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Cancer immunotherapies are associated with remarkable therapeutic response rates but also with unique and severe toxicities, which potentially result in rapid deterioration in health. The number of clinical applications for novel immune effector-cell therapies, including chimeric antigen receptor (CAR)-expressing cells, and other immunotherapies, such as immune-checkpoint inhibitors, is increasing. In this Consensus Statement, members of the Pediatric Acute Lung Injury and Sepsis Investigators (PALISI) Network Hematopoietic Cell Transplantation-Cancer Immunotherapy (HCT-CI) Subgroup, Paediatric Diseases Working Party (PDWP) of the European Society of Blood and Marrow Transplantation (EBMT), Supportive Care Committee of the Pediatric Transplantation and Cellular Therapy Consortium (PTCTC) and MD Anderson Cancer Center CAR T Cell Therapy-Associated Toxicity (CARTOX) Program collaborated to provide updated comprehensive recommendations for the care of children, adolescents and young adults receiving cancer immunotherapies. With these recommendations, we address emerging toxicity mitigation strategies, we advocate for the characterization of baseline organ function according to age and discipline-specific criteria, we recommend early critical care assessment when indicated, with consideration of reversibility of underlying pathology (instead of organ failure scores) to guide critical care interventions, and we call for researchers, regulatory agencies and sponsors to support and facilitate early inclusion of young patients with cancer in well-designed clinical trials.

Osteosarcoma (OS) is a molecularly heterogeneous, aggressive, poorly differentiated pediatric bone cancer that frequently spreads to the lung. Relatively little is known about phenotypic and epigenetic changes that promote lung metastases. To identify key drivers of metastasis, we studied human CCH-OS-D OS cells within a previously described rat acellular lung (ACL) model that preserves the native lung architecture, extracellular matrix, and capillary network. This system identified a subset of cells—termed derived circulating tumor cells (dCTCs)—that can migrate, intravasate, and spread within a bioreactor-perfused capillary network. Remarkably, dCTCs highly expressed epithelial-to-mesenchymal transition (EMT)-associated transcription factors (EMT-TFs), such as ZEB1, TWIST, and SOX9, which suggests that they undergo cellular reprogramming toward a less differentiated state by coopting the same epigenetic machinery used by carcinomas. Since YAP/TAZ and AXL tightly regulate the fate and plasticity of normal mesenchymal cells in response to microenvironmental cues, we explored whether these proteins contributed to OS metastatic potential using an isogenic pair of human OS cell lines that differ in AXL expression. We show that AXL inhibition significantly reduced the number of MG63.2 pulmonary metastases in murine models. Collectively, we present a laboratory-based method to detect and characterize a pure population of dCTCs, which provides a unique opportunity to study how OS cell fate and differentiation contributes to metastatic potential. Though the important step of clinical validation remains, our identification of AXL, ZEB1, and TWIST upregulation raises the tantalizing prospect that EMT-TF-directed therapies might expand the arsenal of therapies used to combat advanced-stage OS.

Current in vitro methods for assessing cancer biology and therapeutic response rely heavily on monolayer cell culture on hard, plastic surfaces that do not recapitulate essential elements of the tumor microenvironment. While a host of tumor models exist, most are not engineered to control the physical properties of the microenvironment and thus may not reflect the effects of mechanotransduction on tumor biology. Utilizing coaxial electrospinning, we developed three-dimensional (3D) tumor models with tunable mechanical properties in order to elucidate the effects of substrate stiffness and tissue architecture in osteosarcoma. Mechanical properties of coaxial electrospun meshes were characterized with a series of macroscale testing with uniaxial tensile testing and microscale testing utilizing atomic force microscopy on single fibers. Calculated moduli in our models ranged over three orders of magnitude in both macroscale and microscale testing. Osteosarcoma cells responded to decreasing substrate stiffness in 3D environments by increasing nuclear localization of Hippo pathway effectors, YAP and TAZ, while downregulating total YAP. Additionally, a downregulation of the IGF-1R/mTOR axis, the target of recent clinical trials in sarcoma, was observed in 3D models and heralded increased resistance to combination chemotherapy and IGF-1R/mTOR targeted agents compared to monolayer controls. In this study, we highlight the necessity of incorporating mechanical cues in cancer biology investigation and the complexity in mechanotransduction as a confluence of stiffness and culture architecture. Our models provide a versatile, mechanically variable substrate on which to study the effects of physical cues on the pathogenesis of tumors. STATEMENT OF SIGNIFICANCE: The tumor microenvironment plays a critical role in cancer pathogenesis. In this work, we engineered 3D, mechanically tunable, coaxial electrospun environments to determine the roles of the mechanical environment on osteosarcoma cell phenotype, morphology, and therapeutic response. We characterize the effects of varying macroscale and microscale stiffnesses in 3D environments on the localization and expression of the mechanoresponsive proteins, YAP and TAZ, and evaluate IGF-1R/mTOR pathway activation, a target of recent clinical trials in sarcoma. Increased nuclear YAP/TAZ was observed as stiffness in 3D was decreased. Downregulation of the IGF-1R/mTOR cascade in all 3D environments was observed. Our study highlights the complexity of mechanotransduction in 3D culture and represents a step towards controlling microenvironmental elements in in vitro cancer investigations.

Chimeric antigen receptor (CAR) therapies such as tisagenlecleucel, indicated for children and young adults with relapsed and/or refractory CD19+ acute lymphoblastic leukemia (ALL), have been associated with striking treatment outcomes and overall survival. Yet, they are also associated with unique and potentially life-threatening complications. Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity (ICANS) are generally reversible complications of CAR therapies, but many patients may require critical care support especially if they are not promptly recognized and appropriately managed by frontline healthcare staff. As CAR therapies become more widely available, it is important that inter-professional staff members be aware of general principles regarding diagnosis and management. We hypothesized that an inter-professional education (IPE) simulation-based education intervention (CAR-TEAM) would improve knowledge base and confidence regarding complications of CAR therapies among inter-professional staff. Here, we demonstrate that following CAR-TEAM training, >90% of participants demonstrated knowledge proficiency and confidence in the IPE content area. CAR-TEAM training may serve as an important tool to establish initial and continued competency among sites introducing CAR therapies.

BACKGROUND: Children with isolated neutropenia (absolute neutrophil count [ANC] METHODS: We performed a 5.5-year institutional review board–approved retrospective chart review of children referred to our pediatric hematology and oncology clinics for isolated neutropenia. Neutropenia was categorized as mild (ANC of 1001–1500/μL), moderate (ANC of 500–1000 μL), severe (ANC of 201–500/μL), or very severe (ANC of ≤200/μL). RESULTS: Among 155 children referred with isolated neutropenia, 45 (29%) had mild neutropenia, 65 (42%) had moderate neutropenia, 30 (19%) had severe neutropenia, and 15 (10%) had very severe neutropenia. Only 29 (19%) children changed to an ANC category lower than their initial referral category. At a median follow-up of 12 months, 101 children had resolution of neutropenia, 40 children had mild neutropenia, 10 children had moderate neutropenia, 3 children had severe neutropenia, and 1 patient had very severe neutropenia. A specific diagnosis was not identified in most (54%) children. The most common etiologies were viral suppression (16%), autoimmune neutropenia (14%), and drug-induced neutropenia (8%). Black children had a 3.5 higher odds of having persistent mild neutropenia. Six (4%) children received granulocyte colony-stimulating factor therapy. CONCLUSIONS: Most children referred for isolated neutropenia do not progress in severity and do not require subspecialty interventions or hospitalizations.

