A Case of X-Linked Moesin-Associated Immune Deficiency in a Pediatric Patient

Background: X-Linked Moesin-Associated Immune Deficiency (X-MAID) is a rare severe combined immunodeficiency (SCID) subtype that can present at any age due to its variability. Depending on severity, patients demonstrate failure to thrive, recurrent bacterial and viral infections, and increased susceptibility to varicella zoster. It has been characterized by marked lymphopenia with hypogammaglobulinemia and impaired T-cell migration and proliferation. Case Presentation: This is a report of a Cuban 7-year-old male with poor weight gain and facial dysmorphia. He had a history of recurrent bacterial gastrointestinal infections and pneumonia beginning at 4 months of age. He additionally had 4-6 upper respiratory tract and ear infections annually. While still living in Cuba, he was admitted for a profound EBV infection in the setting of significant leukopenia. A bone marrow biopsy confirmed no malignancy. After he moved to the United States, his laboratory work-up revealed marked leukopenia with low absolute neutrophil and lymphocyte count with low T and B cells, very low immunoglobulin levels IgG, IgA, and IgM, and poor vaccination responses to streptococcus pneumonia, varicella zoster, and SARS-CoV-2. Genetic testing revealed a missense pathogenic variant c.511C>T (p.Arg171Trp) in the moesin (MSN) gene associated with X-MAID. He was managed with Bactrim and acyclovir prophylaxis, and immunoglobulin replacement therapy, and considered for hematopoietic stem cell transplantation. Discussion(s): Diagnosis of X-MAID should be considered in patients with recurrent infections and profound lymphopenia. As with SCID, early diagnosis and intervention is of utmost importance to prevent morbidity and mortality. This case demonstrates the importance of genetic testing in identifying this disease as it may prompt an immunologist to consider HSCT if conservative management is suboptimal. In the current literature, HSCT appears promising, but the long-term outcomes have yet to be described.Copyright © 2023 Elsevier Inc.

Enabling mRNA medicine for brain tumors

mRNA is a new class of drugs that has the potential to revolutionize the treatment of brain tumors. Thanks to the COVID-19 mRNA vaccines and numerous therapy-based clinical trials, it is now clear that lipid nanoparticles (LNPs) are a clinically viable means to deliver RNA therapeutics. However, LNP-mediated mRNA delivery to brain tumors remains elusive. Over the past decade, numerous studies have shown that tumor cells communicate with each other via small extracellular vesicles, which are around 100 nm in diameter and consist of lipid bilayer membrane similar to synthetic lipidbased nanocarriers. We hypothesized that rationally designed LNPs based on extracellular vesicle mimicry would enable efficient delivery of RNA therapeutics to brain tumors without undue toxicity. We synthesized LNPs using four components similar to the formulation used in the mRNA COVID19 vaccines (Moderna and Pfizer): ionizable lipid, cholesterol, helper lipid and polyethylene glycol (PEG)-lipid. For the in vitro screen, we tested ten classes of helper lipids based on their abundance in extracellular vesicle membranes, commercial availability, and large-scale production feasibility while keeping rest of the LNP components unchanged. The transfection kinetics of GFP mRNA encapsulated in LNPs and doped with 16 mol% of helper lipids was tested using GL261, U87 and SIM-A9 cell lines. Several LNP formations resulted in stable transfection (upto 5 days) of GFP mRNA in all the cell lines tested in vitro. The successful LNP candidates (enabling >80% transfection efficacy) were then tested in vivo to deliver luciferase mRNA to brain tumors via intrathecal administration in a syngeneic glioblastoma (GBM) mouse model, which confirmed luciferase expression in brain tumors in the cortex. LNPs were then tested to deliver Cre recombinase mRNA in syngeneic GBM mouse model genetically modified to express tdTomato under LoxP marker cassette that enabled identification of LNP targeted cells. mRNA was successfully delivered to tumor cells (70-80% transfected) and a range of different cells in the tumor microenvironment, including tumor-associated macrophages (80-90% transfected), neurons (31- 40% transfected), neural stem cells (39-62% transfected), oligodendrocytes (70-80% transfected) and astrocytes (44-76% transfected). Then, LNP formulations were assessed for delivering Cas9 mRNA and CD81 sgRNA (model protein) in murine syngeneic GBM model to enable gene editing in brain tumor cells. Sanger sequencing showed that CRISPR-Cas9 editing was successful in ~94% of brain tumor cells in vivo. In conclusion, we have developed a library of safe LNPs that can transfect GBM cells in vivo with high efficacy. This technology can potentially be used to develop novel mRNA therapies for GBM by delivering single or multiple mRNAs and holds great potential as a tool to study brain tumor biology.

