High-risk sarcomas, such as metastatic and relapsed Ewing and CIC-rearranged sarcoma, still have a poor prognosis despite intensive therapeutic regimens. Precision medicine approaches offer hope, and ex vivo drug response profiling of patient-derived tumor cells emerges as a promising tool to identify effective therapies for individual patients. Here, we establish ex vivo culture conditions to propagate Ewing sarcoma and CIC::DUX4 sarcoma as tumoroids. These models retain their original molecular and functional characteristics, including recurrent ARID1A mutations in CIC::DUX4 sarcoma, and serve as tumor avatars for large-scale drug testing. Screening a large drug library on a small living biobank of such tumors not only reveals distinct differences in drug response between the two entities, but also identifies a dependency of CIC::DUX4 sarcoma cells on MCL1. Mechanistically, MCL1 is identified as a direct transcriptional target of the CIC::DUX4 fusion oncogene. Genetic and pharmacological inhibition of MCL1 induces rapid apoptosis in CIC::DUX4 sarcoma cells and inhibits tumor growth in a xenograft model. Thus, MCL1 represents a potential therapeutic target for CIC::DUX4 sarcoma. Overall, our study highlights the feasibility of drug response profiling for individual sarcoma cases and suggests that further clinical assessments of its benefit are warranted.

BackgroundSpirometry-based assessment of pulmonary function has limitations in detecting pulmonary toxicity following cancer treatment with chemotherapy, haematopoietic stem cell transplantation, radiotherapy or thoracic surgery. Nitrogen single and multiple breath washout tests are sensitive in assessing peripheral airway function, and lung imaging detects structural abnormalities, but little is known about their use in paediatric cancer patients and survivors. We aimed to 1) identify studies using nitrogen single or multiple breath washout tests and/or lung imaging to assess pulmonary toxicity in paediatric cancer patients and survivors, and 2) describe reported abnormalities.MethodWe systematically searched MEDLINE, Embase and the Cochrane Library for studies published in 1995‒2023. Eligible studies included paediatric cancer patients and survivors under 22 years of age receiving haematopoietic stem cell transplantation, chemotherapy, radiotherapy and/or thoracic surgery who underwent nitrogen single or multiple breath washout tests or lung imaging for detecting pulmonary toxicity. Two independent reviewers identified the studies, performed data extraction and assessed risk of bias.ResultsWe included 12 of 6544 publications. Three studies used nitrogen single or multiple breath washout tests, seven conducted lung imaging using computed tomography and two used both nitrogen single or multiple breath washout tests and lung imaging. Abnormal test results for nitrogen single and multiple breath washout tests and lung imaging were mainly reported following haematopoietic stem cell transplantation (67%). All studies performing lung imaging reported structural abnormalities. Study results were heterogeneous due to varying patient and methodological characteristics.ConclusionWe identified a limited number of studies, mainly after haematopoietic stem cell transplantation, reporting functional and structural lung abnormalities in paediatric cancer patients and survivors. Longitudinal studies with standardised assessments using nitrogen single or multiple breath washout tests and lung imaging are needed to improve our understanding of treatment-related pulmonary toxicity.

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of childhood. Histology separates two main subtypes: embryonal RMS (eRMS; 60%-70%) and alveolar RMS (aRMS; 20%-30%). The aggressive aRMS carry one of two characteristic chromosomal translocations that result in the expression of a PAX3::FOXO1 or PAX7::FOXO1 fusion transcription factor; therefore, aRMS are now classified as fusion-positive (FP) RMS. Embryonal RMS have a better prognosis and are clinically indistinguishable from fusion-negative (FN) RMS. Next to histology and molecular characteristics, RMS risk groupings are now available defining low risk tumors with excellent outcomes and advanced stage disease with poor prognosis, with an overall survival of about only 20% despite intensified multimodal treatment. Therefore, development of novel effective targeted strategies to increase survival and to decrease long-term side effects is urgently needed. Recently, immunotherapies and nanomedicine have been emerging for potent and effective tumor treatments with minimal side effects, raising hopes for effective and safe cures for RMS patients. This review aims to describe the most relevant preclinical and clinical studies in immunotherapy and targeted nanomedicine performed so far in RMS and to provide an insight in future developments.