Advances in genomic, transcriptomic and epigenomic profiling now identifies pediatric ependymoma as a defined biological entity. Molecular interrogation has segregated these tumors into distinct biological subtypes based on anatomical location, age and clinical outcome, which now defines the need to tailor therapy even for histologically similar tumors. These findings now provide reasons for a paradigm shift in therapy, which should profile future clinical trials focused on targeted therapeutic strategies and risk-based treatment. The need to diagnose and differentiate the aggressive variants, which include the posterior fossa group A and the supratentorial RELA fusion subtypes, is imperative to escalate therapy and improve survival.

In 2017, an autologous chimeric antigen receptor (CAR) T cell therapy indicated for children and young adults with relapsed and/or refractory CD19+ acute lymphoblastic leukaemia became the first gene therapy to be approved in the USA. This innovative form of cellular immunotherapy has been associated with remarkable response rates but is also associated with unique and often severe toxicities, which can lead to rapid cardiorespiratory and/or neurological deterioration. Multidisciplinary medical vigilance and the requisite health-care infrastructure are imperative to ensuring optimal patient outcomes, especially as these therapies transition from research protocols to standard care. Herein, authors representing the Pediatric Acute Lung Injury and Sepsis Investigators (PALISI) Network Hematopoietic Stem Cell Transplantation (HSCT) Subgroup and the MD Anderson Cancer Center CAR T Cell Therapy-Associated Toxicity (CARTOX) Program have collaborated to provide comprehensive consensus guidelines on the care of children receiving CAR T cell therapy., Chimeric antigen receptor (CAR) T cell therapies have impressive activity in the treatment of cancer but are associated with potentially fatal toxicities. In light of the approval of CAR T cell therapy for paediatric patients, a panel of experts from the Hematopoietic Stem Cell Transplantation (HSCT) Subgroup of the Pediatric Acute Lung Injury and Sepsis Investigators (PALISI) Network, the CAR T Cell Therapy-Associated Toxicity (CARTOX) Program at The University of Texas MD Anderson Cancer Center, and several other institutions have developed consensus guidelines for the use and management of these treatments in paediatric patients, which are presented herein.

Introduction Myelodysplastic syndrome (MDS) is mainly a disease of the elderly, with a median age of 72 years. There is little information regarding Adolescent and Young Adult (AYA) Patients with Myelodysplastic syndrome (MDS). AYA cancer patients are defined as those patients ages between 15-39 years according to NCCN guidelines. This retrospective study describes the general characteristics, cytogenetics, mutational profiles, treatments, and outcomes of AYA with MDS Diagnosis. Methodology We analyzed the clinical database of a single tertiary care center for patients with MDS ages between 18- 39 years from January 2012 through December 2020. We used 18 years as age cut-off, and not 15, due to the structure of our cancer center. Results In this retrospective study, 65 patients were identified. The median age was 30 (18-39) years, with female sex predominance (n=37) (57%). Baseline laboratory findings: median hemoglobin (HgB) was 9.45gm/dL (6.2-14.8), white blood cells (WBC) (3.4x10e9/L [0.3-136.9], platelets 63,000 (5,000-479,000), bone marrow blast 4% [0-17], IPSS was low in 11 patients (17%), intermediate- 1 in 23 (35%), intermediate- 2 16(25%) and high 8 (12%). 58 patients (89%) had MDS and seven (11%) had CMML. Twenty patients (30.7%) had a previous history of other cancers, with sarcomas being the most frequent with 6 cases (9.2%). Therapy-related MDS (t-MDS) was observed in 18 patients (27.6%). Ten patients (15.3%) had bone marrow failure syndrome, with GATA2 syndrome being the most frequent. Fanconi anemia and Schwachman-Diamond Syndrome was documented in two patients respectively. The most recurrent cytogenetics alterations were diploid in 20 patients (30.7%), followed by complex in 11 (16.9%). The most frequent mutations were RUNX1 (somatic)15%, followed by DNMT3A, TP53, NRAS, GATA2 and TET2, as shown in the Figure 1. Hypomethylating agents (HMAs) were the most frequent first line treatment used in 16 patients (24.6%). Forty-three patients (66%) underwent an allogeneic bone marrow transplant with a median OS (95% CI) of 27 months (9-45). While for the group of patients who didn't receive transplant, it was 21 months (7-69) (p=0.19) vs patients who didn't receive transplant. Allogeneic transplantation in TP53-mutated patients resulted in a Median OS (95% CI) of 21 months (12-65). Patients who progressed into AML had an inferior median OS (95% CI) of 21 months (12-65) for vs 28 months (11-47) for those who did not progressed to AML(p=0.025). In multivariate analysis expression of RUNX1 and NOTCH1, was associated with inferior outcomes (p-value=0.035, 0.004 respectively) (Figure 2,3 and 4) Conclusion In our cohort, MDS occurred as part of marrow failure syndrome or consequence of therapy t-MDS. Somatic RUNX1 was the most frequent mutation in AYA group with MDS. RUNX1, NOTCH1 and Tp53 mutated patients had worse outcome. Most patients underwent bone marrow transplant Figure 1 Figure 1. Disclosures Jabbour: Amgen, AbbVie, Spectrum, BMS, Takeda, Pfizer, Adaptive, Genentech: Research Funding. Daver: Abbvie: Consultancy, Research Funding; Gilead Sciences, Inc.: Consultancy, Research Funding; Astellas: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Glycomimetics: Research Funding; Novimmune: Research Funding; Amgen: Consultancy, Research Funding; FATE Therapeutics: Research Funding; Hanmi: Research Funding; Sevier: Consultancy, Research Funding; Genentech: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Trovagene: Consultancy, Research Funding; Trillium: Consultancy, Research Funding; ImmunoGen: Consultancy, Research Funding; Novartis: Consultancy; Jazz Pharmaceuticals: Consultancy, Other: Data Monitoring Committee member; Dava Oncology (Arog): Consultancy; Celgene: Consultancy; Syndax: Consultancy; Shattuck Labs: Consultancy; Agios: Consultancy; Kite Pharmaceuticals: Consultancy; SOBI: Consultancy; STAR Therapeutics: Consultancy; Karyopharm: Research Funding; Newave: Research Funding. Kadia: Liberum: Consultancy; Novartis: Consultancy; Pfizer: Consultancy, Other; Jazz: Consultancy; BMS: Other: Grant/research support; Amgen: Other: Grant/research support; Pulmotech: Other; Genentech: Consultancy, Other: Grant/research support; Aglos: Consultancy; Sanofi-Aventis: Consultancy; Genfleet: Other; Astellas: Other; Ascentage: Other; AstraZeneca: Other; AbbVie: Consultancy, Other: Grant/research support; Dalichi Sankyo: Consultancy; Cure: Speakers Bureau; Cellonkos: Other. Pemmaraju: LFB Biotechnologies: Consultancy; Incyte: Consultancy; Protagonist Therapeutics, Inc.: Consultancy; Abbvie Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; CareDx, Inc.: Consultancy; DAVA Oncology: Consultancy; Stemline Therapeutics, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Cellectis S.A. ADR: Other, Research Funding; Celgene Corporation: Consultancy; Novartis Pharmaceuticals: Consultancy, Other: Research Support, Research Funding; Roche Diagnostics: Consultancy; Daiichi Sankyo, Inc.: Other, Research Funding; Affymetrix: Consultancy, Research Funding; Plexxicon: Other, Research Funding; ASH Communications Committee: Membership on an entity's Board of Directors or advisory committees; Samus: Other, Research Funding; ASCO Leukemia Advisory Panel: Membership on an entity's Board of Directors or advisory committees; Aptitude Health: Consultancy; Springer Science + Business Media: Other; MustangBio: Consultancy, Other; Sager Strong Foundation: Other; HemOnc Times/Oncology Times: Membership on an entity's Board of Directors or advisory committees; Dan's House of Hope: Membership on an entity's Board of Directors or advisory committees; Clearview Healthcare Partners: Consultancy; Blueprint Medicines: Consultancy; Bristol-Myers Squibb Co.: Consultancy; ImmunoGen, Inc: Consultancy; Pacylex Pharmaceuticals: Consultancy. Kantarjian: NOVA Research: Honoraria; KAHR Medical Ltd: Honoraria; Precision Biosciences: Honoraria; BMS: Research Funding; Amgen: Honoraria, Research Funding; Jazz: Research Funding; Ascentage: Research Funding; Immunogen: Research Funding; Daiichi-Sankyo: Research Funding; Ipsen Pharmaceuticals: Honoraria; Astra Zeneca: Honoraria; Astellas Health: Honoraria; Aptitude Health: Honoraria; Pfizer: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; AbbVie: Honoraria, Research Funding; Taiho Pharmaceutical Canada: Honoraria.

