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Background: The Children's Oncology Group clinical trial for intermediate risk rhabdomyosarcoma randomized participants to a combination of vincristine, dactinomycin, and cyclophosphamide (VAC) alone or VAC alternating with vincristine plus irinotecan (VAC/VI). Clinical outcomes were similar, but toxicity profiles differed. This study estimates the cost differences between arms from the health care system's perspective., Methods: A decision-analytic model was used to estimate the incremental cost-effectiveness ratio (ICER) of VAC versus VAC/VI. Protocol-required or recommended medications and laboratory studies were included. Costs were obtained from national databases or supporting literature and inflated to 2019 US dollars. Demographic and outcome data were obtained from the clinical trial and directed chart reviews. Life-years (LY) were estimated from life-expectancy tables and discounted by 3% annually. Probabilistic sensitivity analyses and alternative clinical scenarios identified factors driving costs., Results: Mean direct medical costs of VAC and VAC/VI were $164,757 and $102,303, respectively. VAC was associated with an additional 0.97 LY and an ICER of $64,386/LY compared with VAC/VI. The ICER was sensitive to survival estimations and to alternative clinical scenarios including outpatient cyclophosphamide delivery (ICER $49,037/LY) or substitution of alternative hematopoietic growth factor schedules (ICER $73,191-$91,579/LY). Applying drug prices from 2012 decreased the total costs of VAC by 20% and VAC/VI by 15% because of changes in dactinomycin and pegfilgrastim prices., Conclusions: Neither arm was clearly more cost-effective. Pharmaceutical pricing and location of treatment drove costs and may inform future treatment decisions. Rising pharmaceutical costs added $30,000 per patient, a finding important for future drug-pricing policy decisions., Lay Summary: Two chemotherapy regimens recently tested side-by-side for rhabdomyosarcoma had similar tumor outcomes, but different side effects. The health care costs of each regimen were compared; neither was clearly more cost-effective. However, the costs of each treatment changed dramatically with choices of supportive medicines and location of treatment. Costs of treatment rose by 15% to 20% because of rising US drug costs not associated with the clinical trial., (© 2021 American Cancer Society.)

Objective: This study aims to investigate the characteristics and related high risk factors of second neoplasms after chemotherapy and radiotherapy in children with solid tumors., Methods: The detailed clinical data of seven children with malignant solid tumors, who were treated in our department, were retrospectively analyzed, in order to summarize the clinical characteristics of the secondary onset of second neoplasms, and determined the risk factors related to the occurrence of second neoplasms., Results: (1) Clinical characteristics: Among the seven children with malignant solid tumors, three children had rhabdomyosarcoma (3/132, 2.27%), two children had hepatoblastoma (2/313, 0.64%), one child had neuroblastoma (1/305, 0.33%), and one child had inflammatory myofibroblastoma (1/3, 33.33%). Furthermore, among these children, four children were boys and three children were girls, and their onset age ranged within 5-34 months, with a median onset age of 27 months. Moreover, among these children, three children were ≤1 year old. All second neoplasms exhibited symptoms, and the diagnosis was made after the complete remission of the first primary tumor. The time interval between these two tumors was within 17-78 months, and the median time was 38 months. Three of seven children with rhabdomyosarcoma were treated with chemotherapy in combination with radiotherapy, while four children only received the chemotherapy. The chemotherapy cycles were 6-39 times, and the median chemotherapy cycles were 10 times. Among these children, one child with relapsed stage IV rhabdomyosarcoma and one child with stage IV retroperitoneal neuroblastoma had 39 cycles and 33 cycles of chemotherapy respectively. (2) Characteristics of the accumulated doses of high-risk chemotherapy drugs: The accumulated dose of cyclophosphamide in six patients was within 2.47-44.45 g/m2, with a median of 6.14 g/m2. The accumulated dose of ifosfamide in five patients was within 13.63-96.41 mg/m2, with a median of 31.23g/m2. The accumulated dose of etoposide in six patients was within 1,237.35-3,754.95 mg/m2, with a median of 1,548.67 mg/m2. The accumulated dose of anthracyclines in seven patients was within 150.68-843.78 mg/m2, with a median of 329.73 mg/m2. The accumulated dose of vincristine in seven patients was within 3.11-18.89 mg/m2, with a median of 15.92 mg/m2. The accumulated dose of cisplatin in seven patients was within 271.23-1,681.59 mg/m2, with a median of 733.07 mg/m2. Children with abdominal inflammatory myofibroblastic tumors did not apply cyclophosphamide, ifosfamide and etoposide regimens. The main chemotherapy drugs consisted of methotrexate, pirarubicin, cisplatin and vincristine. (3) Radiotherapy doses. (4) Characteristics of second neoplasms: Among the seven children with second neoplasms, five children had leukemia, 3 patients with rhabdomyosarcoma were combined with radiotherapy. The doses of radiation were 40 and 45GY" after "(3) Radiotherapy doses (four children had acute myeloid leukemia and one children had acute B-lymphoblastic leukemia), one child had myelodysplastic syndrome, and one child had myeloid sarcoma. Furthermore, among these seven children, four children (4/7) had abnormal chromosomes, two children were normal, and one child gave up the treatment and underwent the chromosome test after the diagnosis of second neoplasms., Conclusion: The incidence of secondary onset of second neoplasms in children with malignant solid tumors is not high, considering that this is correlated to the use of alkylating agents, topoisomerase II inhibitors, platinum-based chemotherapy drugs and radiotherapy, and associated with the chromosomal abnormalities of children., Key Words: Chemotherapy, Children, Radiotherapy, Second malignant neoplasm, Solid tumor.

Background: Infants (<12 months) with rhabdomyosarcoma have historically had poorer outcome than the older age groups. We present outcomes for infants and young children aged 12-36 months with localised rhabdomyosarcoma with a particular emphasis on infants., Patients and Methods: All children less than 36 months of age enrolled on the EpSSG RMS 2005 study for localised disease are included. Treatment comprised chemotherapy, local surgery and/or radiation therapy adapted to risk group and age. Main outcome measures were event free survival (EFS) and overall survival (OS)., Results: Outcome data were available for 485/490 patients aged less than 36 months, 110 were infants. Infants received chemotherapy according to the risk group with no toxic deaths. Radiotherapy was delivered to 33.6% of infants and 63.5% of 12-36 months old, with respectively 41.7% and 22.2% receiving brachytherapy. Radical surgery was performed in 62% of infants and 57.1% of 12-36 months old. Median follow up for patients who are alive (n = 393) was 72.7 months (range 6.9-158.2). Five-year OS for infants was 88.4% (95%CI 80.3-93.2), which is significantly better than the OS in 12-36 months old patients of 78.0% (95%CI 73.2-82.0; p = 0.0204). Five-year EFS for infants was 72.5% (95%CI 62.8-80.0) compared with 66.1% (95%CI 61.0-70.7; p = 0.2663) for 12-36 months old., Conclusion: Infants treated on RMS 2005 achieved excellent EFS and OS. The EpSSG RMS 2005 chemotherapy regimen, combined with an increase in the application of adequate local therapy, improvements in imaging and supportive care and potentially favourable patients' characteristics may have contributed to these results., Competing Interests: Conflict of interest statement The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

We report a case of primary breast rhabdomyosarcoma. A 16-year-old girl noticed tumor of her right breast and consulted a local clinic. From the result of core needle biopsy, breast sarcoma was suspected, so she attended our hospital. Breast ultrasonography showed a mosaic pattern tumor occupying the whole right breast. CT images revealed an axillary node metastasis and no distant organ metastasis. Immunohistochemical staining of the tumor yielded positive results for desmin, MyoD1, and myogenin. Based on reverse transcription polymerase chain reaction(RT-PCR), she was diagnosed as an alveolar rhabdomyosarcoma with PAX3-FKHR(FOXO1)fusion transcripts[t(2;13)(q35;q14)]. She underwent total mastectomy and dissection of axillary lymph nodes. After surgery, the whole-body magnetic resonance imaging(MRI) demonstrated metastases of sacrum and left foot, so she was under systemic chemotherapy.

