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CD28-based CD19 chimaeric antigen receptor-modified (CAR-)Tcells were recently FDA-approved for adult acute lymphoblastic leukaemia (ALL). We report long-term outcome of 37 children and young adults treated with autologous CD19 CAR-T cells. The complete remission rate was 86%, of which 71% were polymerase chain reaction (PCR) minimal residual disease (MRD)-negative, 14% were MRD-negative by flow cytometry, and 14% were PCR MRD-positive. 26 patients proceeded to subsequent haematopoietic stem cell transplant (HSCT). 11 patients had a CD19-postive relapse (eight post HSCT and three without) and one had a CD19-negative relapse. All relapse events occurred within two years from cell therapy. With a median follow-up of three years, the median event-free survival (EFS) is 17 months and the median overall survival (OS) is not reached. The three-year EFS is 41% and OS is 56%. Patients with5% blasts in the bone marrow prior to lymphodepletion had an inferior EFS. All patients with a PCR MRD-positive result at day 28 had relapsed after CAR-T-cell therapy. A prior HSCT did not significantly affect outcome, but a consolidative transplant after achieving remission improved long-term results. Overall, prelymphodepletion disease burden and molecular MRD negativity following CAR-T cells are predictors of long-term outcome following CD19 CAR-T-cell therapy for ALL.

Background Cutaneous manifestations of dedicator of cytokinesis 8 gene (DOCK8) deficiency, a combined type of T and B cell immunodeficiency, previously designated as autosomal recessive hyper IgE syndrome, includes dermatitis and skin infections. There are limited treatment options for dermatitis related to the syndrome. Objective To describe a cohort of patients with DOCK8 deficiency with a focus on the treatment of their cutaneous manifestations. Methods A retrospective study on all children with the genetic diagnosis of DOCK8 deficiency treated at the Sheba Medical Center between 1/1/2003 and 1/1/2021 was preformed. Collected data included: demographic features, family history, laboratory, genetic testing, skin manifestations, treatment, and disease course. Description of two cases of severe recalcitrant dermatitis treated with dupilumab is detailed. Results Nine children with a genetic diagnosis of DOCK8 deficiency were included, of whom six were girls (66%) with a median age of 8.5 (±2.2 SD) years. The median age at diagnosis was 2.8 (±2.6 SD) years. Six patients were born to consanguineous parents. Five out of six patients who received hematopoietic stem cell transplantation (HSCT) had a complete response, and one was recently transplanted. Of note, two patients, while awaiting HSCT, were treated with dupilumab for their severe dermatitis resulting in a marked improvement of the cutaneous manifestations and pruritus. Conclusions Hematopoietic stem cell transplantation is the gold standard and most effective therapy for patients with DOCK8 deficiency. Dupilumab, a biological therapy indicated for atopic dermatitis and other Th2 derived dermatoses, is an excellent option for dermatitis in patients with DOCK8 deficiency and can be used as a bridge before HSCT. Larger studies are needed to confirm this observation.

CAR T-cells are approved for the treatment of relapsed and refractory leukemia and lymphoma. Here, we studied the infectious complications in 88 patients treated with CD28-based CD19 CAR T-cells. Overall, 36 infections were documented in 24 patients within the first month after CAR T-cell infusion: Six events of bacteremia, sixteen focal bacterial infections, and fourteen systemic or localized viral infections. Seven patients had nine infectious episodes beyond the first 30 days of follow-up, including three events of bacteremia, three focal bacterial, two viral and one fungal infection. The presence of neutropenia, neutropenic fever and lack of response to treatment were associated with a higher rate of infections. Children had less severe infections than adults. In a multivariate analysis lack of response to treatment was the only significant risk factor. Overall, the incidence of bacterial infections following CAR T-cells is modest especially in children and in patients responding to therapy.