Background : Although in recent clinical trials the 5-year event-free survival rates for pediatric Acute Myeloid Leukemia (AML) range between 49% and 64%, relapse still occurs in up to one-third of cases. Long-term outcomes of children with relapsed or refractory disease remain poor, with overall survival under 40%. Novel drugs directed toward distinct pathways and new molecular targets are required to continue improving outcomes for this aggressive hematological disease. Use of the BCL-2 inhibitor, venetoclax, has improved overall and event-free survival in adult patients with newly diagnosed, intensive-chemotherapy ineligible AML, however, its effects in pediatric AML patients remain unclear. We reviewed our multi-institutional experience with venetoclax in this population. Methods : We performed a retrospective review of patients ages 0 to 23 y/o with AML and treated with at least one cycle of venetoclax at either MD Anderson Cancer Center or Texas Children's Hospital prior to May 2021. Flow cytometry was used to assess morphology and response to therapy. Adverse events (AEs) associated with venetoclax were graded according to the Common Terminology Criteria for Adverse Events version 5.0. Descriptive statistics were used to report efficacy and toxicity data. Results : 46 patients with AML who received venetoclax-containing regimens were identified. There was a similar proportion of males and females (52% and 48%) and most were Caucasian (48%). The median age was 21 years (range, 1-23) with eight patients (17%) Conclusion : Our findings suggest that in pediatric and early young adults, venetoclax is well-tolerated with a variety of cytotoxic agents and has a safety profile similar to that in adults. Patients should be monitored closely for prolonged myelosuppression and febrile neutropenia. As dosing varied significantly in our cohort, more studies are needed to establish an optimal dose in the pediatric population. Longer follow-up is expected to provide more insight on the improvement venetoclax may have on overall and progression-free survival. Figure 1 Figure 1. Disclosures Kadia: Sanofi-Aventis: Consultancy; Dalichi Sankyo: Consultancy; Genentech: Consultancy, Other: Grant/research support; Genfleet: Other; AstraZeneca: Other; Astellas: Other; Pulmotech: Other; Cure: Speakers Bureau; Cellonkos: Other; Jazz: Consultancy; Pfizer: Consultancy, Other; Ascentage: Other; Novartis: Consultancy; Liberum: Consultancy; BMS: Other: Grant/research support; Amgen: Other: Grant/research support; Aglos: Consultancy; AbbVie: Consultancy, Other: Grant/research support. Konopleva: Cellectis: Other: grant support; F. Hoffmann-La Roche: Consultancy, Honoraria, Other: grant support; KisoJi: Research Funding; Calithera: Other: grant support, Research Funding; Rafael Pharmaceuticals: Other: grant support, Research Funding; Ascentage: Other: grant support, Research Funding; Sanofi: Other: grant support, Research Funding; Forty Seven: Other: grant support, Research Funding; Ablynx: Other: grant support, Research Funding; Agios: Other: grant support, Research Funding; AstraZeneca: Other: grant support, Research Funding; Novartis: Other: research funding pending, Patents & Royalties: intellectual property rights; Reata Pharmaceuticals: Current holder of stock options in a privately-held company, Patents & Royalties: intellectual property rights; Stemline Therapeutics: Research Funding; Genentech: Consultancy, Honoraria, Other: grant support, Research Funding; Eli Lilly: Patents & Royalties: intellectual property rights, Research Funding; AbbVie: Consultancy, Honoraria, Other: Grant Support, Research Funding. DiNardo: Takeda: Honoraria; Notable Labs: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; ImmuneOnc: Honoraria, Research Funding; AbbVie: Consultancy, Research Funding; Forma: Honoraria, Research Funding; Agios/Servier: Consultancy, Honoraria, Research Funding; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Honoraria, Research Funding; Novartis: Honoraria; Foghorn: Honoraria, Research Funding; Celgene, a Bristol Myers Squibb company: Honoraria, Research Funding. Daver: Bristol Myers Squibb: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Sevier: Consultancy, Research Funding; Novartis: Consultancy; Astellas: Consultancy, Research Funding; Glycomimetics: Research Funding; Novimmune: Research Funding; Hanmi: Research Funding; Genentech: Consultancy, Research Funding; Trillium: Consultancy, Research Funding; Gilead Sciences, Inc.: Consultancy, Research Funding; FATE Therapeutics: Research Funding; ImmunoGen: Consultancy, Research Funding; Abbvie: Consultancy, Research Funding; Trovagene: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy, Other: Data Monitoring Committee member; Dava Oncology (Arog): Consultancy; Celgene: Consultancy; Syndax: Consultancy; Shattuck Labs: Consultancy; Agios: Consultancy; Kite Pharmaceuticals: Consultancy; SOBI: Consultancy; STAR Therapeutics: Consultancy; Karyopharm: Research Funding; Newave: Research Funding. Short: AstraZeneca: Consultancy; Jazz Pharmaceuticals: Consultancy; NGMBio: Consultancy; Novartis: Honoraria; Astellas: Research Funding; Takeda Oncology: Consultancy, Research Funding; Amgen: Consultancy, Honoraria. Issa: Kura Oncology: Consultancy, Research Funding; Syndax Pharmaceuticals: Research Funding; Novartis: Consultancy, Research Funding. Ravandi: Amgen: Honoraria, Research Funding; Xencor: Honoraria, Research Funding; Taiho: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Agios: Honoraria, Research Funding; Novartis: Honoraria; AstraZeneca: Honoraria; AbbVie: Honoraria, Research Funding; Prelude: Research Funding; Astex: Honoraria, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Syros Pharmaceuticals: Consultancy, Honoraria, Research Funding. Kantarjian: Ascentage: Research Funding; Astra Zeneca: Honoraria; Pfizer: Honoraria, Research Funding; Daiichi-Sankyo: Research Funding; KAHR Medical Ltd: Honoraria; Ipsen Pharmaceuticals: Honoraria; NOVA Research: Honoraria; Novartis: Honoraria, Research Funding; Immunogen: Research Funding; Astellas Health: Honoraria; BMS: Research Funding; Aptitude Health: Honoraria; Jazz: Research Funding; AbbVie: Honoraria, Research Funding; Precision Biosciences: Honoraria; Amgen: Honoraria, Research Funding; Taiho Pharmaceutical Canada: Honoraria.