PURPOSE:Outcomes for children with relapsed and refractory high-risk neuroblastoma (RR-HRNB) remain dismal. The BEACON Neuroblastoma trial (EudraCT 2012-000072-42) evaluated three backbone chemotherapy regimens and the addition of the antiangiogenic agent bevacizumab (B). MATERIALS AND METHODS:Patients age 1-21 years with RR-HRNB with adequate organ function and performance status were randomly assigned in a 3 × 2 factorial design to temozolomide (T), irinotecan-temozolomide (IT), or topotecan-temozolomide (TTo) with or without B. The primary end point was best overall response (complete or partial) rate (ORR) during the first six courses, by RECIST or International Neuroblastoma Response Criteria for patients with measurable or evaluable disease, respectively. Safety, progression-free survival (PFS), and overall survival (OS) time were secondary end points. RESULTS:One hundred sixty patients with RR-HRNB were included. For B random assignment (n = 160), the ORR was 26% (95% CI, 17 to 37) with B and 18% (95% CI, 10 to 28) without B (risk ratio [RR], 1.52 [95% CI, 0.83 to 2.77]; P = .17). Adjusted hazard ratio for PFS and OS were 0.89 (95% CI, 0.63 to 1.27) and 1.01 (95% CI, 0.70 to 1.45), respectively. For irinotecan ([I]; n = 121) and topotecan (n = 60) random assignments, RRs for ORR were 0.94 and 1.22, respectively. A potential interaction between I and B was identified. For patients in the bevacizumab-irinotecan-temozolomide (BIT) arm, the ORR was 23% (95% CI, 10 to 42), and the 1-year PFS estimate was 0.67 (95% CI, 0.47 to 0.80). CONCLUSION:The addition of B met protocol-defined success criteria for ORR and appeared to improve PFS. Within this phase II trial, BIT showed signals of antitumor activity with acceptable tolerability. Future trials will confirm these results in the chemoimmunotherapy era.

Clonal hematopoiesis of indeterminate potential (CHIP) describes recurrent somatic gene mutations in the blood of healthy individuals, associated with higher risk for hematological malignancies and higher all-cause mortality by cardiovascular disease. CHIP increases with age and is more common in adult patients after chemotherapy or radiation for cancer. Furthermore, in some adult patients undergoing autologous stem cell transplantation (ASCT) or thereafter, CHIP has been identified. In children and adolescents, it remains unclear how cellular stressors such as cytotoxic therapy influence the incidence and expansion of CHIP. We conducted a retrospective study on 33 pediatric patients mostly with solid tumors undergoing ASCT for presence of CHIP. We analyzed CD34+ selected peripheral blood stem cell grafts after several cycles of chemotherapy, prior to cell infusion, by next-generation sequencing including 18 "CHIP-genes". Apart from a somatic variant in TP53 in one patient no other variants indicative of CHIP were identified. As a CHIP-unrelated finding, germline variants in CHEK2 and in ATM were identified in two and four patients, respectively. In conclusion, we could not detect "typical" CHIP variants in our cohort of pediatric cancer patients undergoing ASCT. However, more studies with larger patient numbers are necessary to assess if chemotherapy in the pediatric setting contributes to an increased CHIP incidence and at what time point.

