Gargollo, Patricio C.

ABSTRACTIntroductionProton beam therapy (PT) offers a targeted approach to treating pediatric tumors by minimizing radiation exposure to surrounding healthy tissue. However, the specific toxicity profile associated with it remains underexplored. This study aims to investigate the incidence and risk factors of acute and late treatment‐related toxicities following PT in pediatric patients with pelvic tumors.MethodsUsing data from the Pediatric Proton Consortium Registry (PPCR), we analyzed 126 pediatric patients who underwent PT for pelvic tumors. We assessed the incidence of gastrointestinal (GI), genitourinary (GU), and musculoskeletal (MSK) toxicities at baseline, during treatment, and across follow‐up intervals.ResultsAcute toxicities were observed in 61.9% of patients posttreatment, with new GI, GU, and MSK toxicities occurring in 54.3%, 9.7%, and 7.0% of baseline toxicity‐free patients, respectively. Follow‐up indicated that 20.6%, 22.2%, and 13.5% of patients developed late GI, GU, and MSK toxicities, respectively. Use of passive scattering proton therapy and radiation to the abdomen were significant predictors of GI toxicity development, while higher radiation dose was associated with MSK toxicity development.ConclusionOur findings demonstrate the safety profile of PT among pediatric patients while identifying specific risk factors, such as passive scattering proton therapy and abdominal irradiation, that contribute to increased GI toxicity. While proton therapy appears to be a well‐tolerated treatment option, the observed toxicity rates highlight the need for continued monitoring and long‐term follow‐up.

Background/Objectives: Pediatric rhabdomyosarcoma is a rare and poorly understood disease. Patients and parents can have varying experiences including barriers to care, time to treatment, and treatments offered. Here, we report on patient experiences regarding their care of pediatric rhabdomyosarcoma. Methods: Two separate online parent support groups were invited to participate in a survey. The survey included questions that sought to collect patient demographics, history of rhabdomyosarcoma, treatment timelines, and barriers to care. Results: A total of 215 surveys were completed. The average time from diagnosis to treatment was 12 days (SD = 14). Only 26% were offered fertility preservation prior to treatment. For patients with recurrence, an average of 75 days passed between detection of recurrence and treatment re-initiation. Patients traveled to centers with a dedicated sarcoma program in 52% of the cases. A total of 42% of parents sought a second opinion. Of those, the majority had to wait between one week and one month to be seen by another expert. Conclusions: The data collected from the survey suggests there are several opportunities to improve care among patients with pediatric rhabdomyosarcoma. Many patients may benefit from more efficient rhabdomyosarcoma referral networks, delivering patients to experts who can quickly begin multidisciplinary treatment.

PURPOSE: This study aimed to analyze organ system-based causes and non-organ system-based mechanisms of death (COD, MOD) in people with myelomeningocele (MMC), comparing urological to other COD. METHODS: A retrospective review was performed of 16 institutions in Canada/United States of non-random convenience sample of people with MMC (born > = 1972) using non-parametric statistics. RESULTS: Of 293 deaths (89% shunted hydrocephalus), 12% occurred in infancy, 35% in childhood, and 53% in adulthood (documented COD: 74%). For 261 shunted individuals, leading COD were neurological (21%) and pulmonary (17%), and leading MOD were infections (34%, including shunt infections: 4%) and non-infectious shunt malfunctions (14%). For 32 unshunted individuals, leading COD were pulmonary (34%) and cardiovascular (13%), and leading MOD were infections (38%) and non-infectious pulmonary (16%). COD and MOD varied by shunt status and age (p < = 0.04), not ambulation or birthyear (p > = 0.16). Urology-related deaths (urosepsis, renal failure, hematuria, bladder perforation/cancer: 10%) were more likely in females (p = 0.01), independent of age, shunt, or ambulatory status (p > = 0.40). COD/MOD were independent of bladder augmentation (p = >0.11). Unexplained deaths while asleep (4%) were independent of age, shunt status, and epilepsy (p >= 0.47). CONCLUSION: COD varied by shunt status. Leading MOD were infectious. Urology-related deaths (10%) were independent of shunt status; 26% of COD were unknown. Life-long multidisciplinary care and accurate mortality documentation are needed.

