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Decreased cytomegalovirus (CMV)-specific immunity after hematopoietic cell transplantation (HCT) is associated with late CMV reactivation and increased mortality. Whether letermovir prophylaxis-associated reduction in viral exposure influences CMV-specific immune reconstitution is unknown. In a prospective cohort of allogeneic HCT recipients who received letermovir, we compared polyfunctional CMV-specific T-cell responses to those of controls who received PCR-guided preemptive therapy before the introduction of letermovir. Thirteen-color flow cytometry was used to assess T-cell responses at 3 months after HCT following stimulation with CMV immediate early-1 (IE-1) antigen and phosphoprotein 65 (pp65) antigens. Polyfunctionality was characterized by combinatorial polyfunctionality analysis of antigen-specific T-cell subsets. Use of letermovir and reduction of viral exposure were assessed for their association with CMV-specific T-cell immunity. Polyfunctional T-cell responses to IE-1 and pp65 were decreased in letermovir recipients and remained diminished after adjustment for donor CMV serostatus, absolute lymphocyte count, and steroid use. Among letermovir recipients, greater peak CMV DNAemia and increased viral shedding were associated with stronger CD8+ responses to pp65, whereas the CMV shedding rate was associated with greater CD4+ responses to IE-1. In summary, our study provided initial evidence that letermovir may delay CMV-specific cellular reconstitution, possibly related to decreased CMV antigen exposure. Evaluating T-cell polyfunctionality may identify patients at risk for late CMV infection after HCT.

Sinusoidal obstructive syndrome (SOS), also known as hepatic veno-occlusive disease (VOD), is a potentially life-threatening complication following haemopoietic stem cell transplantation (HSCT). The availability of new drugs for malignant hematological conditions has allowed more patients to be eligible for allogeneic haematopoietic stem cell transplants, which has translated into a significant proportion of transplant patients having multiple risk factors for VOD/SOS. Based on these considerations, we undertook a dedicated weekly VOD/SOS ward round, aiming to facilitate early diagnosis of VOD/SOS and pre-emptively identify patients at risk, where a careful evaluation of differential diagnosis is essential. Herein, we present the results of our VOD/SOS ward round; between September 2020 and April 2022, 110 consecutive patients were evaluated in a focused VOD/SOS ward round. From the 110 patients, 108 had undergone HSCT and had at least one known risk factor for developing VOD/SOS. The median number of risk factors present in the VOD/SOS group and non-VOD/SOS group was five (range: three to six) and three (range: zero to seven), respectively. Late-onset VOD/SOS was diagnosed in 45% of our patients. The early identification of patients with multiple risk factors for VOD/SOS allowed an earlier diagnosis and the administration of defibrotide on the same day of diagnosis, which was two days earlier than our previous experience prior to the implementation of this protocol.

Ruxolitinib is a selective, Janus kinase (JAK)1 and JAK2 inhibitor, which is effective in management of chronic graft-versus-host disease (cGvHD). However, the ensuing immunosuppressive effects can give rise to aggressive cutaneous tumours, including Merkel cell carcinoma. We present this case to highlight the development of cutaneous tumours with ruxolitinib, an increasingly used therapy, and the challenge of managing such tumours in the context of refractory cGvHD. Click here for the corresponding questions to this CME article.

Classical veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a serious complication post allogeneic hematopoietic stem cell transplantation (HSCT). Before the recently revised EBMT criteria, the Baltimore and modified Seattle criteria failed to recognize the syndrome of late-onset VOD. We present real-world experience from a large UK transplant center reporting on VOD/SOS in consecutive HSCT adult patients (n = 530), transplanted for hematological cancers. We identified 27 patients treated with Defibrotide for VOD/SOS diagnosis, where detailed data were available for final analysis. Using standard definitions including EBMT criteria, around 30% (n = 8/27) of cases classified as late-onset VOD presenting at median of 46 (22-93) days but with D100 survival (63% vs 58%, Log-rank; P = 0.81) comparable to classical VOD. Hazard ratio for D100 mortality was 2.82 (95% CI: 1.74-4.56, P < .001, Gray test) with all VOD/SOS events. Twenty percent (n = 2/8) of late-onset VOD patients were anicteric and 42% (n = 8) classical VOD patients presented with refractory thrombocytopenia, while less than half met EBMT criteria for classical VOD in adults, highlighting gaps in real-world diagnostic limitations using EBMT criteria. However, challenges remain about underrecognition and difficulties related to early defibrotide access for treatment of late-onset VOD in current treatment guidelines. Our report strongly supports early Defibrotide for the treatment of severe VOD/SOS in adults regardless of time of onset.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is a novel virus that spread worldwide from 2019 causing the Coronavirus disease 19 (COVID-19) pandemic. SARS-CoV-2 infection is characterised by an initial viral phase followed in some patients by a severe inflammatory phase. Importantly, immunocompromised patients may have a prolonged viral phase, shedding infectious viral particles for months, and absent or dysfunctional inflammatory phase. Among haematological patients, COVID-19 has been associated with high mortality rate in acute leukaemia, high risk-myelodysplastic syndromes, and after haematopoietic cell transplant and chimeric-antigen-receptor-T therapies. The clinical symptoms and signs were similar to that reported for the overall population, but the severity and outcome were worse. The deferral of immunodepleting cellular therapy treatments is recommended for SARS-CoV-2 positive patient, while in the other at-risk cases, the haematological treatment decisions must be weighed between individual risks and benefits. The gold standard for the diagnosis is the detection of viral RNA by nucleic acid testing on nasopharyngeal-swabbed sample, which provides high sensitivity and specificity; while rapid antigen tests have a lower sensitivity, especially in asymptomatic patients. The prevention of SARS-CoV-2 infection is based on strict infection control measures recommended for aerosol-droplet-and-contact transmission. Vaccinations against SARS-CoV-2 has shown high efficacy in reducing community transmission, hospitalisation and deaths due to severe COVID-19 disease in the general population, but immunosuppressed/haematology patients may have lower sero-responsiveness to vaccinations. Moreover, the recent emergence of new variants may require vaccine modifications and strategies to improve efficacy in these vulnerable patients. Beyond supportive care, the specific treatment is directed at viral replication control (antivirals, anti-spike monoclonal antibodies) and, in patients who need it, to the control of inflammation (dexamethasone, anti-Il-6 agents, and others). However, the benefit of all these various prophylactic and therapeutic treatments in haematology patients deserves further studies.

