Prognostic immunohistologic markers in human tumors: why are so few used in clinical practice?

Differential expression of miRNAs as biomarkers for predicting the outcomes of diffuse large B-cell lymphoma patients

Background: Diffuse large B-cell lymphoma (DLBCL) used to be defined as germinal center B-like and non-germinal center B-like subtypes, associated with different prognoses, but the conventional classification does not meet the needs of clinical practice because of DLBCL heterogeneity, a problem that might be improved by selection of miRNAs as biomarkers.

Methods: Twelve patients with DLBCLs were used to screen out the aberrant miRNA profile using miRNA microarray technology in two patient subtypes (six germinal center B-like and six non-germinal center B-like patients). The potential biomarkers were further analyzed using the quantitative reverse transcription-polymerase chain reaction method in 95 DLBCL patients to investigate relationships among expression levels of potent miRNA, clinicopathological features and survival rates of patients.

Results: miR-208a-5p, miR-296-5p and miR-1304-5p were screened as potential biomarkers. miR-208a-5p and miR-296-5p were shown to be associated with better survival of patients after Kaplan–Meier analysis, whereas miR-1304-5p overexpression indicated a poor survival prognosis independent of the DLBCL subtype. In addition, changes of miR-296-5p and miR-1304-5p expression, the International Prognostic Index (IPI) status and the age of patients were all independent indicators for DLBCL prognosis. We also found that high miR-208a-5p expression led to better outcomes in DLBCL patients with similar IPI scores; however high miR-1304-5p expression tended to indicate the opposite.

Conclusions: MiR-208a-5p, miR-296-5p and miR-1304-5p levels might be potential biomarkers for the prediction of the prognosis of DLBCL patients.

Lack of association of tumor-associated macrophages with clinical outcome in patients with classical Hodgkin's lymphoma

BACKGROUND

A recent study demonstrated that an increased number of CD68+ macrophages were correlated with primary treatment failure, shortened progression-free survival (PFS) and disease-specific survival (DSS) in patients with classical Hodgkin's lymphoma (cHL).

PATIENTS AND METHODS

The aim of the present study was to verify the relationship between the number of CD68+ and CD163+ macrophages with clinical outcomes in a cohort of 265 well-characterized patients with cHL treated uniformly with the standard doxorubicin, bleomycin, vinblastine and dacarbazine chemotherapy regimen. Two pairs of hematopathologists carried out independent pathological evaluations of tissue microarray slides.

RESULTS

There were no associations between clinical characteristics and the expression of CD68 or CD163. However, higher levels of CD68 and CD163 expression were correlated with the presence of Epstein-Barr virus-positive Hodgkin tumor cells (P = 0.01 and 0.037, respectively). The expression of CD68 or CD163 was not associated with either the PFS or the DSS.

CONCLUSION

CD68 and CD163 expression require further evaluation before their use can be recommended for prognostic stratification of patients with cHL.

MicroRNAs are independent predictors of outcome in diffuse large B-cell lymphoma patients treated with R-CHOP

PURPOSE

Diffuse large B-cell lymphoma (DLBCL) heterogeneity has prompted investigations for new biomarkers that can accurately predict survival. A previously reported 6-gene model combined with the International Prognostic Index (IPI) could predict patients' outcome. However, even these predictors are not capable of unambiguously identifying outcome, suggesting that additional biomarkers might improve their predictive power.

EXPERIMENTAL DESIGN

We studied expression of 11 microRNAs (miRNA) that had previously been reported to have variable expression in DLBCL tumors. We measured the expression of each miRNA by quantitative real-time PCR analyses in 176 samples from uniformly treated DLBCL patients and correlated the results to survival.

RESULTS

In a univariate analysis, the expression of miR-18a correlated with overall survival (OS), whereas the expression of miR-181a and miR-222 correlated with progression-free survival (PFS). A multivariate Cox regression analysis including the IPI, the 6-gene model-derived mortality predictor score and expression of the miR-18a, miR-181a, and miR-222, revealed that all variables were independent predictors of survival except the expression of miR-222 for OS and the expression of miR-18a for PFS.

CONCLUSION

The expression of specific miRNAs may be useful for DLBCL survival prediction and their role in the pathogenesis of this disease should be examined further.