Background: Chemotherapy for rhabdomyosarcoma (RD) is effective, but it has critical side effects and unavoidable challenges. Photodynamic therapy (PDT) is an approach to treating cancer with relatively moderate side effects. Plant products are a rich source of polyphenols, which have potent antioxidant and anticancer activities. Therefore, their research has become an emerging field in recent decades., Purpose: This work aimed to evaluate the potential of hydrophobic extract of Ficus Carica (FC) to determine whether FC in the presence of low dose chemo and Aluminium Phthalocyanine (Photosense®) mediated photodynamic therapy synergistically enhances the treatment efficacy of RD cells., Method: FC with and without combination with individual therapeutic modalities like photosense mediated photodynamic therapy, chemotherapy, and their combinations were studied for cell viability and morphological changes in invitro RD cells. A semiconductor diode laser (630 nm) was used as a light source in PDT. The cytotoxic effect of FC on cell viability and cellular morphological changes were investigated by MTT reagent and a camera attached to an inverted visible light microscope. The effect of FC, followed by di-combination with low dose chemo (doxorubicin-HCl, and dacarbazine), Photosense® mediated PDT and chemo-Photosense® mediated PDT (tri-combination) at 630 nm diode laser and 10 J/cm 2 fluency were also investigated by MTT reagent. The combination index method is used to identify the synergistic effect of combination therapy by using CompuSyn software based on the Chou-Talalay method., Results: The dose-dependent effect of FC on cell viability and cellular morphological changes were observed in the RD cell line. It was found that the pre incubation of FC potentiated the anticancer effect as a neoadjuvant agent for doxorubicin-HCl and decarbazine based chemotherapy, Photosense® mediated PDT and chemo-PDT (tri-combination) with synergistic effect (CI<1)., Conclusion: These results suggest a possible thread that the low dose combination of the aforementioned therapeutic modalities in the presence of FC remarkably enhances the treatment efficacy of RD in comparison with a single-agent treatment modality. The proposed sequence of FC with chemo and PDT might present better therapeutic outcomes in RD therapies and may provide result for RD metastasis. FC may also be used in the application of phyto-PDT to cancer in the future., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Rhabdomyosarcoma (RMS) is the most commonly occurring malignant soft tissue tumor in children. Despite improving its treatment methods, the current outcome in the advanced stages of this tumor is not satisfactory. RMS cells are characterized by abnormal cellular signaling due to the changes in the activity of the tyrosine kinases. Thus, substances blocking the mitogenic signal transmitted by receptors with tyrosine kinase activity raise hopes for inhibition of the uncontrolled cell growth. In this study, we examined the anticancer activity of tyrphostin AG1296, a tyrosine kinase inhibitor that binds to the intracellular domain of the PDGF (platelet-derived growth factor) receptor in human RMS alveolar and embryonal cell lines. We have discovered that tyrphostin AG1296 completely inhibited cell proliferation and effectively inhibited cell viability. Tyrphostin AG1296 induced apoptosis of the RMS cells and significantly inhibited their migration. Additionally, investigated inhibitor slightly inhibited expression of AKT and phosphorylation of ERK in alveolar RMS cells. Importantly, the inhibitor exerted also potent effects on the nanomechanical properties and cytoskeleton organization of RMS cells. To conclude, tyrphostin AG1296 is a promising compound in the treatment of alveolar RMS. Undoubtedly, a better knowledge of receptor pathomechanism of tyrosine kinases may contribute to developing new, more effective ways of RMS treatment.

The Wnt/β-catenin signaling pathway plays a pivotal role during embryogenesis and its deregulation is a key mechanism in the origin and progression of several tumors. Wnt antagonists have been described as key modulators of Wnt/β-catenin signaling in cancer, with Dickkopf-1 (DKK-1) being the most studied member of the DKK family. Although the therapeutic potential of DKK-1 inhibition has been evaluated in several diseases and malignancies, little is known in pediatric tumors. Only a few works have studied the genetic inhibition and function of DKK-1 in rhabdomyosarcoma. Here, for the first time, we report the analysis of the therapeutic potential of DKK-1 pharmaceutical inhibition in rhabdomyosarcoma, the most common soft tissue sarcoma in children. We performed DKK-1 inhibition via shRNA technology and via the chemical inhibitor WAY-2626211. Its inhibition led to β-catenin activation and the modulation of focal adhesion kinase (FAK), with positive effects on in vitro expression of myogenic markers and a reduction in proliferation and invasion. In addition, WAY-262611 was able to impair survival of tumor cells in vivo. Therefore, DKK-1 could constitute a molecular target, which could lead to novel therapeutic strategies in RMS, especially in those patients with high DKK-1 expression.

SP-2577(Seclidemstat), an inhibitor of lysine-specific demthylase KDM1A (LSD1) that is overexpressed in pediatric sarcomas, was evaluated against pediatric sarcoma xenografts. SP-2577 (100 mg/kg/day × 28 days) statistically significantly (p < .05) inhibited growth of three of eight Ewing sarcoma (EwS), four of five rhabdomyosarcoma (RMS), and four of six osteosarcoma (OS) xenografts. The increase in EFS T/C was modest (<1.5) for all models except RMS Rh10 (EFS T/C = 2.8). There were no tumor regressions or consistent changes in dimethyl histone H3(K4), HOXM1, DAX1, c-MYC and N-MYC, or tumor histology/differentiation. SP-2577 has limited activity against these pediatric sarcoma models at the dose and schedule evaluated., (© 2021 Wiley Periodicals LLC.)

Background: In vitro data suggest that the growth of rhabdomyosarcoma (RMS) cells is suppressed in a concentration-dependent manner by 4-hydroxycyclophosphamide (4HCY), the principal precursor to the cytotoxic metabolite of cyclophosphamide (CY). Various retrospective studies on the relationship between genes encoding proteins involved in the formation and elimination of 4HCY (i.e., 4HCY pharmacokinetics) and cyclophosphamide (CY) efficacy and toxicity have been conflicting., Procedures: We evaluated germline pharmacogenetics in 262 patients with newly diagnosed intermediate-risk RMS who participated in one prospective Children's Oncology Group clinical trial, ARST0531. Patients were treated with either vincristine/actinomycin/cyclophosphamide (VAC) or VAC alternating with vincristine/irinotecan (VAC/VI). We analyzed the associations between event-free survival and 394 single-nucleotide polymorphisms (SNP) in 14 drug metabolizing enzymes or transporters involved in 4HCY pharmacokinetics., Results: Eight SNPs were associated (p-value < .05 by univariate analysis) with 3-year event-free survival; no SNPs survived a false discovery rate < 0.05., Conclusions: Our data suggest that a pharmacogenomic approach to therapy personalization of cyclophosphamide in intermediate-risk rhabdomyosarcoma is not viable. Other methods to personalize therapy should be explored., (© 2021 Wiley Periodicals LLC.)

Competing Interests: Maggie Fader Employment: Kidz Medical Services, Inc Travel, Accommodations, Expenses: Kidz Medical Services No other potential conflicts of interest were reported. Maggie Fader Employment: Kidz Medical Services, Inc Travel, Accommodations, Expenses: Kidz Medical Services No other potential conflicts of interest were reported.

Purpose: The VIT-0910 trial was conducted to evaluate efficacy and safety of the vincristine-irinotecan combination with and without temozolomide (VIT and VI, respectively) in relapsed or refractory rhabdomyosarcoma (RMS)., Methods: In this randomized European phase II trial, patients age 0.5-50 years received 21-day cycles combining vincristine (1.5 mg/m 2 once a day on day 1 and day 8) and irinotecan (50 mg/m 2 once a day from day 1 to day 5) with and without temozolomide (125 mg/m 2 once a day from day 1 to day 5 and 150 mg/m 2 once a day from cycle 2), until progression or unacceptable toxicity. The primary end point was objective response rate after two cycles. Secondary end points included best response, progression-free survival, overall survival, and adverse events. A Simon 2-stage design was initially planned to separately analyze 40 patients/arm. After amendment, the trial sample size was increased to 120 and a comparison between arms, adjusted for confounding factors, was added to the statistical plan (ClinicalTrials.gov, NCT01355445)., Results: Overall, 120 patients (60 per arm) were recruited in 37 European centers. The median age was 11 years (range, 0.75-45); 89% of patients had a relapsed RMS. The objective response rate was 44% (24 of 55 evaluable patients) for VIT versus 31% (18 of 58) for VI (adjusted odds ratio, 0.50; 95% CI, 0.22 to 1.12; P = .09). The VIT arm achieved significantly better overall survival (adjusted hazard ratio, 0.55; 95% CI, 0.35 to 0.84; P = .006) compared with VI, with consistent progression-free survival results (adj-hazard ratio, 0.68; 95% CI, 0.46 to 1.01; P = .059). Overall, patients experienced adverse events ≥ grade 3 more frequently with VIT than VI (98% v 78%, respectively; P = .009), including a significant excess of hematologic toxicity (81% v 61%; P = .025)., Conclusion: The addition of temozolomide to VI improved chemotherapy efficacy for patients with relapsed RMS, with manageable increase in toxicity. VIT is considered the new standard treatment in these patients in the European paediatric Soft Tissue Sarcoma Group and will be the control arm in the next randomized trial., Competing Interests: Michela CasanovaConsulting or Advisory Role: Roche, Bayer, BMS, AstraZenecaTravel, Accommodations, Expenses: Roche, Bayer Johannes H.M. MerksConsulting or Advisory Role: Bayer, GlaxoSmithKline Gianni BisognoConsulting or Advisory Role: Bayer, Roche, iQone healthcareTravel, Accommodations, Expenses: Jazz Pharmaceuticals Soledad Gallego MelconConsulting or Advisory Role: Loxo, EUSA Pharma, IQvia, Clinigen Group, BayerTravel, Accommodations, Expenses: Loxo Susanne Andrea GatzConsulting or Advisory Role: Tesaro, BayerTravel, Accommodations, Expenses: AstraZeneca Rick R. van RijnPatents, Royalties, Other Intellectual Property: Royalties from Springer and Thieme Keith WheatleyResearch Funding: Roche, Bio-Cancer Treatment International, EUSA Pharma, Bayer Véronique Minard-ColinResearch Funding: Roche/Genentech, Bristol Myers Squibb/Pfizer Julia C. ChisholmConsulting or Advisory Role: Roche, Bayer, Roche/Genentech, BayerNo other potential conflicts of interest were reported.