Pre-emptive DLI (pDLI) is an effective strategy in lowering the risk of relapse without significantly increasing the risk of graft-versus-host disease (GVHD) in the case of T cell lineage mixed chimerism (MC) post allogeneic transplant in hematological malignancies. Many patients, however, fail to receive timely pDLI and have dismal outcomes, which are not taken into consideration. We compared long-term outcomes of 106 patients having T cell MC after day 60 and undergoing allogeneic stem cell allograft for acute leukemia from an unrelated donor (UD), with 111 patients having complete chimerism (CC). Fifty-three (56%) patients received prophylactic pDLI. Thirty-six patients (67%) had a response (RR), 17 (33%) had no response (NR), and fifty-two (54%) did not receive any pDLI (ND). OS was better in MC group as compared to CC (54% vs 43%, p = 0.04), mainly due to reduction in NRM (14% vs 25%, p = 0.05), and all grade acute and chronic GVHD. Within the MC group, response to pDLI was the only significant factor predicting OS, DFS, and relapses with NR and ND having unfavorable outcomes as compared to RR (p = 0.001). T cell MC in patients undergoing UD allografts with alemtuzumab is no longer an adverse prognostic factor, as compared to patients having CC, after timely implementation of pDLI.

Survival after allogeneic hematopoietic cell transplantation (HSCT) for severe aplastic anemia (SAA) among older patients remains poor and associated with increased risk for graft-versus-host disease (GVHD). In this retrospective study of 65 consecutive patients with acquired SAA who were transplanted using fludarabine, low-dose cyclophosphamide, and alemtuzumab (FCC), outcomes of 27 patients aged at least 50 years were compared with those of 38 patients younger than 50 years. The median age of the older cohort was 61 years (range, 51-71 years); 21 (78%) patients were transplanted from unrelated donors (3 of 21 from HLA 9/10 mismatch donors) and 6 from matched sibling donors. One-year GVHD-free, relapse-free survival (GRFS) was comparable to that of patients younger than 50 years (84% vs 94%, respectively; P 5 .23). Both groups showed low rates of acute (5% vs 4%) and chronic (18% vs 14%) GVHD, with no cases of severe GVHD among matched donor transplants, and similar 1-year transplant-related mortality (14% vs 5.4%, older vs younger; P 5 .23). HSCT comorbidity index (HTC-CI) scores were similar between the groups, but overall survival with an HCT-CI of at least 3 was lower compared with a score less than 3 (76% vs 98%; P 5 .005). Median donor T-cell chimerism among older patients was 64% and 60% at 1 and 3 years, respectively, and was similar to that of younger patients. Increased B regulatory cells potentially contributed to low alloreactivity and mutual donor-recipient tolerance in older patients. Effect of comorbidities rather than age alone may be a more important determinant of suitability for FCC HSCT in older patients.

Determining the underlying cause of persistent eosinophilia is important for effective clinical management but remains a diagnostic challenge in many cases. We identified STAT5B N642H, an established oncogenic mutation, in 27/1715 (1.6%) cases referred for investigation of eosinophilia. Of the 27 mutated cases, a working diagnosis of hypereosinophilic syndrome (HES; n = 7) or a myeloid neoplasm with eosinophilia (n = 20) had been made prior to the detection of STAT5B N642H. Myeloid panel analysis identified a median of 2 additional mutated genes (range 0–4) with 4 cases having STAT5B N642H as a sole abnormality. STAT5B N642H was absent in cultured T cells of 4/4 positive cases. Individuals with SF3B1 mutations (9/27; 33%) or STAT5B N642H as a sole abnormality had a markedly better overall survival compared to cases with other additional mutations (median 65 months vs. 14 months; hazard ratio = 8.1; P