Arteriovenous malformations (AVM) are benign vascular anomalies prone to pain, bleeding, and progressive growth. AVM are mainly caused by mosaic pathogenic variants of the RAS-MAPK pathway. However, a causative variant is not identified in all patients. Using ultra-deep sequencing, we identified novel somatic RIT1 delins variants in lesional tissue of three AVM patients. RIT1 encodes a RAS-like protein that can modulate RAS-MAPK signaling. We expressed RIT1 variants in HEK293T cells, which led to a strong increase in ERK1/2 phosphorylation. Endothelial-specific mosaic overexpression of RIT1 delins in zebrafish embryos induced AVM formation, highlighting their functional importance in vascular development. Both ERK1/2 hyperactivation in vitro and AVM formation in vivo could be suppressed by pharmacological MEK inhibition. Treatment with the MEK inhibitor trametinib led to a significant decrease in bleeding episodes and AVM size in one patient. Our findings implicate RIT1 in AVM formation and provide a rationale for clinical trials with targeted treatments.

Purpose Pediatric patients with cancer often develop chemotherapy-induced fever in neutropenia (FN), requiring emergency broad-spectrum antibiotics. Continuous temperature monitoring can lead to earlier FN detection and therapy with improved outcomes. We aimed to compare the feasibility of continuous core temperature monitoring with timely data availability between two wearable devices (WDs) in pediatric oncology patients undergoing chemotherapy. Methods In this prospective observational two-center study, 20 patients (median age: 8 years) undergoing chemotherapy simultaneously wore two WDs (CORE®, Everion®) for 14 days. The predefined goal was core temperature recorded in sufficient quality and available within ≤ 30 min during ≥ 18/24 h for ≥ 7/14 days in more than 15 patients. Results More patients reached the goal with CORE® ( n = 13) versus Everion® ( n = 3) (difference, 50% p < 0.001). After correcting for the transmission bottleneck caused by two WDs transmitting via one gateway, these numbers increased ( n = 15 versus n = 14; difference, 5%; p = 0.69). CORE® measurements corresponded better to ear temperatures ( n = 528; mean bias, − 0.07 °C; mean absolute difference, 0.35 °C) than Everion® measurements ( n = 532; − 1.06 °C; 1.10 °C). Acceptance rates for the WDs were 95% for CORE® and 89% for Everion®. Conclusion The CORE® fulfilled the predefined feasibility criterion (15 of 20 patients) after correction for transmission bottleneck, and the Everion® nearly fulfilled it. Continuous core temperature recording of good quality and with timely data availability was feasible from preschool to adolescent patients undergoing chemotherapy for cancer. These results encourage the design of randomized controlled trials on continuously monitored core temperature in pediatric patients. Trial registration. ClinicalTrials.gov (NCT04914702) on June 7, 2021.

Purpose Reported prevalence of cancer-related fatigue (CRF) among childhood cancer survivors (CCS) varies widely, and evidence on factors associated with CRF among CCS is limited. We aimed to investigate the prevalence of CRF and its associated factors among adult CCS in Switzerland. Methods In a prospective cohort study, we invited adult CCS who survived at least 5 years since last cancer diagnosis, and were diagnosed when age 0–20 years and treated at Inselspital Bern between 1976 and 2015 to complete two fatigue-measuring instruments: the Checklist Individual Strength subjective fatigue subscale (CIS8R; increased fatigue 27–34, severe fatigue ≥ 35) and the numerical rating scale (NRS; moderate fatigue 4–6, severe fatigue 7–10). We collected information about previous cancer treatment and medical history, and calculated β coefficients for the association between CIS8R/NRS fatigue scores and potential determinants using multivariable linear regression. Results We included 158 CCS (participation rate: 30%) with a median age at study of 33 years (interquartile range 26–38). Based on CIS8R, 19% ( N = 30) of CCS reported increased fatigue, yet none reported severe fatigue. CRF was associated with female sex, central nervous system (CNS) tumors, sleep disturbance, and endocrine disorders. Lower CRF levels were observed among CCS age 30–39 years compared to those younger. Conclusions A considerable proportion of adult CCS reported increased levels of CRF. Implications for Cancer Survivors CCS who are female and < 30 years old, have a history of CNS tumor, report sleep disturbance, or have an endocrine disorder should be screened for CRF.