First-line therapy for most pediatric sarcoma is based on chemotherapy in combination with radiotherapy and surgery. A significant number of patients experience drug resistance and development of relapsed tumors. Drugs that have the potential to re-sensitize relapsed tumor cells toward chemotherapy treatment are therefore of great clinical interest. Here, we used a drug profiling platform with PDX-derived primary rhabdomyosarcoma cells to screen a large drug library for compounds re-sensitizing relapse tumor cells toward standard chemotherapeutics used in rhabdomyosarcoma therapy. We identified ABT-263 (navitoclax) as most potent compound enhancing general chemosensitivity and used different pharmacologic and genetic approaches in vitro and in vivo to detect the NOXA-BCL-XL/MCL-1 balance to be involved in modulating drug response. Our data therefore suggests that players of the intrinsic mitochondrial apoptotic cascade are major targets for stimulation of response toward first-line therapies in rhabdomyosarcoma., (Copyright © 2021. Published by Elsevier Inc.)

Rhabdomyosarcoma exhibits tumor-specific energy metabolic changes that include the Warburg effect. Since targeting cancer metabolism is a promising therapeutic approach, we examined the antitumor effects of suppressing lipid metabolism in rhabdomyosarcoma. We suppressed lipid metabolism in rhabdomyosarcoma cells in vitro by administering an inhibitor of malonyl-CoA decarboxylase, which increases malonyl-CoA and decreases fatty acid oxidation. Suppression of lipid metabolism in rhabdomyosarcoma cells decreased cell proliferation by inducing cell cycle arrest. Metabolomic analysis showed an increase in glycolysis and inactivation of the pentose phosphate pathway. Immunoblotting analysis revealed upregulated expression of the autophagy marker LC3A/B-II due to increased phosphorylation of AMP-activated protein kinase, a nutrient sensor. p21 protein expression level also increased. Inhibition of both lipid metabolism and autophagy suppressed tumor proliferation and increased apoptosis. In vivo studies involved injection of human Rh30 cells into the gastrocnemius muscle of 6-week-old female nude mice, which were divided into normal chow and low-fat diet groups. The mice fed a low-fat diet for 21 days showed reduced tumor growth compared to normal chow diet-fed mice. Suppression of lipid metabolism disrupted the equilibrium of the cancer-specific metabolism in rhabdomyosarcoma, resulting in a tumor growth-inhibition effect. Therefore, the development of treatments focusing on the lipid dependence of rhabdomyosarcoma is highly promising., (© 2021 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Introduction and Objectives: We aim to assess the long-term oncological outcomes of children with bladder/prostate rhabdomyosarcoma (B/P RMS) treated with multiagent chemotherapy as a monotherapy. We hypothesize that a highly select patient subset can be treated with multiagent chemotherapy as a monotherapy and spared the morbidity of local treatment with similar oncological outcomes., Methods: Patients (≤21-year-old) treated for non-metastatic non-alveolar B/P RMS at a tertiary center and followed for>one year, were retrospectively reviewed. After pathological confirmation, patients received 12 weeks of induction VAC chemotherapy (IC) followed by second-look biopsies. Between 1996 and 2006 (group A), patients with>50% tumor size reduction and negative second-look biopsies following IC were spared local treatment and followed-up closely. Between 2007 and 2020 (group B), local treatment was routinely given at 12 weeks according to the COG protocols, irrespective of IC response. For all patients, consolidation chemotherapy was administered for additional 12-18 months., Results: Between 1996 and 2020, 27 patients (10 stage II, 17 stage III) with a median age of 3(1-21) years were included. Median follow-up was 87.5(15.3-247.1) months. Among 15 patients in group A, 3 were ineligible for the monotherapy protocol and received local treatment. The remaining 12 patients [9 complete (CR) and 3 incomplete response (IR) to IC] were treated exclusively with chemotherapy, of whom 9 were alive free of relapse at last follow-up. Two patients with IR to IC had disease relapse: one had pulmonary relapse at 8.2 months and one had local relapse at 35 months. The 5-year OS and EFS of group A were 86.7% and 80%, respectively. Analyzing survival according to IC response, CR to IC was achieved in 10 patients (9 group A and one group B) and was associated with significantly better OS and EFS than IR(p = 0.026 and 0.004, respectively) (Summary figure). All patients with CR to IC were alive free of relapse at last follow-up., Discussion: Treatment of RMS is traditionally multimodal. Local treatment of B/P RMS is associated with significant patient morbidity. In this study, CR to IC predicted better OS and EFS. Patients who achieved CR (radiological and pathological) to IC remained alive free of relapse irrespective of local treatment., Conclusions: Our results suggest that patients with non-metastatic non-alveolar B/P RMS who achieve CR to IC can be treated with combination chemotherapy as a monotherapy and spared the morbidity of local treatment with durable survival outcomes. Prospective validation in a larger patient cohort is needed to support our hypothesis., Competing Interests: Conflicts of interest The authors have nothing to disclose., (Copyright © 2021 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Rhabdomyosarcoma (RMS) is a malignant soft tissue cancer that develops mostly in children and young adults. With regard to histopathology, four rhabdomyosarcoma types are distinguishable: embryonal, alveolar, pleomorphic and spindle/sclerosing. Currently, increased amounts of evidence indicate that not only gene mutations, but also epigenetic modifications may be involved in the development of RMS. Epigenomic changes regulate the chromatin architecture and affect the interaction between DNA strands, histones and chromatin binding proteins, thus, are able to control gene expression. The main aim of the study was to assess the role of protein arginine methyltransferases (PRMT) in the cellular biology of rhabdomyosarcoma. In the study we used two pan-inhibitors of PRMT, called AMI-1 and SAH, and evaluated their effects on proliferation and apoptosis of RMS cells. We observed that AMI-1 and SAH reduce the invasive phenotype of rhabdomyosarcoma cells by decreasing their proliferation rate, cell viability and ability to form cell colonies. In addition, microarray analysis revealed that these inhibitors attenuate the activity of the PI3K-Akt signaling pathway and affect expression of genes related to it.

Rhabdomyosarcomas (RMS) are tumors of the skeletal muscle lineage. Two main features allow for distinction between subtypes: morphology and presence/absence of a translocation between the PAX3 (or PAX7) and FOXO1 genes. The two main subtypes are fusion-positive alveolar RMS (ARMS) and fusion-negative embryonal RMS (ERMS). This review will focus on the role of receptor tyrosine kinases of the human epidermal growth factor receptor (EGFR) family that is comprised EGFR itself, HER2, HER3 and HER4 in RMS onset and the potential therapeutic targeting of receptor tyrosine kinases. EGFR is highly expressed by ERMS tumors and cell lines, in some cases contributing to tumor growth. If not mutated, HER2 is not directly involved in control of RMS cell growth but can be expressed at significant levels. A minority of ERMS carries a HER2 mutation with driving activity on tumor growth. HER3 is frequently overexpressed by RMS and can play a role in the residual myogenic differentiation ability and in resistance to signaling-directed therapy. HER family members could be exploited for therapeutic approaches in two ways: blocking the HER member (playing a driving role for tumor growth with antibodies or inhibitors) and targeting expressed HER members to vehiculate toxins or immune effectors.

The goals of this work were to identify factors favoring patient-derived xenograft (PDX) engraftment and study the association between PDX engraftment and prognosis in pediatric patients with Ewing sarcoma, osteosarcoma, and rhabdomyosarcoma. We used immunodeficient mice to establish 30 subcutaneous PDX from patient tumor biopsies, with a successful engraftment rate of 44%. Age greater than 12 years and relapsed disease were patient factors associated with higher engraftment rate. Tumor type and biopsy location did not associate with engraftment. PDX models retained histology markers and most chromosomal aberrations of patient samples during successive passages in mice. Model treatment with irinotecan resulted in significant activity in 20 of the PDXs and replicated the response of rhabdomyosarcoma patients. Successive generations of PDXs responded similarly to irinotecan, demonstrating functional stability of these models. Importantly, out of 68 tumor samples from 51 patients with a median follow-up of 21.2 months, PDX engraftment from newly diagnosed patients was a prognostic factor significantly associated with poor outcome (p = 0.040). This association was not significant for relapsed patients. In the subgroup of patients with newly diagnosed Ewing sarcoma classified as standard risk, we found higher risk of relapse or refractory disease associated with those samples that produced stable PDX models (p = 0.0357). Overall, our study shows that PDX engraftment predicts worse outcome in newly diagnosed pediatric sarcoma patients., (© 2021 The Authors. The Journal of Pathology: Clinical Research published by The Pathological Society of Great Britain and Ireland & John Wiley & Sons, Ltd.)