Summary Background Human parainfluenza virus type 3 (HPIV3) infections are associated with high mortality in immunocompromised settings, especially in bone marrow transplant recipients. Asymptomatic infection and lack of effective antiviral treatment makes HPIV3 prevention and treatment a real challenge. Aim To retrospectively investigate the epidemiological characteristics, clinical characteristics and outcomes of 51 haematology patients with confirmed HPIV3 infections, detected between February and May 2019 in the haematology unit at King's College Hospital, London. Methods Between February and May 2019, HPIV3 RNA was detected in combined nose and throat swab samples collected from 51 symptomatic haematology patients, 41 of whom attended the haematology outpatient unit. Clinical data were reviewed retrospectively and a timeline of patients' appointments drawn up to investigate transmission. Sequencing analysis was performed on 14 stored samples. Findings Fifty-one patients were identified with HPIV3 infection. Mean age was 54 years (SD: 12; range: 19–72) and 60% (31/51) were male. There were 41 (80%) bone marrow transplant recipients, 24 had an allograft, and 17 an autograft. Thirty-day and 3-month mortality post HPIV3 was 6% and 14%, respectively. Lower respiratory tract infection and inpatient acquisition were associated with higher mortality (6/7 vs 1/7, P = 0.010; and 5/7 vs 2/7, P = 0.031). Onset of HPIV3 infection in patients within 6 days of attending the clinic was associated with the clusters identified in phylogenetic analysis (64% (9/14) vs 21% (8/37); odds ratio: 6.5 (confidence interval: 95% 1.7–25); P = 0.006). Conclusion Timelines suggested community transmission, but also possible transmission patterns within the outpatients and subsequent nosocomial transmission within the same ward. Early recognition of HPIV3 infection and the use of polymerase chain reaction and sequence analysis is fundamental in identifying respiratory virus outbreaks and person-to-person transmission. Careful planning of outpatient clinic attendance is required to minimize contact and prevent respiratory virus transmission in immunosuppressed patients.

Invasive fungal lung disease (IFD) is a well-recognised complication post haematopoietic stem-cell transplant (HSCT), occurring in approximately 5–21% of patients, despite tri-azole anti-fungal prophylaxis. Baseline CT thorax (BCT) pre-HSCT is increasingly considered as standard practise to evaluate lung disease, however evidence on outcomes from previous studies has been limited by either small or heterogenous cohorts (Ceesay et al 2018, Bitterman et al 2019). Kings College Hospital is one of the largest HSCT centres in the UK, as such IFD accounts for a significant patient morbidity and hospital bed days. We conducted a single centre prospective analysis of patients with myeloid malignancies and aplastic anaemia (n=350) who underwent T-cell deplete allo-HSCT between Jan 2015 and April 2019. BCT was performed in 235 patients. IFD was defined by by EORTC criteria. See figure 1 for baseline characteristics. Post HSCT, IFD developed in 9.1% of total patients (n=32/350) and in 12.3% (n=29/235) of those who had BCT. Patients with European Platform of Cancer Research (EORTC) defined changes on BCT developed significantly more IFD (34.2% vs 9.4%, p=0.0004). Univariate analysis of baseline characteristics identified that a significantly higher proportion of those with pre-HSCT IFD developed post-HSCT IFD (33.3% vs 8.3%; P=0.003). Reduced intensity conditioning, poor baseline performance status and co-morbidities, and gas transfer (TLCO Abnormal BCT did not influence overall survival, however in patients with EORTC defined changes on BCT, there was a significant reduction in median IFD-free survival (30.5 months vs 47 months, p=0.009) when compared to non-EORTC and normal CT findings. There was a significant reduction in overall survival at 12 months post HSCT in those who developed IFD (62% vs 76%, p=0.001, log rank). Previous IFD, EORTC BCT changes and abnormal TLCO pre-HSCT influence IFD related outcomes and we suggest early respiratory optimisation pre-HSCT to reduce risk of IFD-related mortality. Further evaluation of impact of interventions in patients with abnormal BCT is warranted.

ObjectiveTo examine outcomes in people with multiple sclerosis (PwMS) treated with autologous hematopoietic stem cell transplantation (AHSCT) in a real-world setting.MethodsThis was a retrospective cohort study of PwMS treated with AHSCT at 2 centers in London, UK, consecutively between 2012 and 2019 who had ≥6 months of follow-up or died at any time. Primary outcomes were survival free of multiple sclerosis (MS) relapses, MRI new lesions, and worsening of Expanded Disability Status Scale (EDSS) score. Adverse events rates were also examined.ResultsThe cohort includes 120 PwMS; 52% had progressive MS (primary or secondary) and 48% had relapsing-remitting MS. At baseline, the median EDSS score was 6.0; 90% of the evaluable cases showed MRI activity in the 12 months preceding AHSCT. Median follow-up after AHSCT was 21 months (range 6–85 months). MS relapse-free survival was 93% at 2 years and 87% at 4 years after AHSCT. No new MRI lesions were detected in 90% of participants at 2 years and in 85% at 4 years. EDSS score progression–free survival (PFS) was 75% at 2 years and 65% at 4 years. Epstein-Barr virus reactivation and monoclonal paraproteinemia were associated with worse PFS. There were 3 transplantation-related deaths within 100 days (2.5%), all after fluid overload and cardiac or respiratory failure.ConclusionsEfficacy outcomes of AHSCT in this real-world cohort are similar to those reported in more stringently selected clinical trial populations, although the risks may be higher.Classification of EvidenceThis study is rated Class IV because of the uncontrolled, open-label design.