During the process of generating diverse T and B cell receptor (TCR and BCR, respectively) repertoires, double-strand DNA breaks are produced. Subsequently, these breaks are corrected by a complex system led by the non-homologous end-joining (NHEJ). Pathogenic variants in genes involved in this process, such as theTo provide new clinical and immunological insights on NHEJ1 deficiency arising from a newly diagnosed patient with severe immunodeficiency.A male infant, born to consanguineous parents, suspected of having primary immunodeficiency underwent immunological and genetic workup. This included a thorough assessment of T cell phenotyping and lymphocyte activation by mitogen stimulation tests, whole-exome sequencing (WES), TCR repertoire Vβ repertoireClinical findings included microcephaly, recurrent pneumonia, and failure to thrive. An immune workup revealed lymphopenia, reduced T cell function, and hypogammaglobulinemia. Skewed TCR Vβ repertoire, TCR gamma (TRG) repertoire, and BCR repertoire were determined in the patient. Genetic analysis identified a novel homozygous missense pathogenic variant inA novel

IntroductionChildhood cancer is a leading cause of death. It is unclear whether the COVID-19 pandemic has impacted childhood cancer mortality. In this study, we aimed to establish all-cause mortality rates for childhood cancers during the COVID-19 pandemic and determine the factors associated with mortality.MethodsProspective cohort study in 109 institutions in 41 countries. Inclusion criteria: children ResultsAll-cause mortality was 3.4% (n=71/2084) at 30-day follow-up, 5.7% (n=113/1969) at 90-day follow-up and 13.0% (n=206/1581) at 12-month follow-up. The median time from diagnosis to multidisciplinary team (MDT) plan was longest in low-income countries (7 days, IQR 3–11). Multivariable analysis revealed several factors associated with 12-month mortality, including low-income (OR 6.99 (95% CI 2.49 to 19.68); pConclusionsChildren with cancer are more likely to die within 30 days if infected with SARS-CoV-2. However, timely treatment reduced odds of death. This report provides crucial information to balance the benefits of providing anticancer therapy against the risks of SARS-CoV-2 infection in children with cancer.

Prolonged cytopenias are a non-specific sign with a wide differential diagnosis. Among inherited disorders, cytopenias predisposing to leukemia require a timely and accurate diagnosis to ensure appropriate medical management, including adequate monitoring and stem cell transplantation prior to the development of leukemia. We aimed to define the types and prevalences of the genetic causes leading to persistent cytopenias in children. The study comprises children with persistent cytopenias, myelodysplastic syndrome, aplastic anemia, or suspected inherited bone marrow failure syndromes, who were referred for genetic evaluation from all pediatric hematology centers in Israel during 2016-2019. For variant detection, we used Sanger sequencing of commonly mutated genes and a custom-made targeted next-generation sequencing panel covering 226 genes known to be mutated in inherited cytopenias; the minority subsequently underwent whole exome sequencing. In total, 189 children with persistent cytopenias underwent a genetic evaluation. Pathogenic and likely pathogenic variants were identified in 59 patients (31.2%), including 47 with leukemia predisposing syndromes. Most of the latter (32, 68.1%) had inherited bone marrow failure syndromes, nine (19.1%) had inherited thrombocytopenia predisposing to leukemia, and three each (6.4%) had predisposition to myelodysplastic syndrome or congenital neutropenia. Twelve patients had cytopenias with no known leukemia predisposition, including nine children with inherited thrombocytopenia and three with congenital neutropenia. In summary, almost one third of 189 children referred with persistent cytopenias had an underlying inherited disorder; 79.7% of whom had a germline predisposition to leukemia. Precise diagnosis of children with cytopenias should direct follow-up and management programs and may positively impact disease outcome.

