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Introduction Pediatric oncology patients are reportedly at risk for progression to severe Coronavirus disease-2019 (COVID-19) infection. Data on the safety and clinical effectiveness of remdesivir in children with cancer remains scarce. The main aims of this study were to describe COVID-19 infection in this cohort and to evaluate the utility of remdesivir treatment in terms of the time to viral clearance and its safety profile. Methods This was a retrospective observational cohort study of pediatric oncology patients ≤18 years of age with SARS-CoV-2 polymerase chain reaction (PCR) confirmed infection. Patients were admitted to KK Women’s and Children’s Hospital from 1 November 2021 to 31 March 2022. Clinical data, investigations and laboratory tests results were collected. Results Eighteen patients were included. Median age was 6.5 years (IQR: 4.64 – 9.83), and there were 13 males (72.2%). The immunosuppressive status of the cohort was: severe (n = 3, 22.2%), moderate (n = 9, 50.0%) and low (5, 27.8%). All patients had mild COVID-19 infection, and there were no COVID-19 attributed deaths. Remdesivir was initiated in four patients. We did not detect any benefit in terms of time to viral clearance or SARS-CoV2 PCR cycle threshold ≥25 between the treated versus non-treated groups. Remdesivir was well tolerated with no safety concerns. Conclusion Our cohort of immunocompromised pediatric oncology patients all had mild clinical COVID-19 with no directly attributable morbidity and mortality. In four patients, treatment with remdesivir was safe but did not lead to early viral clearance.

IntroductionNeurotrophic receptor tyrosine kinase fusions cause overexpression or activation of kinase and are believed to confer oncogenic potential in some non-rhabdomyosarcoma soft tissue sarcomas. TRK inhibitors have recently been shown to induce responses in these tumours though current experience with these agents is still limited.Case reportWe report a case of an adolescent with treatment-refractory non-rhabdomyosarcoma soft tissue sarcomas, carrying a novel DCTN1–NTRK1 gene fusion whose progressive disease was treated with multi-kinase and TRK inhibitors. Management and outcome: Our patient was started on pan-TRK inhibitor larotrectinib, as his disease progressed after chemotherapy, radiation therapy and surgery, based on next-generation sequencing test showing DCTN1–NTRK1 gene fusion. He responded quickly to larotrectinib with the improvement of symptoms and reduction of masses. However, this response was short-lived due to the development of acquired solvent front resistance mutation. This patient did not respond to next-generation TRK inhibitor selitrectinib and eventually succumbed to his disease.DiscussionThe initial rapid and drastic response of our patient to larotrectinib was not sustained due to the development of acquired resistance. This case emphasizes the need for upfront and periodic next-generation sequencing testing to guide treatment of patients with refractory non-rhabdomyosarcoma soft tissue sarcomas.

Thyroglossal duct cyst carcinoma (TGDCa) is a rare cause of neck masses in children. Its pathophysiology stems from two main theories. One suggests that the primary carcinoma originated from ectopic thyroid tissue, whilst the other suggest it is a result of metastasis to the thyroglossal duct cyst from the thyroid gland. A case of a 12-year-old girl who presented with a suspicious neck mass and subsequently diagnosed with TGDCa is reported. A literature review was performed and we conclude that aggressive surgical management of a Sistrunk procedure, total thyroidectomy, bilateral tracheoesophageal groove clearance and neck dissection was justified for this child. We found that if the preoperative diagnosis is TGDCa, a more aggressive surgical approach tends to be taken. However, cases of recurrence remain low and a total thyroidectomy does entail a larger morbidity for the pediatric patient. Hence, we do not recommend an aggressive approach routinely. In this review, we extrapolated AJCC data for thyroid malignancies and staged the TGDCa reported in literature in the last 10 years. It showed us that pT3 tumors tend to have a more aggressive surgical course, whilst a pT1 TGDCa tend to receive a more conservative surgical approach.