The SARS-CoV-2 (COVID-19) virus causes a wide spectrum of disease in healthy individuals as well as those with common comorbidities [1]. Severe COVID-19 is characterised acute respiratory distress syndrome (ARDS) secondary to viral pneumonitis, treatment of which may require mechanical ventilation or extracorporeal membrane oxygenation (ECMO) [2]. Clinicians are alert to the possibility of bacterial co-infection as a complication of lower respiratory tract viral infection; for example a recent review found that 72% of patients with COVID-19 received antimicrobial therapy [3]. However, the risk of fungal co-infection, in particular COVID-19 associated pulmonary aspergillosis (CAPA), remains underappreciated., Cases of COVID-19 associated pulmonary aspergillosis (CAPA) are being increasingly reported and physicians treating patients with COVID-19-related lung disease need to actively consider these fungal co-infections.

Severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2), emerged at the end of 2019 and caused an infection named COVID‐19 (Guan, Ni et al. 2020). Patients with compromised immune systems are at increased risk of complications but this risk is not precisely defined (Liang, Guan et al. 2020). Although age, gender, comorbidities and ethnicity are risk factors for adverse outcomes (Huang, Wang et al. 2020), various pre‐existing conditions, including haematological cancers, have also been reported to correlate with poor outcomes (Aries, Davies et al. 2020, He, Chen et al. 2020, Malard, Genthon et al. 2020, Martin‐Moro, Marquet et al. 2020, medRxiv 2020)

Introduction The emergence of herpes simplex virus (HSV) resistance to aciclovir (ACV) has increasingly been reported among hematopoietic stem cell transplant (HSCT) recipients and often associated with extended ACV prophylaxis. Methods Between June 2011 and June 2019, medical records of 532 HSCT recipients with suspected HSV infection were retrospectively analyzed. HSV-1 and HSV-2 positive samples were identified in 47 and 16 patients respectively. Analysis of HSV resistance to antivirals was performed at the Public Health England reference laboratory in London using phenotypic and/or genotypic resistance assays. Results The prevalence of ACV-resistant HSV accounted for 17% (8/48) of infected HSV-1 cases. All 8 patients received T-cell depleted allogeneic HSCT for hematological malignancies. Half of these patients were male with a median age was 57.5 years (range; 26–63). Chronic Graft versus Host disease (cGVHD) affected 7 patients before HSV-1 diagnosis. HSV-1 infection developed while receiving either intravenous ACV (n = 2) or oral ACV (n = 6 patients) prophylaxis at a median of 373 [range,18–2183] days post-HSCT. ACV resistance was clinically suspected at a median of 25 [range,16–109] days after initial HSV diagnosis and subsequently laboratory confirmed at a median of 25 (range,10–59) days. All patients presented with hemorrhagic oral mucositis refractory to treatment dose ACV. Foscarnet (FOS) treatment was initiated in all 8 patients (pending laboratory confirmation of ACV resistance) with some effect but associated with significant toxicity burden. Four patients presented again with recurrent HSV infection or no resolution. Three with recurrent HSV died from other causes while suffering from persistent oral HSV lesions. Conclusion A prolonged immunosuppressed state following T-deplete HSCTs alongside extended use of ACV, early onset systemic HSV infection, presence of cGVHD, and treatment toxicities pose a significant challenge to the management of ACV resistant HSV infections and alternative effective antiviral options remains an unmet need in this clinical setting.

The primary purpose of the present trial was to evaluate the effect of low-frequency (30Hz) vibrations on the rate of canine retraction.Single-center, split mouth prospective randomized controlled clinical trial.100 screened subjects (aged18-25 years) were selected; out of which 30 subjects having Class I bimaxillary protrusion or Class II div 1 malocclusion, requiring upper 1Independent "t" test.There was no statistically significant differencein the rate of individual canine retraction among the experimental and control groups when the intergroup comparison was done using independent "t" test at T1-T0, (The low-frequency vibratory stimulation of 30 Hz using a customized vibratory device did not significantly accelerate the rate of orthodontic tooth movement.Registered at ctri.nic.in (CTRI/2019/05/019043).

