Current Molecular Targeted Therapies for Bone and Soft Tissue Sarcomas

Detection of Novel Tyrosine Kinase Fusion Genes as Potential Therapeutic Targets in Bone and Soft Tissue Sarcomas Using DNA/RNA-based Clinical Sequencing

BACKGROUND

Approximately 1% of clinically treatable tyrosine kinase fusions, including anaplastic lymphoma kinase, neurotrophic tyrosine receptor kinase, RET proto-oncogene, and ROS proto-oncogene 1, have been identified in soft tissue sarcomas via comprehensive genome profiling based on DNA sequencing. Histologic tumor-specific fusion genes have been reported in approximately 20% of soft tissue sarcomas; however, unlike tyrosine kinase fusion genes, these fusions cannot be directly targeted in therapy. Approximately 80% of tumor-specific fusion-negative sarcomas, including myxofibrosarcoma and leiomyosarcoma, that are defined in complex karyotype sarcomas remain genetically uncharacterized; this mutually exclusive pattern of mutations suggests that other mutually exclusive driver oncogenes are yet to be discovered. Tumor-specific, fusion-negative sarcomas may be associated with unique translocations, and oncogenic fusion genes, including tyrosine kinase fusions, may have been overlooked in these sarcomas.

QUESTIONS/PURPOSES

(1) Can DNA- or RNA-based analysis reveal any characteristic gene alterations in bone and soft tissue sarcomas? (2) Can useful and potential tyrosine kinase fusions in tumors from tumor-specific, fusion-negative sarcomas be detected using an RNA-based screening system? (3) Do the identified potential fusion tumors, especially in neurotrophic tyrosine receptor kinase gene fusions in bone sarcoma, transform cells and respond to targeted drug treatment in in vitro assays? (4) Can the identified tyrosine kinase fusion genes in sarcomas be useful therapeutic targets?

METHODS

Between 2017 and 2020, we treated 100 patients for bone and soft tissue sarcomas at five institutions. Any biopsy or surgery from which a specimen could be obtained was included as potentially eligible. Ninety percent (90 patients) of patients were eligible; a further 8% (8 patients) were excluded because they were either lost to follow-up or their diagnosis was changed, leaving 82% (82 patients) for analysis here. To answer our first and second questions regarding gene alterations and potential tyrosine kinase fusions in eight bone and 74 soft tissue sarcomas, we used the TruSight Tumor 170 assay to detect mutations, copy number variations, and gene fusions in the samples. To answer our third question, we performed functional analyses involving in vitro assays to determine whether the identified tyrosine kinase fusions were associated with oncogenic abilities and drug responses. Finally, to determine usefulness as therapeutic targets, two pediatric patients harboring an NTRK fusion and an ALK fusion were treated with tyrosine kinase inhibitors in clinical trials.

RESULTS

DNA/RNA-based analysis demonstrated characteristic alterations in bone and soft tissue sarcomas; DNA-based analyses detected TP53 and copy number alterations of MDM2 and CDK4 . These single-nucleotide variants and copy number variations were enriched in specific fusion-negative sarcomas. RNA-based screening detected fusion genes in 24% (20 of 82) of patients. Useful potential fusions were detected in 19% (11 of 58) of tumor-specific fusion-negative sarcomas, with nine of these patients harboring tyrosine kinase fusion genes; five of these patients had in-frame tyrosine kinase fusion genes ( STRN3-NTRK3, VWC2-EGFR, ICK-KDR, FOXP2-MET , and CEP290-MET ) with unknown pathologic significance. The functional analysis revealed that STRN3-NTRK3 rearrangement that was identified in bone had a strong transforming potential in 3T3 cells, and that STRN3-NTRK3 -positive cells were sensitive to larotrectinib in vitro. To confirm the usefulness of identified tyrosine kinase fusion genes as therapeutic targets, patients with well-characterized LMNA-NTRK1 and CLTC-ALK fusions were treated with tyrosine kinase inhibitors in clinical trials, and a complete response was achieved.

CONCLUSION

We identified useful potential therapeutic targets for tyrosine kinase fusions in bone and soft tissue sarcomas using RNA-based analysis. We successfully identified STRN3-NTRK3 fusion in a patient with leiomyosarcoma of bone and determined the malignant potential of this fusion gene via functional analyses and drug effects. In light of these discoveries, comprehensive genome profiling should be considered even if the sarcoma is a bone sarcoma. There seem to be some limitations regarding current DNA-based comprehensive genome profiling tests, and it is important to use RNA testing for proper diagnosis and accurate identification of fusion genes. Studies on more patients, validation of results, and further functional analysis of unknown tyrosine kinase fusion genes are required to establish future treatments.

CLINICAL RELEVANCE

DNA- and RNA-based screening systems may be useful for detecting tyrosine kinase fusion genes in specific fusion-negative sarcomas and identifying key therapeutic targets, leading to possible breakthroughs in the treatment of bone and soft tissue sarcomas. Given that current DNA sequencing misses fusion genes, RNA-based screening systems should be widely considered as a worldwide test for sarcoma. If standard treatments such as chemotherapy are not effective, or even if the sarcoma is of bone, RNA sequencing should be considered to identify as many therapeutic targets as possible.

Identification of common factors among fibrosarcoma, rhabdomyosarcoma, and osteosarcoma by network analysis

Sarcoma cancers are uncommon malignant tumors, and there are many subgroups, including fibrosarcoma (FS), which mainly affects middle-aged and older adults in deep soft tissues. Rhabdomyosarcoma (RMS), on the other hand, is the most common soft-tissue sarcoma in children and is located in the head and neck area. Osteosarcomas (OS) is the predominant form of primary bone cancer among young adults, primarily resulting from sporadically random mutations. This frequently results in the dissemination of cancer cells to the lungs, commonly known as metastasis. Mesodermal cells are the origin of sarcoma cancers. In this study, a rather radical approach has been applied. Instead of comparing homogenous cancer types, we focus on three main subtypes of sarcoma: fibrosarcoma, rhabdomyosarcoma, and osteosarcoma, and compare their gene expression with normal cell groups to identify the differentially expressed genes (DEGs). Next, by applying protein-protein interaction (PPI) network analysis, we determine the hub genes and crucial factors, such as transcription factors (TFs), affected by these types of cancer. Our findings indicate a modification in a range of pathways associated with cell cycle, extracellular matrix, and DNA repair in these three malignancies. Results showed that fibrosarcoma (FS), rhabdomyosarcoma (RMS), and osteosarcoma (OS) had 653, 1270, and 2823 differentially expressed genes (DEGs), respectively. Interestingly, there were 24 DEGs common to all three types. Network analysis showed that the fibrosarcoma network had two sub-networks identified in FS that contributed to the catabolic process of collagen via the G-protein coupled receptor signaling pathway. The rhabdomyosarcoma network included nine sub-networks associated with cell division, extracellular matrix organization, mRNA splicing via spliceosome, and others. The osteosarcoma network has 13 sub-networks, including mRNA splicing, sister chromatid cohesion, DNA repair, etc. In conclusion, the common DEGs identified in this study have been shown to play significant and multiple roles in various other cancers based on the literature review, indicating their significance.

