Kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) is a novel human lymphotropic herpesvirus linked to several human neoplasms. To date, no animal model for infection by this virus has been described. We have examined the susceptibility of C.B-17 scid/scid mice implanted with human fetal thymus and liver grafts (SCID-hu Thy/Liv mice) to KSHV infection. KSHV virions were inoculated directly into the implants, and viral DNA and mRNA production was assayed using real-time quantitative polymerase chain reaction. This revealed a biphasic infection, with an early phase of lytic replication accompanied and followed by sustained latency. Ultraviolet irradiation of the inoculum abolished all DNA- and mRNA-derived signals, and infection was inhibited by ganciclovir. Viral gene expression was most abundant in CD19(+) B lymphocytes, suggesting that this model faithfully mimics the natural tropism of this virus. Short-term coinfection with HIV-1 did not alter the course of KSHV replication, nor did KSHV alter levels of HIV-1 p24 during the acute phase of the infection. Although no disease was evident in infected animals, SCID-hu Thy/Liv mice should allow the detailed study of KSHV tropism, latency, and drug susceptibility.

Prognosis of patients with lung metastases of soft-tissue sarcoma is still poor. Therefore, novel systemic therapy is needed to improve the survival of soft-tissue sarcoma. In the present study, tumor-targeting therapy with a genetically-modified auxotrophic strain of Salmonella typhimurium, termed A1-R, was evaluated. Mouse models of primary soft tissue sarcoma and spontaneous lung metastasis were obtained by orthotopic intra-muscular injection of HT1080-RFP human fibrosarcoma cells. S. typhimurium A1-R was administered from day 14, once a week for two weeks. On day 28, lung samples were excised and observed with a fluorescence imaging system. The number of lung metastasis was 8.8 ± 3.4 in the untreated group and 0.8 ± 0.8 in the treated group (P = 0.024). A mouse model of experimental lung metastasis was obtained by tail vein injection of HT1080-RFP cells. The mice were treated with S. typhimurium A1-R (i.v.) on day 7, once a week for three weeks. S. typhimurium A1-R significantly reduced lung metastases and improved overall survival (P = 0.004). S. typhimurium A1-R bacterial therapy has future potential for treating advanced soft tissue sarcoma and improving prognosis of patients with lung metastasis.

Ferroptosis regulators have been found to affect tumor progression. However, studies focusing on ferroptosis and soft tissue sarcoma (STS) are rare. Somatic mutation, copy number variation, reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis, consensus clustering, differentially expressed genes analysis (DEGs), principal component analysis (PCA) and gene set enrichment analysis (GSEA) were used to identify and explore different ferroptosis modifications in STS. A nomogram was constructed to predict the prognosis of STS. Moreover, three immunotherapy datasets were used to assess the Fescore. Western blotting, siRNA transfection, EdU assay and reactive oxygen species (ROS) measurement were performed. 16 prognostic ferroptosis regulators were screened and significant differences were observed in somatic mutation, copy number variation (CNV) and RT-qPCR among these ferroptosis regulators. 2 different ferroptosis modification patterns were found (Fe cluster A and B). Fe cluster A with higher Fescore was correlated with p53 pathway and had better prognosis of STS (p = 0.002) while Fe cluster B with lower Fescore was correlated with angiogenesis and MYC pathway and showed a poorer outcome. Besides, the nomogram effectively predicted the outcome of STS and the Fescore could also well predict the prognosis of other 16 tumors and immunotherapy response. Downregulation of LOX also inhibited growth and increased ROS production in sarcoma cells. The molecular characterization of ferroptosis regulators in STS was explored and an Fescore was constructed. The Fescore quantified ferroptosis modification in STS patients and effectively predicted the prognosis of a variety of tumors, providing novel insights for precision medicine.

Myeloid sarcoma (MS) is a rare, extramedullary tumor consisting of myeloid blasts. Little is known about the genetic background of MS and the prognostic value of genetic abnormalities in MS. In particular, the broad variety of gene fusions that occur in MS is marginally covered by traditional testing methods due to lack of fresh tumor specimens.