Background: Acute myeloid leukemia (AML) is rare but accounts for 20% of leukemia in the pediatric, adolescent and young adult (AYA) population. Five-year survival ranges widely from 22-90% based on subtype and cytogenetic abnormalities. The risk stratification of AML continues to evolve with increased recognition of inferior prognostic factors in the adult population; however, there has been a lack of similar progress in pediatrics. The DNA methyltransferase 3A (DNMT3A) mutation, most frequently at arginine 882 (DNMT3A mut) is observed in 14-34% of adult AML patients and is associated with inferior outcomes. This mutation shows evidence of anthracycline resistance, which may contribute to its poor prognosis as standard induction therapy for AML consists of a backbone of anthracyclines and purine analogs. Overall survival (OS) and disease-free survival (DFS) are improved in adult patients with DNMT3A mutation who receive consolidative allogeneic hematopoietic stem cell transplant (allo-HSCT). DNMT3A mutation has also been reported in the pediatric and AYA AML in 0-1.5% of cases with unclear prognostic implications. In case its presence in this patient population confers inferior outcomes similar to those seen in adults, these patients may also benefit from allo-HSCT Objective: Describe the outcome of pediatric and AYA AML patients with DNMT3A mutations Methods: This study was approved by the institutional review board at the University of Texas at MD Anderson Cancer Center. All patients aged ≤25 years, diagnosed with AML who underwent treatment at our institution between May 1st, 2014 and November 30 th 2020 were screened. Patients who did not undergo testing for DNMT3A mutation were excluded. Outcomes for patients with and without the DNMT3A mutation who underwent allo-HSCT were compared. Results: One hundred and five patients were diagnosed with AML during the study period. Forty-five patients were not tested for the DNMT3A mutation and were excluded. Sixty patients were tested for the DNMT3A mutation and were included in the analysis. Seven patients (11.7%) (4 males, 3 females) were found to be DNMT3A mutation positive (+ve). Four of them had the R882 missense mutation. Thirty-three patients (33/60; 55%) (16 males, 17 females) underwent allo-HSCT, with 6 of those being DNMT3A+ve. The median age of DNMT3A+ve and DNMT3A negative(-ve) patients undergoing allo-HSCT was 18.5 years (12.6-22.7) and 20 years (11.1-24) respectively (Figure1). Five patients who were DNMT3A+ve underwent allo-HSCT due to disease relapse and 1 patient due to associated FLT3 mutation. Median overall survival was similar in patients with and without DNMT3A mutations who received allo-HSCT at 744 (515-2473) days and 729(48-2492) days respectively (p value =0.77) (Figure 1). Median OS was significantly lower in the one DNMT3A +ve patient who did not undergo allo-HSCT at 430 days compared to those who underwent allo-HSCT (p value=0.01). Two of the six (33.3%) DNMT3A +ve patients who underwent allo HSCT died due to disease relapse (DR). The one DNMT3A patient who did not undergo allo HSCT died due to refractory disease. In the 27 patients who were DNMT3A -ve and received allo-HSCT, 13 died (13/27;48.1%), 6 from disease relapse (6/27; 22.2%), 2 due to multiorgan failure (2/27; 7.4%) and 5 unknown (5/27;18.5%). Relapse-free survival (RFS) was not significantly different between DNMT3A+ve and DNMT3A -ve patients who underwent allo-HSCT at 422 (31-1948) days and 271 (65-2048) days respectively (p value = 0.7).Of the four patients with the R882 missense mutation, 2 died due to DR (one patient at 192 days post allo-HSCT, one patient who did not undergo allo-HSCT at 352 days after achieving clinical remission one(CR1). Of the 3 patients with non R882 mutations, one died due to DR at 98 days post allo-HSCT. Conclusion: DNMT3A mutations, although rare in AML, may be associated with poor prognosis and impact risk stratification. This study suggest that consolidative allogeneic HSCT is a reasonable management consideration for this subgroup of patients. DNMT3A is not included in the current AML risk stratification of pediatric and young adult patients and further research is needed to determine the clinical significance of DNMT3A mutations in pediatric and AYA patients with AML and the impact of upfront allo-HSCT. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Hematopoietic cell transplantation (HCT) and cellular therapy (CT) are potentially lifesaving treatments for children with malignant and nonmalignant diseases. Advancements in care have led to expanding patient eligibility, with overall reduced morbidity and improved survival. Survival for HCT patients requiring pediatric intensive care unit (PICU) admission have improved. While almost half of pediatric patients receiving CAR-T therapy may require intensive care support, overall survival remains promising. However, patients undergoing HCT remain at risk for debilitating and life-threatening complications such as sinusoidal obstructive syndrome (S0S), infection, and graft-versus-host disease (GVHD); patients receiving chimeric antigen receptor (CAR) and other T-cell therapies are at risk for unique toxicities such as cytokine release syndrome (CRS) and CAR-T-related encephalopathy syndrome (CRES). Judicious patient and treatment selection, vigilant monitoring, and prompt interventions may reduce the need for PICU admission among HCT and CAR-T recipients. When PICU intervention is required, early intervention, excellent interdisciplinary communication, prognostication, and intensive support may improve outcomes.