Objectives To determine whether the frequencies of SARS‐CoV‐2‐specific T cells are sufficiently high in the blood of convalescent donors and whether it is technically feasible to manufacture clinical‐grade products overnight for T‐cell therapy and assessment of COVID‐19 immunity. Methods One unit of whole blood or leukapheresis was collected from each donor following standard blood bank practices. The leukocytes were stimulated using overlapping peptides of SARS‐CoV‐2, covering the immunodominant sequence domains of the S protein and the complete sequence of the N and M proteins. Thereafter, functionally reactive cells were enriched overnight using an automated device capturing IFNγ‐secreting cells. Results From 1 × 109 leukocytes, a median of 0.98 × 106 (range 0.56‐2.95) IFNγ + T cells were produced from each of the six donors, suggesting a high frequency of SARS‐CoV‐2 reactive T cells in their blood, even though only one donor had severe COVID‐19 requiring mechanical ventilation whereas the other five donors had minor symptoms. A median of 57% of the enriched T cells were IFNγ+ (range 20%‐74%), with preferential enrichment of CD56+ T cells and effector memory T cells. TCRVβ‐spectratyping confirmed distinctively tall oligoclonal peaks in final products. With just six donors, the probability that a recipient would share at least one HLA allele with one of the donors is >88% among Caucasian, >95% among Chinese, >97% among Malay, and >99% among Indian populations. Conclusions High frequencies of rapid antigen‐reactive T cells were found in convalescent donors, regardless of severity of COVID‐19. The feasibility of clinical‐grade production of SARS‐CoV‐2‐specific T cells overnight for therapeutics and diagnostics is revealed.

SUMMARYBackgroundAdoptive therapy with SARS-CoV-2 specific T cells for COVID-19 has not been reported. The feasibility of rapid clinical-grade manufacturing of virus-specific T cells from convalescent donors has not been demonstrated for this or prior pandemics.MethodsOne unit of whole blood was collected from each convalescent donor following standard blood bank practices. After the plasma was separated and stored separately, the leukocytes were stimulated using overlapping peptides of SARS-CoV-2, covering the immunodominant sequence domains of the S protein and the complete sequence of the N and M proteins. Thereaftesr, functionally reactive cells were enriched overnight using an automated device capturing IFNγ-secreting cells.FindingsFrom 1×109 leukocytes, 0.56 to 1.16×106 IFNγ+ T cells were produced from each of the first two donors. Most of the T cells (64% to 71%) were IFNγ+, with preferential enrichment of CD56+ T cells, effector memory T cells, and effector memory RA+ T cells. TCRVβ spectratyping revealed oligoclonal distribution, with over-representation of subfamilies including Vβ3, Vβ16 and Vβ17. With just two donors, the probability that a recipient in the same ethnic group would share at least one donor HLA allele or one haplotype could be as high as >90% and >30%, respectively.InterpretationsThis study is limited by small number of donors and absence of recipient data; however, crucial first proof-of-principle data are provided demonstrating the feasibility of clinical-grade production of SARS-CoV-2 specific T cells for urgent clinical use, conceivably with plasma therapy concurrently. Our data showing that virus-specific T cells can be detected easily after brief stimulation with SARS-CoV-2 specific peptides suggest that a parallel diagnostic assay can be developed alongside serology testing.FundingThe study was funded by a SingHealth Duke-NUS Academic Medicine COVID-19 Rapid Response Research Grant.