Re-vaccination against SARS-COV2 in allogeneic HSCT patients: Repeated primary vaccines doses increases seroconversion rates

Patients undergoing treatment for haematological malignancies have been shown to have reduced antibody responses to vaccination against SARS-COV2. This is particularly important in patients who have undergone allogeneic haemopoietic stem cell transplantation (HSCT), in whom there is limited data about vaccine efficacy. In this retrospective single-centre analysis, we present data on serologic responses following one, two, three or four doses of either Pfizer-BioNTech (PB), AstraZeneca (AZ) or Moderna (MU) SARS-CoV- 2 vaccines from a series of 75 patients who have undergone allogeneic HSCT within 2 years from the time they were revaccinated. The seroconversion rates following post-HSCT vaccination were found to be 50.7%, 78%, 79% and 83% following the first, second, third and fourth primary post -HSCT vaccine doses, respectively. The median time from allograft to first revaccination was 145 days (range 79-700). Our findings suggest that failure to respond to the first SARS-CoV- 2 vaccine post-HSCT was associated with the presence of acute GVHD (p = 0.042) and treatment with rituximab within 12 months of vaccination (p = 0.019). A statistical trend was observed with the presence of chronic GVHD and failure to seroconvert following the second (p = 0.07) and third (p = 0.09) post-HSCT vaccine doses. Patients who had received one or more SARS-CoV- 2 vaccines prior to having an allogeneic stem cell transplant were more likely to demonstrate a positive antibody response following the first dose of revaccination against Sars-CoV- 2 (p = 0.019) and retained this seropositivity following subsequent doses. The incidence of confirmed COVID-19 diagnosis among this cohort at the time of analysis was 16%. 17% of these were hospitalised and there was one recorded death (8%) secondary to COVID-19 in a patient who was 15.7 months post allogeneic transplant. In summary, this study suggests that despite the initial low seroconversion rates observed postallogeneic transplant, increasing levels of antibody response are seen post the second primary vaccine dose. In addition, there seems to be lower risk of mortality secondary to COVID-19 in this vaccinated population, compared to what was reported in the earlier phases of the pandemic prior to use of SARS-COV2 vaccination. This adds support to the widely adopted policy of early full revaccination with repeat of primary vaccine doses and boosters post-HSCT to reduce mortality in this population. Finally, we have identified rituximab use and active GVHD as potential risk factors influencing serological responses to SARS-COV2 vaccination and further work should focus on further characterising this risk and optimum dosing schedule both pre-and post-transplant.

Mild COVID-19 clinical course among paediatric patients with primary immunodeficiency

Background: The clinical course of coronavirus disease-2019 (COVID-19) varies from those who are asymptomatic, experience mild symptoms such as fever, cough, and dyspnea, to more severe outcomes including acute respiratory distress, pneumonia, renal failure, and death. Early reports suggested severe outcomes in patients with primary immunodeficiency (PID), particularly those with type 1 interferon signalling defects. This prompted a rigid approach to social distancing to protect this patient population, particularly children. To date, real-world data describing the course and outcome of COVID-19 in paediatric PID patients remains scarce. Method(s): In this retrospective case series, we describe the clinical course of 36 paediatric patients with underlying primary immunodeficiency (PID) followed by SickKids Hospital (Toronto, Canada) who were symptomatic and tested positive for SARS-CoV-2 infection between October 2020 to November 2022. Result(s): Our cohort consisted of patients with combined immunodeficiency (66.7%), antibody deficiency (22.2%), neutrophil dysfunction (8.3%), and immune dysregulation (2.8%). The median age was 7.5 years (range: 8 months - 17 years), with 21 male and 15 female patients. Three (8.3%) patients were post-hematopoietic stem cell transplant (HSCT) and 12 (33%) patients were on immunoglobulin replacement. Nine (25%) patients had underlying lung problems including bronchiectasis (1), interstitial lung disease on home oxygen therapy (1), and underlying asthma (7). Most patients had mild clinical course and were managed at home. The most common symptoms were fever (80%), cough (75%) and other upper respiratory tract symptoms (72%). Nineteen (52.7%) patients experienced other symptoms which included headache, lethargy, or gastrointestinal upset. At the time of the infection, 13 patients (36.1%) had received 2 doses of a SARS-CoV-2 vaccine, 5 patients (13.9%) had received 1 dose, and 18 (50%) were not vaccinated. None of the patients received antiviral or monoclonal antibody as prophylaxis or treatment. Only 1 patient required hospital admission out of precaution given the close proximity to HSCT. All patients recovered without complications. Conclusion(s): The paediatric patients with PID followed by our centre experienced mild to moderate COVID-19 symptoms and recovered fully without complications. These findings support the return of much needed social interactions among children, which were impacted severely during the COVID-19 pandemic.Copyright © 2023 Elsevier Inc.