Abstract Background: Mutations in RAS is reported in embryonal rhabdomyosarcoma (ERMS). Upregulation of IGF2/IGF1R axis and IGF2 overexpression is a common finding. Targeting RAS downstream is associated with high toxicity. Combination therapies targeting parallel pathways is necessary to overcome treatment resistance. Dual inhibition of RAS downstream and IGF2/IGF1R axis can be a potential mechanism of targeted treatment. The efficacy of this mechanism was studied using a microcancer 3D exvivo tumor cell viability assay in a KRAS mutant ERMS. Design: Tumor was collected for a high-risk pediatric ERMS patient. Comprehensive genomic analysis, for identification of targetable genomic alterations, was performed by integrating WES, MPseq and RNAseq. Tumor spheroids grown in 3D environment were tested against multiple single drugs and combinations. The tumor viability was assed employing the Cell Titer Glow Luminescent Cell Viability Assay. Results were expressed as nMATP and were shown as drug-response curve exhibiting the ATP concentration changes at Cmax. Results: Genomic findings included an oncogenic KRAS (G12D) mutation. BAY-293 has a partial cell killing response as a single agent. Given to the presence of IGF2 over-expression, IGF2/IGF1R pathway was targeted by linsitinib. Addition of BAY-293 to linsitinib led to enhanced effectiveness of this agent (Table 1). Conclusion: Combination of comprehensive genomic profiling and a laboratory-based 3D micro-cancer model using the patient’s own tumor is an effective way to determine drug efficacy. Targeting RAS pathway by single agents, increases the possibility of resistance. Dual targeting of downstream pathways by MEK and PI3K pathway inhibition is highly toxic, and the clinical usage of this combination is limited. Our results have indicated inhibition of IGF-1R/IGF2 axis in combination with other agents targeting RAS pathway, can be a potential method to address these limitations. ABEL 1. Summary of molecular alterations and targeting methods Molecular alteration Drug Target Kill% at Cmax KRAS (G12D) Mutation BAY-293 RAS-SOS1 interaction 55.3 Trametinib MEK1/2 88.3 Selumetinib MEK1/2 76 Paxalisib PI3K/mTOR 89.7 Samotolisib PI3K/mTOR 92.9 Copanlisib PI3K 95.2 Perifosine AKT 89.2 IGF2 Over-expression Linsitinib IGF-1R/InsR 84.1 BMS-754807 IGF-1R/InsR 67.4 NTRK2 mutation Larotrectinib NTRK 41.9 KMT2D mutation Panobinostat HDAC 85.3 Combinations Kill% at Cmax BAY-293+Selumetinib 100 BAY-293+Samotolisib 100 BAY-293+Paxalisib 99.7 BAY-293+Linsitinib 97.5 Selumetinib+Samotolisib 93.1 Citation Format: Dorsay Sadeghian, Wan-Hsin Lin, James Smadbeck, Alan Panheiter, Michael Barrett, Alexa F. Mccune, Giannoula Karagouga, Sarah Johnson, Ryan W. Feathers, Faye R. Harris, Lindsey Kinsella, Taylor Berry, John Cheville, Panos Anastasiadis, Candace Granberg, Patricio Gargollo, Vasmatzis George. Dual inhibition of RAS and the IGF2/IGF1R pathways: a potential targeting strategy for RAS-mutated embryonal rhabdomyosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3391.

Abstract Introduction The transgender population has largely been marginalized by society, causing inequities in health care delivery. The dearth of provider knowledge on transgender health issues further exacerbates these disparities. Objective A survey of the transgender population was conducted to help call attention to the often-overlooked aspect of care: fertility preservation prior to hormone therapy or gender affirmation surgery. Methods A survey of 65 transgender individuals was conducted, with participants recruited through Reddit transgender groups and local transgender associations, to assess their knowledge regarding fertility preservation and their experience with healthcare providers. Results were compiled and analysis was performed. Results Out of the 65 individuals who responded to the survey, approximately 88% were between the ages of 18 and 39. Seventy-four percent were assigned male gender at birth and 26% female. Sixty-two percent of individuals identified as female, 20% as male, and 18% as gender non-conforming. Only 35% of individuals had ever been cared for in a multidisciplinary transgender clinic. Interestingly, while 100% of surveyed individuals were aware that fertility would be irreversibly lost after hormonal or surgical affirmation surgery and 43% believed this to be an important issue, only 46% had any health care providers discuss fertility preservation options with them. Conclusions Hormonal therapy and gender affirming procedures affect the long-term reproductive potential of transgender individuals. While oncofertility is a prominent area of discussion, transgender care is still lagging. With an increase in medical and surgical therapy in younger individuals, health care providers must discuss fertility preservation options prior to affirmation therapy. Disclosure No