Outcome of patients with soft tissue sarcomas of the extremities and trunk treated by (neo)adjuvant intensity modulated radiation therapy with curative intent

BACKGROUND

Soft tissue sarcomas (STS) are a relatively rare group of malignant tumors. Currently, there is very little published clinical data, especially in the context of curative multimodal therapy with image-guided, conformal, intensity-modulated radiotherapy.

METHODS

Patients who received preoperative or postoperative intensity-modulated radiotherapy for STS of the extremities or trunk with curative intent were included in this single centre retrospective analysis. A Kaplan-Meier analysis was performed to evaluate survival endpoints. Multivariable proportional hazard models were used to investigate the association between survival endpoints and tumour-, patient-, and treatment-specific characteristics.

RESULTS

86 patients were included in the analysis. The most common histological subtypes were undifferentiated pleomorphic high-grade sarcoma (UPS) (27) and liposarcoma (22). More than two third of the patients received preoperative radiation therapy (72%). During the follow-up period, 39 patients (45%) suffered from some type of relapse, mainly remote (31%). The two-years overall survival rate was 88%. The median DFS was 48 months and the median DMFS was 51 months. Female gender (HR 0.460 (0.217; 0.973)) and histology of liposarcomas compared to UPS proved to be significantly more favorable in terms of DFS (HR 0.327 (0.126; 0.852)).

CONCLUSION

Conformal, intensity-modulated radiotherapy is an effective treatment modality in the preoperative or postoperative management of STS. Especially for the prevention of distant metastases, the establishment of modern systemic therapies or multimodal therapy approaches is necessary.

Subtype-selective induction of apoptosis in translocation-related sarcoma cells induced by PUMA and BIM upon treatment with pan-PI3K inhibitors

Translocation-related sarcomas (TRSs) harbor an oncogenic fusion gene generated by chromosome translocation and account for approximately one-third of all sarcomas; however, effective targeted therapies have yet to be established. We previously reported that a pan-phosphatidylinositol 3-kinase (PI3K) inhibitor, ZSTK474, was effective for the treatment of sarcomas in a phase I clinical trial. We also demonstrated the efficacy of ZSTK474 in a preclinical model, particularly in cell lines from synovial sarcoma (SS), Ewing's sarcoma (ES) and alveolar rhabdomyosarcoma (ARMS), all of which harbor chromosomal translocations. ZSTK474 selectively induced apoptosis in all these sarcoma cell lines, although the precise mechanism underlying the induction of apoptosis remained unclear. In the present study, we aimed to determine the antitumor effect of PI3K inhibitors, particularly with regards to the induction of apoptosis, against various TRS subtypes using cell lines and patient-derived cells (PDCs). All of the cell lines derived from SS (six), ES (two) and ARMS (one) underwent apoptosis accompanied by the cleavage of poly-(ADP-ribose) polymerase (PARP) and the loss of mitochondrial membrane potential. We also observed apoptotic progression in PDCs from SS, ES and clear cell sarcoma (CCS). Transcriptional analyses revealed that PI3K inhibitors triggered the induction of PUMA and BIM and the knockdown of these genes by RNA interference efficiently suppressed apoptosis, suggesting their functional involvement in the progression of apoptosis. In contrast, TRS-derived cell lines/PDCs from alveolar soft part sarcoma (ASPS), CIC-DUX4 sarcoma and dermatofibrosarcoma protuberans failed to undergo apoptosis nor induce PUMA and BIM expression, as well as cell lines derived from non-TRSs and carcinomas. Thus, we conclude that PI3K inhibitors induce apoptosis in selective TRSs such as ES and SS via the induction of PUMA and BIM and the subsequent loss of mitochondrial membrane potential. This represents proof of concept for PI3K-targeted therapy, particularly such TRS patients.

Tyrosine kinase inhibitor-loaded biomimetic nanoparticles as a treatment for osteosarcoma

Small-molecule tyrosine kinase inhibitors (TKIs) represent a potentially powerful approach to the treatment of osteosarcoma (OS). However, dose-limiting toxicity, therapeutic efficacy, and targeting specificity are significant barriers to the use of TKIs in the clinic. Notably among TKIs, ponatinib demonstrated potent anti-tumor activity; however, it received an FDA black box warning for potential side effects. We propose ponatinib-loaded biomimetic nanoparticles (NPs) to repurpose ponatinib as an efficient therapeutic option for OS. In this study, we demonstrate enhanced targeting ability and maintain potent ponatinib nano-therapeutic activity, while also reducing toxicity. In in vitro two- and three-dimensional models, we demonstrate that ponatinib-loaded biomimetic NPs maintain the efficacy of the free drug, while in vivo we show that they can improve tumor targeting, slow tumor growth, and reduce evidence of systemic toxicities. Though there is limited Pon encapsulation within NPs, this platform may improve current therapeutic approaches and reduce dosage-related side effects to achieve better clinical outcomes in OS patients.

Graphical Abstract

Alveolar soft part sarcoma: progress toward improvement in survival? A population-based study

Background

Alveolar soft part sarcoma (ASPS) is a rare histological subtype of soft-tissue sarcoma, which remains refractory to conventional cytotoxic chemotherapy. We aimed to characterize ASPS and investigate whether the oncological outcome has improved over the past decade.

Methods

One hundred and twenty patients with newly diagnosed ASPS from 2006 to 2017, identified from the Bone and Soft-Tissue Tumor Registry in Japan, were analyzed retrospectively.

Results

The study cohort comprised 34 (28%) patients with localized ASPS and 86 (72%) with metastatic disease at presentation. The 5-year disease-specific survival (DSS) was 68% for all patients and 86% and 62% for localized and metastatic disease, respectively (p = 0.019). Metastasis at presentation was the only adverse prognostic factor for DSS (hazard ratio [HR]: 7.65; p = 0.048). Patients who were > 25 years (80%; p = 0.023), had deep-seated tumors (75%; p = 0.002), and tumors > 5 cm (5–10 cm, 81%; > 10 cm, 81%; p < 0.001) were more likely to have metastases at presentation. In patients with localized ASPS, adjuvant chemotherapy or radiotherapy did not affect survival, and 13 patients (45%) developed distant metastases in the lung (n = 12, 92%) and brain (n = 2, 15%). In patients with metastatic ASPS (lung, n = 85 [99%]; bone, n = 12 [14%]; and brain n = 9 [11%]), surgery for the primary or metastatic site did not affect survival. Prolonged survival was seen in patients who received pazopanib treatment (p = 0.045), but not in those who received doxorubicin-based cytotoxic chemotherapy. Overall, improved DSS for metastatic ASPS has been observed since 2012 (5-year DSS, from 58 to 65%) when pazopanib was approved for advanced diseases, although without a statistically significant difference (p = 0.117).