Macaque RFHV and LCV are close homologs of human KSHV and EBV, respectively. No experimental model of RFHV has been developed due to the lack of a source of culturable infectious virus. Screening of macaques at the Washington National Primate Research Center detected RFHV in saliva of SIV-infected macaques from previous vaccine studies. A pilot experimental infection of two naïve juvenile pig-tailed macaques was initiated by inoculation of saliva from SIV-infected pig-tailed and cynomolgus macaque donors, which contained high levels of DNA (> 10(6) genomes/ml) of the respective species-specific RFHV strain. Both juvenile recipients developed SIV and RFHV infections with RFHV DNA detected transiently in saliva and/or PBMC around week 16 post-infection. One juvenile macaque was infected with the homologous RFHVMn from whole saliva of a pig-tailed donor, which had been inoculated into the cheek pouch. This animal became immunosuppressed, developing simian AIDS and was euthanized 23 weeks after inoculation. The levels of RFHV DNA in saliva and PBMC remained below the level of detection after week 17, showing no reactivation of the RFHVMn infection during the rapid development of AIDS. The other juvenile macaque was infected with the heterologous RFHVMf from i.v. inoculation of purified virions from saliva of a cynomolgus donor. The juvenile recipient remained immunocompetent, developing high levels of persistent anti-RFHV and -SIV antibodies. After the initial presence of RFHVMf DNA in saliva and PBMC decreased to undetectable levels by week 19, all attempts to reactivate the infection through additional inoculations, experimental infection with purified SRV-2 or SIV, or immunosuppressive treatments with cyclosporine or dexamethasone were unsuccessful. An heterologous LCV transmission was also detected in this recipient, characterized by continual high levels of LCVMf DNA from the cynomolgus donor in both saliva (> 10(6) genomes/ml) and PBMC (> 10(4) genomes/million cells), coupled with high levels of anti-LCV antibodies. The macaque was sacrificed 209 weeks after the initial inoculation. Low levels of LCVMf DNA were detected in salivary glands, tonsils and other lymphoid organs, while RFHVMf DNA was below the level of detection. These results show successful co-transmission of RFHV and LCV from saliva and demonstrate differential lytic activation of the different gammaherpesvirus lineages due to presumed differences in biology and tropism and control by the host immune system. Although this initial pilot transmission study utilized only two macaques, it provides the first evidence for experimental transmission of the macaque homolog of KSHV, setting the stage for larger transmission studies to examine the differential activation of rhadinovirus and lymphocryptovirus infections and the pathological effects of immunosuppression.

Sarcomas are heterogeneous malignant tumors of mesenchymal origin characterized by more than 100 distinct subtypes. Unfortunately, 25-50% of patients treated with initial curative intent will develop metastatic disease. In the metastatic setting, chemotherapy rarely leads to complete and durable responses; therefore, there is a dire need for more effective therapies. Exploring immunotherapeutic strategies may be warranted. In the past, agents that stimulate the immune system such as interferon and interleukin-2 have been explored and there has been evidence of some clinical activity in selected patients. In addition, many cancer vaccines have been explored with suggestion of benefit in some patients. Building on the advancements made in other solid tumors as well as a better understanding of cancer immunology provides hope for the development of new and exciting therapies in the treatment of sarcoma. There remains promise with immunologic checkpoint blockade antibodies. Further, building on the success of autologous cell transfer in hematologic malignancies, designing chimeric antigen receptors that target antigens that are over-expressed in sarcoma provides a great deal of optimism. Exploring these avenues has the potential to make immunotherapy a real therapeutic option in this orphan disease.

Background: Soft-tissue sarcoma (STS) is a heterogeneous group of sarcomas with a low incidence. The treatment of advanced disease is poor, and mortality is high. We aimed to generate an overview of the clinical experiences with targeted treatments based on a pre-specified target in patients with STS. Methods: A systematic literature search was conducted in PubMed and Embase databases. The programs ENDNOTE and COVIDENCE were used for data management. The literature was screened to assess the article's eligibility for inclusion. Results: Twenty-eight targeted agents were used to treat 80 patients with advanced STS and a known pre-specified genetic alteration. MDM2 inhibitors were the most-studied drug (n = 19), followed by crizotinib (n = 9), ceritinib (n = 8), and 90Y-OTSA (n = 8). All patients treated with the MDM2 inhibitor achieved a treatment response of stable disease (SD) or better with a treatment duration of 4 to 83 months. For the remaining drugs, a more mixed response was observed. The evidence is low because most studies were case reports or cohort studies, where only a few STS patients were included. Conclusions: Many targeted agents can precisely target specific genetic alterations in advanced STS. The MDM2 inhibitor has shown promising results.

