New medical treatment options and strategies to assess clinical outcome in soft-tissue sarcoma

Strategies for Targeting Serine/Threonine Protein Phosphatases with Small Molecules in Cancer

Among numerous posttranslational regulation patterns, phosphorylation is reversibly controlled by the balance of kinases and phosphatases. The major form of cellular signaling involves the reversible phosphorylation of proteins on tyrosine, serine, or threonine residues. However, altered phosphorylation levels are found in diverse diseases, including cancer, making kinases and phosphatases ideal drug targets. In contrast to the success of prosperous kinase inhibitors, design of small molecules targeting phosphatase is struggling due to past bias and difficulty. This is especially true for serine/threonine phosphatases, one of the largest phosphatase families. From this perspective, we aim to provide insights into serine/threonine phosphatases and the small molecules targeting these proteins for drug development, especially in cancer. Through highlighting the modulation strategies, we aim to provide basic principles for the design of small molecules and future perspectives for the application of drugs targeting serine/threonine phosphatases.

Tazemetostat for advanced epithelioid sarcoma: current status and future perspectives

Epithelioid sarcoma (ES) is an aggressive ultra-rare soft-tissue sarcoma marked by SMARCB1/INI1 deficiency. SMARCB1/INI1 deficiency leads to elevated expression of EZH2, a component of polycomb repressive complex 2, which mediates gene silencing by catalyzing H3K27me3. Tazemetostat is an oral, SAM-competitive inhibitor of EZH2, whose blockade prevents the methylation of histone H3K27, thus decreasing the growth of EZH2 mutated or over-expressing cancer cells. Tazemetostat has been approved for the treatment of patients aged 16 years and older with metastatic or advanced ES not eligible for complete resection, based on the positive results of a single-arm Phase II basket study. Tazemetostat though represents a new treatment option for ES patients, although clinical/molecular predictors of response are still to be identified. The combination of tazemetostat with other drugs like doxorubicin and immunotherapeutic agents is currently under investigation in ES patients.

LB100, a small molecule inhibitor of PP2A with potent chemo- and radio-sensitizing potential

Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase that plays a significant role in mitotic progression and cellular responses to DNA damage. While traditionally viewed as a tumor suppressor, inhibition of PP2A has recently come to attention as a novel therapeutic means of driving senescent cancer cells into mitosis and promoting cell death via mitotic catastrophe. These findings have been corroborated in numerous studies utilizing naturally produced compounds that selectively inhibit PP2A. To overcome the known human toxicities associated with these compounds, a water-soluble small molecule inhibitor, LB100, was recently developed to competitively inhibit the PP2A protein. This review summarizes the pre-clinical studies to date that have demonstrated the anti-cancer activity of LB100 via its chemo- and radio-sensitizing properties. These studies demonstrate the tremendous therapeutic potential of LB100 in a variety of cancer types. The results of an ongoing phase 1 trial are eagerly anticipated.

Sorafenib in advanced, heavily pretreated patients with soft tissue sarcomas

Therapeutic options for patients with advanced pretreated soft tissue sarcomas are limited. However, in this setting, sorafenib has shown promising results. We reviewed the data of 33 patients with soft tissue sarcoma treated with sorafenib within a named patient program in Austria. Twelve physicians from eight different hospitals provided records for the analysis of data. Among the 33 patients, the predominant histological subtype of sarcoma was leiomyosarcoma (n=18, 55%). Other subtypes were represented by only one or two cases. Fifteen patients presented with metastases at the time of diagnosis. Another 17 patients developed metastases later in the course of the disease (data on one patient are missing). Most of the 33 patients had undergone resection of the primary (n=29, 88%) and half of the patients had received radiotherapy (n=17, 52%). Chemotherapy for metastatic disease had been administered to 30 patients (91%). The majority had received two or more regimens of chemotherapy (n=25, 76%) before sorafenib treatment. The use of sorafenib resulted in a median time to treatment failure of 92 days in patients with leiomyosarcoma and 45 days in patients with other histological subtypes. One-third of the patients derived benefits from treatment: four patients were documented with partial response and six with stabilized disease. In terms of treatment-related toxicity, skin problems of various degrees and gastrointestinal disturbances were frequently reported. In this retrospective analysis of heavily pretreated patients with advanced soft tissue sarcomas, sorafenib was associated with some antitumor activity and an acceptable toxicity profile.