Conclusion

The national study confirmed a unique feature of ASPS with frequent metastasis to the lung and brain but an indolent clinical course. An overall trend toward prolonged survival after the introduction of targeted therapy encourages continuous efforts to develop novel therapeutic options for this therapeutically resistant soft-tissue sarcoma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09968-5.

Nanomaterial Technology and Soft Tissue Sarcomas

Soft tissue sarcomas (STSs) are relatively rare heterogeneous solid tumors of the mesenchymal origin. They account for approximately 1% of all malignant tumors in adults and have more than 70 histological subtypes. Consequently, the rarity and heterogeneity of STSs make their diagnosis and treatment very challenging. Nanotechnology has attracted increasing attention from researchers due to the unique physicochemical and biological properties of nanomaterials with potential medical applications as nanoprobes, drug delivery systems, photosensitizers, radioenhancers, antitumor agents, and their combinations for cancer diagnosis and treatment. This review discusses the progress made in the use of nanotechnology for the diagnosis and treatment of STSs and highlights future prospects of the STS multimodality therapy.

New adjustable modular hemipelvic prosthesis replacement with 3D-print osteotomy guide plate used in periacetabular malignant tumors: a retrospective case series

BACKGROUND

Periacetabular malignant tumor seriously endangers the life and health of patients. Hemipelvic replacement provides a good method for patients who want complete resection of the tumor while retaining or restoring the function of the affected limb.

OBJECTIVE

To investigate the performance and clinical application of the new adjustable modular hemipelvic prosthesis and to compare the effects of three kinds of hemipelvic prosthesis.

METHODS

In this study, 23 patients, with an average age of 44.6 years (21-75 years), were collected, who received hemipelvic replacement with new adjustable, modular, and screw-rod system hemipelvic prosthesis. Preoperative preparation was conducted on them, and operative complications were recorded. Postoperative functional follow-up was performed regularly.

RESULTS

The average operation time was 319 min (170-480 min), and the average blood loss was 2813 ml (1000 mL-8000 ml). The incidence of complications was 47.8%, and type A (wound-related complications) had the highest incidence (34.8%). Postoperative dislocation occurred in 3 cases (13.0%), and no dislocation occurred in the new adjustable modular hemipelvic prosthesis group. The average MSTS score of the patients was 18.6 (10-23), and the average Harris score was 73.7 (53-87).

CONCLUSIONS

The new adjustable modular hemipelvic prosthesis has the feasibility of reconstruction and good functional outcome, making it ideal for periacetabular tumors. Furthermore, preoperative tumor-feeding artery embolization and abdominal aortic balloon implantation may be an effective choice to reduce intraoperative blood loss and facilitate the operation of tumor resection.

Tyrosine kinase inhibitors in sarcoma treatment (Review)

Sarcomas are a group of rare mesenchymal malignant tumors that arise from transformed cells of the mesenchymal connective tissue, which are challenging to treat. The majority of sarcomas are soft tissue sarcomas (STSs; 75%) and this heterogeneous group of tumors is further comprised of gastrointestinal stromal tumors (~15%) and bone sarcomas (10%). Although surgery remains the current primary therapeutic approach for localized disease, recurrent, metastatic and refractory sarcomas require cytotoxic chemotherapy, which usually yields poor results. Therefore the efficiency of sarcoma treatment imposes a difficult problem. Furthermore, even though progress has been made towards understanding the underlying molecular signaling pathways of sarcoma, there are limited treatment options. The aim of the present study was therefore to perform a systematic literature review of the available clinical evidence regarding the role of tyrosine kinase inhibitors (TKIs) in patients with recurrent or refractory STSs and bone sarcomas over the last two decades. Tyrosine kinases are principal elements of several intracellular molecular signaling pathways. Deregulation of these proteins has been implicated in driving oncogenesis via the crosstalk of pivotal cellular signaling pathways and cascades, including cell proliferation, migration, angiogenesis and apoptosis. Subsequently, small molecule TKIs that target these proteins provide a novel potential therapeutic approach for several types of tumor by offering significant clinical benefits. Among the eligible articles, there were 45 prospective clinical trials, primarily multicentric, single arm, phase II and non-randomized. Numerous studies have reported promising results regarding the use of TKIs, mainly resulting in disease control in patients with STSs. The lack of randomized clinical trials demonstrates the ambiguous efficiency of various studied treatment options, which therefore currently limits the approved drugs used in clinical practice. Research both in clinical and preclinical settings is needed to shed light on the underlying molecular drivers of sarcomagenesis and will identify novel therapeutic approaches for pretreated patients.

A Rationale for the Activity of Bone Target Therapy and Tyrosine Kinase Inhibitor Combination in Giant Cell Tumor of Bone and Desmoplastic Fibroma: Translational Evidences

Giant cell tumor of bone (GCTB) and desmoplastic fibroma (DF) are bone sarcomas with intermediate malignant behavior and unpredictable prognosis. These locally aggressive neoplasms exhibit a predilection for the long bone or mandible of young adults, causing a severe bone resorption. In particular, the tumor stromal cells of these lesions are responsible for the recruiting of multinucleated giant cells which ultimately lead to bone disruption. In this regard, the underlying pathological mechanism of osteoclastogenesis processes in GCTB and DF is still poorly understood. Although current therapeutic strategy involves surgery, radiotherapy and chemotherapy, the benefit of the latter is still debated. Thus, in order to shed light on these poorly investigated diseases, we focused on the molecular biology of GCTB and DF. The expression of bone-vicious-cycle- and neoangiogenesis-related genes was investigated. Moreover, combining patient-derived primary cultures with 2D and 3D culture platforms, we investigated the role of denosumab and levantinib in these diseases. The results showed the upregulation of RANK-L, RANK, OPN, CXCR4, RUNX2 and FLT1 and the downregulation of OPG and CXCL12 genes, underlining their involvement and promising role in these neoplasms. Furthermore, in vitro analyses provided evidence for suggesting the combination of denosumab and lenvatinib as a promising therapeutic strategy in GCTB and DF compared to monoregimen chemotherapy. Furthermore, in vivo zebrafish analyses corroborated the obtained data. Finally, the clinical observation of retrospectively enrolled patients confirmed the usefulness of the reported results. In conclusion, here we report for the first time a molecular and pharmacological investigation of GCTB and DF combining the use of translational and clinical data. Taken together, these results represent a starting point for further analyses aimed at improving GCTB and DF management.