Many patients after pediatric cancer suffer from long-term cognitive difficulties. This study investigates the development of cognitive and psychosocial functions between diagnosis and one year after cancer treatment and reveals insight into the association between cognitive and psychosocial development and various risk factors. This retrospective clinical record review included fifty-seven patients, aged 4-16 years, that were examined at the beginning of the cancer treatment (T1) and one year after cancer treatment (T2) to evaluate the development of working memory (WM), processing speed (PS), psychosocial functions, and quality of life (QoL). About half of the patients showed stable/favorable cognitive development (PS 51.9%; WM 41.4%). The other half exhibited a non-favorable cognitive development, with a decrease of performance between T1 and T2. In 51.6-77.4%, psychosocial functions remained stable/increased between T1 and T2 and QoL scores remained stable in 42.9-61.9%. Changes in prosocial behavior correlated with the development of PS (r = 0.472, p = 0.010). Age at T1 predicted PS at T2 (p = 0.020) and sex predicted peer relations at T2 (p = 0.046). About half of the patients showed stable/favorable whereas the other half experiencing non-favorable cognitive development. The observed disparities in initial and subsequent cognitive performances highlight the importance of early individualized patient monitoring and interventions. IMPACT: We investigated the cognitive and psychosocial development of pediatric cancer patients between diagnosis and one year after termination of cancer treatment. About half of the patients showed stable or favorable cognitive development in processing speed and working memory. The other half exhibited a non-favorable cognitive development, with decreasing performance. Baseline working memory and processing speed was negatively correlated with the respective change score. Changes in prosocial behavior were positively correlated with the development of processing speed. Early individualized patient monitoring and intervention is of crucial importance after pediatric cancer and its treatment.

PIK3CA variants are known to cause vascular malformations. We were interested in studying the phenotypic spectrum, the location within the PIK3CA gene, and the variant allele frequency (VAF) of somatic PI3KCA variants in vascular malformations. Clinical data of consecutive patients with extracranial/extraspinal vascular malformations were collected in the context of the VASCOM cohort (2008-2022, n = 558). Starting October 2020, biopsy samples were tested with the TSO500 gene panel (Illumina). All consenting patients with PIK3CA variants were included in this study. Eighty-nine patients had available genetic results by June 2022. PIK3CA variants (n = 25) were found in 16 simple/combined (nonsyndromic) vascular malformations and in nine vascular malformations associated with other anomalies (syndromic). Four hotspot variants in exons 9 and 20 (c.1624G>A, c.1633G>A, c.3140A>G, c.3140A>T) were identified in 16/25 patients (VAF 0.9%-9.7%). Six non-hotspot variants (c.328_330del, c.323_337del, c.353G>A, c.1258T>C, c.3132T>A, c.3195_3203delinsT) were detected in nine patients (VAF 3.6%-31.7%). Non-hotspot variants were more frequent in syndromic than nonsyndromic vascular malformations (p = 0.0034) and exhibited a higher VAF than hotspot variants (p = 0.0253). Our study contributes to the growing body of knowledge of the genetic background in vascular malformations. Further studies will enrich the ever-growing list of pathogenic PIK3CA variants associated with vascular malformations.

Abstract We describe porous silicon nanoparticles (pSiNP) chemically functionalized with an analog of mannose 6‐phosphate (AMFA) and a porphyrin derivative to target aggressive pediatric Rhabdomyosarcoma (RMS) tumor cells. Our findings demonstrate that the pSiNP@AMFA@porphyrin nanosystems are efficiently internalized by RMS cells, which overexpress mannose 6‐phosphate receptors, and induce cytotoxicity and phototoxicity when exposed to two‐photon excitation light. These results provide an interesting potential for targeting and treating RMS pediatric tumors.