Background: Haploidentical hematopoietic cell transplantation (HCT) provides an alternative option for patients without HLA-matched donors. Graft-versus-host disease (GVHD), engraftment failure, and infectious complications are main causes of non-relapse mortality (NRM). We hypothesized that selective depletion of TCRαβ+ and CD45RA+ naïve T cells will permit hematopoietic engraftment while effectively reducing GVHD and providing donor immune reconstitution through adoptive transfer of donor's mature NK cells, γδ T cells and CD45RO+ memory T cells. Methods: Mobilized PBSC products were divided into two fractions in 9:1 ratio and depleted using CliniMACS device after labelling with TCRαβ and CD45RA reagents (Miltenyi Biotec, Bergish-Gladbach, Germany) respectively. All except 6 patients received the standard conditioning regimen of fludarabine 160mg/m 2 divided daily over 4 days, thiotepa 10mg/kg divided twice daily for 1 day, and melphalan 70 - 140mg/m 2 for 1 day, in combination with either total lymphoid irradiation 6Gy (n=53) or 7.5Gy (n=12) over 3 equal fractions, or total body irradiation of 2Gy (n=17), or thymoglobulin (n=2). Short term GVHD prophylaxis was given for 30 days to 1 patient using MMF, 73 using tacrolimus, and 2 using sirolimus. Results: Between January 2017 and July 2021, we transplanted 85 patients, including 78 adults (median age, 48 years; range 20 - 70) and 7 children (median age, 13 years, range 7 - 17), with high risk AML (n=44), ALL (n=19), MDS (n=9), plasma cell neoplasm (n=4), mast cell leukemia (n=1), acute undifferentiated leukemia (n=1), CMMoL (n=2), CML (n=1) and lymphoma (n=2). Patients were infused with TCRαβ and CD45RA depleted grafts containing median of 6.19 x 10 6 (range 3.54 - 20.78) CD34+ cells/kg, 0.00 x 10 4 (range 0 - 0.97) CD45RA+CD3+ cells/kg, and 1.10 x 10 6 (range 0.15 - 11.67) CD45RO+CD3+ cells/kg. TCRαβ depleted graft fraction contained a median of 0.42 x 10 4 (range 0 - 11.30) TCRαβ+ cells/kg, and 7.61 x 10 6 (range 0.62 - 31.84) TCRγδ+ cells/kg. Only 1 patient experienced primary graft failure with no secondary graft failures. All others had engraftment of ANC > 500 cells/µL at median of 12 days (range 8 - 22) and PLT > 20,000 cells/µL at median of 11 days (range 7 - 17). 6 patients with high donor-specific HLA antibodies (DSA) titres engrafted successfully after desensitisation with plasma exchange, rituximab, and immunoglobulin. 29 patients (34%) developed acute GVHD of grade II - IV (Gd II, n=20; Gd III, n=5; Gd IV, n=4), with a cumulative incidence (CI) of grade II-IV and grade III-IV of 31% (95% CI 21-42%) and 11% (95% CI 5-19%) respectively, at 100 days. Chronic GVHD was seen in only 4 patients at a 2-year CI of 6% (95% CI 2-13%). 1-year CI of non-relapse mortality (NRM) and relapse were 22.7% (95% CI 13.9 - 32.9%) and 15.7% (95% CI 8.3 - 25.3%) respectively. 4 of the 17 NRM were attributed to aGVHD. Viral reactivation included CMV (n=32), HHV-6 (n=22), EBV (n=15), and adenovirus (n=8). 15 patients (17.6%) died of infection within 180 days, including 6 patients with fatal bacteraemia (bacteria, n=4; candidemia, n=2) and 1 patient from disseminated adenovirus infection. At a median follow up of 448 days (range 16- 1648) in surviving patients, 2-year overall (OS), event-free (EFS), and GVHD-free/relapse-free (GRFS) survival were 64.2 %, 54.0 %, and 49.0%, respectively (Figure 1). In multivariate analysis, only HCT-comorbidity index (HCT-CI) showed significant impact on OS (HR 3.38; 95% CI 1.42 - 8.02; p=0.0059), EFS (HR 2.62; 95% CI 1.18 - 5.76; p=0.0017), and NRM (HR 4.92; 95% CI 1.79 - 13.58; p=0.0021). Disease risk index (DRI) showed a trend in higher risk of relapse (HR 2.83; 95% CI 0.96 - 8.33; p=0.059). 2-year OS, EFS, and GRFS for the subset of 58 patients (adults, n=52; children, n=6) with HCT-CI score of 0 were 76.6 %, 63.4%, and 57.5 %, respectively (Figure 2). Conclusions: Our preliminary results suggest that RIC haplo-HCT with TCRαβ and CD45RA+ depleted grafts allow successful allograft in high-risk patients lacking suitable matched donors, including patients with high levels of DSA. Acute GVHD was generally abortive, leading to low incidence of chronic GVHD. Best outcomes are seen in patients with favourable HCT-CI. Further efforts are needed to reduce the risk of infection-related death in patients with high risk HCT-CI, and relapse in patients with high risk DRI, through optimization of anti-microbial prophylaxis or prophylactic infusion of memory-cell DLI. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Background: Haploidentical hematopoietic cell transplantation (HCT) provides an alternative option for patients without HLA-matched donor. Graft-versus-host disease (GVHD), engraftment failure, and infectious complications continue to be the main causes of non-relapse mortality (NRM). We hypothesized that selective depletion of TCRαβ+ and CD45RA+ naïve T-cells subset will permit hematopoietic engraftment, while effectively reducing GVHD, and provide improved donor immune reconstitution through adoptive transfer of donor's mature NK-cells, γδ T-cells, and CD45RO+ memory T-cells. Methods: Mobilized PBSC products were divided into two fractions in 9:1 ratio and depleted using CliniMACS device after labeling with TCRαβ and CD45RA reagents (Miltenyi Biotec, Bergish-Gladbach, Germany), respectively. The conditioning regimen consisted of fludarabine 160mg/m2 divided daily over 4 days, thiotepa 10mg/kg divided twice daily for 1 day, and melphalan 70-140mg/m2 for 1 day, in combination with total lymphoid irradiation 6Gy (n=35) or 7.5Gy (n=12) over 3 equal fractions, total body irradiation of 2Gy (n=13) or antithymocyte globuline (n=2). Short term GVHD prophylaxis for 30 days was given to 1 patient using MMF, 50 patients using tacrolimus, and 2 patients using sirolimus. Results: We transplanted 62 patients, including 55 adults (median age, 47 years; range 20-69) and 7 children (median age, 13 years, range 7-17) with high risk AML (n=34), ALL (n=15), MDS (n=7), plasma cell neoplasm (n=2), mast cell leukemia (n=1), acute undifferentiated leukemia (n=1), and NK/T-cell lymphoma (n=1). The patients were infused with TCRαβ and CD45RA depleted graft containing a median of 6.79 x 106 (range 3.54-20.78) CD34+ cells/kg, 0.00 x 104 (range 0-0.97) CD45RA+CD3+ cells/kg, and 1.09 x 106 (range 0.15-11.67) CD45RO+CD3+ cells/kg. The TCRαβ depleted graft fraction contained a median of 0.20 x 104 (range 0-11.30) TCRαβ+ cells/kg, and 8.52 x 106 (range 0.62-30.00) TCRγδ+ cells/kg. Only 1 patient experienced primary graft failure. All others had engraftment of ANC > 500 cells/µL at a median of 10 days (range 8-22) and platelet > 20,000 cells/µL at a median of 12 days (range 8-22). There was no secondary graft failure. Six patients with high titers of donor-specific HLA antibodies (DSA) engrafted successfully after effective desensitisation with plasma exchange, rituximab, and immunoglobulin. Twenty-two patients (35%) developed acute GVHD of grade II - IV (Gd II, n=15; Gd III, n=5; Gd IV, n=2). Three patients experienced chronic GVHD, giving 2-year cumulative incidence of 7 %. Day 180 cumulative incidence of NRM and relapse were 24.8% (95% CI 14.3-36.8%) and 14.9% (95% CI 6.3-27.0%), respectively. Four of the 16 NRM were attributed to aGVHD. Viral reactivation included CMV (n=25), HHV-6 (n=14), EBV (n=11), and adenovirus (n=7). Fourteen patients died of infection, including 5 patients who had fatal blood stream infection (bacteria, n=3; candidemia, n=2) and 1 patient from disseminated adenovirus infection within 180 days. With a median follow-up of 298 days (range 21-1298) in surviving patients, the 2-year overall (OS), event-free (EFS), and GVHD-free/relapse-free (GRFS) survival were 58% (95% CI 37.6-73.4%), 43% (95% CI 27-57%), and 39% (95% CI 24-54%), respectively (Figure 1). In multivariable analysis, only HCT-comorbidity index (HCT-CI) showed significant impact on OS (HR 6.24; 95% CI 2.05-19.05; p=0.0013), EFS (HR 4.80; 95% CI 1.73-13.35; p=0.0027), and RRM (HR 6.49; 95% CI 1.44-29.25; p=0.015), whereas disease risk index (DRI) impacts risk of relapse (HR 4.50; 95% CI 1.39-14.52; p=0.012). The 2-year OS, EFS, and GRFS for the subset of 30 patients (adults, n=25; children, n=5) with HCT-CI score of 0 and low/intermediate risk DRI were 68%, 68%, and 60%, respectively (Figure 2). Conclusions: Our preliminary results suggest that RIC haplo-HCT with TCRαβ and CD45RA+ depleted grafts allowed successful allograft in high-risk patients lacking a suitable matched donor, including patients with high level of DSA. Acute GVHD was generally abortive, leading to low incidence of chronic GVHD. The best outcome is seen in patients with favorable HCT-CI and DRI. Further efforts are needed to lower the risk of death due to blood stream infection, and relapse in patients with high risk DRI, such as optimisation of anti-microbial prophylaxis or repeated doses of memory-cell donor lymphocyte infusion (DLI). Disclosures No relevant conflicts of interest to declare.