Desmoplastic Small Round Cell Tumor in a Pregnant Woman: A Case Report and Literature Review

Background: Desmoplastic small round cell tumor (DSRCT) is an aggressive malignant tumor commonly found in young men; most occurs in the abdominal cavity. Here we conducted an in-depth analysis of a pregnant patient in our hospital and explored all the case information in the literature on small round cell carcinoma of women. Case presentation: A 27-year-old pregnant woman underwent tumor resection in our hospital at 29 weeks gestational age for a large progressive shoulder lump. The postoperative pathology showed that the mass was a DSRCT. Genetic testing found no fusion gene. At 36 weeks gestation, a painful mass was found in the breast and proved to be a metastatic focus of the desmoplastic small round cell tumor. Twenty days after a successful cesarean section at 40 weeks gestation, she received the VAC-IE chemotherapy regimen, successfully completed the first course, but when awaiting the next chemotherapy, unfortunately, the patient died during follow-up due to tumor recurrence and metastasis. Conclusion: The treatment of DSRCT in pregnant women requires a multidisciplinary consultation, and the treatment and examination during pregnancy are subject to many constraints, which may have a negative impact on the patient's prognosis. Also, a review of the literature found that there is still no standard treatment protocol for DSRCT, and its prognosis in female patients is independent of age and tissue origin.

Liquid Biopsy: A New Translational Diagnostic and Monitoring Tool for Musculoskeletal Tumors

Soft tissue and bone sarcomas represent a group of aggressive neoplasms often accompanied by dismal patient prognosis, especially when distant metastases are present. Moreover, effective treatment can pose a challenge, as recurrences are frequent and almost half of patients present with advanced disease. Researchers have unveiled the molecular abnormalities implicated in sarcomas' carcinogenesis, paving the way for novel treatment strategies based on each individual tumor's characteristics. Therefore, the development of new techniques aiding in early disease detection and tumor molecular profiling is imperative. Liquid biopsy refers to the sampling and analysis of patients' fluids, such as blood, to identify tumor biomarkers, through a variety of methods, including qRT-PCR, qPCR, droplet digital PCR, magnetic microbeads and digital PCR. Assessment of circulating tumor cells (CTCs), circulating free DNA (ctDNA), micro RNAs (miRs), long non-coding RNAs (lncRNAs), exosomes and exosome-associated proteins can yield a plethora of information on tumor molecular signature, histologic type and disease stage. In addition, the minimal invasiveness of the procedure renders possible its wide application in the clinical setting, and, therefore, the early detection of the presence of tumors. In this review of the literature, we gathered information on biomarkers assessed through liquid biopsy in soft tissue and bone sarcoma patients and we present the information they can yield for each individual tumor type.

Anlotinib: A Novel Targeted Drug for Bone and Soft Tissue Sarcoma

Bone and soft tissue sarcomas account for approximately 15% of pediatric solid malignant tumors and 1% of adult solid malignant tumors. There are over 50 subtypes of sarcomas, each of which is notably heterogeneous and manifested by remarkable phenotypic and morphological variability. Anlotinib is a novel oral tyrosine kinase inhibitor (TKI) targeting c-kit, platelet-derived growth factor receptors, fibroblast growth factor receptor, and vascular endothelial growth factor receptor. In comparison with the placebo, anlotinib was associated with better overall survival and progression-free survival (PFS) in a phase III trial of patients with advanced non-small cell lung cancer (NSCLC), albeit with cancer progression after two previous lines of treatment. Recently, the National Medical Products Administration approved anlotinib monotherapy as a third-line treatment for patients with advanced NSCLC. Additionally, a phase IIB randomized trial substantiated that anlotinib is associated with a significant longer median PFS in patients with advanced soft tissue sarcoma. Moreover, anlotinib is also effective in patients with advanced medullary thyroid carcinoma and metastatic renal cell carcinoma. Anlotinib has similar tolerability to other TKIs targeting vascular endothelial growth factor receptors and other tyrosine kinase-mediated pathways. However, anlotinib has a notably lower rate of side effects ≥grade 3 relative to sunitinib. This review discussed the remarkable characteristics and major dilemmas of anlotinib as a targeted therapy for sarcomas.

Heterogeneous Circulating Tumor Cells in Sarcoma: Implication for Clinical Practice

Simple Summary

The present review is aimed to discuss the relevance of assaying for the presence and isolation of circulating tumor cells (CTCs) in patients with sarcoma. Just a few studies have been performed to detect and enumerate viable CTCs in sarcoma and a majority of them still represent proof-of-concept studies, while more frequently tumor cells have been detected in the circulation by using the PCR-based method. Nevertheless, recent advances in technologies allowed detection of epithelial–mesenchymal transitioned CTCs from patients with mesenchymal malignancies, despite results being mostly preliminary. The possibility to identify CTCs holds a great promise for both applications of liquid biopsy in sarcoma for precision medicine, and for research purposes to pinpoint the mechanism of the metastatic process through the characterization of tumor mesenchymal cells. Coherently, clinical trials in sarcoma have been designed accordingly to detect CTCs, for diagnosis, identification of novel therapeutic targets and resistance mechanisms of systemic therapies, and patient stratification.

Abstract

Bone and soft tissue sarcomas (STSs) represent a group of heterogeneous rare malignant tumors of mesenchymal origin, with a poor prognosis. Due to their low incidence, only a few studies have been reported addressing circulating tumor cells (CTCs) in sarcoma, despite the well-documented relevance for applications of liquid biopsy in precision medicine. In the present review, the most recent data relative to the detection and isolation of viable and intact CTCs in these tumors will be reviewed, and the heterogeneity in CTCs will be discussed. The relevance of epithelial–mesenchymal plasticity and stemness in defining the phenotypic and functional properties of these rare cells in sarcoma will be highlighted. Of note, the existence of dynamic epithelial–mesenchymal transition (EMT)-related processes in sarcoma tumors has only recently been related to their clinical aggressiveness. Also, the presence of epithelial cell adhesion molecule (EpCAM)-positive CTC in sarcoma has been weakly correlated with poor outcome and disease progression, thus proving the existence of both epithelial and mesenchymal CTC in sarcoma. The advancement in technologies for capturing and enumerating all diverse CTCs phenotype originating from these mesenchymal tumors are presented, and results provide a promising basis for clinical application of CTC detection in sarcoma.