Mastocytosis and COVID19 infection and vaccination: A pediatric series

Introduction: Mastocytosis encompasses a heterogeneous group of diseases characterized by an accumulation of clonal mast cells (MC) in the skin and/or internal organs, and symptoms of MC activation. This MC activation can be elucidated by several factors, including infections or vaccination. Objective(s): We present our experience with COVID infection and vaccination in a series of 133 patients with pediatric mastocytosis. Method(s): Between January 1998 and December 2022, 133 pediatric patients have been referred to our hospital owing to clinically suspected MC disorder, mainly with mastocytosis in the skin. The final diagnoses of mastocytosis were established by the presence of typical skin lesions together with an increase of MC numbers in a biopsy from lesional skin or activating KIT mutations in lesional skin tissue. Serum baseline tryptase and total immunoglobulin E levels were measured, and patients underwent a comprehensive allergy workup to confirm atopic status and history of anaphylaxis. Regarding vaccination, REMA's (Spanish Network on Mastocytosis) protocol was followed. Result(s): 13 patients with COVID infection were identified, of which 25 (56,8%) were female and 0% had symptoms of MC activation. All of them had an asymptomatic or mild course of COVID infection. None of the patients experimented MC activation symptoms during viral illness. Regarding COVID vaccination, all patients received premedication with antihistamine 60 minutes prior vaccination. No one experimented immediate reactions and only one patient (0,75%) referred worsening of MC activation symptoms (baseline pruritus, urtication and brain fog) only after the first doses, recovering without changes in his treatment (oral cromoglycate and antihistamine) in two months. Discussion(s): Although MC have been implicated in the pathogenesis of cytokine storm in COVID19, there is no clinical evidence of SARSCoV- 2-induced MC activation, perhaps related to the fact that bone marrow MC lack angiotensin-converting enzyme 2 receptors.

Preliminary results from phase 2 of CC-92480- MM- 001: Mezigdomide plus dexamethasone in relapsed/refractory multiple myeloma (RRMM)

In phase 1 of CC-92480- MM- 001 (NCT03374085), the recommended phase 2 dose (RP2D) of mezigdomide plus dexamethasone (MEZI-d) was selected at 1 mg once daily for 21/28 days. Here we report preliminary results from the MEZI-d dose-expansion cohort in patients with heavily pretreated RRMM. Key eligibility criteria were: RRMM;>=3 prior lines of therapy;disease progression <=60 days of last myeloma therapy;refractoriness to lenalidomide/pomalidomide, a proteasome inhibitor, a glucocorticoid, and an anti-CD38 monoclonal antibody. Oral mezigdomide 1 mg was given on days 1-21 of each 28-day cycle, plus weekly dexamethasone (40 mg;20 mg if >75 years of age). Primary objective was to evaluate efficacy (overall response rate [ORR]);secondary objectives included safety/tolerability and additional efficacy assessments. Pharmacodynamics was an exploratory objective. As of 16/Sep/2022, 101 patients had received MEZI-d at the RP2D. Median age was 67 (range 42-85) years, median time since initial diagnosis was 7.4 (1.1-37.0) years;39.6% of patients had plasmacytomas and 37/101 patients had high-risk cytogenetics (56/101 not evaluable). Median number of prior regimens was 6 (3-15);prior therapies included stem cell transplantation (77.2%) and anti-BCMA therapy (29.7%). All patients were refractory to last myeloma regimen and triple-class refractory. Median follow-up was 7.5 (0.5-21.9) months, with a median of 4 (1-20) cycles;10.0% of patients continued treatment;progressive disease was the main reason for discontinuation (60.4%). ORR was 40.6% for all patients. Whilst data are not mature yet, median PFS was 4.4 (95% CI 3.0-5.5) months and median duration of response was 7.6 (95% CI 5.4-9.5) months. ORR was 30.0% in patients with plasmacytomas (N = 40) and 50.0% in patients with prior anti-BCMA therapy (N = 30). Ninety-one (91.1%) patients experienced a grade 3/4 treatment-emergent adverse event (TEAE). Most frequent hematologic grade 3/4 TEAEs were neutropenia (75.2%), anaemia (35.6%), and thrombocytopenia (27.7%);34.7% of patients had grade 3/4 infections, including grade 3/4 pneumonia (15.8%) and COVID-19 (7.0%). Occurrence of other grade 3/4 non-hematologic TEAEs was generally low. Due to TEAEs, 76.2% and 29.7% of patients had mezigdomide dose interruptions and reductions, respectively;90.1% of patients discontinued mezigdomide. Mezigdomide induced substrate degradation and increases in activated and proliferating T cells in patients, including those directly refractory to pomalidomide-based therapies. MEZI-d had a manageable safety profile with encouraging efficacy in patients with triple-class refractory RRMM, including patients with prior BCMA-targeted therapies. These results strongly support the continued development of mezigdomide in MM, and especially in combination.