Dihydroartemisinin (DHA), an anti-malarial drug, has been shown to possess potent anticancer activity, partly by inhibiting the mammalian target of rapamycin (mTOR) complex 1 (mTORC1) signaling. However, how DHA inhibits mTORC1 is still unknown. Here, using rhabdomyosarcoma (RMS) as a model, we found that DHA reduced cell proliferation and viability in RMS cells, but not those in normal cells, which was associated with inhibition of mTORC1. Mechanistically, DHA did not bind to mTOR or FK506 binding protein 12 (FKBP12). In addition, DHA neither inhibited insulin-like growth factor-1 receptor (IGF-1R), phosphoinositide 3-kinase (PI3K), and extracellular signal-regulated kinase ½ (Erk1/2) , nor activated phosphatase and tensin homolog (PTEN) in the cells. Rather, DHA activated AMP-activated protein kinase (AMPK). Pharmacological inhibition of AMPK, ectopic expression dominant negative or kinase-dead AMPK, or knockdown of AMPKa attenuated the inhibitory effect of DHA on mTORC1 in the cells. Additionally, DHA was able to induce dissociation of regulatory-associated protein of mTOR (raptor) from mTOR and inhibit mTORC1 activity. Moreover, treatment with artesunate, a prodrug of DHA, dose-dependently inhibited tumor growth and concurrently activated AMPK and suppressed mTORC1 in RMS xenografts. The results indicated that DHA inhibits mTORC1 by activating AMPK in tumor cells. Our finding supports that DHA or artesunate has a great potential to be repositioned for treatment of RMS.

Background: Rhabdomyosarcoma (RMS) arises from abnormal muscle development. We reported previously that Fragile-X-Related 1 (FXR1), essential to normal myogenesis, was highly expressed in RMS relative to other embryonal tumors. This current study explored FXR1 expression across RMS disease characteristics and treatment response., Methods: RMS patients ≤18 years (1980-2019; n = 152) were categorized according to tumor histology, PAX/FOXO1 translocation, and vital status. FXR1 protein expression was compared before and after chemotherapy. Impact of FXR1 expression on relapse-free (RFS) and overall survival (OS) was analyzed., Results: FXR1 was most intensely expressed in the cytosol of undifferentiated rhabdomyoblasts. At diagnosis, FXR1 expression was ubiquitous and strong across all disease characteristics and foremost associated with worse RFS in translocation-positive patients (p = 0.0411). Among embryonal and translocation-negative RMS, survivors showed a significantly greater decrease in FXR1 expression after chemotherapy (p < 0.001) compared to decedents (p = 0.8). In contrast, alveolar and translocation-positive RMS specimens showed insignificant changes in FXR1 expression across therapy. As expected, alveolar histology, translocation presence, stage, and clinical group associated with worse survival., Conclusions: FXR1 was expressed strongly across RMS specimens at diagnosis regardless of disease or patient characteristics, and particularly in undifferentiated cells. Reduction in FXR1 expression after chemotherapy associated with improved survival for embryonal and translocation-negative RMS patients., (Copyright © 2021. Published by Elsevier Inc.)

Background: Biliary rhabdomyosarcoma (RMS) is the most common biliary tumor in children. The biliary tract is classified as a favorable primary site. Therefore, patients with localized biliary RMS were included in two consecutive low-risk studies, D9602 and ARST0331, by the Children's Oncology Group (COG). The outcome for these patients treated with low-risk therapy has not been reported., Procedure: Patients with biliary RMS enrolled on COG low-risk trials D9602 or ARST0331 were analyzed. All patients received systemic chemotherapy and those with Group II (microscopic residual) or Group III (macroscopic residual) disease received 36-50.4 Gy adjuvant radiotherapy (RT). Delayed primary excision (DPE) was allowed on both studies., Results: Seventeen patients with biliary RMS were treated on D9602 (n = 7) or ARST0331 (n = 10). Median age was 3.5 years (range 1.7-10.3). Ten (59%) patients had tumors >5 cm and 14 (82%) had Group III disease. Fifteen (88%) patients received RT. The 5-year event-free survival (EFS) and overall survival (OS) were 70.6% (95% confidence interval [CI]: 46.9-94.3%) and 76.5% (95% CI: 54.6-98.4%), respectively. The majority of patients (80%) who received RT did not have disease recurrence while both patients who did not receive RT had local relapse. Five (36%) of 14 patients with Group III disease underwent DPE; two experienced a local relapse. In the nine patients without DPE, two developed local relapse., Conclusions: Patients with localized biliary RMS treated on low-risk studies had suboptimal outcomes. These patients may benefit from therapy on intermediate-risk studies., (© 2021 Wiley Periodicals LLC.)

Rhabdomyosarcoma (RMS) is a rare type of soft tissue sarcoma most commonly found in pediatric patients. Despite progress, new and improved drug regimens are needed to increase survival rates. Citral, a natural product plant oil can induce cell death in cancer cells. Another compound, metformin, isolated originally from French lilac and used by diabetics, has been shown to reduce the incidence of cancer in these patients. Application of citral to RMS cells showed increase in cell death, and RD and RH30 cells showed half maximal inhibitory concentration (IC 50 ) values as low as 36.28 μM and 62.37 μM, respectively. It was also shown that the citral initiated cell apoptosis through an increase in reactive oxygen species (ROS) and free calcium. In comparison, metformin only showed moderate cell death in RMS cell lines at a very high concentration (1,000 μM). Combinatorial experiments, however, indicated that citral and metformin worked antagonistically when used together. In particular, the ability of metformin to quench the ROS induced by citral could lead to the suppression of activity. These results clearly indicate that while clinical use of citral is a promising anti-tumor therapy, caution should be exercised in patients using metformin for diabetes., (© 2020 The Authors. Phytotherapy Research published by John Wiley & Sons Ltd.)

Relapsed pediatric rhabdomyosarcomas (RMS) and neuroblastomas (NBs) have a poor prognosis despite multimodality therapy. In addition, the current standard of care for these cancers includes vinca alkaloids that have severe toxicity profiles, further underscoring the need for novel therapies for these malignancies. Here, we show that the small-molecule rigosertib inhibits the growth of RMS and NB cell lines by arresting cells in mitosis, which leads to cell death. Our data indicate that rigosertib, like the vinca alkaloids, exerts its effects mainly by interfering with mitotic spindle assembly. Although rigosertib has the ability to inhibit oncogenic RAS signaling, we provide evidence that rigosertib does not induce cell death through inhibition of the RAS pathway in RAS-mutated RMS and NB cells. However, the combination of rigosertib and the MEK inhibitor trametinib, which has efficacy in RAS-mutated tumors, synergistically inhibits the growth of an RMS cell line, suggesting a new avenue for combination therapy. Importantly, rigosertib treatment delays tumor growth and prolongs survival in a xenograft model of RMS. In conclusion, rigosertib, through its impact on the mitotic spindle, represents a potential therapeutic for RMS., (©2020 American Association for Cancer Research.)

The Pediatric Preclinical Testing Program (PPTP) previously reported the activity of the EZH2 inhibitor tazemetostat (EPZ6438) against xenograft models of rhabdoid tumors. Here, we determined whether an inhibitor of EZH2 enhanced the effect of standard of care chemotherapeutic agents: irinotecan, vincristine, and cyclophosphamide. EPZ011989 significantly prolonged time to event in all the six rhabdoid models studied but did not induce tumor regression. The addition of EPZ011989 to standard of care agents significantly improved time to event in at least one model for each of the agents studied, although this effect was observed in only a minority of the combination testing experiments., (© 2020 Wiley Periodicals LLC.)

Background: The importance of this paper is to help to emphasize the importance of chemotherapy for children with pure intratesticular rhabdomyosarcoma after radical inguinal orchiectomy is done as first treatment of rhabdomyosarcoma. The information provided in this paper about the follow-up outcomes of the patient described in this paper, it highlights that, recurrence and even metastasis of intratesticular rhabdomyosarcoma in children are more likely to occur if surgery it not combined with chemotherapy., Case Presentation: Herein, we present a 6-year old African male child with a 3 months history of a painless right intratesticular tumour. The tumour was poorly vascularized and was in continuity with the spermatic cord. Pelvic computer tomography (CT) scan showed a heterogeneous mass with well-defined margins without microcalcification and multiple bilateral inguinal enlarged lymph nodes were noticed without pelvic lymphadenopathy. The tumour measured 3.8 × 2.8 × 3.9 cm. The tumour marker panel showed: lactate dehydrogenase of (472 UI/l), alpha-fetoprotein (1.43 UI/ml) and human chorionic gonadotrophin beta (2.9 mUI/ml). Microscopically, the tumour was composed of small to medium size undifferentiated cells. These were oval to spindle, hyperchromatic cells to stromal myxoid degeneration were noted. Tunica albuginea and rete testis both were infiltrated by tumour. The tumour showed high mitotic count which measured 50 mitoses per 10 High Power Field (HPF). The diagnosis of rhabdomyosarcoma (RMS) was confirmed by immunohistochemistry (IHC) testing using myoD antibody which showed strong and diffuse intranuclear staining of the tumour cells. Currently, he is on cyclophosphamide and vincristine chemotherapy regime and his condition has improved much., Conclusions: The experience obtained from the index case is crucial for the management of patients with intratesticular rhabdomyosarcoma which should always make sure that radical inguinal orchiectomy is covered by chemotherapy and/or radiotherapy. This will potentially lower the possibilities of recurrence and/or metastasis of the tumour, hence improving the prognosis of the patients. We report the clinical, radiological, and laboratory characteristics as well as the outcome of the patient.