Adult genitourinary sarcoma: The era of optional chemotherapeutic agents for soft tissue sarcoma

OBJECTIVE

To report our institutional experience with treatment of primary genitourinary soft tissue sarcoma.

METHODS

We retrospectively reviewed the medical records of adult soft tissue sarcoma patients treated between March 2005 and May 2019. The primary tumor sites included the prostate, kidney, urinary bladder and the paratesticular structures.

RESULTS

A total of 19 patients - 16 men (84%) and three women (16%) - were enrolled in the study. The median age was 41 years (range 20-79 years). The most common primary site was the prostate (in eight patients; 42%), and prostatic sarcoma patients were younger than patients with sarcomas of other origins. The most common histological subtype was leiomyosarcoma (in five patients; 26%). The overall survival rates after 1, 3 and 5 years were 61.5%, 34.4% and 25.8%, respectively. The median survival time was 20.7 months (95% confidence interval 5.9-35.5 months). Univariate analysis showed that an absence of metastasis at diagnosis and complete surgical resection were predictive of favorable survival. In the chemotherapy group, the objective response rate was 20.5%. Pazopanib was administered to nine patients in the late-line setting, and the objective response rate was 11.1%; six grade ≥3 adverse events were observed in three patients.

CONCLUSIONS

Inoperable metastatic genitourinary soft tissue sarcoma remains difficult to treat, as previously reported. Further investigation on this malignancy, including optimization of currently available antitumor drugs and the development of novel therapeutic agents, is required.

Efficacy and safety of apatinib in advanced sarcoma: an open-label, nonrandomized, single-center study of 45 patients

Sarcoma is a rare tumor with more than 50 histologic subtypes. Patients with advanced sarcoma have a poor prognosis. The aim of this study was to evaluate the efficacy and safety of apatinib, an oral vascular endothelial growth factor receptor-2 inhibitor, as salvage treatment for advanced bone and soft tissue sarcomas. From May 2017 to July 2018, a prospective, open-label, nonrandomized, clinical trial of apatinib was carried out in selected patients with advanced sarcoma. After apatinib dosing, progression-free survival (PFS), overall survival (OS), objective response rate, disease control rate, and treatment-related adverse events (AEs) were reviewed and evaluated. Patients were administered apatinib for at least 1 month. Median follow-up time was 6.00 months (1-13 months). The median PFS was 7.88 months, with the longest PFS of 13 months observed in a patient with epithelial sarcoma. The 3-month PFS rate was 66.44%. The median OS was 11.64 months with significant differences observed based on disease subtypes. Four patients achieved a partial response, and 36 patients achieved stable disease. The objective response rate was 8.88% (4/45), and the disease control rate was 88.89% (40/45). The most common grade 3/4 treatment-related AEs were hypertension (12.50%), hand-foot syndrome (6.67%), diarrhea (12.50%), fatigue (6.25%), and proteinuria (14.29%). One drug-related severe AE of thrombocytopenia (21×10/l) occurred 2 months after therapy. Apatinib treatment in our study exhibited objective efficacy in PFS, OS, and manageable toxicity in patients with advanced sarcoma. This result supports future randomized controlled trials to further define apatinib activity in stage IV sarcomas.

Bone-targeting polymer vesicles for simultaneous imaging and effective malignant bone tumor treatment

We present a bone-targeting polymer vesicle with excellent single photon emission computed tomography/computed tomography (SPECT/CT) imaging capability and high antitumor drug delivery efficiency as an integrated platform for the simultaneous diagnosing and treatment of malignant bone tumors. This polymer vesicle can be self-assembled from poly(ε-caprolactone)₆₇-b-poly[(L-glutamic acid)₆-stat-(L-glutamic acid-alendronic acid)₁₆] (PCL₆₇-b-P[Glu₆-stat-(Glu-ADA)₁₆]), directly in water without the aid of a cosolvent. SPECT/CT dynamically tracked the drug distribution in the bone tumor rabbit models, and the tumor size was significantly reduced from >2.0 cm³ to <0.6 cm³ over 11 days. The pathological analysis demonstrated obvious necrosis and apoptosis of the tumor cells. Overall, this bone-targeting polymer vesicle provides us with a new platform for the combination of real-time diagnosis and therapy of malignant bone tumors.

A phase II study of pazopanib as front-line therapy in patients with non-resectable or metastatic soft-tissue sarcomas who are not candidates for chemotherapy

BACKGROUND

Cytotoxic chemotherapy remains the standard of care first-line treatment for advanced and metastatic soft-tissue sarcomas (STSs). Certain patients may not be chemotherapy candidates based upon age or co-morbidities, leaving limited treatment options. Pazopanib is a multi-targeted tyrosine kinase inhibitor that is FDA-approved for metastatic STS after the first line. We proposed a phase II study evaluating pazopanib as a first-line agent in patients with advanced disease who are deemed not to be candidates for chemotherapy.

METHODS

Eligible patients were at least 18 years old, not candidates for chemotherapyand were treatment naive. Pazopanib was titrated from 200 mg twice daily to a goal of 800 mg daily. The primary end point was the clinical benefit rate (CBR) (CBR = completed response + partial response + stable disease per Response Evaluation Criteria in Solid Tumours [RECIST 1.1]) at 16 weeks. The sample size of 56 evaluable patients was calculated to provide 80% power to test a hypothesised CBR of ≥35% against an unfavourable CBR of ≤20%. If ≥ 17 patients achieved benefit, the null CBR of 20% would be rejected at a nominal 5% alpha level. Secondary end points included progression-free survival (PFS), overall survival (OS), quality of life and serum biomarkers.

FINDINGS

Fifty-six patients were enrolled from May 2015 to February 2019 and are included in the intention-to-treat analysis. Median PFS was 3.67 (2.62-7.25) months. Median OS was 14.16 (95% confidence interval [CI]: 8.4-NR) months, CBR = 39.29% (22/56) (CI = 0.265-0.533, p = 0.0007). No new or unexpected adverse events were seen. The most common grade I-II events were diarrhoea, nausea and fatigue. The most common grade III-IV events were hypertension and liver function test abnormalities.

INTERPRETATION

These data suggest that there is a benefit to front-line pazopanib in patients with STS who are not candidates for cytotoxic chemotherapy.

Expression of DNA repair genes in oral squamous cell carcinoma using reverse transcription-quantitative polymerase chain reaction

OBJECTIVE

The aim of this study was to evaluate the expression of DNA repair genes in cases of oral squamous cell carcinoma (OSCC).

STUDY DESIGN

Expression of the MLH1, MSH2, MLH3, ATM, MRE11A, XRCC1, and PMS2 genes was evaluated by reverse transcription-quantitative polymerase chain reaction in the OSCC group (32 patients) and the control group (15 patients). The groups were compared by using the Mann-Whitney test, with Bonferroni correction. Associations between gene expression levels and clinical data were explored by using Pearson's and Spearman's correlation coefficients, with P value less than .05 indicating a significant difference.