Demand-side management has the potential to reduce the cost of solar based community micro-grids and solar home systems for electricity access. This paper presents a methodology for optimal least-cost sizing of generation assets while meeting explicit reliability constraints in micro-grids that are capable of active demand management. The battery management model considers kinetic constraints on battery operation and represents dispatch in the field to regulate the depth of discharge. The model allows consideration of the trade-off between depth of discharge, cycle life, and calendar lifetime in lead-acid batteries. Separate reliability targets for disaggregated, residential load profiles at hourly timesteps are considered to evaluate the performance and cost reduction potential of demand-side management capabilities — with economic results and sensitivity analyses around key input assumptions subsequently presented. We find that demand-side management can reduce the number and cost of requisite solar panels and batteries with the integration of real-time management and controls – a key result for justifying next generation micro-grids for electricity access. Keywords: Micro-grids, Electricity access, Demand-side management, Reliability, Asset selection, Off-grid, Techno-economic model, Cost, Massachusetts Institute of Technology. Tata Center for Technology and Design

Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to unprecedented healthcare challenges on a global scale. Impressive efforts have led to rapid development of multiple efficacious vaccines against SARS-CoV-2, however concerns remain over the degree of protection vaccination offers to immunocompromised recipients. To answer this question, we have designed a prospective study to evaluate response to vaccination in patients with haematological malignancies (Harrington, Leukaemia 2021; Harrington, BJHaem, 2021). 103 patients were included with samples collected in 60 patients after first dose and 71 patients following second dose. We have analysed humoral and T cell response to a first dose of vaccine against SARS-CoV-2 in patients post allogeneic stem cell transplantation (HSCT) and compared those to patients with CML or MPN. Methods: ELISA plates were coated with antigen Nuclear (N) protein or the S protein. Serial dilutions of plasma were added to wells and incubated for 2 h at room temperature. Control reagents included N-specific monoclonal antibody, S-specific monoclonal antibody, negative control plasma, positive control plasma and blank wells. Secondary antibody was added and incubated for 1h at room temperature. IgG was detected using goat-anti-human-Fc-AP and plates read at 405 nm. Where an EC50 was not reached at 1:25, a plasma was considered seropositive if the OD at 405nm was 4-fold above background and a value of 25 was assigned. T cell functionality was assessed using intracellular cytokine staining after incubation with SARS-CoV-2 specific peptides covering immunogenic domains of the Spike (S) protein. A response was considered positive if there was a 3-fold increase in pro-inflammatory cytokine expression from baseline, and above a threshold of 0.01. Specific peptides (0.25 µg/ml), anti-CD28 and BFA were added to cells. Unstimulated cells were utilised as negative controls. Cells were stained with viability dye, then with antibodies directed against surface markers, and fixed and permeabilised prior to staining for intracellular cytokines TNFa and IFNg. Gating on lymphocytes, single cells, live cells, CD3+ cells, CD4+ cells and CD4- (CD8+) was performed. Results: Of the 103 patients included in this study, post vaccination evaluation on 56 patients have been analysed so far, including 37 patients with chronic myeloid malignancies (MPN n=21 and CML n=16) and 19 patients post HSCT. From the latter group, median time since transplant was 53.9 months (18.7 to 76.8) with 12 participants on extracorporeal photopheresis (ECP) therapy for graft versus host disease (GvHD) with median frequency of 24.5 days (14-42). BNT162b2 vaccine was administered to 48 patients (85.7%). An anti-S IgG response was observed after a first dose in 16/21 (76.1%) of the MPN group and 14/16 (87.5%) of CML patients, but in only 7/19 (36.8%) of post HSCT patients (Fishers Exact Test - p=0.02/0.002, Fig 1a). Of the latter group a low positive value where an EC50 was not reached was observed in 4/19 (21.1%) and a moderate response in 3/19 patients (15.8%). Of the 12 patients with active GvHD on ECP, a positive response was observed in 4 patients (33.3%), however only one patient recorded a response where an EC50 was measurable. A T cell response was observed in 16/20 (80%) of the MPN group and 14/15 (93.3%) of those with CML after a single dose, with a polyfunctional T cell response (>1 cytokine) observed in 65% and 80% respectively. In comparison only 5/19 patients (38.5%) post HSCT mounted a T cell response (p=0.027/p=0.002, Fig 1b), with a CD4+ response in 4 (30.8%) and a CD8+ response in 3 (23.1%). In this group, a polyfunctional T cell response was found in 4/19 patients (30.8%). 33.3% of patients with GVHD requiring ECP had a T cell response, compared with 42.9% in post HSCT without GVHD. Summary: Despite encouraging results of antibody and T cell response to a first vaccination dose in patients with chronic myeloid malignancies, these results raise concerns regarding the humoral and T cell responses to vaccination in patients post HSCT, recognised as a particularly immunosuppressed group. Further longitudinal data is required to determine if these results translate into a reduction in cases and severity of infection in these groups. We are currently analysing the response to a second vaccine injection and responses to sequential doses of vaccination across the whole cohort will be presented. Figure 1 Figure 1. Disclosures Harrington: Bristol Myers Squibb: Research Funding; Incyte: Honoraria. Radia: Blueprint Medicines Corporation: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Study steering group member, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Education events; Cogent Biosciences Incorporated: Other: Study Steering Committee; EXPLORER and PATHFINDER studies: Other: Member of the Response Adjudication Committee. Kordasti: Beckman Coulter: Honoraria; Celgene: Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Alexion: Honoraria. Dillon: Menarini: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Session chair (paid to institution), Speakers Bureau; Astellas: Consultancy, Other: Educational Events , Speakers Bureau; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Research Support, Educational Events; Amgen: Other: Research support (paid to institution); Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: educational events; Jazz: Other: Education events; Shattuck Labs: Membership on an entity's Board of Directors or advisory committees. Harrison: Promedior: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AOP Orphan Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte Corporation: Speakers Bureau; Gilead Sciences: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Constellation Pharmaceuticals: Research Funding; Galacteo: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Geron: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sierra Oncology: Honoraria; Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Shire: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; CTI BioPharma: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Keros: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. de Lavallade: Bristol Myers Squibb: Research Funding; Incyte: Honoraria, Research Funding; Novartis: Speakers Bureau.