In couples dealing with health problems, we-disease appraisals can influence dyadic coping strategies to alleviate distress. This study describes the development and validation of a self-report scale to assess we-disease appraisals of health problems. The newly developed We-Disease Questionnaire (WDQ) was administered in three samples: parents of children with type 1 diabetes (n = 240) or cancer (n = 125) and individuals with visual impairment and their partners (n = 216). Reliability was measured by coefficient omega. To assess construct validity, correlations with other measures of individual and dyadic adjustment were examined. Descriptive statistics across all samples were compared. A 4-item version of the WDQ demonstrated good reliability and validity and showed meaningful associations with established scales. We-disease appraisals were highest among parents of children with cancer and lowest among couples with visual impairment. The WDQ is a reliable and valid measure that can be used across different health problems.

Objectives In our study, we aimed to characterise adult childhood cancer survivors (ACCS), assess their health issues, gauge health-related quality of life (HRQOL) and evaluate visit satisfaction.Design Prospective cohort study using data from clinical visits and questionnaires.Setting Interdisciplinary follow-up programme for ACCS based on the long-term follow-up (LTFU) guidelines of the Children’s Oncology Group and overseen by internists in two Swiss hospitals.Participants ACCS attending our LTFU clinics between April 2017 and January 2022 were eligible.Interventions We documented medical history, current health status and assessed HRQOL using Short Form-36 V.2, comparing it with Swiss general population (SGP) norms (T mean=50, SD=10; age stratified). 3 months post visit, a feedback questionnaire was distributed.Main results Among 102 ACCS (mean age: 32 years (range: 18–62 years), 68% women), 43 had no prior follow-up (36 ACCS>28 years, 7 ACCS≤28 years). A notable 94% had health issues, affecting an average of 6.1 (SD=3.3) organ systems. HRQOL was lower in ACCS>28 years than the SGP>28 years (physical: 44.8 (SD=11.65) vs 49.3 (SD=10.29), p=0.016; mental: 44.4 (SD=13.78) vs 50.53 (SD=9.92), p=0.004). Older ACCS (>28 years) reported inferior physical (44.8 vs 50.1 (SD=9.30), p=0.017) and mental HRQOL (44.4 vs 50.3 (SD=7.20), p=0.009) than younger ACCS. The majority of respondents reported high levels of satisfaction with the consultation, exceeding 90%.Conclusion ACCS attending LTFU clinics face diverse health issues impacting multiple organ systems and exhibit lower HRQOL compared with the SGP. Thus, internist-led LTFU clinics are crucial for optimising follow-up care.

Paediatric cancer survivors often suffer from cognitive long-term difficulties. Consequently, strengthening cognition is of major clinical relevance. This study investigated cerebral changes in relation to cognition in non-brain tumour paediatric cancer survivors after working memory or physical training compared to a control group. Thirty-four children (>= one-year post-treatment) either underwent eight weeks of working memory training (n = 10), physical training (n = 11), or a waiting period (n = 13). Cognition and MRI, including arterial spin labelling and diffusion tensor imaging, were assessed at three time points (baseline, post-training, and three-month follow-up). Results show lower cerebral blood flow immediately after working memory training (z = -2.073, p = .038) and higher structural connectivity at the three-month follow-up (z = -2.240, p = .025). No cerebral changes occurred after physical training. Short-term changes in cerebral blood flow correlated with short-term changes in cognitive flexibility (r = -.667, p = .049), while long-term changes in structural connectivity correlated with long-term changes in working memory (r = .786, p = .021). Despite the caution given when interpreting data from small samples, this study suggests a link between working memory training and neurophysiological changes. Further research is needed to validate these findings.