Abstract Introduction The transgender population has long been marginalized by society. Societal stigmata, fear to seek care, and dearth of provider knowledge regarding transgender health issues has caused disparities to widen. Objective The purpose of this case study is to call to attention the often-overlooked aspect of pediatric transgender care: the importance of fertility preservation prior to instituting gender-affirming therapy. Methods Twenty-one genetically XY females, followed by their multidisciplinary transgender care teams, were interested in starting hormone therapy due to impending onset and/or progression of puberty. Fortunately for these patients, their physicians were aware of fertility struggles after undergoing hormone therapy. Results Sperm cryopreservation via open gonadal biopsy, testicular tissue cryopreservation (TTC), and semen sample (when age/maturity-appropriate) were discussed. Though requiring surgery, biopsy/TTC relieves patients of the psychological impact of semen sample production. With IRB approval, 20 patients (median age 12 years, range 10-16 years) underwent TTC (Figure 1). One patient (age 16 years) opted for semen sample. All patients had success with spermatogonial stem cells cryopreserved for future patient use. Conclusions Gender affirming procedures and hormone therapy affect the long-term reproductive potential of transgender individuals. While cost concerns and insurance coverage regarding oncofertility is a prominent area of discussion, the transgender community is often excluded. With more individuals beginning medical and surgical therapy at a younger age, fertility preservation discussions are essential but often overlooked, depriving these individuals the joy of becoming a biological parent. As health care providers, addressing psychological, emotional, physical, and spiritual needs of patients is crucial, and fertility is a key aspect of this care. TTC can be safely done in pediatric populations, though research is necessary to expand beyond current experimental stage of tissue-development. Disclosure No

Abstract Introduction: Pediatric rhabdomyosarcoma (RMS) is the most common soft tissue tumor in children, with nearly 20% of children presenting with locally aggressive and/or metastatic disease. Despite aggressive chemotherapy and radiotherapy, the 5-year overall survival rate is still less than 40%. In addition, resistance to chemotherapy remains the major cause of cancer-related mortality. Therefore, there is an unmet need to develop more effective and tolerable therapeutic strategies for the treatment of RMS. Our overall objective is to leverage transcriptomic and proteomic profiling methods to identify RMS-specific surface proteins targetable with immune-based therapies. Methods: To identify therapeutic targets, we performed cell-surface capture and mass spectrometry on fusion-positive (FP), fusion-negative (FN) RMS and normal skeletal muscle. Transcriptomic datasets of RMS tumor specimens and normal tissue were employed to identify high-confidence RMS-specific cell-surface proteins. Expression of immune checkpoint molecules was confirmed by flow cytometry, western blot and PCR. Paraffin-embedded tissue sections were used to determine protein expression and prognostic value in RMS patients. We developed an in vitro T-cell killing assay to assess the functional role of immune checkpoint molecules on the antitumor immune response. Results: Surfaceome profiling of RMS cells revealed unique protein signatures specific for each tumor type and normal tissue. We have identified 5061 cell-surface proteins in RMS and 31.6% of proteins were correctly located at the plasma membrane. By integrating proteomic and transcriptomic data, we have identified 30 and 38 proteins significantly overexpressed in fusion-negative and fusion-positive RMS respectively compared to normal muscle. We have identified the immune checkpoint molecule B7-H3 as cell-surface protein overexpressed in both RMS subtypes. Strong expression of B7-H3 was also observed in patient’s tumor specimens. Genetic deletion of B7-H3 gene in RMS cells was associated with higher antitumor immune response in tumor cells co-cultured with CD8+-T cells. No difference was observed in tumor cell proliferation and radioresistance. Conclusions: Through integrated transcriptomic and proteomic profiling, we have discovered B7-H3 as a key regulator of tumor immune-evasion in RMS. B7-H3 is a suitable immunotherapy target for the treatment of RMS. Further studies are warranted to elucidate underlying mechanisms of B7-H3 function in RMS. Citation Format: Roxane R. Lavoie, Fabrice Lucien, Patricio C. Gargollo, Mohamed E. Ahmed, Yohan Kim, Emily Baer, Doris Phelps, Cristine M. Charlesworth, Benjamin J. Madden, Liguo Wang, Peter J. Hougthon, John Cheville, Haidong Dong, Candace F. Granberg. Surfaceome profiling of rhabdomyosarcoma reveals B7-H3 as a mediator of immune evasion [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr A036.