EBV-related lymphoproliferative disease in Wiskott-Aldrich Syndrome patient

Case: Wiskott-Aldrich Syndrome (WAS) is a rare X-linked inborn error of immunity caused by mutations in the WAS gene. It is classically characterized by immunodeficiency, eczema, and micro-thrombocytopenia. It has been known since the 1960s that patients with WAS have an increased risk of lymphoproliferative disease though the exact incidence remains unknown in the American population. Limited case reports have discussed EBV-related lymphoproliferative disease in patients with WAS. We present a case of a 9-year-old boy with known WAS complicated by eczematous rash, thrombocytopenia, recurrent ear infections, and monoclonal gammopathy who was found to have submandibular EBV-associated lymphoid hyperplasia with associated lung and retroperitoneal lymphadenopathy. Family had been offered treatment with hematopoietic stem cell transplant but declined multiple times in the past. Earlier in the year, he presented with possible MIS-C with negative SARS-CoV-2 PCR. He presented to our hospital with mastoiditis and lymphadenopathy. Physical examination showed severe eczema on hands and tender right mastoid. Laboratory evaluation showed thrombocytopenia, elevated IgG of 6290, IgA of 744, IgE of 827, low IgM of 41, and 14% response to pneumococcal titers. He was empirically treated with intravenous antibiotics. ENT performed right postauricular incision and drainage and the culture grew Hemophilus influenza. Throughout his hospital stay, his submandibular lymphadenopathy became more prominent despite treatment. Core needle biopsy of right submandibular lymph node was suggestive of EBV-associated lymphoid hyperplasia. EBV PCR and antibodies were both positive. CT chest, abdomen, and pelvis revealed multifocal pulmonary lymphadenopathy and a diffuse, bilateral nodularity as well as retroperitoneal and mesenteric lymphadenopathy. He was given four doses of weekly Rituximab, which successfully decreased EBV viremia below linear detectability. Immunoglobulin replacement therapy (IgRT) was initiated. Bronchoalveolar lavage and lung biopsy were performed and are results are currently pending. Discussion(s): We present a case of a 9-year-old boy with known WAS awaiting transplant who was found to have submandibular EBV-associated lymphoid hyperplasia with associated lung and retroperitoneal lymphadenopathy. While lymphoproliferative disease is a known complication of WAS, EBV-related lymphoproliferative disease in WAS patients has only been reported as case reports and remains a rare but known complication of patient with WAS.Copyright © 2023 Elsevier Inc.

A retrospective observational study of CAR T-cell therapy outcomes-Experience from MSE Foundation Trust

The most common non-Hodgkin's lymphoma (NHL) is diffuse large B-cell lymphoma (DLBCL), an aggressive lymphoma that can be cured with standard frontline chemo-immunotherapy in 60%-70% of patients but with historically poor outcomes for relapsed/refractory disease. Patients with relapsed DLBCL after autologous stem cell transplant (ASCT) or with chemotherapy-refractory disease have a particularly dismal prognosis, with a median overall survival (OS) of only 6 months. Chimeric antigen receptor (CAR) T-cell therapy has significantly improved outcomes for patients with relapsed/refractory large B-cell lymphoma, mantle cell lymphoma and follicular lymphoma, with multiple FDA approved CAR T products now commercially available in many developed world including European countries. Ongoing studies seek to move CAR T cells to earlier lines of therapy and to characterise the efficacy and safety of CAR T-cell approaches in additional lymphoma histologies including relapsed/refractory follicular lymphoma and chronic lymphocytic leukaemias. Other areas of active research address CAR T in combination with other lymphoma-directed therapies, and mechanisms of CAR T resistance. We conducted a retrospective observational study assessing the outcomes of patients referred to our tertiary centre, University College London hospital NHS foundation Trust (UCLH) from January 2018 to December 2022, over a 48-month period. We collected data including patients' demographics, types of lymphomas, prior lines of therapies including stem cell transplantation, bridging therapies as appropriate, complications and overall response rate. We also analysed the communication between teams during the challenging period of the COVID-19 pandemic.

We should be learning as much from failure as success

'You do not know what you will find, you may set out to find one thing and end up discovering something entirely different'-Alexander Fleming As the pace at which medicine is advancing continues to accelerate, haematologists will increasingly find themselves practising unfamiliar medicine and using novel treatments. Whilst most scientific breakthroughs hopefully lead to an overall improvement in quality of life and prognosis, it is imperative that enough attention is paid to the shortcomings of new treatments and adverse events. The recent COVID-19 pandemic is a stark reminder of the cyclical nature of history and the need for healthcare professionals to utilise lessons learnt by our predecessors. Fleming and the discovery of penicillin highlights how mistakes in practice can sometimes lead to unexpected but useful revelations. The use of thalidomide as a treatment for hyperemesis gravidarum in the 1960s devastatingly lead to birth defects in thousands of people. Today, the repurposing of thalidomide, through lateral thinking and further study, has contributed to significant improvements in the prognosis of patients with Multiple Myeloma.1 Mortality following allogenic stem cell transplant continues to decrease overtime as knowledge surrounding complications and how to manage these improves, despite the fact that patients receiving stem cell transplants are becoming increasingly complex.2 These examples from history demonstrate the merit in studying adverse events and undesired outcomes. National reviews of patient health records indicate that errors currently occur in 10% of hospital admissions.3 With new treatments and more complex patients this will likely increase. It is estimated that voluntary reporting by healthcare professionals of such events only occurs 70% of the time.3 History should be used to guide essential changes in attitudes towards error reporting and help to create an ethos where 'failings' are more willingly recognised as a tool to guide improvement and innovation.