The prognosis of patients with Ewing sarcoma (ES) has improved over the course of the last decades. However, those patients suffering from metastatic and recurrent ES still have only poor chances of survival and require new therapeutic approaches. Interleukin-6 (IL6) is a pleiotropic cytokine expressed by immune cells and a great variety of cancer cells. It induces inflammatory responses, enhances proliferation and inhibits apoptosis in cancer cells, thereby promoting chemoresistance.

Ewing sarcoma (EWS) is a pediatric malignancy driven by the EWSR1-FLI1 fusion protein formed by the chromosomal translocation t(11; 22). The small molecule TK216 was developed as a first-in-class direct EWSR1-FLI1 inhibitor and is in phase II clinical trials in combination with vincristine for patients with EWS. However, TK216 exhibits anti-cancer activity against cancer cell lines and xenografts that do not express EWSR1-FLI1, and the mechanism underlying cytotoxicity remains unresolved. We apply a forward-genetics screening platform utilizing engineered hypermutation in EWS cell lines and identify recurrent mutations in TUBA1B, encoding ⍺-tubulin, that prove sufficient to drive resistance to TK216. Using reconstituted microtubule (MT) polymerization in vitro and cell-based chemical probe competition assays, we demonstrate that TK216 acts as an MT destabilizing agent. This work defines the mechanism of cytotoxicity of TK216, explains the synergy observed with vincristine, and calls for a reexamination of ongoing clinical trials with TK216.

As a developing region, Latin America faces unique cancer control and prevention challenges, which are intensified when considering rare cancers, including sarcomas. Sarcomas are a group of malignancies that arise in the connective tissues of the body-such as muscle, fat, nerves, blood vessels, and bones-accounting for a diverse range of tumours that, although rare, require specialized attention. Sarcoma care and research in Latin America require a comprehensive approach that includes deeper epidemiologic knowledge, diagnostic capacity building, access to innovative treatments, increased patient advocacy, and strengthening of clinical research capacity. This article will review current challenges and opportunities for treating patients with sarcoma in Latin America and outline a pathway toward improvement for regional collaborative groups.

Vaginal endometrial stromal sarcoma (VESS) is a rare disease. To the best of our knowledge, there have only been a few reported cases in the literature. Therefore, we conducted a literature review to obtain specific knowledge of this disease. Thirteen cases of VESS were found by searching the Medline and EMBASE databases in the English language. The mechanism of VESS may be associated with endometriosis, and its diagnosis largely depends on pathological examination because it has no typical symptoms. Treatment of VESS incorporates surgery, chemotherapy, radiotherapy, and hormonal therapy. Some novel drugs targeting its mechanism may become alternative therapies. Its prognostic factors may include tumor stage and the expression of hormonal receptors.

Personalised oncology is at the forefront of cancer research. The goal of personalised oncology is to selectively kill cancer cells while minimising side effects on normal tissue. This can be achieved by identifying and targeting cancer vulnerabilities that distinguish it from normal cells. Many cancers are deficient in high-fidelity DNA repair pathways that maintain genomic stability, such as homologous recombination (HR). Such cancers are highly sensitive to targeted therapies that induce DNA damage or inhibit DNA repair pathways. A notable example and a poster child of personalised oncology are PARP1/2 inhibitors (PARPi) that selectively kill HR-deficient (HRD) cancer cells by preventing repair of DNA gaps or single-strand breaks (SSBs) (Slade, 2020). Inhibitors of cell cycle checkpoints such as CHK1 and WEE1 can also eliminate HRD cancers by pushing cancer cells through the cell cycle despite unrepaired DNA damage and causing death by mitotic catastrophe (Groelly et al, 2022). PARPi have been approved for the treatment of ovarian, breast, pancreatic, and prostate cancer but other cancer types with an HRD signature (HRDness) may also respond to PARPi treatment. Planas-Paz et al (2023) now show that many sarcomas show HRDness and respond to PARP1/2 and WEE1 inhibitors, thus offering a new personalised oncology approach for this treatment-refractory cancer.

