Targeted therapies for sarcomas: new roles for the pathologist

Feasibility of BK Virus Real-Time PCR Testing in Renal Graft Biopsies With Negative SV40 Staining

BACKGROUND

BK virus (BKV)-associated nephropathy (BKVAN) is often associated with renal graft dysfunction. When renal transplant recipients present with high clinical suspicion for BKVAN (high serum and urine BKV titer with graft dysfunction) but their graft biopsies stain negatively for BKV, non-correlated situations between the two tests often lead to a dilemma about how to treat them.

METHODS

This retrospective investigation was conducted to determine how real-time quantitative PCR (qPCR) for BKV, routinely applied to serum and urine, could be helpful in identifying the existing BKV in biopsy tissue stained negatively for BKV.

RESULTS

DNA was extracted from each specimen through the use of five 10-μm curls from the tissue block with use of the QIAamp DNA FFPE Tissue Kit (Qiagen), followed by BKV qPCR to determine copies of BKV/μg of biopsy tissue DNA. Group 1 (11 negative renal controls for BKV) demonstrated 0 to 9 BKV copies/μg DNA. Except for 3 focally staining cases showing low BKV, the remaining 10 positive renal controls in group 2 (13 positive transplant biopsies staining positively) demonstrated elevated BKV up to 160 million copies/μg DNA. Group 3 transplants (13 uncertain transplants with negative BKV staining but positive liquid BKV) were negative for BKV (0-12 copies/μg) in 4 of 13, had low BKV copies (36-346 copies/μg) in 5 of 13, and had high BKV copies (17,240-526,945 copies/μg) in 4 of 13 cases, through the use of qPCR.

CONCLUSIONS

The data indicate that qPCR from paraffin-embedded tissue as a backup test is sensitive for ruling in/out BKV infection in renal transplant biopsies, particularly in uncertain cases.

Molecular profiling of sarcomas: new vistas for precision medicine

Sarcoma is a large and heterogeneous group of malignant mesenchymal neoplasms with significant histological overlap. Accurate diagnosis can be challenging yet important for selecting the appropriate treatment approach and prognosis. The currently torrid pace of new genomic discoveries aids our classification and diagnosis of sarcomas, understanding of pathogenesis, development of new medications, and identification of alterations that predict prognosis and response to therapy. Unfortunately, demonstrating effective targets for precision oncology has been elusive in most sarcoma types. The list of potential targets greatly outnumbers the list of available inhibitors at the present time. This review will discuss the role of molecular profiling in sarcomas in general with emphasis on selected entities with particular clinical relevance.

Current update on the diagnosis and management of head and neck soft tissue sarcomas

Head and neck soft tissue sarcomas are a group of rare heterogeneous tumours arising from embryonic mesoderm. They comprise <1% of all head and neck malignancies and 5-15% of all sarcomas with most head and neck sarcomas arising from soft tissues. Although rare, they are associated with both high recurrence and mortality rates. We review the current management of head and neck soft tissue sarcomas.

Pathologists and liquid biopsies: to be or not to be?

Recently, the advent of therapies targeting genomic alterations has improved the care of patients with certain types of cancer. While molecular targets were initially detected in nucleic acid samples extracted from tumor tissue, detection of nucleic acids in circulating blood has allowed the development of what has become known as liquid biopsies, which provide a complementary and alternative sample source allowing identification of genomic alterations that might be addressed by targeted therapy. Consequently, liquid biopsies might rapidly revolutionize oncology practice in allowing administration of more effective treatments. Liquid biopsies also provide an approach towards short-term monitoring of metastatic cancer patients to evaluate efficacy of treatment and/or early detection of secondary mutations responsible for resistance to treatment. In this context, pathologists, who have already been required in recent years to take interest in the domain of molecular pathology of cancer, now face new challenges. The attitude of pathologists to and level of involvement in the practice of liquid biopsies, including mastering the methods employed in molecular analysis of blood samples, need close attention. Regardless of the level of involvement of pathologists in this new field, it is mandatory that oncologists, biologists, geneticists, and pathologists work together to coordinate the pre-analytical, analytical, and post-analytical phases of molecular assessment of tissue and liquid samples of individual cancer patients. The challenges include (1) implementation of effective and efficient procedures for reception and analysis of liquid and tissue samples for histopathological and molecular evaluation and (2) assuring short turn-around times to facilitate rapid optimization of individual patient treatment. In this paper, we will review the following: (1) recent data concerning the concept of liquid biopsies in oncology and its development for patient care, (2) advantages and limitations of molecular analyses performed on blood samples compared to those performed on tissue samples, and (3) short-term challenges facing pathologists in dealing with liquid biopsies of cancer patients and new strategies to early detect metastatic tumor cell clones.