DNA mismatch repair machinery is an integral part of the human genome and its defect has been involved in tumorigenesis and treatment resistance. Heterozygous monoallelic germline loss of function in MLH-1, MSH-2, MSH-6 or PMS-2 is involved in Lynch syndrome, whereas biallelic mutations cause constitutional mismatch repair deficiency (CMMRD) which is associated with hematologic malignancies and glioblastoma. We report here the clinical characterization and molecular analyses of 7 patients who presented with gliomas and MMR machinery aberrations. Two patients had a clinical diagnosis of NF-1 with dermatologic stigmata, of whom one patient has CMMRD and the other has Lynch syndrome. Two patients had a known family history of Lynch syndrome upon their diagnosis of glioma. Three patients with high-grade glioma and negative family history, 2 had germline mutations in MMR genes, and one had numerous mutations including MMR genes with microsatellite instability. Patients were initially treated with chemotherapy and radiation for high-grade gliomas (HGG); 5/7 had progression. Median time to progression was 12 months (range: 5–52), and median time from progression to death was 7 months (range: 2–25). One patient had low-grade glioma initially but progressed to HGG and is currently on therapy. Another patient treated with temozolomide and radiation is currently receiving maintenance therapy without any disease recurrence. Although the literature data on brain tumors with MMR deficiency is limited, these consistently show that MMRD-associated gliomas are treatment-resistant and have a dismal outcome. Collaborative efforts are needed to better understand this subgroup of pediatric HGG and to define optimal treatment strategy.

Background : Ten to fourteen percent of Ewing sarcoma (ES) study participants treated nationwide with IGF-1 receptor (IGF-1R)-targeted antibodies achieved tumor regression. Despite this success, low response rates and short response durations (approximately 7-weeks) have slowed the development of this therapy. Methods: We performed a meta-analysis of five phase-1b/2 ES-oriented trials that evaluated the anticancer activity of IGF-1R antibodies +/&minus, mTOR inhibitors (mTORi). Our meta-analysis provided a head-to-head comparison of the clinical benefits of IGF-1R antibodies vs. the IGF-1R/mTOR-targeted combination. Available pretreatment clinical samples were semi-quantitatively scored using immunohistochemistry to detect proteins in the IGF-1R/PI3K/AKT/mTOR pathway linked to clinical response. Early PET/CT imaging, obtained within the first 2 weeks (median 10 days), were examined to determine if reduced FDG avidity was predictive of progression-free survival (PFS). Results: Among 56 ES patients treated at MD Anderson Cancer Center (MDACC) with IGF-1R antibodies, our analysis revealed a significant ~two-fold improvement in PFS that favored a combination of IGF-1R/mTORi therapy (1.6 vs. 3.3-months, p = 0.042). Low pIGF-1R in the pretreatment specimens was associated with treatment response. Reduced total-lesion glycolysis more accurately predicted the IGF-1R response than other previously reported radiological biomarkers. Conclusion: Synergistic drug combinations, and newly identified proteomic or radiological biomarkers of IGF-1R response, may be incorporated into future IGF-1R-related trials to improve the response rate in ES patients.

Introduction: Patients with absolute neutrophil count (ANC) Methods: We performed a five-year IRB-approved, retrospective chart review of patients referred to a Pediatric Hematology-Oncology clinic for isolated neutropenia. Patients were excluded if they also had anemia or thrombocytopenia at the time of the referral. Degree of neutropenia was categorized: 1) at the time of referral, 2) at the lowest value, and 3) at the current ANC as Mild: 1.001-1.500 x109/L, Moderate: 0.501-1.000 x109/L, Severe: 0.201-0.5 x109/L, or Very Severe ≤0.2 x109/L. Descriptive statistics and odds ratios were performed. Results: Among 154 patients referred with isolated neutropenia over five years, 45 (29%) had mild neutropenia, 65 (42%) had moderate neutropenia, 29 (19%) had severe neutropenia, and 15 (10%) had very severe neutropenia. Only 29 (19%) patients progressed to a lower ANC category than their referral ANC category. At a median follow-up of 12 months, 101 (66%) patients had resolved neutropenia, 40 (26%) patients had mild, ten (6%) patients had moderate, three patients had severe, and one patient had very severe neutropenia. Most patients (54%) were not identified with a specific diagnosis. The most common diagnoses included viral suppression (16%), autoimmune neutropenia (14%) and drug induced neutropenia (8%). The most common medications reported as responsible for neutropenia were either anti-epileptic medications or immunosuppressant medications. No patients were diagnosed with a malignancy. Black patients had a 3.5 times higher odds of having persistent, mild, undiagnosed neutropenia which, for some patients, may be benign ethnic neutropenia. Seven (4.5%) patients received G-CSF therapy. Five patients were either managed by a Rheumatologist or an Immunologist. Finally, there were 16 hospitalizations that occurred in 10 patients for a prevalence of one admission for every 21 patient years. The most common admission diagnosis was febrile neutropenia without subsequent bacteremia (n=13). Conclusion: Most pediatric patients referred for isolated neutropenia do not progress, develop leukemia, or require sub-specialty interventions. Hospitalization of patients referred for isolated neutropenia is rare as is bacteremia. This study provides important outcome data that can improve our counseling of pediatric patients identified with isolated neutropenia. Disclosures Howard: Novartis: Consultancy. Lebensburger:Novartis: Consultancy; Pfizer: Research Funding.

INTRODUCTION The new understanding of molecular pathways in cancer is paving the way towards personalized cancer medicine, especially in refractory disease. High-grade gliomas (HGG) are common pediatric brain tumors that tend to recur, with no available standard therapy upon recurrence. HGG are challenging tumors with illusive biology and poor outcome. We report here the molecular testing of 27 pediatric HGG patients. MATERIALS AND METHODS An analysis of pediatric patients with HGG treated at UT MD Anderson Cancer Center (MDACC) who underwent molecular genetic profiling using next generation sequencing with different genomic panels (AmpliSeq™Cancer Hotspot and Oncomine Panels – by Thermo Fisher Scientific). RESULTS 27 patients with HGG (median age 14 years, range 3–18 years old) underwent genomic profiling. Primary diagnoses were glioblastoma multiforme (n=22), anaplastic astrocytoma (n = 2), gliosarcoma (n= 1), anaplastic pleomorphic xanthoastrocytoma (n= 1) and anaplastic oligoastrocytoma (n= 1). There are 46 genes common to the panels used. The most common mutation was in TP53 (73%). Other mutations included PIK3CA (19%), IDH1 (11.5%), 7.7% for ATM, EGFR and PTEN, and 3.8% for BRAF, FGFR1 and FGFR2. 24 out of 27 patients were tested at initial diagnosis and 3 upon relapse/progression. Patients at initial diagnosis received standard of care therapy of radiation and temozolomide. Only 5 patients received targeted therapy upon progression/recurrence. Some challenges of genomically-matched therapy included lack of clinical trials accepting pediatric patients, unavailability of a liquid form of a drug, and insurance disapproval for off-label use. CONCLUSION The next generation of therapy for childhood cancers will be based upon in-depth molecular phenotyping that may facilitate the development of rational risk-adapted and target-based therapies. This cohort, though limited by sample size, highlights the opportunity to perform molecular testing and identification of alterations in actionable genes.

