Part II. Telomerase expression in cerebrospinal fluid specimens as an adjunct to cytologic diagnosis

SHP-1 promoter 2 methylation in cerebrospinal fluid for diagnosis of leptomeningeal epithelial-derived malignancy (carcinomatous meningitis)

Current diagnostic methods for leptomeningeal metastasis (LM) from epithelial-derived malignancy (EDM) have limited sensitivity. Here, we explored SHP-1 promoter 2 methylation (SHP1P2)-an epithelial-specific methylation marker previously proven as risk stratification and potential diagnostic marker in non-small cell lung cancer-for EDM with LM. We prospectively recruited 136 patients who were diagnosed EDM with LM (n = 25), EDM without LM (n = 14), non-EDM with LM (n = 8), and benign meningeal diseases (n = 89). The primary cancer sites for EDM with LM were lung (n = 17), breast (n = 5), and colon (n = 3). We performed quantitative analyses of cell-free (cfSHP1P2) and whole fraction (wSHP1P2) from cerebrospinal fluid (CSF); results were correlated with the clinicopathological data, including CSF cytology. Median cfSHP1P2 and wSHP1P2 were 3.08 [range: 0-163.5] and 9.35 [0.69-91.63] ng/ml, respectively, in EDM with LM; 0 [0-0.08] and 0.23 [0-7.84] ng/ml in EDM without LM; and were undetectable in most cases of benign meningeal diseases and non-EDM with LM. The cut-off values of 0.22 ng/ml for methylated cfSHP1P2 and 0.59 ng/ml for wSHP1P2 were the best to discriminate EDM with LM from EDM without LM (sensitivity: 79-100 %; specificity: 83-100 %), as well as from other benign conditions (sensitivity: 85-100 % specificity: 78-100 %). CSF cytology yielded 76 % sensitivity for diagnosing EDM with LM. Further validation of CSF SHP1P2 methylation detection as a role of adjunctive tool for LM from EDM should be interested based on our study.

Adenoviral vectors for prodrug activation-based gene therapy for cancer

Cancer cell heterogeneity is a common feature - both between patients diagnosed with the same cancer and within an individual patient's tumor - and leads to widely different response rates to cancer therapies and the potential for the emergence of drug resistance. Diverse therapeutic approaches have been developed to combat the complexity of cancer, including individual treatment modalities designed to target tumor heterogeneity. This review discusses adenoviral vectors and how they can be modified to replicate in a cancer-specific manner and deliver therapeutic genes under multi-tiered regulation to target tumor heterogeneity, including heterogeneity associated with cancer stem cell-like subpopulations. Strategies that allow for combination of prodrug-activation gene therapy with a novel replication-conditional, heterogeneous tumor-targeting adenovirus are discussed, as are the benefits of using adenoviral vectors as tumor-targeting oncolytic vectors. While the anticancer activity of many adenoviral vectors has been well established in preclinical studies, only limited successes have been achieved in the clinic, indicating a need for further improvements in activity, specificity, tumor cell delivery and avoidance of immunogenicity.

Neoplastic meningitis from solid tumors: new diagnostic and therapeutic approaches

Neoplastic meningitis is a result of the spread of malignant cells to the leptomeninges and subarachnoid space and their dissemination within the cerebrospinal fluid. This event occurs in 4%-15% of all patients with solid tumors and represents an important prognostic factor for poor survival. Neoplastic meningitis should be diagnosed in the early stages of disease to prevent important neurological deficits and to provide the most appropriate treatment. Despite new diagnostic approaches developed in recent years, such as positron emission tomography-computed tomography and new biological markers, the combination of magnetic resonance imaging without and with gadolinium enhancement and cytology still has the greatest diagnostic sensitivity. Recently, no new randomized studies comparing intrathecal (i.t.) with systemic treatment have been performed, yet there have been a few small phase II studies and case reports about new molecularly targeted substances whose successful i.t. or systemic application has been reported. Trastuzumab, gefitinib, and sorafenib are examples of possible future treatments for neoplastic meningitis, in order to better individualize therapy thus allowing better outcomes. In this review, we analyze the most recent and interesting developments on diagnostic and therapeutic approaches.

Detection of Meningeosis neoplastica by real-time quantitation of telomerase activity

BACKGROUND

Analysis of cerebrospinal fluid (CSF) to discriminate between benign and malignant conditions is of fundamental importance for the physician and the patient because of the differential therapeutic options and resulting morbidity and mortality. Most human tumours demonstrate increased telomerase activity (TA). Recent technical advances in the detection of TA allow for sensitive and specific detection within 4 h. Thus, the detection of TA is suitable for routine clinical testing.

METHODS

This study examines TA in cellular proteins in CSF from 111 patients compared to cytomorphological and laboratory examination.

RESULTS

A positive result for TA in cellular proteins of CSF was correlated significantly with Meningeosis neoplastica, but not with non-malignant conditions. Telomerase was not detected in CSF supernatant, despite positive results in cellular proteins from identical patients. Furthermore, a 48-h time delay during the pre-analytic processing is not critical for detection of TA detection in native CSF when stored at room temperature.