Spontaneous lytic reactivation of Kaposi's sarcoma-associated herpesvirus (KSHV) occurs at a low rate in latently infected cells in disease and culture. This suggests imperfect epigenetic maintenance of viral transcription programs, perhaps due to variability in chromatin structure at specific loci across the population of KSHV episomal genomes. To characterize this locus-specific chromatin structural diversity, we used MAPit single-molecule footprinting, which simultaneously maps endogenous CG methylation and accessibility to M.CviPI at GC sites. Diverse chromatin structures were detected at the LANA, RTA and vIL6 promoters. At each locus, chromatin ranged from fully closed to fully open across the population. This diversity has not previously been reported in a virus. Phorbol ester and RTA transgene induction were used to identify chromatin conformations associated with reactivation of lytic transcription, which only a fraction of episomes had. Moreover, certain chromatin conformations correlated with CG methylation patterns at the RTA and vIL6 promoters. This indicated that some of the diverse chromatin conformations at these loci were epigenetically distinct. Finally, by comparing chromatin structures from a cell line infected with constitutively latent virus, we identified products of lytic replication. Our findings show that epigenetic drift can restrict viral propagation by chromatin compaction at latent and lytic promoters.

Sarcomas are heterogeneous and clinically challenging soft tissue and bone cancers. Although constituting only 1% of all human malignancies, sarcomas represent the second most common type of solid tumors in children and adolescents and comprise an important group of secondary malignancies. More than 100 histological subtypes have been characterized to date, and many more are being discovered due to molecular profiling. Owing to their mostly aggressive biological behavior, relative rarity, and occurrence at virtually every anatomical site, many sarcoma subtypes are in particular difficult-to-treat categories. Current multimodal treatment concepts combine surgery, polychemotherapy (with/without local hyperthermia), irradiation, immunotherapy, and/or targeted therapeutics. Recent scientific advancements have enabled a more precise molecular characterization of sarcoma subtypes and revealed novel therapeutic targets and prognostic/predictive biomarkers. This review aims at providing a comprehensive overview of the latest advances in the molecular biology of sarcomas and their effects on clinical oncology; it is meant for a broad readership ranging from novices to experts in the field of sarcoma.

A review is made of the clinical, diagnostic, therapeutic and survival characteristics of Ewing sarcoma (ES) of the oral cavity.

Pelvic sarcoma is associated with a relatively poor prognosis, due to the difficulty in obtaining an adequate surgical margin given the complex pelvic anatomy. Magnetic resonance imaging and computerized tomography allow valuable surgical resection planning, but intraoperative localization remains hazardous. Surgical navigation systems could be of great benefit in surgical oncology, especially in difficult tumor location; however, no commercial surgical oncology software is currently available. A customized navigation software was developed and used to perform a synovial sarcoma resection and allograft reconstruction. The software permitted preoperative planning with defined target planes and intraoperative navigation with a free-hand saw blade. The allograft was cut according to the same planes. Histological examination revealed tumor-free resection margins. Allograft fitting to the pelvis of the patient was excellent and allowed stable osteosynthesis. We believe this to be the first case of combined computer-assisted tumor resection and reconstruction with an allograft.