The past few decades have seen marked improvements in survival rates of osteosarcoma due to the advent of modern chemotherapy, radiotherapy, and surgical techniques. However, for patients presenting with metastatic disease, five-year survival rates have remained dismal, hovering around 20%. Repeated failures of clinical trials to confirm potential therapeutic options highlight the need for more accurate pre-clinical testing. Currently, the field of cancer research relies heavily on monolayer culture methods on hard plastic or glass in vitro models; there is a dearth of pre-clinical models that accurately recapitulate the tumor-microenvironment interactions. Matrix stiffness has been implicated in modulating intracellular signaling pathways that promote cancer cell survival, proliferation, and stem cell fate. We have developed a novel three-dimensional (3D) tumor model with variable mechanical properties in order to determine the effect of substrate stiffness and tissue architecture on osteosarcoma cell phenotype, plasticity, and response to therapy. We employed coaxial electrospinning techniques to fabricate highly porous fibrous mesh scaffolds that mimic the bone microenvironment. By controlling the ratio of poly(ϵ-caprolactone) (PCL) and gelatin (PCL:gelatin, core:shell, respectively) in constituent fibers, we were able to manipulate the range of tensile moduli of individual fibers over three orders of magnitude, from 68.91 ± 8.77 kPa to 66.05 ± 7.61 MPa. Osteosarcoma cells cultured in these variable mechanical environments responded by modulating the localization and expression of Hippo pathway regulators. YAP downregulation correlated with decreasing fiber stiffness while both YAP and TAZ had decreasing nuclear:cytoplasmic ratio in less stiff environments. Furthermore, the IGF-1/mTOR axis was downregulated in 3D conditions compared to monolayers and a strong upregulation of Sox2, a stem cell transcription factor, was observed in all 3D conditions. Correspondingly, in the presence of agents targeting the IGF-1/mTOR axis, dose response curves to doxorubicin indicated that IC50 values increase with decreasing substrate stiffness. These phenotypic changes indicate that osteosarcoma cells respond to both stiffness and architecture by modulating the Hippo and IGF-1R/mTOR pathways and increasing cancer stem cell qualities and chemoresistance. We sought to validate our model using osteosarcoma patient biopsies. Analysis of tumor samples from 36 osteosarcoma patients confirmed that YAP/TAZ localization and nuclear pIGF-1R/IGF-1R in our 3D models recapitulated phenotypes observed in patient samples. Our models highlight the need for incorporation of mechanical and architectural cues in the preclinical study of cancer biology as these signals have drastic impacts on osteosarcoma phenotypes and responses to therapy. Citation Format: Eric R. Molina, Letitia K. Chim, Maria C. Salazar, Shail M. Mehta, Brian A. Menegaz, Salah-Eddine Cherradi-Lamhamedi, Tejus Satish, David McCall, Sana Mohiuddin, Ana Maria Zaska, Katherine Jane Grande-Allen, Joseph A. Ludwig, Antonios G. Mikos. Mechanically tunable 3D microenvironments modulate tumor cell phenotype: Models of mechanotransduction and drug resistance in osteosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-028.

The present study was carried out to evaluate the effects of biologically active atriopeptin II (APII) in synchronously contracting monolayer cultures of rat ventricular myocytes. The effects of 10 nM APII on Ca influx, contractile behavior and cyclic nucleotide content of the cells were measured. Applied acutely APII had no effect on Ca influx. There was however a time-dependent effect such that after 30 min Ca influx (pmol/cm2/s) had declined from a control (mean +/- S.E.M.) of 1.53 +/- 0.16 to 1.02 +/- 0.07 (P less than 0.001; n = 6). There was parallel decline in both the magnitude and velocity of cell edge motion which was maximal in 30 min at which time cell edge motion measured 65.3 +/- 4.4% of control. Treatment with APII for 30 min decreased cAMP (pmol/mg protein) from 5.35 +/- 0.17 to 2.86 +/- 0.24 (P less than 0.001; n = 5). At the same time cGMP (pmol/mg protein) increased from 0.86 +/- 0.21 to 2.14 +/- 0.33 (P less than 0.001; n = 5). Further studies elucidated the fact that the decline in Ca influx and contractile behavior was dependent on the decrease in cAMP rather than the increase in cGMP. Pre-treatment of the cells with 5 ng/ml of pertussis toxin to ADP-ribosylate the Gi protein abolished the effects of APII on cAMP, Ca influx and contractile behavior. The results indicate that in myocardial cells, as in other cells, APII stimulates guanylate cyclase and inhibits adenylate cyclase. The resultant fall in cAMP decreases Ca influx and negatively influences the contractile behavior of the cells.

Thrombocytopenia is a common reason for referral to a Pediatric Hematologist Oncologist. However, the need for acute intervention in patients with mild or moderate thrombocytopenia is likely a rare event. Because mild and moderate thrombocytopenia is less likely to need intervention and could resolve, the potentially stressful impact of referral to an Oncology center needs consideration. But with minimal literature to support the hypothesis that mild to moderate thrombocytopenia is unlikely associated with severe or progressive hematologic diseases, our ability to provide evidence based recommendations for need for referral is limited. To better understand the course for patients with mild and moderate thrombocytopenia, we conducted a retrospective chart review to assess the prevalence, outcomes, and need for intervention among patients referred for thrombocytopenia. Methods: We conducted a retrospective chart review of 1,140 patients referred to a large Pediatric Hematology Oncology program over a three year period (2012-2014). The diagnosis and demographics were recorded for every patient. Platelet counts at time of referral, lowest platelet count, and current platelet count were recorded and categorized as mild (plt: 100-149x103/mL), moderate (plt: 50-99 x103/mL), severe (plt: 20-49 x103/mL), and very severe (plt: Results: In a three year period (2012-2014), 1140 patients were referred to Pediatric Hematology Oncology, 902 of these patients for hematologic diagnoses. One hundred and three (11.4%) of 902 Hematology patients were referred for thrombocytopenia. The mean age of patients with thrombocytopenia was 9.2 years (s.d. 5.8yrs) and 58% were male. At the time of referral, 29% were categorized as mild, 33% were moderate, 17% severe and 21% very severe. The mean platelet count was 68 x103/mL (range 3-143). Younger patients had lower platelet counts (p Conclusion: Mild and moderate thrombocytopenia does not often progress or require interventions. Pediatricians should evaluate for Rheumatologic disorders in their initial work-up for mild to moderate thrombocytopenia as well as consider medication-induced thrombocytopenia. A safe and cost-effective approach to a patient with mild to moderate thrombocytopenia could be to observe repeat laboratory data (including ANA) in lieu of any other co-morbid condition. This approach could save families time, money, effort, and emotional stress in making appointments at large referral institutions. Disclosures No relevant conflicts of interest to declare.