Systemic therapy in primary angiosarcoma of the spleen

Primary splenic angiosarcoma is a very rare neoplasm with a high propensity for metastatic disease and poor prognosis. There is a paucity of literature concerning this specific sarcoma subtype and the role of systemic therapy is not well defined. A retrospective review of the prospectively maintained University of Washington/Seattle Cancer Care Alliance Sarcoma Unit database was performed to identify patients with splenic angiosarcoma treated between 2007 and 2012. In total there were 19 patients with angiosarcoma treated at the Seattle Cancer Care Alliance from 2007 to 2012. The number of patients with splenic angiosarcoma was 2 (11%). The first patient was a woman aged 57 years who was referred with metastatic splenic angiosarcoma to the liver, post-splenectomy. She was treated with 4 cycles of weekly paclitaxel prior to metastatic resection and 4 cycles of the same drug in an adjuvant scenario, achieving a pathological complete response to treatment. She is alive and on third-line systemic therapy. The second patient was a male patient aged 30 years who presented with metastatic high-grade splenic angiosarcoma and was treated with 3 lines of systemic therapy, including doxorubicin, paclitaxel and gemcitabine+docetaxel, but developed a gastrointestinal metastasis with subsequent gastrointestinal bleeding. Splenic angiosarcoma is a very rare neoplasm. Surgery remains the mainstay of management for localized disease. Paclitaxel administered weekly proved to be well-tolerated and resulted in a good radiological response in one of our patients, enabling resection of metastatic disease. Durable clinical benefit can be achieved in metastatic splenic angiosarcoma with multi modality management.

Pazopanib: a promising new agent in the treatment of soft tissue sarcomas

Pazopanib (GW786034) is a novel, small-molecule tyrosine kinase inhibitor. The primary mechanism of action of pazopanib can be described through its antiangiogenic properties via inhibition of the intracellular tyrosine kinase of VEGF receptor (VEGFR) and PDGF receptor (PDGFR). It is an orally available angiogenesis inhibitor that targets VEGFR-1, -2 and -3, PDGFR-α and -β, and c-kit. Pazopanib exhibits distinct pharmacokinetic and toxicity profiles compared with other agents in that class. Phase I studies defined the recommended monotherapy dose of pazopanib as 800 mg once daily. In 2009, it was approved in the USA for the treatment of advanced and metastatic renal cell carcinoma, and subsequently approved in other countries and demonstrated clinically and statistically significant activity in Phase II and III studies in advanced soft tissue sarcoma patients. This article focuses on its emerging role in the treatment of advanced soft tissue sarcomas.

Spindle Cell Sarcomas

Information is presented on the pathology of spindle cell sarcomas. Synovial sarcoma, malignant peripheral nerve sheath tumor, fibrosarcoma, inflammatory myofibroblastic tumor, low-grade myofibrosarcoma, leiomyosarcoma, spindle cell rhabdomyosarcoma, and endothelial neoplasms are discussed in terms of an overview of the tumor, microscopic and gross features, diagnostic techniques, genetic markers, differential diagnosis, clinical details, and prognosis.

Management of adult soft tissue sarcomas of the head and neck

Adult soft tissue sarcoma of the head and neck are rare and represent a heterogeneous group of tumours of different histological variants. Management of these neoplasms presents a great challenge. Malignant fibrous histiocytoma, fibrosarcoma, angiosarcoma and malignant peripheral nerve sheath tumour are the most frequently found sarcoma types in the head and neck. Although traditional morphological assessment is the foundation of clinical decision making, the role of immunohistochemistry and molecular biology are useful for diagnosis, prognosis and identification of possible targets for molecular therapy. The most frequently involved tumour sites are scalp/face, sinonasal tract/anterior skull base and parotid/neck. The management of soft tissue sarcomas in the head and neck is primarily surgical. Since it is difficult to obtain wide margins during surgical treatment in head and neck sarcomas, because of anatomic constraints, most patients undergo post-operative irradiation. Survival varies from 50 to 80%. Prognostic factors are tumour grade, margin status and tumour size. With further insight into the biology of soft tissue sarcoma, modern imaging techniques and new treatment options, we will most certainly be able to improve clinical outcome in patients with soft tissue sarcoma in the upcoming years.

Synovial sarcoma individual chemotherapy directed by collagen gel droplet embedded culture drug sensitivity test: A case report

The collagen gel droplet embedded culture-drug sensitivity test (CD-DST) is an anticancer drug sensitivity test developed about 10 years ago. This study reports the application of this test in the choice of neoadjuvant chemotherapy for the treatment of one patient with a large synovial sarcoma in the right shank. A 28-year old man presented at our hospital with a large mass in his right shank which had a hard texture and an obscure boundary. The histopathological diagnosis of excisional biopsy specimens was synovial sarcoma with low differentiation. Theprubicin/Cisplatin (THP/CDDP) neoadjuvant chemotherapy was selected based on the results obtained from the CD-DST. After three courses, a computed tomography (CT) scan was performed which indicated that the volume of the tumor had decreased significantly. Additionally, tumor necrosis, as well as the clinical response, showed complete response. The histopathological diagnosis of wide excision specimens indicated a grade III chemotherapy response. The patient was alive and without recurrence after a follow-up of 16 months. Our results indicated that the CD-DST is a useful tool for selecting neoadjuvant chemotherapeutic drugs for patients with synovial sarcoma.