Mesenchymal Stem/Stromal Cells: DEVELOPMENT OF A GMP BANKING PROCESS FOR UMBILICAL CORD MESENCHYMAL STROMAL CELLS (UC-MSCS) AND USE OF UC-MSC IN CHARACTERISATION ASSAYS, FUNCTIONAL ASSAYS AND GENE EDITING STUDIES

Background & Aim: The pro-angiogenic, immunoregulatory and anti- inflammatory properties of MSCs are being exploited for the development of cellular therapies, including the treatment of graft versus host disease (GvHD), inflammatory bowel disease and COVID-19. SNBTS have developed a GMP process to bank umbilical cord MSCs (UC-MSCs) whereby we can reliably bank 100 vials of 10 million P2 UC-MSCs per cord. Each of these vials can be extensively expanded and stored for specific applications. The ultimate aim of the bank is for off-the-shelf clinical use, e.g., in GvHD or as an adjuvant therapy in Islet transplantations. Methods, Results & Conclusion(s): During process development, different basal media and supplements were screened for proliferation and MSC marker expression. Cells grown in promising media combinations were then tested for tri-lineage differentiation (identity), their chemokine/cytokine expression and T-cell inhibition (function) assessed. Medium selected for further GMP development and scale up was ultimately determined by all round performance and regulatory compliance. GMP-like UC-MSCs were shown to have immune-modulatory activity in T-cell proliferation assays at 4:1 or 16:1 ratios. Co-culture of UC-MSCs and freshly isolated leukocytes, +/- the immune activating agent LPS, show a dose dependent survival effect on leukocytes. In particular, neutrophils, which are normally very short lived in vitro demonstrated increased viability when co-cultured with UCMSCs. The survival effect was partially reproduced when UC-MSC were replaced with conditioned medium or cell lysate indicating the involvement of soluble factors. This improved neutrophil survival also correlates with results from leukocyte migration studies that demonstrate neutrophils to be the main cell type attracted to MSCs in in vitro and in vivo. Genetic modification of UC-MSC may improve their therapeutic potential. We have tested gene editing by CRISPR/Cas9 technology in primary UC-MSCS. The CXCL8 gene, highly expressed in UC-MSC, was targeted in isolates from several different donors with editing efficiencies of 78-96% observed. This translated to significant knockdown of CXCL8 protein levels in resting cells, however after stimulation levels of CXCL8 were found to be very similar in edited and non-edited UC-MSCs. This observation requires further study, but overall the results show the potential to generate future banks of primary UC-MSCS with genetically enhanced pro-angiogenic, immunoregulatory and/or anti-inflammatory activities.Copyright © 2023 International Society for Cell & Gene Therapy

Celebrating the Sickle Cell Disease World Day on June 19th after Two Years of Pandemic: My Life with Scd, Patients' Perspective

Background: After two years of COVID in which activities were reduced due to the pandemic and each one's life was affected by restrictions and limitations, the Sickle Cell Disease (SCD) Association in Padova teamed up with the Sickle Cell Group at the Pediatric Hematology Oncology and Bone Marrow Transplant Unit to celebrate the Sickle Cell Disease world day by organizing an online meeting with children/youths and their families. Theme of the meeting was: "My Life with SCD: poems, pictures and writings express our view on disease and care". Aim(s): One of the goals of this meeting was to create an opportunity for individuals with SCD to meet and have a constructive discussion with each other about the disease and express their feelings after two years of pandemic. Method(s): One month before the meeting children, teenager and parents were asked to sharer with the organizing team any drawing, painting, poem, writing, that they felt could express their feelings or experience of the disease itself or how it affected their life, or their experience in the hospital. The materials received were organized in a power point presentation and At the meeting, families were able to see a PowerPoint presentation with the poems, drawings, writings. Each author had the choice to personally share their production or have it read out loud by a member of the team. Free time to comment or share experiences was given. Result(s): 20 children, teenagers and parents participated. Countries of origin (Nigeria, Ghana, Congo, Albania, Italy), religious background (catholic, muslim, no religion, other) were different as well as disease genotype (HbSS, HbSC, HbSBdegree), severity or treatment received (Hydroxyurea, transfusion, Hematopoietic stem cell transplantation -HSCT, none). Drawings and writings regarded experience with the disease (mechanism of action, admissions), feelings experienced (fear, hope, light at the end of the tunnel), aspirations (sports) and gratitude (to the social and medical team, to parents) (Figure 1). Surprisingly, families who had a child having undergone HSCT, reported on the need and importance to talk about this experience for years after the event and made a request of a support goup. Finally, all families underlined the need to meet again soon to discuss together issues related to personal experience with SCD, even via web. of discussion with each other and with the drepanocytosis group;and that throug the online telematics platform it is still possible to involve all families, listening and trying to comfort them on doubts and perplexities about the disease, In conclusion, it can be said that after two years of pandemic, in our setting, online meeting can help patients and families reconnect with each other and activities can be planned to aid experiences and feelings. Patients' associations and Health Care Teams can collaborate in this area.