Summary Mesenchymal stromal cells (MSCs) have been successfully used for the treatment of steroid‐resistant graft‐versus‐host‐disease (GvHD). However, the lack of early predictors of clinical responses impacts on the time at which to add further treatment and consequently the design of informative clinical trials. Here, we present the UK experience of one of the largest cohorts of GvHD patients undergoing MSC infusions so far reported. We show that clinical responses assessed as early as 1 week after MSC infusion predict patients’ overall survival. In our cohort, cell dose, patients’ age and type of organ involvement are crucial factors associated with clinical responses.

Introduction Autologous hematopoietic stem cell transplantation (AHSCT) with anti-thymocyte globulin (ATG) conditioning as treatment of active multiple sclerosis (MS) is rapidly increasing across Europe (EBMT registry data 2017). Clinically significant Epstein-Barr virus reactivation (EBV-R) following AHSCT with ATG for severe autoimmune conditions is an underrecognized complication relative to T-cell deplete transplants performed for hematological diseases. This retrospective study reports EBV-R associated significant clinical sequelae in MS patients undergoing AHSCT with rabbit ATG. Methods Retrospective data were analyzed for 36 consecutive MS-AHSCT patients at Kings College Hospital, London. All patients routinely underwent weekly EBV DNA polymerase chain reaction monitoring and serum electrophoresis for monoclonal gammopathy (MG or M-protein). EBV-R with rising Epstein-Barr viral load, M-protein, and associated clinical sequelae were captured from clinical records. Results All patients had evidence of rising EBV DNA-emia, including 7 who were lost to long-term follow-up, with a number of them developing high EBV viral load and associated lymphoproliferative disorder (LPD). Nearly 72% (n = 18/29) developed de novo MG, some with significant neurological consequences with high M-protein and EBV-R. Six patients required anti-CD20 therapy (rituximab) with complete resolution of EBV related symptoms. Receiver operating characteristics estimated a peak EBV viremia of >500 000 DNA copies/mL correlated with high sensitivity (85.5%) and specificity (82.5%) (area under the curve: 0.87; P = .004) in predicting EBV-R related significant clinical events. Conclusion Symptomatic EBV reactivation increases risk of neurological sequelae and LPD in MS-AHSCT. We recommend regular monitoring for EBV and serum electrophoresis for MG in MS patients in the first 3 months post-AHSCT.

Introduction Acute graft versus host disease may affect the gastrointestinal track (aGI-GvHD) in up to 60% of haematopoetic stem cell transplant (HSCT) recipients who develop GvHD resulting in significant morbidity. Half of these patients will develop steroid refractory disease which is associated with high mortality (up to 90%) due to lack of safe and efficacious therapies. Here we test the hypothesis that the integrin α4β7/Madcam-1 pathway is clinically important in the pathogenesis of human aGI-GvHD. Methods Prospective experimental study, recruiting HSCT recipients with aGI-GvHD (n=10) and controls [IBD (n=36) and non-IBD controls (n=32)]. Samples collected included peripheral blood and distal colonic biopsies. The β7 +CD4+compartment was phenotyped with a multiparametric flow cytometry panel. MADCAM-1 and S100A8 (the calprotectin subunit, biomarker of intestinal damage) expression in the gut were tested with RT-PCR. Clinical data on aGI-GvHD patients treated with vedolizumab were prospectively collected. Results Within the effector memory population (CD3 +CD4+CD45RA-CD45RO+CCR7-) there was significant enrichment of β7 +effector memory cells in both inflammatory conditions (IBD: 24%±2.7, aGI-GvHD: 29%±6.5 vs. controls: 17%±1.1, both p Conclusions For the first time, we show that aGI-GvHD is associated with significant expansion of gut homing effector lineages, most notably Th1 and Th17 cells. Interestingly the ligand for the α4β7 integrin (Madcam-1) is also highly expressed in gut tissue from aGI-GvHD patients, supporting further the therapeutic targeting of this gut homing pathway. Our promising clinical data on vedolizumab use have the potential to change the landscape of treatment in this condition.