CONCLUSIONS

We conclude that TA is a promising marker for the detection of Meningeosis neoplastica and warrants further study.

Real-time quantitative polymerase chain reaction: a potential tool for genetic analysis in neuropathology

Since its introduction in the early- to mid-1980s, the polymerase chain reaction (PCR) has been modified and optimized for an increasing number of applications. Early on, the focus was on the amplification of a specific nucleic acid template into quantities amenable to identification and experimental manipulation. While this remains an important application, recent technology has allowed the use of PCR to accurately quantitate the amount of a specific nucleic acid template present in a complex sample. Rather than simply analyzing the final product amount following the course of sequential cycles of amplification, quantitative PCR allows one to measure the accumulation of PCR product during the course of the reaction ("real-time PCR"). Under the appropriate conditions the number of PCR cycles required for the accumulation of a specific amount of product (during the exponential phase of the reaction) is a reflection of the relative amount of nucleic acid template present in the sample under analysis. Real-time quantitative PCR allows one to analyze a relatively large number of samples in a short period of time, potentially allowing multiple markers to be applied on a sample within a time frame consistent with clinical settings. In this overview, we will highlight the uses of real-time quantitative PCR as a potential diagnostic tool in neuropathology, focusing on the analysis of CNS tumors.

Leptomeningeal metastases

LM is an increasingly common neurologic complication of cancer with variable clinical manifestations. Although there are no curative treatments, currently available therapies can preserve neurologic function and potentially improve quality of life. Further research into the mechanisms of leptomeningeal metastasis will elucidate molecular and cellular pathways that may allow identification of potential targets to interrupt this process early or to prevent this complication. Animal models are needed to further define the pathophysiology of LM and to provide an experimental system to test novel treatments [242-245]. There is an urgent need to develop new drug-based or radiation-based treatments for patients with LM. Randomized clinical trials are the appropriate study design to determine the efficacy of new treatments for LM. However, surrogate markers for response must be developed to facilitate the identification of effective regimens. Survival is not the optimal end point for such studies as most patients who develop this complication already have advanced, incurable cancer. Prevention of or delay in neurologic progression is one objective that has been utilized in recent randomized trials in patients with LM, and this end point deserves further attention. Although the development of LM represents a poor prognostic marker in patients with cancer it is important for physicians to recognize the symptoms and signs of the disease and establish the diagnosis as early in the disease course as possible. This may provide an opportunity for effective intervention that can improve quality of life, prevent further neurologic deterioration and, for a subset of patients, improve survival.

Telomerase and cancer: time to move from a promising target to a clinical reality

The past 25 years have seen unparalleled advances in our understanding of the molecular basis of cancer. As a result, novel molecular targets have been identified that provide great potential for the development of new cancer diagnostics and therapies. Four key features of cancer cells distinguish them from their normal counterparts: loss of cell-cycle regulation, loss of control over invasion and metastasis, failure of apoptotic mechanisms, and bypass of senescence. This review examines our understanding of the bypass of senescence and the process of immortalization during carcinogenesis. In addition, the realistic opportunities for telomerase in cancer diagnostics and the challenges faced in clinical trial design for telomerase therapeutics are discussed.

Telomerase is a highly sensitive and specific molecular marker in fine-needle aspirates of breast lesions

PURPOSE

Telomerase has been detected in a majority of human malignant tumors, making telomerase activity (TA) one key difference between mortal and immortal cells. In this study, we evaluated in blind-trial fashion the association of TA with cytologic and final clinical/pathologic diagnosis in fine-needle aspirates (FNAs) of breast lesions.

MATERIALS AND METHODS

In 172 FNAs, including 80 samples that were cytologically malignant, 18 that were atypical but not diagnostic for malignancy, and 74 that were cytologically benign, TA was determined by a modified nonradioactive telomeric repeat amplification protocol (TRAP) assay. Final diagnosis was made by pathologic examination of follow-up surgical material available for all the cytologically malignant samples, a majority of the cytologically atypical samples, and a portion of the cytologically benign samples.

RESULTS

TA was detected in 85 of 172 samples. Comparison of the cytologic and histologic diagnoses with TA showed that 80 of 87 samples from patients with breast cancer were telomerase-positive, resulting in a sensitivity of 92%. TA was found in four of five FNAs from carcinomas that were considered cytologically atypical but not diagnostic for malignancy. Eighty of 85 samples from patients with benign breast lesions were telomerase-negative, revealing a specificity of 94%. The five positive cases in this group were all fibroadenomas with low TA. Among the 18 cases with a cytologic diagnosis of atypia, there was a strong positive relationship between TRAP findings and histologic diagnosis.

CONCLUSION

The detection of TA in FNAs of breast lesions is a highly sensitive and specific marker of malignancy and may be used as an adjunct in cases with an equivocal cytologic diagnosis.