Clinical application of molecular pathology in sarcomas

An update in the management of pediatric sarcoma

PURPOSE OF REVIEW

Nonrhabdomyosarcoma soft tissue sarcoma (NRSTS) is a rare subgroup of malignancy in childhood that is composed of a variety of soft tissue and bony tumors. Prognosis for resectable localized disease is usually good and improved with systemic treatment. However, survival from locally advanced and metastatic disease remains poor. There have been numerous preclinical and clinical studies to define histopathology, biology, and genetic alteration of sarcomas. The purpose of this review is to clarify the progress in the management of NRSTS.

RECENT FINDINGS

Genomic analysis, including the use of next-generation sequencing, has revealed fusion transcripts or specific genetic alterations which provide diagnostic biomarkers and potential targets for novel therapies.

SUMMARY

Most cases are sporadic, but some are associated with genetic predispositions. Most present as a painless mass and diagnosis is frequently delayed because of a low index of suspicion. There is a wide array of histopathological subtypes. Investigations usually involve core, incisional or excisional biopsy for tissue diagnosis, and cross-sectional and nuclear imaging for staging. Management of pediatric sarcoma is largely dependent on the patient's histopathological diagnosis, age, disease stage, and co-morbidities but usually involves a combination of systemic and local therapies. Preclinical studies and phase I/II trials of newer targeted therapies are ongoing.

Non-rhabdomyosarcoma

Pediatric non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) are a heterogeneous group encompassing more than 50 different histological diagnoses arising from primitive mesenchymal tissue. Together, they comprise about half the soft tissue sarcomas diagnosed in children and young adults. Despite each histologies relative rarity, their management schema is similar among the different NRSTS histologies. Surgical management is an important component of the multimodal treatment strategy of all these tumors. Resection with negative margins, while maintaining function, plays an important role as a primary treatment of these patients as well as diminishing the risks of local and distant recurrence.

Identification of sequence polymorphisms in the D-loop region of mitochondrial DNA as risk biomarker for liposarcoma

Single nucleotide polymorphisms (SNPs) in the Displacement-loop (D-loop) region of mitochondrial DNA have been reported to be associated with cancer risk in various types of cancer. To assess the frequency of D-loop SNPs in a large series of liposarcoma and establish correlations with cancer risk, we sequenced the D-loop of 82 liposarcoma patients and analyzed their use as predictive biomarkers for liposarcoma risk. The minor alleles of nucleotides 73G, 523-524del, 16,290T, 16,319A, 16,356C were associated with an increased risk for liposarcoma patients, whereas the insertion of C at the site 315 (located within the D310) were associated with a decreased risk for liposarcoma patients. These results suggest that SNPs in the mitochondrial D-loop should be considered as a biomarker which may be useful for the early detection of liposarcoma in individuals at risk of this cancer.

The off-label use of targeted therapies in sarcomas: the OUTC'S program

Background

Few targeted therapies (TTs) are registered for sarcoma treatment despite numerous phase II studies and yet there are potential treatment options for patients after standard treatment escape. The French Sarcoma Group - Bone Tumor Study Group (GSF-GETO) created a national registry to evaluate the outcome of patients treated with off-label TTs.

Methods

Every consecutive sarcoma-patient receiving an off-label TT outside a clinical trial was included. The objective was to describe this patient efficacy and safety data in routine practice.

Results

From October 2008 to October 2011, 249 patients in 24 centers received 278 treatment lines with TTs. Twenty-five histological subtypes were included: most frequent were leiomyosarcoma (n = 48, receiving sorafenib in 63%, and sunitinib in 27%), GIST (n = 39, receiving sorafenib in 79%), and angiosarcoma (n =18, receiving sorafenib in 78%). The overall response rate to TTs was 15% (95% CI [10,6-20,2]), the disease control rate at 2 months was 59%. The median progression-free survival was 4,1 months (IC 95% [3,2-4,8]). Three complete responses were observed. No toxic death occurred, grade 3 and 4 toxicities were reported in 74 (27%) and 14 patients (5%) respectively.

Conclusion

Off-label TTs can be used for sarcoma patients in routine practice with an acceptable toxicity profile and efficacy similar to that reported in non-randomized clinical trials.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-870) contains supplementary material, which is available to authorized users.

Genetic polymorphisms of interleukin-1 beta and osteosarcoma risk

PURPOSE

Osteosarcoma is the most common childhood bone cancer. Interleukin-1 beta (IL-1B) is crucially involved in osteosarcoma carcinogenesis. Whether genetic polymorphisms of IL-1B also influence osteosarcoma risk is unknown. The aim of this study was to investigate the association between IL-1B gene polymorphisms and osteosarcoma risk in Chinese Han patients.

METHODS

A hospital-based case-control study involving 120 osteosarcoma patients and 120 controls was conducted. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis was performed to detect three IL-1B gene polymorphisms (-31 T/C, -511 C/T and +3954 C/T) in these patients.

RESULTS

Patients with osteosarcoma had a significantly lower frequency of -31 CC genotype [odds ratio (OR) = 0.40, 95% confidence interval (CI) = 0.17-0.92; P = 0.03] and -31 C allele (OR = 0.67, 95% CI = 0.46-0.99; P = 0.04) than controls. Patients with osteosarcoma had a significantly lower frequency of -511 TT genotype (OR = 0.40, 95% CI = 0.17-0.95; P = 0.04) than controls. The +3954 C/T gene polymorphisms were not associated with a risk of osteosarcoma. When stratified by Enneking stage, tumour location, histological type, tumour metastasis of osteosarcoma and family history of cancer, no statistically significant results were found.

CONCLUSIONS

This is the first study to provide evidence for an association of IL-1B gene polymorphisms with osteosarcoma risk.

Metabolomics strategy reveals subpopulation of liposarcomas sensitive to gemcitabine treatment

Unlike many cancers that exhibit glycolytic metabolism, high-grade liposarcomas often exhibit low 2[18F]fluoro-2-deoxy-D-glucose uptake by positron emission tomography (PET), despite rapid tumor growth. Here, we used liquid chromatography tandem mass spectrometry to identify carbon sources taken up by liposarcoma cell lines derived from xenograft tumors in patients. Interestingly, we found that liposarcoma cell lines consume nucleosides from culture media, suggesting nucleoside salvage pathway activity. The nucleoside salvage pathway is dependent on deoxycytidine kinase (dCK) and can be imaged in vivo by PET with 1-(2'-deoxy-2'-[18F]fluoroarabinofuranosyl) cytosine (FAC). We found that liposarcoma cell lines and xenograft tumors exhibit dCK activity and dCK-dependent FAC uptake in vitro and in vivo. In addition, liposarcoma cell lines and xenograft tumors are sensitive to treatment with the nucleoside analogue prodrug gemcitabine, and gemcitabine sensitivity is dependent on dCK expression. Elevated dCK activity is evident in 7 of 68 clinical liposarcoma samples analyzed. These data suggest that a subpopulation of liposarcoma patients have tumors with nucleoside salvage pathway activity that can be identified noninvasively using [18F]-FAC-PET and targeted using gemcitabine.

SIGNIFICANCE

Patients with high-grade liposarcoma have poor prognoses and often fail to respond to chemotherapy. This report identifies elevated nucleoside salvage activity in a subset of liposarcomas that are identifiable using noninvasive PET imaging with FAC and that are sensitive to gemcitabine. Thus, we suggest a new treatment paradigm for liposarcoma patients that uses [18F]-FAC-PET in the clinic to delineate gemcitabine responders from nonresponders.