Aims Acute graft-versus-host disease (aGVHD) is a leading cause of morbidity and mortality following allogeneic haematopoietic stem cell transplantation (HSCT). The aim of this study was to evaluate the clinical utility of a composite biomarker panel to help identify individuals at risk of developing aGVHD, and to help predict and differentiate between severity of aGVHD following T-cell-depleted allogeneic HSCT.Methods We retrospectively analysed our cohort of biopsy confirmed patients with aGVHD, who underwent T-cell-depleted HSCT and matched them with negative controls without any evidence of aGVHD. Post-transplant serum samples on days 0 and 7 and at onset of aGVHD were analysed for elafin, regenerating islet-derived 3-α, soluble tumour necrosis factor receptor-1, soluble interleukin-2 receptor-α and hepatocyte growth factor. Biomarker data were combined as composite panels A–F (table 2) using logistic regression analysis. Receiver operating characteristic analysis was performed to study sensitivity and specificity of the composite panels.Results Our composite biomarker panels significantly differentiated between aGVHD and no GVHD patients at time of onset (panel E) and reliably predicted severity of GVHD grades at days 0 and 7 post-transplant (panels B and D). The area under the curve for the composite panel at time of onset was 0.65 with specificity, sensitivity, positive and negative predictive values of 100%, 55.6%, 100% and 78.9%, respectively (p=0.03).Conclusions This pilot data support the usefulness of these composite biomarker panels in the prediction of severity and diagnosis of aGVHD in patients undergoing T-cell-depleted reduced intensity allogeneic HSCT.

Introduction Telomere length is shortened in patients with idiopathic aplastic anemia (AA) and other bone marrow failure disorders (BMFD) and predicts risk of clonal evolution (CE), relapse and overall survival (OS). Telomereopathies predominantly cause bone marrow failure, are multi-systemic disorders with variable penetrance, and may involve inter-play of other factors in disease manifestation and organ affliction. Telomere length (TL) in AA and other hypocellular BMFD, independent of mutations in telomere genes (TGC), has not been studied as a scoring tool, as well predicting the risk of affliction of other organ/systems in these disorders. We systematically review a large cohort of 472 patients in a single centre with AA/BMFD using TL and TGC analysis as a discriminator, to study risk of CE and OS, manifesting with liver/lung and skin complications, cancer predisposition and likelihood of a family member presenting with cytopenias. Methods We screened 1060 consecutive patients at a single centre from the years 2011-18, with AA or unexplained cytopenias for telomere length (TL) analysis using a multiplex qPCR methodology as described by Cawthon et al. 472 (44.5%) patients had TL less than the 25th centile, of whom 243 had Results Table attached. The median age and gender across the 3 cohorts studied (TL 10-25th centile, A third of patients with BMFD and TL TL does not correlate with the manifestation and presence of liver, respiratory and skin problems of telomere disease. TL in BMFD does not associate with increased predisposition to cancer, as their presence was not statistically significant across the 3 groups. Disease manifestation with bone marrow failure, haematological indices, need for blood transfusions, presence of a PNH clone and karyotypic abnormalities, including complex and monosomal karyotype were not dissimilar across the 3 TL cohorts. Not surprisingly, there were more family members with features of cytopenias and BMFD, on screening of patients with a confirmed TGC mutation. TL did not predict a difference in treatment strategies used across the 3 groups, although more patients with a TGC mutation received anabolic steroids. The risk of clonal evolution to PNH or MDS/AML and overall survival was again similar across the 3 TL cohorts with an OS of 93% at 1078 days follow-up for the entire cohort. Conclusion TL can reliably be used as a screening tool to investigate patients for further TGC mutation analysis in patients with AA or BMFD. Heterozygous state mutations in TERT are the commonest, and can be associated with mutations in other TGC genes, particularly RTEL1 and TERC. This may cause a compounding factor in shortening the TL further. However, TL TL and TGC mutation analysis in a single centre study from 2011-18. Table Disclosures Kizilors: Incyte biosciences: Research Funding. Mufti:Celgene: Consultancy, Research Funding.