Novel therapeutic strategies are needed for the treatment of rhabdomyosarcoma (RMS), the most common soft-tissue sarcoma in children. By using a combination of cell surface proteomics and transcriptomic profiling of RMS and normal muscle, we generated a catalog of targetable cell surface proteins enriched in RMS tumors. Among the top candidates, we identified B7-H3 as the major immunoregulatory molecule expressed by RMS tumors. By using a large cohort of tissue specimens, we demonstrated that B7-H3 is expressed in a majority of RMS tumors while not detected in normal human tissues. Through a deconvolution analysis of the RMS tumor RNA-seq data, we showed that B7-H3-rich tumors are enriched in macrophages M1, NK cells, and depleted in CD8+-T cells. Furthermore, in vitro functional assays showed that B7-H3 knockout in RMS tumor cells increases T-cell mediated cytotoxicity. Altogether, our study uncovers new potential targets for the treatment of RMS and provides the first biological insights into the role of B7-H3 in RMS biology, paving the way for the development of next-generation immunotherapies.

Abstract Introduction: Pediatric rhabdomyosarcoma (RMS) is the most common soft tissue tumor in children, with nearly 20% of children presenting with locally aggressive and/or metastatic disease. Despite aggressive chemotherapy and radiotherapy, the 5-year overall survival rate is still less than 40%. In addition, resistance to chemotherapy remains the major cause of cancer-related mortality. Therefore, there is an unmet need to develop more effective and tolerable therapeutic strategies for the treatment of RMS. Our overall objective is to leverage transcriptomic and proteomic profiling methods to identify RMS-specific surface proteins targetable with immune-based therapies. Methods: To identify therapeutic targets, we performed cell-surface capture and mass spectrometry on fusion-positive (FP), fusion-negative (FN) RMS and normal skeletal muscle. Transcriptomic datasets of RMS tumor specimens and normal tissue were employed to identify high-confidence RMS-specific cell-surface proteins. Expression of immune checkpoint molecules was confirmed by flow cytometry, western blot and PCR. Paraffin-embedded tissue sections were used to determine protein expression and prognostic value in RMS patients. We developed an in vitro T-cell killing assay to assess the functional role of immune checkpoint molecules on the antitumor immune response. Results: Surfaceome profiling of RMS cells revealed unique protein signatures specific for each tumor type and normal tissue. We have identified 5061 cell-surface proteins in RMS and 31.6% of proteins were correctly located at the plasma membrane. By integrating proteomic and transcriptomic data, we have identified 30 and 38 proteins significantly overexpressed in fusion-negative and fusion-positive RMS respectively compared to normal muscle. We have identified the immune checkpoint molecule B7-H3 as cell-surface protein overexpressed in both RMS subtypes. Strong expression of B7-H3 was also observed in patient's tumor specimens. Genetic deletion of B7-H3 gene in RMS cells was associated with higher antitumor immune response in tumor cells co-cultured with CD8+-T cells. No difference was observed in tumor cell proliferation and radioresistance. Conclusion: Through integrated transcriptomic and proteomic profiling, we have discovered B7-H3 as a key regulator of tumor immune-evasion in RMS. B7-H3 is a suitable immunotherapy target for the treatment of RMS. Further studies are warranted to elucidate underlying mechanisms of B7-H3 function in RMS. Citation Format: Roxane R. Lavoie, Yohan Kim, Mohamed E. Ahmed, Doris Phelps, Emily Baer, Cristine Charlesworth, Benjamin Madden, Liguo Wang, Haidong Dong, Peter Houghton, John Cheville, Patricio Gargollo, Candace Granberg, Fabrice Lucien. Surfaceome profiling identifies the immune checkpoint molecule B7-H3 as a key player of immune-evasion in rhabdomyosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3048.