Purpose: Herein we describe the in vitro and in vivo activity of FK228 (Romidepsin), an inhibitor of class I HDACs, in counteracting and radiosensitizing embryonal (ERMS, fusion-negative) and alveolar (ARMS, fusion-positive) rhabdomyosarcoma (RMS)., Methods: RH30 (ARMS, fusion-positive) and RD (ERMS, fusion-negative) cell lines and human multipotent mesenchymal stromal cells (HMSC) were used. Flow cytometry analysis, RT-qPCR, western blotting and enzymatic assays were performed. Irradiation was delivered by using an x-6 MV photon linear accelerator. FK228 (1.2 mg/kg) in vivo activity, combined or not with radiation therapy (2 Gy), was assessed in murine xenografts., Results: Compared to HMSC, RMS expressed low levels of class I HDACs. In vitro, FK228, as single agents, reversibly downregulated class I HDACs expression and activity and induced oxidative stress, DNA damage and a concomitant growth arrest associated with PARP-1-mediated transient non-apoptotic cell death. Surviving cells upregulated the expression of cyclin A, B, D1, p27, Myc and activated PI3K/Akt/mTOR and MAPK signaling, known to be differently involved in cancer chemoresistance. Interestingly, while no radiosensitizing effects were detected, in vitro or in vivo, on RD cells, FK228 markedly radiosensitized RH30 cells by impairing antioxidant and DSBs repair pathways in vitro. Further, FK228 when combined with RT in vivo significantly reduced tumor mass in mouse RH30 xenografts., Conclusion: FK228 did not show antitumor activity as a single agent whilst its combination with RT resulted in radiosensitization of fusion-positive RMS cells, thus representing a possible strategy for the treatment of the most aggressive RMS subtype.

Background: Lorvotuzumab mertansine (IMGN901) is an antibody-drug conjugate linking an antimitotic agent (DM1) to an anti-CD56 antibody (lorvotuzumab). Preclinical efficacy has been noted in Wilms tumor, rhabdomyosarcoma, and neuroblastoma. Synovial sarcoma, malignant peripheral nerve sheath tumor (MPNST), and pleuropulmonary blastoma also express CD56. A phase 2 trial of lorvotuzumab mertansine was conducted to assess its efficacy, recommended phase 2 dose, and toxicities., Methods: Eligible patients had relapsed after or progressed on standard therapy for their tumor type. Lorvotuzumab mertansine (110 mg/m 2 per dose) was administered at the adult recommended phase 2 dose intravenously on days 1 and 8 of 21-day cycles. Dexamethasone premedication was used. Pharmacokinetic samples, peripheral blood CD56-positive cell counts, and tumor CD56 expression were assessed., Results: Sixty-two patients enrolled. The median age was 14.3 years (range, 2.8-29.9 years); 35 were male. Diagnoses included Wilms tumor (n = 17), rhabdomyosarcoma (n = 17), neuroblastoma (n = 12), synovial sarcoma (n = 10), MPNST (n = 5), and pleuropulmonary blastoma (n = 1). Five patients experienced 9 dose-limiting toxicities: hyperglycemia (n = 1), colonic fistula (n = 1) with perforation (n = 1), nausea (n = 1) with vomiting (n = 1), increased alanine aminotransferase in cycle 1 (n = 2), and increased alanine aminotransferase in cycle 2 (n = 1) with increased aspartate aminotransferase (n = 1). Non-dose-limiting toxicities (grade 3 or higher) attributed to lorvotuzumab mertansine were rare. The median values of the maximum concentration, half-life, and area under the curve from zero to infinity for DM1 were 0.87 µg/mL, 35 hours, and 27.9 µg/mL h, respectively. Peripheral blood CD56+ leukocytes decreased by 71.9% on day 8. One patient with rhabdomyosarcoma had a partial response, and 1 patient with synovial sarcoma achieved a delayed complete response., Conclusions: Lorvotuzumab mertansine (110 mg/m 2 ) is tolerated in children at the adult recommended phase 2 dose; clinical activity is limited., (© 2020 American Cancer Society.)

Sclerosing spindle cell rhabdomyosarcoma (SSRMS) is a rare rhabdomyosarcomas (RMS) subtype. Especially cases bearing a myogenic differentiation 1 ( MYOD1 ) mutation are characterized by a high recurrence and metastasis rate, often leading to a fatal outcome. SSRMS cell lines are valuable in vitro models for studying disease mechanisms and for the preclinical evaluation of new therapeutic approaches. In this study, a cell line established from a primary SSRMS tumor of a 24-year-old female after multimodal chemotherapeutic pretreatment has been characterized in detail, including immunohistochemistry, growth characteristics, cytogenetic analysis, mutation analysis, evaluation of stem cell marker expression, differentiation potential, and tumorigenicity in mice. The cell line which was designated SRH exhibited a complex genomic profile, including several translocations and deletions. Array-comparative genomic hybridization (CGH) revealed an overall predominating loss of gene loci. The mesenchymal tumor origin was underlined by the expression of mesenchymal markers and potential to undergo adipogenic and osteogenic differentiation. Despite myogenic marker expression, terminal myogenic differentiation was inhibited, which might be elicited by the MYOD1 hotspot mutation. In vivo tumorigenicity could be confirmed after subcutaneous injection into NOD/SCID/γ c null mice. Summarized, the SRH cell line is the first adult SSRMS cell line available for preclinical research on this rare RMS subtype.

Combinational therapy is among the most used treatment modality's to increase cancer treatment efficacy. It may also reduce side effects, treatment time, and development of drug resistance. The effects of different analogues of vitamin A (VA) as neoadjuvant agent were observed in this study with chemotherapeutic drugs (doxorubicin and methotrexate) and photodynamic therapy (PDT) using 5-ALA and Photogem as photosensitizers in RD cells. The uptake time of photosensitizer was optimized by means of spectrophotometric measurements. Diode laser (λ = 635 nm ± 1 nm) was used as an illumination source for PDT. Responses of administered drugs were assessed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. VA and its analogues exert prophylactic and therapeutic effects. Protective or antagonistic effects (CI > 1) were observed in each of the case. These results propose that the use of VA as a neoadjuvant agent in combinational therapeutic modalities may reduce the efficacy of cancer treatment protocols as well as the existing side effects. Thus, VA is not the successful drug for combinational therapies and under treatment cancer patients should try to avoid its use with oxidative stress induction therapies (e.g. PDT, Radiotherapy, chemotherapy)., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Purpose: The aim of this study was to evaluate outcomes based on surgical approach for retroperitoneal lymph node dissection (RPLND) in patients with paratesticular rhabdomyosarcoma (PT-RMS)., Methods: Patients undergoing RPLND for PT-RMS over 10 years at a single institution were retrospectively reviewed. Length of stay (LOS), complications, oral morphine equivalents per kilogram (OME/Kg), lymph node yield, and time to chemotherapy were assessed. The surgical approaches compared were: open transabdominal, open extraperitoneal, laparoscopic, and retroperitoneoscopic. For cases with lymphatic mapping, indocyanine green (ICG) was injected into the spermatic cord., Results: Twenty patients were included: five open transabdominal, six open extraperitoneal, three laparoscopic, and six retroperitoneoscopic operations. LOS was shorter in the retroperitoneoscopic group than laparoscopic (p = 0.029) and both open groups (p < 0.001). Mean OME/kg used was lowest in the retroperitoneoscopic (0.13 ± 0.15) group compared to laparoscopic (0.68 ± 0.53, p = 0.043), open transabdominal (14.90 ± 8.87, p = 0.003), and extraperitoneal (10.11 ± 2.44, p < 0.001). Time to chemotherapy was shorter for retroperitoneoscopic patients (0.13 days ± 0.15) compared to open transabdominal (15.6 days±6.5, p = 0.005). There was no difference in lymph node yield between groups. Spermatic cord ICG demonstrated iliac lymph node avidity on near-infrared spectroscopy., Conclusions: Minimally invasive RPLND appears to offer a faster recovery without compromising lymph node yield for patients with PT-RMS., Level of Evidence: III., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Magnoflorine (MGN) is a quaternary aporphine alkaloid that exhibits numerous therapeutic properties, including neuropsychopharmacological, anti-anxiety, immunomodulatory, anti-inflammatory, antioxidant, or antifungal activities. The aim of the present study was an investigation of the influence of MGN on viability, proliferation, induction of apoptosis, and cell cycle arrest in NCI-H1299 lung, MDA-MB-468 breast, T98G glioma, and TE671 rhabdomyosarcoma cancer cells. MGN was isolated from the roots of Berberis cretica L. by counter-current partition chromatography (CPC). Cell viability and proliferation assessments were performed by means of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and 5-bromo-2'-deoxyuridine (BrDU) assays, respectively. The induction of apoptosis and cell cycle progression was measured using fluorescence-activated cell sorting analysis. MGN in high doses inhibits proliferation, induces apoptosis, and inhibits cell cycle in S/G2 phases in a dose-dependent manner. MGN seems to be a promising anti-cancer compound in therapy of some types of lung, breast, glioma, and rhabdomyosarcoma cancers, for which current standard therapies are limited or have severe strong side effects.