Mesenchymal Stem/Stromal Cells: HUMAN MESENCHYMAL STEM CELL THERAPY IN SEVERE COVID-19 PATIENTS: 2-YEAR FOLLOW-UP RESULTS OF A RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED TRIAL

Background & Aim: The long-term effects of human mesenchymal stem cell (MSC) treatment on COVID-19 patients have not been fully characterized. The aim of this study was to evaluate the safety and efficacy of a MSC treatment administered to severe COVID-19 patients enrolled in a randomized, double-blind, placebo-controlled clinical trial (NCT 04288102). Methods, Results & Conclusion(s): A total of 100 patients experiencing severe COVID-19 received either MSC treatment (n = 65, 4x107 cells per infusion) or a placebo (n = 35) combined with standard of care on days 0, 3, and 6. Patients were subsequently evaluated 18 and 24 months after treatment to evaluate the long-term safety and efficacy of the MSC treatment. The outcomes measured included: 6-minute walking distance (6-MWD), lung imaging, quality of life according to the Short Form 36 questionnaire, COVID-19-related symptoms, titers of SARS-CoV-2 neutralizing antibodies, MSC-related adverse events (AEs), and tumor markers. Two years after treatment, a marginally smaller proportion of patients had a 6-MWD below the lower limit of the normal range in the MSC group than in the placebo group (OR = 0.19, 95% CI: 0.04-0.80, Fisher's exact test, p = 0.015). On the SF-36 questionnaire, a marginally higher general health score was received by the MSC group at month 18 compared with the placebo group (50.00 vs. 35.00;95% CI: 0.00-20.00, Wilcoxon rank sum test, p = 0.016). In contrast, there were no differences in the total severity score of lung imaging or the titer of neutralizing antibodies between the two groups. Meanwhile, there were no MSC-related AEs reported at the 18- or 24-month follow-ups. The serum levels of most of the tumor markers examined remained within normal ranges and were similar between the MSC and placebo groups. Long-term safety was observed for the COVID-19 patients who received MSC treatment. Yet few sustained efficacy of MSC treatment was observed at the end of the 2-year follow-up period. Funding(s): The National Key Research and Development Program of China (2022YFA1105604, 2020YFC0860900), the specific research fund of The Innovation Platform for Academicians of Hainan Province (YSPTZX202216) and the Fund of National Clinical Center for Infectious Diseases, PLA General Hospital (NCRCID202105,413FZT6). [Figure presented]Copyright © 2023 International Society for Cell & Gene Therapy

COVID-19 pre-exposure prophylaxis with tixagevimab/cilgavimab in patients with haematological malignancy: A single-centre experience

Background: COVID-19 pandemic still pose a substantial threat worldwide despite increasing vaccine availability. Patients with haematological malignancies have been shown to have increased risk of contracting COVID-19 and are more susceptible to develop severe illness from SARS-CoV- 2 infection. The immune response to vaccines is impaired in patients with haematological malignancy due to underlying disease or antineoplastic therapies. The monoclonal-antibody combination, Evusheld is composed of tixagevimab and cilgavimab, two neutralising antibodies against SARS-CoV- 2. It has been shown to be safe and have efficacy for the prevention of COVID-19. Our aim of study is to describe the incidence and outcome of breakthrough COVID-19 infection among patients who received Evusheld in our centre and analyse the factors that possibly increase the risk of breakthrough infection. Material(s) and Method(s): A retrospective review of all adult patients with haematological malignancy who received tixagevimab/ cilgavimab 150/150 mg injection in Hospital Pulau Pinang from 1 July 2022 to 31 August 2022 with a follow-up period to 30 November 2022 was conducted. Demographic data, clinical characteristics and outcome will be retrieved from patient's medical records. Data were analysed using Statistical Package for Social Sciences software (version 21.0). Result(s): A total of 96 patients (50 males and 46 females) received tixagevimab/cilgavimab injection during the study period with a median age of 61 years (range 19-82). Majority of them were diagnosed with multiple myeloma (42.7%), followed by lymphoma (33.3%) and leukaemia (24%). One third of them had history of therapy with monoclonal antibody and 20% had haematopoietic stem cell transplantation. No major adverse effects of tixagevimab/cilgavimab injection were noted among the study population. Of the 12 patients (12.5%) who had COVID-19 infection, all of them had mild infection;three were asymptomatic and six patients received Paxlovid antiviral therapy. The median time from tixagevimab/cilgavimab to the onset of COVID-19 infection was 35 days (range 5-97 days). The mean age of patients with breakthrough COVID-19 infection were older compared to those without breakthrough infection but was not statistically significant. The incidence of breakthrough COVID-19 infection was not affected by type of haematological malignancy, history of monoclonal antibody therapy or COVID-19 vaccination. Discussion and Conclusion(s): Our findings showed that tixagevimab/cilgavimab was safe and effective in preventing COVID-19- related morbidity and mortality among patients with haematological malignancy during the study period. However, the limitation is the lack of access to whole genome sequencing for detection of resistant variants for breakthrough infections.

