based assay exhibits test performance of 90.0% sensitivity and 91.7% specificity. BRAF mutation analysis of melanoma cells isolated from culture or spiked control blood, or from pilot patient samples was found to match the known BRAF mutation status of the cell lines and primary tumors.

Conclusions

To our knowledge, this is the first report of a telomerase-based assay effective for detecting and isolating live melanoma CTCs. These promising findings support further studies, including towards integrating into the management of patients with melanoma receiving multimodality therapy.

Tracking viable circulating tumor cells (CTCs) in the peripheral blood of non-small cell lung cancer (NSCLC) patients undergoing definitive radiation therapy: pilot study results

BACKGROUND

Assays identifying circulating tumor cells (CTCs) allow noninvasive and sequential monitoring of the status of primary or metastatic tumors, potentially yielding clinically useful information. However, to the authors' knowledge, the effect of radiation therapy (RT) on CTCs in patients with non-small cell lung cancer (NSCLC) has not been previously explored.

METHODS

This report describes results from a pilot study of 30 patients with NSCLC who received RT. Peripheral blood samples obtained from these patients were assayed for CTCs using an assay that identified live cells using an adenoviral probe that detected the elevated telomerase activity present in almost all cancer cells, but not in normal cells, and the validity of the assay was confirmed with secondary tumor-specific markers. Patients were assayed before initiation of RT (pre-RT), during the RT course, and/or after the completion of RT (post-RT).

RESULTS

The assay successfully detected CTCs in the majority of patients, including 65% of patients before the start of RT, and in patients with both epidermal growth factor receptor wild-type and mutation-positive tumors. The median CTC counts in patients before RT was 9.1 CTCs per mL (range, undetectable to 571 CTCs per mL) and was significantly higher than the average post-RT count of 0.6 CTCs per mL (range, undetectable to 1.8 CTCs per mL; P<.001). Sequential CTC counts were available in a subset of patients and demonstrated decreases after RT, except for 1 patient who subsequently developed distant failure.

CONCLUSIONS

The current pilot data suggest that CTC counts appear to reflect response to RT in patients with localized NSCLC. On the basis of these promising results, the authors have launched a more comprehensive and detailed clinical trial.