Introduction Alemtuzumab is a monoclonal anti-CD52 antibody, a pan-lymphodepleting immunosuppressive agent in common use as part of conditioning for allogeneic stem cell transplantation (Allo-HSCT) in United Kingdom and many other centres across the globe, with benefits related to reduced graft versus Host disease (GVHD) and lower non-relapse mortality (NRM). However, evidence for effective dose schedule in Allo-HSCT remains debatable with some concerns related to delayed immune reconstitution and increased relapses with higher dosages; but increased risk of acute and chronic GVHD observed with lower doses. We present a large single-centre UK experience evaluating differential dosage effect of Alemtuzumab on HSCT outcomes. Methods: We retrospectively evaluated 330 patients undergoing Allo-HSCTs for myeloid malignancies (AML/MDS/MPNs) during a 10-year period (Jan 2010 to April 2019) at King's College Hospital, London. Two dosage schedules of Alemtuzumab based T-cell deplete conditioning regimen using 100mg (n-96) were compared to those receiving 60mg (n-234; Results Baseline characteristics (Table-1) were similar between the 2 groups in terms of conditioning intensity, patient age, underlying disease (AML/MDS), disease risk and donor HLA matching. Median follow up of survivors was 34 months (range 01-112months) with significantly longer follow up available for 100mg dose group (median 90 months vs 28 months; p Higher Alemtuzumab dosage (100mg) was associated with a significant improvement in GVHD & Relapse free survival (GRFS)(32% vs 20% at 12 months;p-0.003; Fig 1a) and significantly lower incidence of both grade 3-4 acute (18% vs 42% at D100;p- Multivariate adjusted cox analysis (MVA) confirmed older age>60 years, mismatched unrelated donor, absence of chronic GVHD, disease relapse, ITU admission event, CMV reactivation and absence of any EBV reactivation post HSCT as significant predictive factors for poor OS. This was not affected by different Alemtuzumab dosages, disease risk index or type of disease. However, GFRS was positively influenced by standard 100mg Alemtuzumab dose (HR 0.67; 95%CI: 0.51-0.86; p-0.005), no ITU admission event (HR-0.51; 95%CI:0.38-0.70; p Conclusions With improved supportive care, effective infection management and pre-emptive cellular therapy approaches available in current era, standard dosage (100mg) of alemtuzumab is safe and effective in both RIC and myeloablative allo-HSCTs for myeloid malignancies, with significantly lower GVHD related morbidity and overall better GFRS. Despite concerns of relapses and delayed immune reconstitution, this report on a homogenous cohort of allo-HSCTs in myeloid malignancies confirms the contrary with no impact on OS, NRM or relapses and no significant increase in opportunistic infections with 100mg dose. Disclosures Mufti: Celgene: Consultancy, Research Funding. De Lavallade:Bristol Myers Squibb: Research Funding; Bristol Myers Squibb: Research Funding.

Metagenomics approach involves extraction, sequencing and characterization of the genomic content of entire community of microbes present in a given environment. In contrast to genomic data, accurate assembly of metagenomic sequences is a challenging task. Given the huge volume and the diverse taxonomic origin of metagenomic sequences, direct application of single genome assembly methods on metagenomes are likely to not only lead to an immense increase in requirements of computational infrastructure, but also result in the formation of chimeric contigs. A strategy to address the above challenge would be to partition metagenomic sequence datasets into clusters and assemble separately the sequences in individual clusters using any single-genome assembly method. The current study presents such an approach that uses tetranucleotide usage patterns to first represent sequences as points in a three dimensional (3D) space. The 3D space is subsequently partitioned into "Grids". Sequences within overlapping grids are then progressively assembled using any available assembler. We demonstrate the applicability of the current Grid-Assembly method using various categories of assemblers as well as different simulated metagenomic datasets. Validation results indicate that the Grid-Assembly approach helps in improving the overall quality of assembly, in terms of the purity and volume of the assembled contigs.

Background: Acute Graft-versus-host disease (aGVHD) is a leading cause of morbidity and mortality following allogeneic haematopoietic stem cell transplantation (HSCT). The diagnosis and management of aGVHD relies on clinical criteria and graded according to the number and extent of organ involvement. Clinical diagnosis of aGVHD is one of exclusion and usually requires tissue biopsy to aid diagnosis. The aim of this study was to evaluate the clinical utility of a biomarker panel to help identify individuals at risk of developing aGVHD and its ability to differentiate severity at onset of acute graft-versus-host disease (aGVHD) following T-cell depleted allogeneic HSCT. Methods: This retrospective study of T-cell depleted reduced intensity allogeneic HSCT patients in our centre included 12 biopsy confirmed aGVHD patients (Grade I-IV; Modified Glucksberg criteria) and 14 patients as negative controls without any evidence of aGVHD, matched for age, sex, underlying haematological disease, time since transplant and conditioning regimen, within 100 days of transplantation. Serum samples on Day 0, Day +7 and at onset of aGVHD were analysed by ELISA for Elafin, regenerating islet-derived 3-α(REG3α), soluble tumour necrosis factor receptor 1 (sTNFR1), soluble interleukin-2 receptor-α (sIL-2Rα) and hepatocyte growth factor (HGF). Biomarker data was combined as composite panels A-F (Table 1) using binary and ordinal logistic regression analysis as best fit model. Receiver Operating Characteristic curves (ROC) analysis was performed to study sensitivity and specificity of the composite panel for diagnosis of aGVHD. Results: Composite biomarker panel B (Elafin+ sIL-2Rα + sTNFR1) and panel D (Elafin+ HGF + REG3α) at Day 0 and at Day 7 post-transplant differentiated significantly between biopsy confirmed severe aGVHD (Grade III-IV) and patients with no GVHD respectively (p=0.02). Panel F (Elafin+ sIL-2Rα + REG3α) strongly differentiated between various grades of aGVHD (Grade I-IV) at time of aGVHD onset (p Conclusions: This pilot data supports the usefulness of these composite biomarker panels in the prediction of severity and diagnosis of acute GVHD in patients undergoing T-cell depleted reduced intensity allogeneic HSCT. Further larger studies are needed to validate their use in the clinical management of aGVHD. Disclosures No relevant conflicts of interest to declare.

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