BackgroundA previously well 15-year-old girl presented with a 2-month history of facial swelling that progressively worsened to involve the neck. There was associated dyspnoea, orthopnoea, headache and throat discomfort. Two weeks before presentation, the patient had an episode of fever for 5 days. On examination, vital signs were within normal limits. Swelling, plethora and venous distension of the face and neck were apparent (figure 1).Figure 1(A) Patient before the onset of symptoms. (B) Patient at presentation.QuestionsWhat is the most likely diagnosis?Superior vena cava syndromeAngioedemaAnasarcaDiphtheriaDescribe the chest X-ray (figure 2).What are the acute concerns?What investigations would you order?Figure 2Chest X-ray of the patient at presentation.Answers can be found on page 02.

Assessment of cancer predisposition syndromes (CPS) in childhood tumours is challenging to paediatric oncologists due to inconsistent recognizable clinical phenotypes and family histories, especially in cohorts with unknown prevalence of germline mutations. Screening checklists were developed to facilitate CPS detection in paediatric patients; however, their clinical value have yet been validated. Our study aims to assess the utility of clinical screening checklists validated by genetic sequencing in an Asian cohort of childhood tumours. We evaluated 102 patients under age 18 years recruited over a period of 31 months. Patient records were reviewed against two published checklists and germline mutations in 100 cancer-associated genes were profiled through a combination of whole-exome sequencing and multiplex ligation-dependent probe amplification on blood-derived genomic DNA. Pathogenic germline mutations were identified in ten (10%) patients across six known cancer predisposition genes: TP53, DICER1, NF1, FH, SDHD and VHL. Fifty-four (53%) patients screened positive on both checklists, including all ten pathogenic germline carriers. TP53 was most frequently mutated, affecting five children with adrenocortical carcinoma, sarcomas and diffuse astrocytoma. Disparity in prevalence of germline mutations across tumour types suggested variable genetic susceptibility and implied potential contribution of novel susceptibility genes. Only five (50%) children with pathogenic germline mutations had a family history of cancer. We conclude that CPS screening checklists are adequately sensitive to detect at-risk children and are relevant for clinical application. In addition, our study showed that 10% of Asian paediatric solid tumours have a heritable component, consistent with other populations., Cancer: Screening checklists catch Asian children at risk of hereditary tumours Existing checklists designed to screen children for a genetic predisposition to cancer are sensitive enough to detect at-risk individuals in an Asian population. Joanne Ngeow from the National Cancer Centre Singapore and colleagues reviewed the medical records of 102 paediatric patients diagnosed with cancer and profiled for inherited mutations in 100 cancer-associated genes. They crosschecked the records against two published screening instruments used by clinical geneticists to identify patients with a hereditary cancer risk. Although only ten patients harboured known cancer predisposition mutations, the checklists flagged 54 individuals. However, all ten pathogenic gene carriers screened positive on the diagnostic aids. The checklists thus seem to err on the side of over-identification and don’t miss many true cases of hereditary cancer in this Asian population.