Background Indoleamine 2,3-dioxygenase (IDO) is an enzyme with immune-suppressive properties that is commonly exploited by tumors to evade immune destruction. Anti-tumor T cell responses can be initiated in solid tumors, but are immediately suppressed by compensatory upregulation of immunological checkpoints, including IDO. In addition to these known effects on the adaptive immune system, we previously showed widespread, T cell-dependent complement deposition during allogeneic fetal rejection upon maternal treatment with IDO-blockade. We hypothesized that IDO protects glioblastoma from the full effects of chemo-radiation therapy by preventing vascular activation and complement-dependent tumor destruction. Methods To test this hypothesis, we utilized a syngeneic orthotopic glioblastoma model in which GL261 glioblastoma tumor cells were stereotactically implanted into the right frontal lobes of syngeneic mice. These mice were treated with IDO-blocking drugs in combination with chemotherapy and radiation therapy. Results Pharmacologic inhibition of IDO synergized with chemo-radiation therapy to prolong survival in mice bearing intracranial glioblastoma tumors. We now show that pharmacologic or genetic inhibition of IDO allowed chemo-radiation to trigger widespread complement deposition at sites of tumor growth. Chemotherapy treatment alone resulted in collections of perivascular leukocytes within tumors, but no complement deposition. Adding IDO-blockade led to upregulation of VCAM-1 on vascular endothelium within the tumor microenvironment, and further adding radiation in the presence of IDO-blockade led to widespread deposition of complement. Mice genetically deficient in complement component C3 lost all of the synergistic effects of IDO-blockade on chemo-radiation-induced survival. Conclusions Together these findings identify a novel mechanistic link between IDO and complement, and implicate complement as a major downstream effector mechanism for the beneficial effect of IDO-blockade after chemo-radiation therapy. We speculate that this represents a fundamental pathway by which the tumor regulates intratumoral vascular activation and protects itself from immune-mediated tumor destruction.

In recent years there have been encouraging developments in the therapy for congestive heart failure. Vasodilator therapy, as an adjunct to digitalis and diuretics, has made a major impact. Vasodilator therapy results in improved left ventricular (LV) ejection fraction, improved functional capacity, and enhanced quality of life. When an angiotensin-converting enzyme (ACE) inhibitor is used, several studies published since 1988 show that these improvements are accompanied by improved survival. Yet many questions remain. Principal among these is how to approach the patient who has significantly depressed LV function, but is asymptomatic or has only minimal symptoms. In these patients the prognosis cannot be based on New York Heart Association (NYHA) functional class, but must reflect objective measurements of ventricular function. Any intervention should be specifically designed to improve survival, since functional capacity and quality of life are apparently unimpaired. On the other hand, there are no data at present to suggest that intervention in these patients will improve survival. This article considers the evaluation of such asymptomatic patients and potential therapeutic approaches. These are the use of cardiac glycosides, the use of ACE inhibitors, or their combination. Circumstantial evidence supporting their use in this select patient population is considered. It is stressed that any decision to intervene therapeutically in the asymptomatic patient must be made by the physician on an individual basis.

The accuracy of duplex pulsed Doppler echocardiography (d-PDE) for detecting mitral regurgitation was evaluated in 35 patients undergoing d-PDE, cardiac auscultation, and left ventriculography. With three transducer positions, the overall d-PDE sensitivity was 95%, specificity was 100%, positive predictive value was 100%, negative predictive value was 94%, and diagnostic accuracy was 97% compared with ventriculography. This technique was superior to auscultation (sensitivity 74%, specificity 94%, positive predictive value 93%, negative predictive value 75%, diagnostic accuracy 83%). No false-positive d-PDE results occurred, but discordant false-negative results occurred frequently among the three transducer positions. If discordant negative results are considered to be false negatives, then d-PDE is both sensitive and specific when mitral regurgitation is defined as systolic spectral broadening in any one transducer position.

A 50-year-old woman with chest pain and an exercise thallium-201 scintigram positive for focal ischemia was found on coronary arteriography to have a heretofore unreported variant of single left coronary artery with the right coronary artery originating as a branch from the first septal perforator. Proximally, the aberrant vessel coursed through the ventricular septum at the level of the right ventricular outflow tract. A conus artery was absent and this is a possible basis for the focal basal ventricular ischemia and the patient's symptoms.

The effect of procainamide on membrane cation exchange was investigated using monolayer cultures of Girardi heart cells. The initial effect of procainamide (10(-6) to 10(-3) mol/litre) was to produce a prompt reduction of the passive Na influx, dose-dependent along a sigmoid log dose-response curve. This effect was complete within 3 min and thereafter showed no further time-dependent increase. Mean passive Na influx (pmol-cm-2/s) decreased from 19.1 to 17.7 (P less than 0.05) and 10.4 (P less than 0.001) in 10(-5) and 10(-3) mol/litre procainamide, respectively. No effect on active Na extrusion was noted before 3 min following exposure to the drug, after which time it progressively declined reaching a minimum value for each concentration by 6 min and remaining at this level throughout a further 60 min exposure. For each concetnration this minimum value was similar to the Na influx measured under identical conditions. Na-coupled active K influx showed a parallel pattern of inhibition. K efflux was not decreased until approximately 20 min following exposure to the drug, but once present the reduction was similar in magnitude to that in the correspondingly measured K influx. Kinetic flux analysis revealed a decrease in both PNa and PK but indicated a greater effect on PNa. The results suggest that all of the above effects could be explained on the basis of one direct action of the drug, namely, the prompt initial decrease in PNa and Na influx. All other effects noted, both active and passive, could then be secondary to this phenomenon.

The Na/K-exchange characteristics, ouabain-binding kinetics, and Na pump turnover rates of synchronously contracting monolayers of neonatal rat myocardial cells were studied. The cells exchange Na rapidly (T1/2 = 35 s) with a mean Na flux of approximately 25 (pmol/cm2)/s. The half time (T1/2) of K exchange is much longer (12 min); the mean K flux is 13 (pmol/cm2)/s. Active Na/K transport, as measured by K influx, is relatively ouabain sensitive, and 10(-6) M ouabain produces half-maximal inhibition. Ouabain (10(-2)M) inhibits 60% of the Na efflux and 75% of the K influx. The cells bind [3H]ouabain rapidly (T1/2 = 8 min), but release it very slowly (T1/2 = 11 h), and both the amount bound and the rate of binding were inversely proportional to extracellular K. Specific [3H]ouabain binding demonstrates saturation reaching a maximum of 1.6 x 10(6) molecules per cell at 2 x 10(-7) M [3H]ouabain. From cell surface area and ouabain-sensitive flux measurements, the Na pump density was calculated at 720/micrometer2 with an individual pump turnover rate of 50/s. Thus the studies indicate that despite their neonatal origin, the behavior of the Na pump in these cells is very similar to that in other mammalian tissues.

Monolayer cultures of myocardial cells were prepared by trypsin dispersion of neonatal rat ventricles. The cells were cultured for 4-5 days by which time a synchronously contracting monolayer of some 1.0 x 10(6) cells per 6-cm diam petri dish had formed. The contraction frequency and Na influx of the cells were unaffected by tetrodotoxin (2 x 10(-5) mg/ml) but both were markedly reduced by the addition of verapamil (10(-9) M to 10(-5) M). The effect of verapamil on both parameters occurred very rapidly. Although unresponsive to change in [Ca]0 between 0.3 mM and 3.0 mM, the contraction frequency of the cells declined rapidly as the [Ca]0 was reduced below 0.3 mM. On the other hand the beating rate of the cells was linearly related to [Na]0 below 40 mM the cells ceased to contract. It is therefore apparent that both [Ca]0 and [Na]0 contribute to the maintenance of the contraction frequency of cultured myocardial cells, but the latter is by far the more important. There also appeared to be, under all conditions, a close relationship between verapamilsensitive Na influx and contraction frequency. For the greater part this relationship was linear although at higher Na influx values it appeared to show evidence of saturation.