The study reports the treatment feasibility, and secondly efficacy, of a novel chemotherapy regimen, which adds vinorelbine to the ifosfamide-vincristine-actinomycin-D combination (VIVA regimen), used in four patients with high-risk rhabdomyosarcoma. All patients received nine cycles of the VIVA regimen followed by maintenance chemotherapy with vinorelbine and cyclophosphamide. All patients experienced significant hematological toxicity, but no other major complications (in particular neurotoxicity) or required treatment dose modifications. We observed a major response after three cycles in all patients, and they remained alive after a median follow up of 11 months from diagnosis., (© 2020 Wiley Periodicals LLC.)

Cancer therapy is currently shifting from broadly used cytotoxic drugs to patient-specific precision therapies. Druggable driver oncogenes, identified by molecular analyses, are present in only a subset of patients. Functional profiling of primary tumor cells could circumvent these limitations, but suitable platforms are unavailable for most cancer entities. Here, we describe an in vitro drug profiling platform for rhabdomyosarcoma (RMS), using a living biobank composed of twenty RMS patient-derived xenografts (PDX) for high-throughput drug testing. Optimized in vitro conditions preserve phenotypic and molecular characteristics of primary PDX cells and are compatible with propagation of cells directly isolated from patient tumors. Besides a heterogeneous spectrum of responses of largely patient-specific vulnerabilities, profiling with a large drug library reveals a strong sensitivity towards AKT inhibitors in a subgroup of RMS. Overall, our study highlights the feasibility of in vitro drug profiling of primary RMS for patient-specific treatment selection in a co-clinical setting.

Functional genomic screening of KRAS-driven mouse sarcomas was previously employed to identify proliferation-relevant genes. Genes identified included Ubiquitin-conjugating enzyme E2 (Ube2c), Centromere Protein E (Cenpe), Hyaluronan Synthase 2 (Has2), and CAMP Responsive Element Binding Protein 3 Like 2 (Creb3l2). This study examines the expression and chemical inhibition of these candidate genes, identifying variable levels of protein expression and significant contributions to rhabdomyosarcoma (RMS) cell proliferation. Chemical treatment of human and murine RMS cell lines with bortezomib, UA62784, latrunculin A and sorafenib inhibited growth with approximate EC50 concentrations of 15-30nM for bortezomib, 25-80nM for UA62784 and 80-220nM for latrunculin A. The multi-kinase inhibitor sorafenib increased in vitro proliferation of 4 of 6 sarcoma cell lines tested. Latrunculin A was further associated with disruption of the actin cytoskeleton and reduced ERK1/2 phosphorylation. Together, this work advances opportunities for developing therapies to block progression of soft-tissue sarcomas and demonstrates that disruption of the actin cytoskeleton in sarcoma cells by latrunculin A is associated with a reduction in RMS cell growth. (167 words)., Competing Interests: The authors have declared that no competing interests exist.

A subset of patients with initially unresected (Clinical Group III) rhabdomyosarcoma achieve less than a complete response (CR) despite multimodal therapy. We assessed outcome based upon tumor response at the completion of all planned therapy. We studied 601 Clinical Group III participants who completed all protocol therapy without developing progressive disease on two Children's Oncology Group studies ARST0531 (n = 285) and D9803 (n = 316). Response was defined by imaging and categorized by response; complete resolution (CR), partial response (PR) or no response (NR). Failure-free survival (FFS) and overall survival (OS) between response groups were compared using the log-rank test. We found that radiographic response was CR in 393 (65.4%) and PR/NR in 208 (34.6%) patients. Achieving CR status was associated with study D9803, nonparameningeal (PM) primary sites, tumors ≤5 cm, noninvasive tumors and alveolar histology/FOXO fusion-positive tumors. The overall 5-year FFS was 75% for those achieving CR and 66.5% in those with PR/NR (adj. p = 0.094). Patients with PM primary site who achieved CR had significantly improved FFS (adj. p = 0.037) while those with non-PM primary sites had similar outcomes (adj. p = 0.47). Radiographic response was not associated with OS (adj. p = 0.21). Resection of the end-of-therapy mass did not improve FFS (p = 0.12) or OS (p = 0.37). In conclusion, CR status at the end of protocol therapy in patients with PM Clinical Group III RMS was associated with improved FFS but not OS. Efforts to understand the biology and treatment response in patients with PM primary site are under investigation., (© 2020 UICC.)

Purpose: Overall prognosis of advanced sarcoma remains poor, optimization of systemic treatment is urgently needed in this setting. Materials and methods: We systematically reviewed fully published English-speaking literature about maintenance therapy and drug holiday in sarcoma patients management. Results: We found that switch maintenance therapy with cyclophosphamide/vinorelbine improves the outcome of localized high-risk rhabdomyosarcoma. There is no other maintenance therapy recommended in sarcoma patients. After classical chemotherapy, maintenance therapy with immune-stimulating agents for localized osteosarcoma, bevacizumab for advanced angiosarcoma or pediatric advanced sarcoma, or mTOR inhibitors for metastatic sarcoma does not improve the outcome. Drug holiday has been assessed for metastatic gastrointestinal stromal tumor treated with imatinib as the first-line therapy or for metastatic soft-tissue sarcoma treated with trabectedin. Drug holiday has been found to lead to rapid disease progression and should be avoided. Conclusions: Data about both maintenance and drug holiday are spare in sarcoma management.

Targeting the epigenome of cancer cells with the combination of Bromodomain and Extra Terminal (BET) protein inhibitors and histone deacetylase (HDAC) inhibitors has shown synergistic antitumor effects in several cancer types. In this study, we investigate the antitumor potential of the novel dual BET/HDAC inhibitor TW09 in rhabdomyosarcoma (RMS) cells. TW09 reduces cell viability, suppresses long-term clonogenic survival and induces cell death in RMS cells in a dose-dependent manner. Compared to BET/HDAC co-inhibition using JQ1 and MS-275, TW09 induces similar cell death at equimolar concentrations and regulates BET and HDAC target proteins (e.g. c-MYC, H3 acetylation). Mechanistic studies revealed that TW09 upregulates BIM, NOXA, PUMA and BMF, while downregulating BCL-X L , leading to proapoptotic rebalancing of BCL-2 proteins. This results in BAK and BAX activation and caspase-dependent apoptosis, since individual genetic silencing of BIM, NOXA, PUMA, BMF, BAK or BAX, overexpression of BCL-2 or the caspase inhibition with zVAD.fmk all rescue JQ1/BYL719-induced cell death. In conclusion, TW09 shows potent antitumor activity in RMS cells in vitro by inducing mitochondrial apoptosis and may represent a promising new therapeutic option for the treatment of RMS., Competing Interests: Declaration of competing interest None to declare., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in childhood and adolescence. Refractory/relapsed RMS patients present a bad prognosis that combined with the lack of specific biomarkers impairs the development of new therapies. Here, we utilize dynamic BH3 profiling (DBP), a functional predictive biomarker that measures net changes in mitochondrial apoptotic signaling, to identify anti-apoptotic adaptations upon treatment. We employ this information to guide the use of BH3 mimetics to specifically inhibit BCL-2 pro-survival proteins, defeat resistance and avoid relapse. Indeed, we found that BH3 mimetics that selectively target anti-apoptotic BCL-xL and MCL-1, synergistically enhance the effect of clinically used chemotherapeutic agents vincristine and doxorubicin in RMS cells. We validated this strategy in vivo using a RMS patient-derived xenograft model and observed a reduction in tumor growth with a tendency to stabilization with the sequential combination of vincristine and the MCL-1 inhibitor S63845. We identified the molecular mechanism by which RMS cells acquire resistance to vincristine: an enhanced binding of BID and BAK to MCL-1 after drug exposure, which is suppressed by subsequently adding S63845. Our findings validate the use of DBP as a functional assay to predict treatment effectiveness in RMS and provide a rationale for combining BH3 mimetics with chemotherapeutic agents to avoid tumor resistance, improve treatment efficiency, and decrease undesired secondary effects.