Background Autologous CD19 chimeric-antigen receptor (CAR) T-cells are an effective salvage therapy for patients with relapsed or refractory B cell malignancies. The essential first step in the production is the collection of mature lymphocytes through leukapheresis. It is a challenging procedure given the fact patients are heavily pretreated and the special considerations of pediatric apheresis. Methods We analyzed the data of leukapheresis outcome for CAR T production in a phase 1b/2 clinical trial enrolling 34 children, adolescents and young adults with relapsed or refractory B-cell malignancies. Results All patients underwent a single leukapheresis. Given a short production time for CAR T-cells, most patients received bridging therapy prior to apheresis. Leukapheresis was performed using peripheral venous access in the majority (82%) of patients, and the remainder required arterial line or central venous access. T-cell collection efficiency (CE) was variable with a median of 18%. No apheresis-related adverse events were noted, and all procedures were successful but two: one resulting in lower than target dose (1 × 106 CAR + cells/kg) and the other in failure of CAR T-cell production. Conclusions Collection of sufficient T-cells in heavily pretreated pediatric patients via a single apheresis procedure is feasible even with relatively low T-cell CE.

This chapter recounts the history of classification of LCH, the association with certain risk factors and with other malignancies, and the patterns of disease reported. In it, the history of LCH as a disease is told, from classification as three different diseases to unification as a single disease with a variable presentation. The chapter goes into further detail about the variety of different manifestations in different organ systems and assesses the evidence for suspected risk factors to LCH.

Patients with antibody deficiency rely on immunoglobulin products for protection against many vaccine-preventable diseases. We measured antibody titers against Bordetella pertussis and Neisseria meningitidis in patients receiving immunoglobulin (IG) therapy to determine if they have any protection against infections from these organisms. In an unblinded, prospective assessment we measured antibody titers against B. pertussis filamentous hemagglutinin (FHA) and pertussis toxin (PT) antigens and N. meningitidis serogroups A, C, W-135, and Y in patients receiving immunoglobulin therapy for primary immune deficiency (PI). We measured steady state levels in patients receiving subcutaneous immunoglobulin therapy while in patients receiving intravenous immunoglobulin therapy we measured titers immediately before and after infusion to more clearly define the contribution of the infused product. Thirty subjects, 17 females and 13 males, participated in the study, 22 were receiving intravenous IG products and 8 were receiving subcutaneous IG products. Diagnoses included common variable immunodeficiency in 12, combined immunodeficiency in 6, specific antibody deficiency in 6, X-linked agammaglobulinemia in 4 and ataxia telangiectasia and hyper-IgE syndrome in one each. All subjects had detectable IgG antibodies against the pertussis antigens measured and most had antibody to the meningococcus serotypes measured. However, only 26.6 % had protective levels (>= 2 mcg/mL) against serogroup C at trough or steady state. Patients receiving immunoglobulin therapy have antibodies against B. pertussis and most of them have antibodies against the four measured serogroups of N. meningitidis. There is significant variability in the levels of antibody between patients and the low titers against group C may suggest a role for active immunization in those who may respond to conjugated polysaccharide vaccine administration.

We present a case of simultaneous endobronchial and adrenal Epstein-Barr Virus-associated smooth muscle tumors in a 20-year-old female with AIDS. Blood Epstein-Barr Virus polymerase chain reaction was negative at the time of diagnosis.