The effects of quinidine and temperature on Na influx and contraction frequency of synchronously contracting rat myocardial cells in monolayer cultures were studied. Quinidine (10(-6) M to 10(-1) M) produced a prompt reduction in Na influx, maximum after 30 seconds of exposure, and dose-dependent along a sigmoid log dose-response curve. At 37 degrees C, Na influx (mumol/10(11) cells per sec) decreased from 30.19 to 24.70 (P less than 0.001) and 10.49 (P less than 0.001) on exposure to quinidine, 10(-6) and 10(-2) M, respectively. Simultaneously the contraction frequency decreased from a control of 120/min to 105/min and 48/min with 10(-6) M and 5 X 10(-4) M quinidine. At higher concentrations spontaneous contractions ceased. The effects on Na influx and contraction were reversible by washing the cells free of the drug (30 seconds). A temperature-dependent decrease in the Na influx between 37 degrees C and 22 degrees C also induced a decrease in contraction frequency. Between 25 degrees C and 35 degrees C the Q10 values for Na influx and contraction frequency were 2.41 and 2.44 respectively. Under all conditions tested there was a constant linear relationship (r = 0.98) between Na influx and contraction frequency for all values of Na influx greater than 11.82 mumol/10(11) cells per sec. Na influx and contraction frequency were insensitive to tetrodotoxin (10(-5) g/ml) but very sensitive to verapamil and to changes in extracellular Na. Quinidine affected only the verapamil-sensitive Na influx. The results indicate a close relationship between verapamil-sensitive inward Na movement and automaticity in these cells and demonstrate that the quinidine-induced changes in automaticity are closely linked to the effect on Na influx.

Eight patients had cardiac manifestations that were life-threatening in five while taking psychotropic drugs, either phenothiazines or tricyclic antidepressants. Although most patients were receiving several drugs, Mellaril (thioridazine) appeared to be responsible for five cases of ventricular tachycardia, one of which was fatal in a 35 year old woman. Supraventricular tachycardia developed in one patient receiving Thorazine (chlorpromazine). Aventyl (nortriptyline) and Elavil (amitriptyline) each produced left bundle branch block in a 73 year old woman. Electrocardiographic T and U wave abnormalities were present in most patients. The ventricular arrhythmias responded to intravenous administration of lidocaine and to direct current electric shock; ventricular pacing was required in some instances and intravenous administration of propranolol combined with ventricular pacing in one. The tachyarrhythmias generally subsided within 48 hours after administration of the drugs was stopped. Five of the eight patients were 50 years of age or younger; only one clearly had antecedent heart disease. Major cardiac arrhythmias are a potential hazard in patients without heart disease who are receiving customary therapeutic doses of psychotropic drugs. A prospective clinical trial is suggested to quantify the risk of cardiac complications to patients receiving phenothiazines or tricyclic antidepressant drugs.

Histamine has been shown to have both positive inotropic and chronotropic effects. To evaluate the chronotropic effects, spontaneously contracting monolayers of cultured rat myocardial cells were treated with histamine, 10(-7) M-10(-4) M. This resulted in a dose-dependent increase in contraction frequency reaching a maximum in 10(-5) M histamine. Contraction frequency (mean +/- SEM) increased from a control of 121 +/- 5 contractions per minute to 153 +/- 4.5, 181 +/- 9, 212 +/- 4, and 216 +/- 1 in 10(-7) M, 10(-6) M, 10(-5) M, and 10(-4) M histamine, respectively (for each n = 10, p less than 0.001). The effect was time-dependent, taking 30 minutes to develop fully. Changes in contraction frequency were accompanied by parallel dose- and time-dependent increases in the verapamil-sensitive sodium influx. Verapamil-sensitive sodium influx (pmol/cm2/sec) increased from a control of 10.45 +/- 1.44 (mean +/- SEM) to 24.34 +/- 2.41 and 32.57 +/- 2.35 at 10- and 30-minute treatment with 10(-6) M histamine (n = 5, p less than 0.001). These data fit the previously described relation between verapamil-sensitive sodium influx and contraction frequency in these cells. Cimetidine (10(-4) M) but not diphenhydramine (10(-4) M) abolished both the contraction frequency and sodium influx response to histamine. Subsequent studies showed a dose- and time-dependent elevation of cyclic adenosine monophosphate (cAMP) with histamine treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of procainamide and lignocaine, in concentrations from 10(-6) to 10(-2) mol.litre(-1), on the Na influx and contraction frequency of cultured heart cells were studied. Both drugs produced a prompt, dose-dependent reduction in Na influx which was significant (P less than 0.01) for all concentrations tested. Lignocaine affected only that portion of the Na influx which was also verapamil-sensitive, whereas procainamide suppressed in addition, the verapamil-insensitive influx. In addition both drugs produced a concomitant decrease in the spontaneous contraction frequency of the cells. A close linear correlation (r = 0.99) between verapamil-sensitive Na influx and contraction frequency, in the presence of both procainamide and lignocaine was found. From this, and previous studies indicating a dependency of contraction frequency on the inward verapamil-sensitive Na influx, it is suggested that the drugs modify the automaticity of this preparation by a primary influence on membrane Na exchange.

We report a 25-year-old female with characteristic features of eosinophilic heart disease on clinical presentation, echocardiography, cardiac catheterization, and LV endomyocardial biopsy. Concomitant physical examination and echocardiographic findings suggesting hypertrophic obstructive cardiomyopathy resolved during treatment with anticoagulation and prednisone therapy.

Methods of precordial counting of radio-active isotopes in the detection of left-to-right intracardiac shunts are presented. Both iodine-131 labelled albumin and technetium-99m were used but the latter is preferred, especially for children, since it has a short physical half-life and emits a single gamma ray. Investigations were done to establish normal values and those in patients who had either rheumatic or congenital heart disease. All left-to-right shunts were confirmed at cardiac catheterization. False negative results were rare but false positive results can occur in the presence of congestive cardiac failure. It is possible to detect left-to-right shunts with a pulmonary to systemic flow ratio as low as 1·2:1 and an estimate of this ratio can be made from the precordial curve. The main value of the method is as a preliminary investigation in the detection of intracardiac shunts.

SUMMARY The effects of a new steroid anaesthetic agent (CT1341) were studied in twenty volunteers divided into three groups. In group I, serial measurements were made of heart rate, blood pressure and respiratory rate. In group II, detailed haemodynamic studies were made in patients undergoing diagnostic cardiovascular investigations. These studies included measurement of cardiac output, stroke volume and arterial blood gases. In group III, time from induction to “true recovery” was measured following a single intravenous injection of the drug. This agent produced a stable anaesthetic state in all cases. Anaesthesia was characterized by a rise in respiratory rate and pulse rate with a slight fall in systolic and diastolic blood pressure. A significant fall in Pao2 occurred in those patients breathing air. The mean recovery time in six patients was 24.3 min. CT1341 produced safe and stable anaesthesia in all twenty cases and is worthy of further clinical trial.