RESULTS

The MLH1, MSH2, MLH3, ATM, MRE11A, XRCC1, and PMS2 genes were downregulated in the OSCC group compared with the control group, with significant values for MLH1 (P < .0001); MSH2 (P = .038); MLH3 (P < .0001); ATM (P < .0001); MRE11A (P < .0001); XRCC1 (P = .0004); and PMS2 (P = .008). Analysis of the correlation between gene expression and clinical data only revealed a significant negative correlation between age and expression of the PMS2 gene.

CONCLUSIONS

Expression of the DNA repair genes MLH1, MSH2, MLH3, ATM, MRE11 AMRE11A, XRCC1, and PMS2 was reduced in OSCC.

Current Approaches for Personalized Therapy of Soft Tissue Sarcomas

Soft tissue sarcomas (STS) are a highly heterogeneous group of cancers of mesenchymal origin with diverse morphologies and clinical behaviors. While surgical resection is the standard treatment for primary STS, advanced and metastatic STS patients are not eligible for surgery. Systemic treatments, including standard chemotherapy and newer chemical agents, still play the most relevant role in the management of the disease. Discovery of specific genetic alterations in distinct STS subtypes allowed better understanding of mechanisms driving their pathogenesis and treatment optimization. This review focuses on the available targeted drugs or drug combinations based on genetic aberration involved in STS development including chromosomal translocations, oncogenic mutations, gene amplifications, and their perspectives in STS treatment. Furthermore, in this review, we discuss the possible use of chemotherapy sensitivity and resistance assays (CSRA) for the adjustment of treatment for individual patients. In summary, current trends in personalized management of advanced and metastatic STS are based on combination of both genetic testing and CSRA.

Comprehensive review into the challenges of gastrointestinal tumors in the Gulf and Levant countries

Although gastrointestinal stromal tumors (GISTs) are rare, with an incidence of 1/100000 per year, they are the most common sarcomas in the peritoneal cavity. Despite considerable progress in the diagnosis and treatment of GIST, about half of all patients are estimated to experience recurrence. With only two drugs, sunitinib and regorafenib, approved by the Food and Drug Administration, selecting treatment options after imatinib failure and coordinating multidisciplinary care remain challenging. In addition, physicians across the Middle East face some additional and unique challenges such as lack of published local data from clinical trials, national disease registries and regional scientific research, limited access to treatment, lack of standardization of care, and limited access to mutational analysis. Although global guidelines set a framework for the management of GIST, there are no standard local guidelines to guide clinical practice in a resource-limited environment. Therefore, a group of 11 experienced medical oncologists from across the Gulf and Levant region, part of the Rare Tumors Gastrointestinal Group, met over a period of one year to conduct a narrative review of the management of GIST and to describe regional challenges and gaps in patient management as an essential step to proposing local clinical practice recommendations.

Detection of circulating sarcoma tumor cells using a microfluidic chip-type cell sorter

Analyses of circulating tumor cells have been shown to be effective for the detection of cancer relapse and prognosis prediction. However, research regarding its utility in sarcoma remains scarce. In this study, the microfluidic chip-type cell sorter On-chip Sort was used to construct a system for detecting circulating sarcoma cells (CSCs). A pilot study using normal fibroblast or sarcoma cell lines was designed to establish a reliable protocol to separate CSCs by On-chip Sort. A single CSC was separated and recovered from 10 ml of whole blood from a patient with locally advanced myxofibrosarcoma. The nonsynonymous mutation for KMT2B p.Ile2602Val identified in the formalin-fixed paraffin-embedded tumor sample was also confirmed in the CSC. Use of the developed protocol may allow CSCs to become an early predictor for metastasis and recurrence of sarcoma. Further, it may aid in optimizing post-operative therapies for patients without metastasis.

Hypoxia-Inducible Factor 1A Upregulates HMGN5 by Increasing the Expression of GATA1 and Plays a Role in Osteosarcoma Metastasis

Osteosarcoma is one of the most common malignant tumors in children and adolescents and is characterized by early metastasis. High-mobility group N (HMGN) domains are involved in the development of several tumors. Our previous study found that HMGN5 is highly expressed in osteosarcoma tissues and knockdown of HMGN5 inhibits migration and invasion of U-2 OS and Saos-2 cells. A hypoxic environment is commonly found in solid tumors such as osteosarcoma and is likely to be associated with tumor metastasis, so we further explored the relationship between HMGN5 and the hypoxic environment. Hypoxia-inducible factor 1A (HIF1A) is an adaptive factor in the hypoxic environment. We found that HIF1A and HMGN5 were upregulated in osteosarcoma (OS) cells cultured in the hypoxic environment, and the results of overexpression and knockdown experiments showed that HIF1A upregulated the transcription factor GATA1 and further promoted the expression of HMGN5. In addition, MMP2 and MMP9 were subsequently upregulated through the c-jun pathway, and finally, this promoted the migration and invasion of OS cells. It is suggested that HMGN5 may be an important downstream factor for HIF1A to promote osteosarcoma metastasis. It has an important clinical significance for the selection of therapeutic targets for osteosarcoma.

Surgical Outcomes and Risk Analysis of Primary Pulmonary Sarcoma

BACKGROUND

Primary pulmonary sarcoma (PPS) is a rare malignant lung neoplasm, and there is very little medical evidence about treatment of PPS. The aim of this study is to clarify the clinical characteristics and therapeutic outcome of patients who underwent surgical resection for PPS.

METHODS

We retrospectively reviewed the records of patients who underwent surgical resection for PPS in our institution between 1995 and 2014. Cases who only underwent biopsy were excluded.

RESULTS

A total of 24 patients (18 males, 6 females), with a median age of 60 (interquartile range: 44-67) years, were analyzed. The surgical procedures performed in these patients were pneumonectomy (n = 10), lobectomy (n = 11), and wedge resection (n = 3). Complete resection was achieved in 16 patients. The pathological stages (tumor, node, metastases lung cancer classification, 8th edition) of the patients were I (n = 4), II (n = 12), III (n = 2), and IV (n = 5), and there were four cases of lymph node metastasis. The 5-year overall survival rate of the patients was 50% (95% confidence interval [CI]: 29-72). Adverse prognostic factors for overall survival were incomplete resection (hazard ratio [HR]: 4.4, 95% CI: 2.1-42), advanced pathological stage (HR 14, 95% CI: 2.8-66), higher pathological grade (HR 4.5, 95% CI: 1.2-17), and tumor size ≥ 7 cm (HR 4.7, 95% CI: 1.1-21).