Abstract Rhabdomyosarcoma (RMS) is the most common pediatric soft tissue sarcoma. Overall survival rates are low for metastatic RMS, emphasizing the urgent need of improved therapies. Chimeric Antigen Receptor (CAR) Ts have shown remarkable results against hematological malignancies, but CAR T cell therapy remains challenging in solid tumors, mainly due to a lack of ideal tumor specific targets, and of the immunosuppressive tumor microenvironment (TME). To maximize antitumoral activity against RMS and to address optimal CAR T persistence in vivo, novel CAR constructs were investigated against upregulated RMS targets. By surfaceome profiling, we recently identified L1CAM as promising candidate for RMS CAR T cell therapy, and confirmed CD276 and FGFR4 expression. CD276- (CD276.CD28HD.28TM.28CSD.3z) and Dual-CAR Ts targeting both CD276 and FGFR4 (F8-FR4.CD28HD.28TM.28CSD.3z) showed tumor eradication in an orthotopic RMS model, whereas FGFR4-CAR Ts exhibited only a partial response in vivo. Moreover, CD276-CAR Ts showed a limited activity against RMS tumors expressing lower amounts of CD276, eradicating the tumor in 1/5 mice, underlying the need of improved CAR T cell potency against low-density target-expressing tumors. First, to improve FGFR4-CAR Ts activity, we optimized the recognition of FGFR4 epitope by modifying the CAR moiety “hinge”. We replaced the CD28-derived hinge with various hinges of different length: no hinge, IgG4 (12aa), IgG4CH3 (119aa), and IgG4CH2CH3 (229aa). Luciferase assays showed effective in vitro killing capacity of FGFR4-CAR Ts expressing an IgG4-derived hinge, with a tumor cell survival less than 10% at Effector to Target (E:T) ratio of 5:1. They also released the double amount of IFN-γ (50pg/ml) compared to the other constructs, when co-incubated with Rh4 cells. Next, to verify the potential of L1CAM as CAR T target for RMS, we generated a panel of L1CAM-CARs expressing either a long (IgG4CH2CH3, 229aa) or a short (CD28, 35aa) Hinge, and a CD28- or 41BB-derived costimulatory domain (CSD). L1CAM.IgG4CH2CH3Hinge.28TM.28CSD.3z CAR Ts outperformed the other constructs, killing ~60% of Rh30 at the E:T ratio of 1:1 and more than 90% at the E:T ratio of 5:1. They also exhibited a 3-fold higher IFN-γ release (120 pg/ml) compared to the other constructs. However, although our examination of patient-derived TMA revealed a strong immunoreactivity for L1CAM, more expressed in aggressive RMS subtypes, the selected L1CAM-CAR Ts against Rh30 cells, exhibiting ~10’000 L1CAM copies, showed limited activity in an in vivo pilot study. Based on these results and on the RMS TME investigation, which revealed consistent collagen (COL4A1, COL4A2 and COL18A1) deposition in RMS-derived mice tumor xenografts, we hypothesize that co-expressing a collagenase, able to partially degrade the dense extracellular matrix surrounding tumors, will lead to an improved CAR T cell infiltration and activity in vivo. Citation Format: Caroline Piccand, Andrea Timpanaro, Stenija Anton-Joseph, Michele Bernasconi, Jochen Karl Rössler. Improvement of CAR T cell potency against low-density targets like L1CAM and FGFR4 in rhabdomyosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4015.

OBJECTIVE:The way in which parental posttraumatic stress symptoms (PTSS) unfold in the first year after a cancer diagnosis in their child is poorly understood. The aims of this study were to identify parental PTSS trajectories and to examine couple-related predictors (dyadic coping and we-disease appraisals), sociodemographic predictors (education and sex), and medical predictors (child's physical impairment) of trajectory membership. METHOD:A 1-year prospective study was conducted, and 157 parents of children newly diagnosed with cancer were assessed. PTSS was measured with the Posttraumatic Diagnostic Scale for DSM-5 (PDS-5) at 3-6 weeks (T1), 6 months (T2), and 12 months (T3) after the diagnosis. The trajectories were identified with Latent Class Growth Analysis, the predictors were explored with binomial logistic regression. RESULTS:Two distinct trajectories were found. The majority of parents (86.0%) followed a low PTSS trajectory, characterized by initially low scores that slightly decreased over 12 months. In contrast, 14.0% of parents displayed a stable, high PTSS trajectory. A high trajectory of child's physical impairment and low scores in parental dyadic coping were significantly associated with the likelihood of a high parental PTSS trajectory. CONCLUSIONS:The findings provide new insights into the critical period of the first year after a child's cancer diagnosis. While most parents display a resilient, low PTSS trajectory, a minority consistently experience high PTSS levels. Child's physical impairment and dyadic coping should be considered as predictors for early identification of vulnerable parents. Incorporating dyadic coping in parental support following a childhood cancer diagnosis could be beneficial for parental mental health.