Background: Approximately 50% of children with cancer in the United States who are aged <15 years receive primary treatment on a therapeutic clinical trial. To the authors' knowledge, it remains unknown whether trial enrollment has a clinical benefit compared with the best alternative standard therapy and/or off trial (ie, clinical trial effect). The authors conducted a retrospective matched cohort study to compare the morbidity and mortality of pediatric patients with cancer who are treated on a phase 3 clinical trial compared with those receiving standard therapy and/or off trial., Methods: Subjects were aged birth to 19 years; were diagnosed between 2000 and 2010 with acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML), rhabdomyosarcoma, or neuroblastoma; and had received initial treatment at the Children's Hospital of Philadelphia. On-trial and off-trial subjects were matched based on age, race, ethnicity, a diagnosis of Down syndrome (for patients with ALL or AML), prognostic risk level, date of diagnosis, and tumor type., Results: A total of 428 participants were matched in 214 pairs (152 pairs for ALL, 24 pairs for AML, 32 pairs for rhabdomyosarcoma, and 6 pairs for neuroblastoma). The 5-year survival rate did not differ between those treated on trial versus those treated with standard therapy and/or off trial (86.9% vs 82.2%; P = .093). On-trial patients had a 32% lower odds of having worse (higher) mortality-morbidity composite scores, although this did not reach statistical significance (odds ratio, 0.68; 95% confidence interval, 0.45-1.03 [P = .070])., Conclusions: There was no statistically significant difference in outcomes noted between those patients treated on trial and those treated with standard therapy and/or off trial. However, in partial support of the clinical trial effect, the results of the current study indicate a trend toward more favorable outcomes in children treated on trial compared with those treated with standard therapy and/or off trial. These findings can support decision making regarding enrollment in pediatric phase 3 clinical trials., (© 2020 American Cancer Society.)

Purpose: Clinical trials with immune checkpoint inhibition in sarcomas have demonstrated minimal response. Here, we interrogated the tumor microenvironment (TME) of two contrasting soft-tissue sarcomas (STS), rhabdomyosarcomas and undifferentiated pleomorphic sarcomas (UPS), with differing genetic underpinnings and responses to immune checkpoint inhibition to understand the mechanisms that lead to response., Experimental Design: Utilizing fresh and formalin-fixed, paraffin-embedded tissue from patients diagnosed with UPS and rhabdomyosarcomas, we dissected the TME by using IHC, flow cytometry, and comparative transcriptomic studies., Results: Our results demonstrated both STS subtypes to be dominated by tumor-associated macrophages and infiltrated with immune cells that localized near the tumor vasculature. Both subtypes had similar T-cell densities, however, their in situ distribution diverged. UPS specimens demonstrated diffuse intratumoral infiltration of T cells, while rhabdomyosarcomas samples revealed intratumoral T cells that clustered with B cells near perivascular beds, forming tertiary lymphoid structures (TLS). T cells in UPS specimens were comprised of abundant CD8 + T cells exhibiting high PD-1 expression, which might represent the tumor reactive repertoire. In rhabdomyosarcomas, T cells were limited to TLS, but expressed immune checkpoints and immunomodulatory molecules which, if appropriately targeted, could help unleash T cells into the rest of the tumor tissue., Conclusions: Our work in STS revealed an immunosuppressive TME dominated by myeloid cells, which may be overcome with activation of T cells that traffic into the tumor. In rhabdomyosarcomas, targeting T cells found within TLS may be key to achieve antitumor response., (©2020 American Association for Cancer Research.)

Background: The phase I component of a phase I/II study defined the recommended phase II dose and established the tolerability of nab-paclitaxel monotherapy in paediatric patients with recurrent or refractory solid tumours. The activity and safety of nab-paclitaxel monotherapy was further investigated in this phase II study., Patients and Methods: Paediatric patients with recurrent or refractory Ewing sarcoma, neuroblastoma or rhabdomyosarcoma received 240 mg/m 2 of nab-paclitaxel on days 1, 8 and 15 of each 28-day cycle. The primary end-point was the overall response rate (ORR; complete response [CR] + partial response [PR]). Secondary end-points included duration of response, disease control rate (DCR; CR + PR + stable disease [SD]), progression-free survival, 1-year overall survival, safety and pharmacokinetics., Results: Forty-two patients were enrolled, 14 each with Ewing sarcoma, neuroblastoma and rhabdomyosarcoma. The ORRs were 0%, 0% and 7.1% (1 confirmed PR), respectively. The DCRs were 30.8% (4 SD), 7.1% (1 SD) and 7.1% (1 confirmed PR and 0 SD) in the Ewing sarcoma, neuroblastoma and rhabdomyosarcoma groups, respectively. The median progression-free survival was 13.0, 7.4 and 5.1 weeks, respectively, and the 1-year overall survival rates were 48%, 25% and 15%, respectively. The most common grade III/4IVadverse events were haematologic (neutropenia [50%] and anaemia [48%]), and grade III/IV peripheral neuropathy occurred in 2 patients (14%) in the rhabdomyosarcoma group. Pharmacokinetics analyses revealed that paclitaxel tissue distribution was both rapid and extensive., Conclusions: In this phase II study, limited activity was observed; however, the safety of nab-paclitaxel in paediatric patients was confirmed., Trial Registration: NCT01962103 and EudraCT 2013-000144-26., Competing Interests: Conflict of interest statement G.B. reports serving in a consulting or advisory role for Clinigen Group and receiving travel expenses from Jazz Pharmaceuticals. J.C.C. reports serving in a consulting or advisory role for Bayer and Roche. F.D. reports serving in a consulting or advisory role for Bristol-Myers Squibb and Celgene (a Bristol-Myers Squibb Company), from which his institution has received funds, and receiving travel expenses from Bristol-Myers Squibb. L.M. reports serving in a consulting or advisory role for Novartis, AstraZeneca, Roche Genentech, Bayer, Amgen and MundiPharma; receiving honoraria for educational events from Celgene (a Bristol-Myers Squibb Company) and Novartis and receiving travel expenses from MundiPharma, Celgene (a Bristol-Myers Squibb Company) and Amgen. S.G.M. reports being in a paid advisory role for Loxo Oncology and Clinigen Group for work performed outside of the current study. R.S. reports serving as an employee of and holding stock/ownership in Bristol-Myers Squibb. N.C. reports serving as an employee of and holding stock/ownership in Bristol-Myers Squibb. Y.l.-B. reports serving as an employee of Celgene (a Bristol-Myers Squibb Company) International A Bristol-Myers Squibb Company and holding stock/ownership in Bristol-Myers Squibb. M.S. reports serving as an employee of Celgene (a Bristol-Myers Squibb Company) International A Bristol-Myers Squibb Company and holding stock/ownership in Bristol-Myers Squibb. G.V. reports receiving travel expenses from Bristol-Myers Squibb. All other authors declare no conflict of interest, (Published by Elsevier Ltd.)

Rhabdomyosarcoma is the most common childhood soft-tissue sarcoma, yet patients with metastatic or recurrent disease continue to do poorly, indicating a need for new treatments. The SRC family tyrosine kinase YES1 is upregulated in rhabdomyosarcoma and is necessary for growth, but clinical trials using single agent dasatinib, a SRC family kinase inhibitor, have failed in sarcomas. YAP1 (YES-associated protein) is highly expressed in rhabdomyosarcoma, driving growth and survival when the upstream Hippo tumor suppressor pathway is silenced, but efforts to pharmacologically inhibit YAP1 have been unsuccessful. Here we demonstrate that treatment of rhabdomyosarcoma with DNA methyltransferase inhibitor (DNMTi) upregulates Hippo activators RASSF1 and RASSF5 by promoter demethylation, activating canonical Hippo signaling and increasing inactivation of YAP1 by phosphorylation. Treatment with DNMTi decreased rhabdomyosarcoma cell growth and increased apoptosis and differentiation, an effect partially rescued by expression of constitutively active YAP (S127A), suggesting the effects of DNMTi treatment are, in part, due to Hippo-dependent inhibition of YAP1. In addition, YES1 and YAP1 interacted in the nucleus of rhabdomyosarcoma cells, and genetic or pharmacologic suppression of YES1 resulted in cytoplasmic retention of YAP1 and decreased YAP1 target gene expression, suggesting YES1 regulates YAP1 in a Hippo-independent manner. Combined treatment with DNMTi and dasatinib targeted both Hippo-dependent and Hippo-independent regulation of YAP1, ablating rhabdomyosarcoma cell growth in vitro and trending toward decreased tumor growth in vivo . These results show that the mechanisms regulating YAP1 in rhabdomyosarcoma can be inhibited by combinatorial therapy of DNMTi and dasatinib, laying the groundwork for future clinical investigations. SIGNIFICANCE: This study elucidates the signaling pathways that regulate the oncogenic protein YAP1 and identifies a combination therapy to target these pathways in the childhood tumor rhabdomyosarcoma., (©2020 American Association for Cancer Research.)