CONCLUSIONS

Our series of PPS revealed that incomplete resection, advanced pathological stage, higher pathological grade, and tumor size were unfavorable factors for long-term survival.

[Is there a magic bullet for sarcomas? : Personalised treatment for maligant tumours of bone and soft tissue]

BACKGROUND

Personalised tumour therapies aim to selectively target pathways and structures to which a tumour shows an oncogenic addiction.

OBJECTIVE AND METHOD

This article aims to provide an overview of relevant genetic alterations in bone and soft-tissue tumours, which might serve as potential therapeutic targets for personalised medicines in the future. Recent approaches towards a personalised treatment of various tumours of bone and soft tissues are reviewed.

RESULTS

Molecular diagnosis has become an essential tool for the characterisation of bone and soft-tissue tumours. Currently, no targeted therapies are routinely available for bone sarcomas. Denosumab is merely a symptomatic treatment for giant cell tumours of the bone. Imatinib has become the paradigm of a targeted treatment for subgroups of malignant gastrointestinal stromal tumours (GISTs) and dermatofibrosarcoma protuberans. Antiangiogenic multikinase inhibitors, various other tyrosine kinase inhibitors (TKIs) and monoclonal antibodies are currently being evaluated in several (sub-)types of soft-tissue sarcomas. Sorafenib showed promising results in the treatment of aggressive desmoid-type fibromatosis. Histology-tailored chemotherapies did not yield superior results in a prospective randomised multicentre trial.

CONCLUSION

More in-depth knowledge is required for many sarcomas to link their genetic alterations to tumorigenesis in order to develop efficient personalised treatment strategies. Clinical trial designs need to be adapted to evaluate new therapeutic strategies in these ultra-rare tumours and their various sub-types more efficaciously.

The clinical prognostic significance of ezrin in patients with bone and soft tissue sarcomas: a meta-analysis

Ezrin is a member of the ezrin–radixin–moesin (ERM) protein family and has been shown to be associated with poor prognosis in patients with a variety of solid tumors. However, the clinical prognostic significance of ezrin in patients with bone and soft tissue sarcomas remains unclear. Here, we performed a systematic meta‐analysis by searching PubMed, the Cochrane Library Database, EMBASE, the Web of Science, and the CBM, WanFang Med Online and CNKI databases. In total, 19 studies with a total of 1316 bone and soft tissue sarcoma patients were included. Pooled analyses showed that ezrin overexpression was correlated with a higher rate of tumor metastasis (OR 6.59, 95% CI: 2.84–15.33, P < 0.01, P_FDR < 0.01) and recurrence (OR 3.18, 95% CI: 1.88–5.37, P < 0.01, P_FDR < 0.01) and a more advanced tumor grade (OR 3.252, 95% CI: 1.371–7.715, P = 0.01, P_FDR = 0.03). Moreover, elevated ezrin expression could predict poor OS (HR 3.02, 95% CI: 2.35–3.89, P < 0.01, P_FDR < 0.01), MFS (HR 5.22, 95% CI: 2.08–13.08, P < 0.01, P_FDR < 0.01), and EFS (HR 1.07, 95% CI: 1.03–1.11, P < 0.01, P_FDR < 0.01). Subgroup analyses revealed the underlying sources of heterogeneity. Publication bias was observed in the analysis of metastasis. Sensitivity analysis revealed that the results were robust. Our findings indicated that ezrin overexpression was significantly correlated with poor survival and more advanced tumor progression in bone and soft tissue sarcomas, which suggests that ezrin might be a valuable prognostic biomarker and a potential therapeutic target.

Safety and efficacy of combination therapy with apatinib and doxorubicin in metastatic soft tissue sarcomas: an observational study from multiple institutions

Purpose: Apatinib has shown effectiveness in treating sarcoma. This study aimed to assess the safety and efficacy of apatinib and doxorubicin combination therapy in metastatic soft tissue sarcomas (STS) and to compare the therapeutic effects of two treatments (apatinib after doxorubicin vs apatinib plus doxorubicin) on STS.

Patients and methods: A total of 76 patients with metastatic STS who received apatinib and doxorubicin between May 2016 and June 2017 were retrospectively reviewed. Patients were divided into either the apatinib after doxorubicin group (in which apatinib was used after six cycles of doxorubicin chemotherapy) or the apatinib plus doxorubicin group (in which apatinib was used in combination with doxorubicin chemotherapy).

Results: There were 55 patients in the apatinib after doxorubicin group and 21 patients in the apatinib plus doxorubicin group. There were significant differences between the apatinib plus doxorubicin group and the apatinib after doxorubicin group in the objective response rate (57.14% vs 25.45%, respectively, p=0.016) and average change from baseline in the target lesion size (−41.71±43.75% vs −1.89±51.61%, respectively, p=0.03). There were no significant differences in disease control rate (85.71% vs 63.64%, p=0.093) and median progression-free survival (8.8 months vs 10.3 months, p=1). Grade 3–4 adverse events were more common with apatinib plus doxorubicin than with apatinib after doxorubicin, and these included leukopenia (5.45% vs 38.1%, respectively, p=0.001), anemia (7.27% vs 28.57%, respectively, p=0.023), oral mucositis (3.64% vs 19.05%, respectively, p=0.046), transaminase increases (0% vs 14.29%, respectively, p=0.011).

Conclusion: Our results do not support the use of apatinib plus doxorubicin for metastatic STS unless the specific objective is tumor shrinkage.

Trends in practice patterns and outcomes: A decade of sarcoma care in the United States

BACKGROUND

Soft tissue sarcomas (STS) represent a rare and heterogeneous group of tumors. We sought to characterize national trends in referral patterns, treatment strategies, and overall survival (OS) over the course of a decade.

METHODS

Adult patients with extra-abdominal STS were identified using the National Cancer Database and categorized by diagnosis year (2005-2009 and 2010-2014). High-volume hospitals (HVH) were defined as those >90^th percentile in volume of STS patients treated, and others were defined as low-volume hospitals (LVH). Standard statistical methods were used to compare treatment strategies and OS by diagnosis period.

RESULTS

Of 55,212 patients, 25,469 (46.1%) were diagnosed in 2005-2009 and 29,743 (53.9%) in 2010-2014. Despite increased utilization of neoadjuvant radiation therapy (26.6% vs. 34.8%, P < 0.001), the rate of R0 resections did not change (75.0% vs. 74.8%, P = 0.067). Furthermore, at a national level, OS did not improve over time (HR 0.99, 95% CI 0.96-1.01). When outcomes were stratified by volume, treatment at HVH compared to LVH was associated with improved rates of R0 resection (OR 1.27, 95% CI 1.20-1.35) and OS (HR 0.92, 95% CI 0.89-0.95). Moreover, there was a modest improvement in OS at HVH (HR 0.95, 95% CI 0.91-1.00), but not at LVH (HR 1.01, 95% CI 0.97-1.04). However, referral to HVH did not change over time (40.7% vs. 40.7%, P = 0.91).