Advances in the Molecular Analysis of Soft Tissue Tumors and Clinical Implications

The emergence of high-throughput molecular technologies has accelerated the discovery of novel diagnostic, prognostic and predictive molecular markers. Clinical implementation of these technologies is expected to transform the practice of surgical pathology. In soft tissue tumor pathology, accurate interpretation of comprehensive genomic data provides useful diagnostic and prognostic information, and informs therapeutic decisions. This article reviews recently developed molecular technologies, focusing on their application to the study of soft tissue tumors. Emphasis is made on practical issues relevant to the surgical pathologist. The concept of genomically-informed therapies is presented as an essential motivation to identify targetable molecular alterations in sarcoma.

Molecular Pathology of Soft-Tissue Neoplasms and Its Role in Clinical Practice

BACKGROUND

Soft-tissue neoplasms embody a histologically diverse group of mesenchymal tumors. Oftentimes the histopathological diagnosis of soft-tissue tumors is challenging due to overlapping pathological features.

METHODS

We reviewed the current and most importantly known recurrent or tumor-specific genetic abnormalities involving soft-tissue tumors, focusing on how they are useful in working up differential diagnoses and the relevance of potentially targeted therapies.

RESULTS

Molecular diagnostic tools have shown great advantage as an aid in the differentiation between different soft-tissue tumor entities, providing a potential avenue in the identification of novel therapeutic targets. Gastrointestinal stromal tumor is a well-known example of a soft-tissue tumor with a successful, molecularly driven treatment with response rates of more than 80% in stable disease and partial remission. Classifying soft-tissue neoplasms by their molecular genetic pathology has been considered as molecular testing becomes more integrated into various diagnostic and prognostic algorithms.

CONCLUSIONS

Molecular pathology provides a unique opportunity for pathologists to play a crucial role in the multidisciplinary care of patients with sarcoma. These opportunities include but are not limited to the appropriate triage of tissue for molecular testing and the integration of molecular testing results, with histological and immunohistochemical findings providing actionable information for the diagnosis, prognosis, and choice of therapeutic modality.

The Hippo signal transduction pathway in soft tissue sarcomas

Sarcomas are rare cancers (≈1% of all solid tumours) usually of mesenchymal origin. Here, we review evidence implicating the Hippo pathway in soft tissue sarcomas. Several transgenic mouse models of Hippo pathway members (Nf2, Mob1, LATS1 and YAP1 mutants) develop various types of sarcoma. Despite that, Hippo member genes are rarely point mutated in human sarcomas. Instead, WWTR1-CAMTA1 and YAP1-TFE3 fusion genes are found in almost all cases of epithelioid haemangioendothelioma. Also copy number gains of YAP1 and other Hippo members occur at low frequencies but the most likely cause of perturbed Hippo signalling in sarcoma is the cross-talk with commonly mutated cancer genes such as KRAS, PIK3CA, CTNNB1 or FBXW7. Current Hippo pathway-targeting drugs include compounds that target the interaction between YAP and TEAD G protein-coupled receptors (GPCR) and the mevalonate pathway (e.g. statins). Given that many Hippo pathway-modulating drugs are already used in patients, this could lead to early clinical trials testing their efficacy in different types of sarcoma.