Recently, we described porphyrin-based periodic mesoporous organosilica (PMO) nanoparticles synthesized from a large functional octatriethoxysilylated porphyrin precursor. The framework of the nanoparticles was formed by J-aggregates of porphyrins allowing two-photon excitation photodynamic therapy (TPE-PDT) and NIR imaging. In this study, we functionalized these PMO with polyethylene glycol (PEG) moieties and an analogue of mannose 6-phosphate functionalized on anomeric position (AMFA). These AMFA are known to efficiently target mannose 6-phosphate receptors (M6PR) which are over-expressed in various cancer cell lines (breast, prostate). Here we show that M6PR is also over-expressed in rhabdomyosarcoma (RMS) cell lines. We targeted this receptor with PMO-AMFA and efficiently performed TPE imaging and TPE-PDT of RMS cells. Furthermore the same treatment did not affect healthy myoblasts, which have a low expression of M6PR.

Background Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in childhood, whose prognosis is still poor especially for metastatic, high-grade, and relapsed RMS. New treatments are urgently needed, especially systemic therapies. Chimeric Antigen Receptor T cells (CAR Ts) are very effective against hematological malignancies, but their efficacy against solid tumors needs to be improved. CD276 (B7-H3) is a target upregulated in RMS and detected at low levels in normal tissues. FGFR4 is a very specific target for RMS. Here, we optimized CAR Ts for these two targets, alone or in combination, and tested their anti-tumor activity in vitro and in vivo. Methods Four different single-domain antibodies were used to select the most specific FGFR4-CAR construct. RMS cell killing and cytokine production by CD276- and FGFR4-CAR Ts expressing CD8α or CD28 HD/TM domains in combination with 4-1BB and/or CD28 co-stimulatory domains were tested in vitro . The most effective CD276- and FGFR4-CAR Ts were used to generate Dual-CAR Ts. Tumor killing was evaluated in vivo in three orthotopic RMS mouse models. Results CD276.V-CAR Ts (276.MG.CD28HD/TM.CD28CSD.3ζ) showed the strongest killing of RMS cells, and the highest release of IFN-γ and Granzyme B in vitro. FGFR4.V-CAR Ts (F8-FR4.CD28HD/TM.CD28CSD.3ζ) showed the most specific killing. CD276-CAR Ts successfully eradicated RD- and Rh4-derived RMS tumors in vivo, achieving complete remission in 3/5 and 5/5 mice, respectively. In CD276 low JR-tumors, however, they achieved complete remission in only 1/5 mice. FGFR4 CAR Ts instead delayed Rh4 tumor growth. Dual-CAR Ts promoted Rh4-tumors clearance in 5/5 mice. Conclusions CD276- and CD276/FGFR4-directed CAR Ts showed effective RMS cell killing in vitro and eradication of CD276 high RMS tumors in vivo. CD276 low tumors escaped the therapy highlighting a correlation between antigen density and effectiveness. FGFR4-CAR Ts showed specific killing in vitro but could only delay RMS growth in vivo. Our results demonstrate that combined expression of CD276-CAR with other CAR does not reduce its benefit. Introducing immunotherapy with CD276-CAR Ts in RMS seems to be feasible and promising, although CAR constructs design and target combinations have to be further improved to eradicate tumors with low target expression.