SeroNet Pooling Project of immunocompromised populations

Introduction: COVID-19 vaccination substantially reduces morbidity and mortality associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and severe illness. However, despite effective COVID-19 vaccines many questions remain about the efficacy of vaccines and the durability and robustness of immune responses, especially in immunocompromised persons. The NCI-funded Serological Sciences Network (SeroNet) is a coordinated effort including 11 sites to advance research on the immune response to SARS-CoV-2 infection and COVID-19 vaccination among diverse and vulnerable populations. The goals of the Pooling Project are: (1) to conduct real-world data (RWD) analyses using electronic medical records (EMR) data from four health care systems (Kaiser Permanente Northern California, Northwell Health, Veterans Affairs-Case Western, and Cedars-Sinai) to determine vaccine effectiveness in (a) cancer patients;(b) autoimmune diseases and (c) solid organ transplant recipients (SOTR);(2) to conduct meta-analyses of prospective cohort studies from eight SeroNet institutions (Cedars-Sinai, Johns Hopkins, Northwell Health, Emory University, University of Minnesota, Mount Sinai, Yale University) to determine post-vaccine immune responses in (a) lung cancer patients;(b) hematologic cancers/hematopoietic stem cell transplant (HSCT) recipients;(c) SOTR;(d) lupus. Method(s): For our RWD analyses, data is extracted from EMR using standardized algorithms using ICD-10 codes to identify immunocompromised persons (hematologic and solid organ malignancy;SOTR;autoimmune disease, including inflammatory bowel disease, rheumatoid arthritis, and SLE). We use common case definitions to extract data on demographic, laboratory values, clinical co morbidity, COVID-19 vaccination, SARS-CoV-2 infection and severe COVID-19, and diseasespecific variables. In addition, we pool individual-level data from prospective cohorts enrolling patients with cancer and other immunosuppressed conditions from across network. Surveys and biospecimens from serology and immune profiling are collected at pre-specified timepoints across longitudinal cohorts. Result(s): Currently, we have EMR data extracted from 4 health systems including >715,000 cancer patients, >9,500 SOTR and >180,000 with autoimmune conditions. Prospective cohorts across the network have longitudinal data on >450 patients with lung cancer, >1,200 patients with hematologic malignancies, >400 SOTR and >400 patients with lupus. We will report results examining vaccine effectiveness for prevention of SARS-CoV-2 infection, severe COVID-19 and post-acute sequelae of COVID-19 (PAS-C or long COVID) in cancer patients compared to other immunocompromised conditions. Conclusion(s): Our goal is to inform public health guidelines on COVID-19 vaccine and boosters to reduce SARS-CoV-2 infection and severe illness in immunocompromised populations.

Exosomes/EVs: BIOXOME: A NATURAL LIPOSOME MIMETIC AS DRUG DELIVERY SYSTEM

Background & Aim: Liposomes are spherical-shaped vesicles composed of one or more lipid bilayers. The ability of liposomes to encapsulate hydro- or lipophilic drugs allowed these vesicles to become a useful drug delivery system. Natural cell membranes, such as Bioxome, have newly emerged as new source of materials for molecular delivery systems. Bioxome are biocompatible and GMP-compliant liposome-like membrane that can be produced from more than 200 cell types. Bioxome self-assemble, with in-process self-loading capacity and can be loaded with a variety of therapeutic compounds. Once close to the target tissue, Bioxome naturally fuse with the cell membrane and release the inner compound. Orgenesis is interested in evaluating the potential of Bioxome as new drug delivery system for treatment of several diseases, including skin repair, local tumour or COVID19. Methods, Results & Conclusion(s): Bioxome were obtained from adipose- derived Mesenchymal Stem Cells, with a process of organic- solvent lipid extraction, followed by lyophilization and sonication assemblage. During the sonication process, Bioxome were charged or not with several cargos. Size distribution of empty Bioxome was detected by Particle Size Analyzer (NanoSight). Electron Microscopy (EM) was performed to assess Bioxome morphology. Lipid content was evaluated by electrospray ionization system. Dose response in vitro test on human lung fibroblasts treated or not with Bioxome encapsulating a specific cargo (API) against COVID19 were performed. NanoSight analysis showed that nanoparticle size in Bioxome samples ranged between 170+/-50 nm, with a concentration ranging between 109-1010+/-106 particles/mL. EM clearly showed the double phospholipid layers that composes the Bioxome. Stability study demonstrated that Bioxome are stable in size and concentration up to 90 days at +4Cdegree or even at RT. No change in size between encapsulated Bioxome with small size (~340 Da) cargo vs empty Bioxome was observed up to 30 days storage. Lipidomic analysis approach revealed that the yield of lipids and their composition are satisfactory for a therapeutic product using Bioxome. Lastly, in the in vitro model of COVID19, Bioxome encapsulating API effectively saved cells from death (20x vs untreated cells) and at lower doses of API than these of non-encapsulated cargo (0.005 microM vs 0.1 microM). Bioxome seems to be an excellent candidate for liposome mimetic tool as drug delivery system for targeting specific organs and diseases treatment.Copyright © 2023 International Society for Cell & Gene Therapy