BACKGROUND: ALL cells are physically anchored in the bone marrow (BM) microenvironment through a network of adhesion molecules. Adhesion also creates intracellular signals that regulate proliferation and cell death. We have previously identified integrin α4 (α4) as a critical molecule for such cell-adhesion-mediated drug resistance in pre-B ALL. In chronic lymphocytic leukemia (CLL), α4-mediated activation of the PI3K/AKT pathway was reported. In ALL, stromal cell protection of B-lineage ALL cells has also been shown to require active Akt. In addition, we have shown that treatment with CAL-101, a commercially available PI3Kδ inhibitor, de-adheres pre-B ALL cells from the α4-counter-receptor VCAM1, downregulates p-Akt and induces apoptosis in primary pre-B ALL cells. However, the microenvironmental stimuli that activate PI3K/AKT in ALL remain unknown. PI3Kδ can be activated by extracellular signals upon engagement with extracellular matrix, however specific ligands remain elusive, the identification of which would be critical to understand the mechanism of PI3Kδ inhibition. These studies were designed to determine which extracellular ligands activate PI3K/AKT in patient-derived (primary) pre-B ALL cells and whether CAL-101 affects adhesion and migration of ALL cells. METHODS: Four samples ofpatient-derived (primary) pre-B ALL cells, co-cultured with murine calvaria-derived mesenchymal stromal (OP9) cells were treated with a commercially available PI3Kδ inhibitor, CAL-101 (Selleckchem), or its vehicle DMSO control. Culture plates with and without transwells were used for in vitro assays. Annexin V/7-AAD staining was used for viability determination by flow cytometry and Western Blot was used for determination of total Akt and p-Akt expression. RESULTS: To determine which ligands activate p-Akt, ALL cells were adhered to fibronectin (FN), VCAM-1 (both counter-receptors of integrin α4), laminin-1 (hLam-1; counter-receptor for integrin α6) and albumin (BSA). OP9 cells were used in direct contact with ALL cells or separated through a transwell insert. α-MEM or RPMI were used as media controls. hVCAM-1 and hLam-1 activated p-Akt in one out of three samples. In all 3 samples, OP9 cells activated p-Akt compared to media control, but only in direct contact, not when separated through a transwell. This suggests that direct adhesion of ALL cells to stromal cells rather than diffusible factors are associated with p-Akt activation. Next, we determined if CAL-101 de-adheres ALL cells independently from the ligands ALL cells are bound to. Primary pre-B ALL cells were plated in triplicates onto FN, VCAM-1, hLam1-coated 96-well plates and incubated with CAL-101 (10µM) ± HUTS-21 antibody (20µg/mL). HUTS-21 is an antibody that binds only to the active form of integrin β1, CD29, and can activate outside-in signaling via integrin β1 stimulation. CAL-101 inhibited cell-adhesion from FN (15±4.2% vs. 51±9.9%, p=0.04) and VCAM-1 (54.6 x±8.6%vs. 95.8±3.8%, p=0.03), but not from hLam1 indicating that it acts specifically on the VCAM-1/FN-mediated adhesion of ALL cells. HUTS-21 restored cell-adhesion of ALL cells to FN (67.0±1.4% vs. 81±7.1%, p=0.19) and VCAM-1 (42.5±16.2% vs. 50.6±8.6%, p=0.59) indicating adhesion recovering upon HUTS-21 addition to CAL-101-treated cells. Next, we determined if CAL-101 has an impact on migration of ALL cells. ALL cells were treated with CAL-101 (10μM) or DMSO control for 24 hours and added to a migration assay. We observed that migration of ALL cells to stromal cell-derived factor 1alpha (SDF-1alpha; CXCL12) was significantly decreased (1.7 x103 ±0.3x103 vs. 3.1x103 ±2.4x103 p=0.004), while migration to OP9 cells was partially inhibited compared to DMSO control (2.1 x103 ±0.5x103 vs. 4.2 x103 ±0.5x103 p=0.005). CONCLUSION: Taken together, our data demonstrate that the PI3Kδ/AKT pathway is stimulated by extracellular matrices and that PI3Kδ inhibition with CAL-101 inhibits adhesion of ALL cells to FN/VCAM-1 but not Lam1, which can be restored using HUTS-21. Data derived from further studies will determine the potential of the FDA-approved PI3Kδinhibitor Idelalisib as a novel therapy for pre-B ALL. Disclosures Wayne: NIH: Patents & Royalties; Medimmune: Honoraria, Other: travel support, Research Funding; Kite Pharma: Honoraria, Other: travel support; Pfizer: Honoraria; Spectrum Pharmaceuticals: Honoraria, Other: travel support, Research Funding.