Objective: Generalized lymphatic anomaly (GLA), Gorham-Stout disease (GSD), kaposiform lymphangiomatosis (KLA), and central conducting lymphatic anomaly (CCLA) are rare, multisystem lymphatic disorders, referred to as complex lymphatic anomalies (CLAs). Their etiology remains poorly understood; however, somatic activating mutations have recently been discovered, and the results of targeted treatments are promising. This study aimed to elaborate on the phenotypic description of CLA.Methods: Thirty-six consecutive patients were recruited for the "GLA/GSD Registry" of the University Hospital of Freiburg, Germany (2015-2021). Clinical data were prospectively collected provided that a signed informed consent form was obtained. The latest proposed diagnostic guidelines were retrospectively applied.Results: Thirty-two patients (38% males) were included in the study; 15 GLA, 10 GSD, 3 KLA, and 4 CCLA patients were identified. Eighty-four percent already had symptoms by the age of 15 years. Osteolysis and periosseous soft-tissue infiltration were associated with GSD (p < 0.001 and p = 0.011, respectively), ascites and protein-losing enteropathy with CCLA (p = 0.007 and p = 0.004, respectively), and consumption coagulopathy with KLA (p = 0.006). No statistically significant differences were found in organ involvement, distribution of osteolytic lesions, number of affected bones and fractures. Twenty-five patients had complications; one patient with GLA died despite multimodal treatment. Spontaneous regression was seen in one patient with untreated KLA.Conclusions: CLA are rare, and their overlapping clinical presentations make differential diagnosis difficult. The characterization of our case series contributes to the phenotypic description and differentiation of these four clinical entities. A further understanding of their pathogenesis is crucial for evaluating targeted therapies and optimizing medical care.

Objective: In recent years, genotypic characterization of congenital vascular malformations (CVMs) has gained attention; however, the spectrum of clinical phenotype remains difficult to attribute to a genetic cause and is rarely described in the adult population. The aim of this study is to describe a consecutive series of adolescent and adult patients in a tertiary center, where a multimodal phenotypic approach was used for diagnosis.Methods: We analyzed clinical findings, imaging, and laboratory results at initial presentation, and set a diagnosis ac-cording to the International Society for the Study of Vascular Anomalies (ISSVA) classification for all consecutively registered patients older than 14 years of age who were referred to the Center for Vascular Malformations at the University Hospital of Bern between 2008 and 2021.Results: A total of 457 patients were included for analysis (mean age, 35 years; females, 56%). Simple CVMs were the most common (n = 361; 79%), followed by CVMs associated with other anomalies (n = 70; 15%), and combined CVMs (n = 26; 6%). Venous malformations (n = 238) were the most common CVMs overall (52%), and the most common simple CVMs (66%). Pain was the most frequently reported symptom in all patients (simple, combined, and vascular malformation with other anomalies). Pain intensity was more pronounced in simple venous and arteriovenous malformations. Clinical problems were related to the type of CVM diagnosed, with bleeding and skin ulceration in arteriovenous malformations, localized intra-vascular coagulopathy in venous malformations, and infectious complications in lymphatic malformations. Limb length difference occurred more often in patients with CVMs associated with other anomalies as compared with simple or com-bined CVM (22.9 vs 2.3%; P < .001). Soft tissue overgrowth was seen in one-quarter of all patients independent of the ISSVA group. Conclusions: In our adult and adolescent population with peripheral vascular malformations, simple venous malfor-mations predominated, with pain as the most common clinical symptom. In one-quarter of cases, patients with vascular malformations presented with associated anomalies on tissue growth. The differentiation of clinical presentation with or without accompanying growth abnormalities need to be added to the ISSVA classification. Phenotypic characterization considering vascular and non-vascular features remains the cornerstone of diagnosis in adult as well as pediatric patients.