Application of MSCs therapy in COVID-19

The year 2019 ended with the official report of an unknown pneumonia outbreak in Wuhan, Hubei Province, China. Subsequently, this novel pneumonia was named COVID-19, which mainly attacks the respiratory system, causing severe damage. Although vaccination has relieved the stress of combating pandemics around the world after one year, there are still unknowns and challenges that come with hope. In this regard, stem cell therapy has been proposed as an effective approach to treating COVID-19. Mesenchymal stem cells (MSCs) can potentially be used as a hopeful tool in the cell-based therapy due to their ability to regenerate and regulate immune response. Although research and clinical results have shown encouraging achievement in patients who were treated with MSCs, drawbacks and challenges still exist in the face of new opportunities. This review aims to introduce the challenges of the COVID-19 vaccine and the possible clinical use of MSC-based therapy. Through analysis of COVID-19 and MSC-based therapy, the author aims to find the possibilities and feasibility of using MSCs to treat acute respiratory diseases, such as COVID. As a result, the author finds that MSC treatment is very practical, and it shows significant potential to treat COVID-19. © 2023 SPIE.

Mesenchymal Stem/Stromal Cells: BIOLOGICAL THREAT AGENT RICIN INTOXICATION OF THE LUNGS IS EFFECTIVELY TREATED BY MESENCURE, A PROFESSIONALIZED ALLOGENEIC MESENCHYMAL CELL THERAPY, PREFERABLY VIA THE SUBCUTANEOUS ROUTE

Background & Aim: Ricin is one of the most lethal toxins, particularly if inhaled, and is considered a biological threat agent due to its wide availability and ease of production. Pulmonary ricin intoxication manifests in ARDS, cytokine storm, immune infiltration, and severe edema. Passive immunization is the preferred measure against pulmonary ricinosis, but only if administered shortly after exposure. Despite their potential to remedy pulmonary injury and inflammation, mesenchymal cell (MSC) therapies were never investigated in ricinosis. Here, we report the potential for treating pulmonary ricinosis with MesenCure, a professionalized allogeneic MSC therapy shown to reduce the mortality of patients suffering from severe pulmonary manifestations of COVID by 68%. Methods, Results & Conclusion(s): Preliminary studies demonstrated positive MesenCure effects in a sub-lethal pulmonary ricinosis model in CD1 mice. This model is regarded as highly translational due to the broad heterogeneity of these outbred mice. Positive effects included a reduction in excess protein content of the bronchoalveolar lavage fluid (BALF) by 45% when MesenCure was injected intravenously (IV) at 125k cells/animal, 48h post-exposure (PE) and evaluated one day later (p<0.05, Fig. 1A). Moreover, we found up to 52% reduction in the excess BALF leukocytes, when MesenCure was injected IV, 24h PE using the same dose (p<0.05, Fig. 1B) or 6h PE using a double dose (p<0.01, Fig. 1C), and evaluated two days PE. Optimizing the dose and administration route further improved the therapeutic outcome of MesenCure applied 6h PE as assessed by weight loss. As shown in Fig. 1D-E, IV injection of 250k-500k MesenCure cells/animal slightly protected the intoxicated animals against weight loss (p for treatment x time interaction <0.01 or <0.05 for 250k and 500k cells/animal, respectively). Interestingly, one million cells IV resulted in a lesser effect (not shown), however when injected subcutaneously (SC), 1M cells were very effective (p<0.001, Fig. 1F), seemingly even more effective than 2M cells/animal SC (Fig. 1G). Surprisingly, 2M thawed cells/animal injected SC protected the animals against weight loss almost completely (p<0.0001, Fig. H). In conclusion, we provide evidence for the potential of SC MSCs, specifically MesenCure, for treating pulmonary ricinosis and possibly other forms of ARDS. In agreement with Giri and Galipeau (2020), we provide further evidence for the dependency of MSC outcomes on their specific state and administration route. [Figure presented]Copyright © 2023 International Society for Cell & Gene Therapy

SARS-CoV-2 infection in patients with multiple myeloma: survey in 23 centers across Europe and USA

Introduction: Despite several studies, the impact of coronavirus disease 2019 on patients with multiple myeloma remains uncertain. Material(s) and Method(s): We performed a survey that covered the period of the first and second waves of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic in 23 centers inseven countries. Out of 352 patients with myeloma and SARS-CoV-2, 23% died. Results/Conclusions: Logistic regression showed a lower risk of death among patients treated with proteasome inhibitor and a higher risk of death for those who had a severe or a very severe course of disease.Copyright © 2023 Sciendo. All rights reserved.