Calcium electroporation (CaEP) describes the use of electric pulses (electroporation) to transiently permeabilize cells to allow supraphysiological doses of calcium to enter the cytosol. Calcium electroporation has successfully been investigated for treatment of cutaneous metastases in a clinical study. This preclinical study explores the possible use of calcium electroporation for treatment of sarcoma. A normal murine muscle cell line (C2C12), and a human rhabdomyosarcoma cell line (RD) were used in the undifferentiated and differentiated state. Electroporation was performed using 8 pulses of 100 μs at 600-1000 V/cm; with calcium (0, 0.5, 1, and 5 mM). Viability was examined by MTS assay, intracellular calcium levels were measured, and expression of plasma membrane calcium ATPase (PMCA) was investigated using western blotting. Calcium/sodium exchanger (NCX1), ryanodine receptor (RyR1) expression and cytoskeleton structure (zyxin/actin) were assessed by immunofluorescence. CaEP efficiency on RD tumors was tested in vivo in immuno-deficient mice. CaEP was significantly more efficient in RD than in normal cells. Intracellular Ca2+ levels after CaEP increased significantly in RD, whereas a lower increase was seen in normal cells. CaEP caused decreased expression of PMCA and NCX1 in malignant cells and RyR1 in both cell lines whereas normal cells exhibited increased expression of NCX1 after CaEP. Calcium electroporation also affected cytoskeleton structure in malignant cells. This study showed that calcium electroporation is tolerated significantly better in normal muscle cells than sarcoma cells and as an inexpensive and simple cancer treatment this could potentially be used in connection with sarcoma surgery for local treatment.

Myeloid sarcomas are extramedullary accumulations of immature myeloid cells that may present with or without evidence of pathologic involvement of the bone marrow or peripheral blood, and often coincide with or precede a diagnosis of acute myeloid leukemia (AML). A dearth of experimental models has hampered the study of myeloid sarcomas and led us to establish a new system in which tumor induction can be evaluated in an easily accessible non-hematopoietic tissue compartment. Using ex-vivo transduction of oncogenic Kras(G12V) into p16/p19(-/-) bone marrow cells, we generated transplantable leukemia-initiating cells that rapidly induced tumor formation in the skeletal muscle of immunocompromised NOD.SCID mice. In this model, murine histiocytic sarcomas, equivalent to human myeloid sarcomas, emerged at the injection site 30-50 days after cell implantation and consisted of tightly packed monotypic cells that were CD48+, CD47+ and Mac1+, with low or absent expression of other hematopoietic lineage markers. Tumor cells also infiltrated the bone marrow, spleen and other non-hematopoietic organs of tumor-bearing animals, leading to systemic illness (leukemia) within two weeks of tumor detection. P16/p19(-/-); Kras(G12V) myeloid sarcomas were multi-clonal, with dominant clones selected during secondary transplantation. The systemic leukemic phenotypes exhibited by histiocytic sarcoma-bearing mice were nearly identical to those of animals in which leukemia was introduced by intravenous transplantation of the same donor cells. Moreover, murine histiocytic sarcoma could be similarly induced by intramuscular injection of MLL-AF9 leukemia cells. This study establishes a novel, transplantable model of murine histiocytic/myeloid sarcoma that recapitulates the natural progression of these malignancies to systemic disease and indicates a cell autonomous leukemogenic mechanism.

Synovial sarcoma (SS) is a rare and aggressive disease that accounts for 5%-10% of all soft tissue sarcomas. Although it can occur at any age, it typically affects younger adults and children, with a peak incidence in the fourth decade of life. In >95% of cases, the oncogenic driver is a translocation between chromosomes X and 18 that leads to the formation of the SS18::SSX fusion oncogenes. Early and accurate diagnosis is often a challenge; optimal outcomes are achieved by referral to a specialist center for diagnosis and management by a multidisciplinary team as soon as SS is suspected. Surgery with or without radiotherapy and/or chemotherapy can be effective in localized disease, especially in children. However, the prognosis in the advanced stages is poor, with treatment strategies that have relied heavily on traditional cytotoxic chemotherapies. Therefore, there is an unmet need for novel effective management strategies for advanced disease. An improved understanding of disease pathology and its molecular basis has paved the way for novel targeted agents and immunotherapies that are being investigated in clinical trials. This review provides an overview of the epidemiology and characteristics of SS in children and adults, as well as the patient journey from diagnosis to treatment. Current and future management strategies, focusing particularly on the potential of immunotherapies to improve clinical outcomes, are also summarized.

Alternative endpoints to overall survival (OS) are frequently used to assess treatment efficacy in randomized controlled trials (RCT). Their properties in terms of surrogate outcomes for OS need to be assessed. We evaluated the surrogate properties of progression-free survival (PFS), time-to-progression (TTP) and time-to-treatment failure (TTF) in advanced soft tissue sarcomas (STS).