Tumor-Specific Diagnostic Marker for Transmissible Facial Tumors of Tasmanian Devils

Devil facial tumor disease (DFTD) is a transmissible neoplasm that is threatening the survival of the Tasmanian devil. Genetic analyses have indicated that the disease is a peripheral nerve sheath neoplasm of Schwann cell origin. DFTD cells express genes characteristic of myelinating Schwann cells, and periaxin, a Schwann cell protein, has been proposed as a marker for the disease. Diagnosis of DFTD is currently based on histopathology, cytogenetics, and clinical appearance of the disease in affected animals. As devils are susceptible to a variety of neoplastic processes, a specific diagnostic test is required to differentiate DFTD from cancers of similar morphological appearance. This study presents a thorough examination of the expression of a set of Schwann cell and other neural crest markers in DFTD tumors and normal devil tissues. Samples from 20 primary DFTD tumors and 10 DFTD metastases were evaluated by immunohistochemistry for the expression of periaxin, S100 protein, peripheral myelin protein 22, nerve growth factor receptor, nestin, neuron specific enolase, chromogranin A, and myelin basic protein. Of these, periaxin was confirmed as the most sensitive and specific marker, labeling the majority of DFTD cells in 100% of primary DFTD tumors and DFTD metastases. In normal tissues, periaxin showed specificity for Schwann cells in peripheral nerve bundles. This marker was then evaluated in cultured devil Schwann cells, DFTD cell lines, and xenografted DFTD tumors. Periaxin expression was maintained in all these models, validating its utility as a diagnostic marker for the disease.

A Bayesian derived network of breast pathology co-occurrence

In this paper, we present the validation and verification of a machine-learning based Bayesian network of breast pathology co-occurrence. The present/not present occurrences of 29 common breast pathologies from 1631 pathology reports were used to build the network. All pathology reports were developed by a single pathologist. The resulting network has 25 diagnosis nodes interconnected by 40 arcs. Each arc represents a predicted co-occurrence or null co-occurrence. Model verification involved assessing the robustness of the original network structure after random exclusion of 25%, 50%, and 75% of the pathology report dataset. The structure of the network appears stable as random removal of 75% of the records in the original dataset leaves 81% of the original network intact. Model validation was primarily assessed by review of the breast pathology literature for each arc in the network. Almost all network identified co-occurrences (95%) have been published in the breast pathology literature or were verified by expert opinion. In conclusion, the Bayesian network of breast pathology co-occurrence presented here is both robust with respect to incomplete data and validated by consistency with the breast pathology literature and by expert opinion. Further, the ability to utilize a specific pathology observation to predict multiple co-current pathologies enables exploration of pathology co-occurrence patterns in an intuitive manner that may have broader application in both the breast pathologist clinical community and the breast cancer research community.

The utility of PAX5 immunohistochemistry in the diagnosis of undifferentiated malignant neoplasms

PAX5 is a B-cell transcription factor whose expression at the protein level is reliably detected by immunohistochemistry in routine biopsies. The purpose of this study was to investigate whether PAX5 immunohistochemistry has diagnostic benefit as a B-cell marker in the work-up of undifferentiated malignant neoplasms. Twenty-five cases previously diagnosed as undifferentiated malignant neoplasms were selected. In addition, 59 hematolymphoid and 884 non-hematolymphoid malignancies were studied such that the specificity of PAX5 immunohistochemistry could be addressed. Two of the 25 (8%) undifferentiated neoplasms showed diffuse staining for PAX5, which indicated a B-cell derivation for these neoplasms that was not appreciated at the time of initial diagnosis. PAX5 staining was detected in the vast majority of hematolymphoid tumors of B-cell derivation but only in 5 of 884 (less than 1%) non-hematolymphoid tumors. Our results further show that PAX5 may be the only detectable marker of B lineage in lymphomas that lack or show equivocal CD45RB and CD20 expression. We conclude that the addition of PAX5 to a panel of immunohistologic markers used in the interrogation of undifferentiated neoplasms is of diagnostic benefit. Its expression can also facilitate the diagnosis of classical and nodular lymphocyte-predominant Hodgkin lymphoma with atypical morphologic and immunohistologic features. Lastly, we have shown that the lack of its expression at the protein level in many epithelial and mesenchymal neoplasms renders PAX5 expression an extremely specific marker of the B lineage.

Why microscopy will remain a cornerstone of surgical pathology

Recent years have seen increasing predictions of the demise of conventional microscopy in patient care and investigative medicine. However, these predictions fail to recognize the power of morphologic analysis by a skilled observer. The amount of information that can be obtained from a simple H&E slide represents a windfall in terms of data quality, quantity and cost when compared to any other available technique. Moreover, the value of such interpretation is irreplaceable as we develop newer and more sophisticated technologies. Overall, it appears that reports of the death of microscopy have been greatly exaggerated.