With the development of potent and selective inhibitors of MCL-1 (S63845) and BCL-X L (A-1331852) novel cancer treatment options have emerged. BCL-2 family proteins are important regulators of apoptosis in pediatric solid tumors. In the current study, we discover that rhabdomyosarcoma, Ewing sarcoma, osteosarcoma and neuroblastoma cell lines are co-dependent on BCL-X L and MCL-1 for survival. A-1331852/S63845 co-treatment, but not combinations of either inhibitor with ABT-199, synergistically induces rapid intrinsic apoptosis in vitro and demonstrates efficiency in an in vivo embryonic chicken model of rhabdomyosarcoma. Interestingly, A-1331852/S63845-induced apoptosis is BAX/BAK-dependent and mediated by displacement of BAK from BCL-X L and MCL-1, respectively. Moreover, BAK interacts with BAX to build a pore-forming complex in the outer mitochondrial membrane, leading to loss of mitochondrial outer membrane potential and caspase activation. Furthermore, in RD cells A-1331852/S63845 co-treatment disrupts BIM and NOXA in their interactions with BCL-X L and MCL-1, respectively, thereby contributing to apoptosis. Altogether, this study is the first to demonstrate the potency of A-1331852/S63845 in pediatric solid tumor cells and to describe the molecular mechanisms of A-1331852/S63845 co-treatment underlining the potential of BCL-X L and MCL-1 inhibition as treatment regime., Competing Interests: Declaration of competing interest None to declare., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Porphyrin-based periodic mesoporous organosilica nanoparticles (PMO) synthesized from a large functional octatriethoxysilylated porphyrin precursor and allowing two-photon excitation photodynamic therapy (TPE-PDT) and NIR imaging were synthesized. These PMO were grafted with polyethylene glycol (PEG) moieties and an analogue of mannose 6-phosphate functionalized at the anomeric position (AMFA). AMFAs are known to efficiently target mannose 6-phosphate receptors (M6PRs) which are over-expressed in various cancers. Here, we demonstrated for the first time that M6PRs were over-expressed in rhabdomyosarcoma (RMS) cells and could be efficiently targeted with PMO-AMFA allowing TPE imaging and TPE-PDT of RMS cells. The comparison with healthy myoblasts demonstrated an absence of biological effects, suggesting a cancer cell specificity in the biomedical action observed.

Rhabdomyosarcoma (RMS) is the most common type of pediatric soft tissue sarcoma. The prognosis of advanced stage RMS remains poor, and metastatic invasion is a major cause of treatment failure. Therefore, there is an urgent need for treatment alternatives focusing on metastatic invasion and drug resistance. The stromal cell‑derived factor‑1 (SDF‑1)/chemokine receptor 4 (CXCR4) axis is a crucial factor for metastatic invasion in RMS. Clinical data has revealed that high CXCR4 expression is associated with a poor outcome and a high metastatic rate in several malignancies, including RMS. Thus, targeting CXCR4 in addition to classical chemotherapy may improve the effectiveness of RMS treatment. In the present study, flow cytometry and reverse transcription‑quantitative PCR were used to assess the effects of the combined treatment with a CXCR4 antagonist and chemotherapy on CXCR4 expression in the embryonal RMS (RME) cell line RD and in the alveolar RMS (RMA) cell line RH30. The functional effect of CXCR4 expression on the migratory behavior of RMS cells was analyzed using Transwell assays. Treatment with cytotoxic agents modulated CXCR4 expression in RMS cells in a dose‑, drug‑ and cell line dependent manner; however, this was not observed in RD cells with vincristine. The expression levels of CXCR4 significantly increased the migratory behavior of RMA and did not affect RME cell migration towards stromal cell‑derived factor‑1α (SDF‑1α). AMD3100 markedly reduced the migration of RH30 cells in the Transwell assays compared with SDF‑1α alone, and the cytotoxic agents doxorubicin and vincristine increased this effect. The results of the combined treatment in RMS cells using the CXCR4 antagonist AMD3100 together with cytotoxic drugs demonstrated that this approach may be a promising alternative for the treatment of advanced stage pediatric RMS. The observed effects of circumventing metastatic invasion and drug resistance should be further investigated in vivo.

Purpose: Vincristine combined with camptothecin derivatives showed synergy in preclinical pediatric cancer models, and the combinations are effective in treatment of childhood solid tumors. We determined whether the synergy between vincristine and irinotecan extends to eribulin, another microtubule inhibitor., Experimental Design: Vincristine or eribulin, alone or combined with irinotecan, was studied in 12 xenograft models. Tumor regression and time to event were used to assess antitumor activity. Pharmacodynamic studies and RNA sequencing (RNA-seq) were conducted 24 and 144 hours after single-agent or combination treatment. Effects on vascular development were studied in Matrigel plugs implanted in mice. The interaction between binary combinations was examined in vitro ., Results: Eribulin combined with irinotecan was more effective than vincristine-irinotecan in 6 of 12 models. Pharmacodynamic markers induced by eribulin (phospho-histone H3) and irinotecan (γ-H2A.X) were abrogated in combination-treated tumors. The predominant RNA-seq signature in combination-treated tumors was activation of the TP53 pathway with increased nuclear TP53. Massive apoptosis was observed 24 hours only after treatment with the eribulin combination. In vitro , neither combination showed interaction using combination index analysis. Eribulin alone and the combination caused alterations in developing vasculature., Conclusions: The eribulin combination is very active in these xenograft models, but not synergistic in vitro . The combination reduced pharmacodynamic markers indicative of single-agent mechanisms but in tumors, dramatically activated the TP53 pathway. Although a mechanism for in vivo synergy requires further study, it is possible that eribulin-induced inhibition of microtubule dynamics enhances irinotecan-induced nuclear accumulation of TP53, leading to rapid cell death., (©2020 American Association for Cancer Research.)

Background: The clinical significance of GLI1 expression either through canonical Hedgehog signal transduction or through non-canonical mechanisms in rhabdomyosarcoma (RMS) or Ewing sarcoma (EWS) is incompletely understood. We tested a role for Hedgehog (HH) signal transduction and GL11 expression in development of vincristine (VCR) resistance in RMS and EWS., Methods: We characterized baseline expression and activity of HH pathway components in 5 RMS (RD, Rh18, Ruch-2, Rh30, and Rh41) and 5 EWS (CHLA9, CHLA10, TC32, CHLA258, and TC71) cell lines. We then established VCR-resistant RMS and EWS cell lines by exposing cells to serially increasing concentrations of VCR and determining the IC 50 . We defined resistance as a ≥ 30-fold increase in IC 50 compared with parental cells. We determined changes in gene expression in the VCR-resistant cells compared with parental cells using an 86-gene cancer drug resistance array that included GLI1 and tested the effect of GLI1 inhibition with GANT61 or GLI1 siRNA on VCR resistance., Results: We found evidence for HH pathway activity and GLI1 expression in RMS and EWS cell lines at baseline, and evidence that GLI1 contributes to survival and proliferation of these sarcoma cells. We were able to establish 4 VCR-resistant cell lines (Ruch-2VR, Rh30VR, Rh41VR, and TC71VR). GLI1 was significantly up-regulated in the Rh30VR, Rh41VR, and TC71VR cells. The only other gene in the drug resistance panel that was significantly up-regulated in each of these VCR-resistant cell lines compared with their corresponding parental cells was the GLI1 direct target and multidrug resistance gene, ATP-binding cassette sub-family B member 1 (MDR1). We established major vault protein (MVP), which was up-regulated in both vincristine-resistant alveolar RMS cell lines (Rh30VR and Rh41VR), as another direct target of GLI1 during development of drug resistance. Treatment of the VCR-resistant cell lines with the small molecule inhibitor GANT61 or GLI1 siRNA together with VCR significantly decreased cell viability at doses that did not reduce viability individually., Conclusions: These experiments demonstrate that GLI1 up-regulation contributes to VCR resistance in RMS and EWS cell lines and suggest that targeting GLI1 may benefit patients with RMS or EWS by reducing multidrug resistance.

Background: Regorafenib is a small molecule multikinase inhibitor that inhibits multiple kinases including BRAF, KIT, PDGFRB, RAF, RET, and VEGFR1-3., Procedures: The in vivo anticancer effects of regorafenib were assessed in a panel of six osteosarcoma models, three rhabdomyosarcoma models, and one Ewing sarcoma model., Results: Regorafenib induced modest inhibition of tumor growth in the models evaluated., Conclusion: The overall pattern of response to regorafenib appears similar to that of the kinase inhibitor sorafenib, with pronounced slowing of tumor growth in some models, limited to the period of agent administration, being the primary treatment effect., (© 2020 Wiley Periodicals, Inc.)

The prognosis of patients with metastatic rhabdomyosarcoma (RMS), the most common type of soft tissue sarcoma in children, is poor and no strategies have been identified to improve their dismal prognosis. Alpha-9 integrin (ITGA9) plays a particularly crucial role in cancer progression and invasiveness. Despite the consensus on the remarkable pro-oncogenic potential of this protein, the miRNA-mediated regulation of ITGA9 has barely been studied to date. In the present study, miR-7 and miR-324-5p were selected as the best candidates after a screening to find ITGA9 regulators, and their effects on cell proliferation and invasion in RMS are described and characterized for the first time. Interestingly, the overexpression of both miRNA produced a clear impairment of cell proliferation, while miR-7 also induced a remarkable drop in cell invasion. Furthermore, the stable overexpression of both miRNA was found to reduce tumor growth in orthotopic RMS models and miR-7 was able to impair metastatic lung colonization. Consequently, we conclude that miR-7 and miR-324-5p show anti-oncogenic and anti-metastatic potential, thereby opening up the possibility of being used as novel therapeutic tools to avoid RMS progression., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest regarding the publication of this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)