CONCLUSION

OS for STS did not change at a national level over the course of a decade, although it improved at HVH. Further outcome improvements will likely require more effective systemic therapies.

Axitinib plus pembrolizumab in patients with advanced sarcomas including alveolar soft-part sarcoma: a single-centre, single-arm, phase 2 trial

BACKGROUND

VEGF promotes an immunosuppressive microenvironment and contributes to immune checkpoint inhibitor resistance in cancer. We aimed to assess the activity of the VEGF receptor tyrosine-kinase inhibitor axitinib plus the anti-PD-1 immune checkpoint inhibitor pembrolizumab in patients with sarcoma.

METHODS

This single-centre, single-arm, phase 2 trial was undertaken at a tertiary care academic medical centre in Miami, FL, USA, and participants were recruited from all over the USA and internationally. Patients were eligible if they were aged 16 years or older, and had histologically confirmed advanced or metastatic sarcomas, including alveolar soft-part sarcoma (ASPS); measurable disease with one site amenable to repeated biopsies; an ECOG performance status of 0-1; and progressive disease after previous treatment with at least one line of systemic therapy (unless no standard treatment existed or the patient declined therapy). The first five patients were enrolled in a lead-in cohort and were given axitinib 5 mg orally twice daily and pembrolizumab 200 mg intravenously for 30 min on day 8 and every 3 weeks for cycles of 6 weeks for up to 2 years. Thereafter, patients received escalating doses of axitinib (2-10 mg) plus flat dose pembrolizumab according to the schedule above. The primary endpoint was 3-month progression-free survival. All patients were evaluable for survival and safety analyses. This study is registered with ClinicalTrials.gov, number NCT02636725, and is closed to accrual.

FINDINGS

Between April 19, 2016, and Feb 7, 2018, of 36 patients assessed for eligibility, 33 (92%) were enrolled and given study treatment (intention-to-treat population and safety population), 12 (36%) of whom had ASPS. With a median follow-up of 14·7 months (IQR 10·1-19·1), 3-month progression-free survival for all evaluable patients was 65·6% (95% CI 46·6-79·3). For patients with ASPS, 3-month progression-free survival was 72·7% (95% CI 37·1-90·3). The most common grade 3 or 4 treatment-related adverse events included hypertension (five [15%] of 33 patients), autoimmune toxicities (five [15%]), nausea or vomiting (two [6%]), and seizures (two [6%]). Serious treatment-related adverse events occurred in seven (21%) patients, including autoimmune colitis, transaminitis, pneumothorax, haemoptysis, seizures, and hypertriglyceridemia. There were no treatment-related deaths.

INTERPRETATION

Axitinib plus pembrolizumab has manageable toxicity and preliminary activity in patients with advanced sarcomas, particularly patients with ASPS, warranting further investigation in randomised controlled trials.

FUNDING

Merck, Pfizer, American Cancer Society, and Sylvester Comprehensive Cancer Center.

Drug sensitivity testing on patient-derived sarcoma cells predicts patient response to treatment and identifies c-Sarc inhibitors as active drugs for translocation sarcomas

Background

Heterogeneity and low incidence comprise the biggest challenge in sarcoma diagnosis and treatment. Chemotherapy, although efficient for some sarcoma subtypes, generally results in poor clinical responses and is mostly recommended for advanced disease. Specific genomic aberrations have been identified in some sarcoma subtypes but few of them can be targeted with approved drugs.

Methods

We cultured and characterised patient-derived sarcoma cells and evaluated their sensitivity to 525 anti-cancer agents including both approved and non-approved drugs. In total, 14 sarcomas and 5 healthy mesenchymal primary cell cultures were studied. The sarcoma biopsies and derived cells were characterised by gene panel sequencing, cancer driver gene expression and by detecting specific fusion oncoproteins in situ in sarcomas with translocations.

Results

Soft tissue sarcoma cultures were established from patient biopsies with a success rate of 58%. The genomic profile and drug sensitivity testing on these samples helped to identify targeted inhibitors active on sarcomas. The cSrc inhibitor Dasatinib was identified as an active drug in sarcomas carrying chromosomal translocations. The drug sensitivity of the patient sarcoma cells ex vivo correlated with the response to the former treatment of the patient.

Conclusions

Our results show that patient-derived sarcoma cells cultured in vitro are relevant and practical models for genotypic and phenotypic screens aiming to identify efficient drugs to treat sarcoma patients with poor treatment options.

Investigating a chimeric anti-mouse PDGFRα antibody as a radiosensitizer in primary mouse sarcomas

BACKGROUND

Olaratumab (LY3012207/IMC-3G3/Lartruvo™) is a fully human monoclonal antibody specific for platelet-derived growth factor receptor alpha (PDGFRα). Phase Ib/II trial results of olaratumab plus doxorubicin in adult patients with advanced soft tissue sarcoma (STS) supported accelerated FDA approval of this regimen. Radiation therapy (RT) is frequently used for high-risk localized STS. However, olaratumab has not been tested with concurrent RT. Here, we evaluate the chimeric anti-mouse PDGFRα antibody 1E10Fc as a radiosensitizer in a primary mouse model of STS.

METHODS

Primary STS were initiated in mice. When tumors reached 70 mm³, mice were allocated into treatment groups: 1) isotype, 2) 1E10Fc, 3) isotype + RT, 4) 1E10Fc + RT. 1E10Fc or isotype was given biweekly. RT (25 Gy delivered in 5 daily 5 Gy fractions) was initiated on Day 0 with first drug treatment. Tumors were measured 3× per week. Upon reaching 900 mm³, tumors and lungs were harvested. A two-way ANOVA was performed to compare tumor growth delay. Primary tumors were stained for CD31 and PDGFRα and lungs were assessed for micrometastases. A Chi-square test was performed to compare the development of micrometastases in the lungs after treatment with 1E10Fc or isotype.

FINDINGS

RT significantly delayed time to tumor quintupling compared to no RT (p < 0·0001) [two-way ANOVA], but no difference in tumor growth was seen between mice receiving isotype or 1E10Fc treatment regardless of concurrent RT. Lower microvessel density was observed in the 1E10Fc + RT group. Fewer mice treated with 1E10Fc had micrometastases, but this difference was not statistically significant (p < 0·09).

INTERPRETATION

1E10Fc did not act as a radiosensitizer in this primary STS model.

FUNDING

This study was funded by a research agreement from Eli Lilly and Company.