Background: Haploidentical hematopoietic cell transplantation (HCT) provides an alternative option for patients without HLA-matched donor. Graft-versus-host disease (GVHD), engraftment failure, and infectious complications continue to be the main causes of non-relapse mortality (NRM). We hypothesized that selective depletion of TCRαβ+ and CD45RA+ naive T-cells subset will permit hematopoietic engraftment, while effectively reducing GVHD, and provide improved donor immune reconstitution through adoptive transfer of donor’s mature NK-cells, γδ T-cells, and CD45RO+ memory T-cells. Methods: Mobilized PBSC products were divided into two fractions in 9:1 ratio and depleted using CliniMACS device after labeling with TCRαβ and CD45RA reagents (Miltenyi Biotec, Bergish-Gladbach, Germany), respectively. The conditioning regimen consisted of fludarabine 160mg/m2 divided daily over 4 days, thiotepa 10mg/kg divided twice daily for 1 day, and melphalan 70-140mg/m2 for 1 day, in combination with total lymphoid irradiation 6Gy (n=35) or 7.5Gy (n=12) over 3 equal fractions, total body irradiation of 2Gy (n=13) or antithymocyte globuline (n=2). Short term GVHD prophylaxis for 30 days was given to 1 patient using MMF, 50 patients using tacrolimus, and 2 patients using sirolimus. Results: We transplanted 62 patients, including 55 adults (median age, 47 years; range 20-69) and 7 children (median age, 13 years, range 7-17) with high risk AML (n=34), ALL (n=15), MDS (n=7), plasma cell neoplasm (n=2), mast cell leukemia (n=1), acute undifferentiated leukemia (n=1), and NK/T-cell lymphoma (n=1). The patients were infused with TCRαβ and CD45RA depleted graft containing a median of 6.79 x 106 (range 3.54-20.78) CD34+ cells/kg, 0.00 x 104 (range 0-0.97) CD45RA+CD3+ cells/kg, and 1.09 x 106 (range 0.15-11.67) CD45RO+CD3+ cells/kg. The TCRαβ depleted graft fraction contained a median of 0.20 x 104 (range 0-11.30) TCRαβ+ cells/kg, and 8.52 x 106 (range 0.62-30.00) TCRγδ+ cells/kg. Only 1 patient experienced primary graft failure. All others had engraftment of ANC > 500 cells/µL at a median of 10 days (range 8-22) and platelet > 20,000 cells/µL at a median of 12 days (range 8-22). There was no secondary graft failure. Six patients with high titers of donor-specific HLA antibodies (DSA) engrafted successfully after effective desensitisation with plasma exchange, rituximab, and immunoglobulin. Twenty-two patients (35%) developed acute GVHD of grade II - IV (Gd II, n=15; Gd III, n=5; Gd IV, n=2). Three patients experienced chronic GVHD, giving 2-year cumulative incidence of 7 %. Day 180 cumulative incidence of NRM and relapse were 24.8% (95% CI 14.3-36.8%) and 14.9% (95% CI 6.3-27.0%), respectively. Four of the 16 NRM were attributed to aGVHD. Viral reactivation included CMV (n=25), HHV-6 (n=14), EBV (n=11), and adenovirus (n=7). Fourteen patients died of infection, including 5 patients who had fatal blood stream infection (bacteria, n=3; candidemia, n=2) and 1 patient from disseminated adenovirus infection within 180 days. With a median follow-up of 298 days (range 21-1298) in surviving patients, the 2-year overall (OS), event-free (EFS), and GVHD-free/relapse-free (GRFS) survival were 58% (95% CI 37.6-73.4%), 43% (95% CI 27-57%), and 39% (95% CI 24-54%), respectively (Figure 1). In multivariable analysis, only HCT-comorbidity index (HCT-CI) showed significant impact on OS (HR 6.24; 95% CI 2.05-19.05; p=0.0013), EFS (HR 4.80; 95% CI 1.73-13.35; p=0.0027), and RRM (HR 6.49; 95% CI 1.44-29.25; p=0.015), whereas disease risk index (DRI) impacts risk of relapse (HR 4.50; 95% CI 1.39-14.52; p=0.012). The 2-year OS, EFS, and GRFS for the subset of 30 patients (adults, n=25; children, n=5) with HCT-CI score of 0 and low/intermediate risk DRI were 68%, 68%, and 60%, respectively (Figure 2). Conclusions: Our preliminary results suggest that RIC haplo-HCT with TCRαβ and CD45RA+ depleted grafts allowed successful allograft in high-risk patients lacking a suitable matched donor, including patients with high level of DSA. Acute GVHD was generally abortive, leading to low incidence of chronic GVHD. The best outcome is seen in patients with favorable HCT-CI and DRI. Further efforts are needed to lower the risk of death due to blood stream infection, and relapse in patients with high risk DRI, such as optimisation of anti-microbial prophylaxis or repeated doses of memory-cell donor lymphocyte infusion (DLI). Download : Download high-res image (119KB) Download : Download full-size image Disclosures No relevant conflicts of interest to declare.