Case presentationsCase 1. Robert Davies, a 50-year-old man, presents with tiredness and lethargy. Examination demonstrates pallor and jaundice. Investigations reveal anemia that is consistent with warm autoimmune hemolytic anemia (AIHA; Figure 1). He has no evidence of any other autoimmune disease or chronic lymphocytic leukemia (CLL) and is not taking any medications; these factors suggest idiopathic AIHA. How should he be treated?* AIHA is an uncommon but potentially fatal condition. It results from autoantibodies with specificity against RBC Ags leading to the premature removal of red cells from the circulation. Anemia may occur if the rate of red cell removal exceeds the ability of the BM to produce new red cells. AIHA may be secondary to drugs or underlying conditions such as CLL, infections, or autoimmune disorders. This guideline will deal specifically with idiopathic AIHA, and will not discuss secondary AIHA.Several of the treatments in this article are not licensed for the treatment of AIHA and come with little evidence, so clinicians and patients should be informed of known risks.A decision was made a priori to limit this review to published data only. Where there is no published evidence, or only expert opinion, we suggest referring to the recent Blood "How I treat" article on AIHA. 1 Medline, Embase, and the Cochrane Library were searched for relevant articles, along with reference lists of identified articles. Search strategies are found in supplemental Data (available on the Blood Web site; see the Supplemental Materials link at the top of the online article). Identified articles were then screened for inclusion. English-language articles were included only if they provided useful extractable data on adult (Ͼ 18 years) patients with idiopathic AIHA. Secondary AIHA, cold hemagglutinin disease, and patients with concomitant thrombocytopenia (Evans syndrome) were excluded.Secondary AIHA was defined as AIHA in the presence of other autoimmune conditions, hematologic malignancies, or drugs known to cause AIHA, or where the authors of the article described the anemia as secondary. Conference abstracts were not searched. To reduce the number of articles, it was decided a priori that if a randomized controlled trial (RCT) was found, then nonrandomized controlled studies and case series would be excluded. If no RCT was found, only nonrandomized controlled studies would be included. If there were no nonrandomized controlled studies then case series with Ͼ 10 participants would be included; if there were no case series with Ͼ 10 participants then any case series would be included. Case reports were excluded. This is similar to the method used in the recent American Society of Hematology (ASH) Immune Thrombocytopenia Guidelines. 2 Articles meeting the inclusion criteria underwent data extraction and quality assessment using pre-prepared forms (example found in supplemental data). Searching, data extraction, and quality assessment were all done in duplicate. The guidelines were given a Grading of Recommendation...

Background: Natural killer (NK) cells are cytotoxic lymphocytes that lack CD3 and express variable levels of CD16, CD56 and CD57. In recent years NK cells have been categorised into two major groups based on the level of CD56 expression. This phenotypic classification correlates with functional activity as CD56 bright NK cells are the major cytokine producing subset whereas CD56 dim NK cells exhibit greater cytotoxic activity. Previous studies have revealed a reduction in total NK cell numbers in association with ageing and this study sought to determine the potential influence of ageing on the number of NK cell subsets within peripheral blood.

Natural killer (NK) cells rapidly reconstitute following allogeneic stem cell transplantation (allo‐SCT), at the time when alloreactive T cell immunity is being established. We investigated very early NK cell reconstitution in 82 patients following T cell‐depleted allo‐SCT. NK cell number rapidly increased, exceeding T cell reconstitution such that the NK:T cell ratio was over 40 by day 14. NK cells at day 14 (NK‐14) were donor‐derived, intensely proliferating and expressed chemokine receptors targeted to lymphoid and peripheral tissue. Spontaneous production of the immunoregulatory cytokine IL‐10 was observed in over 70% of cells and transcription of cytokines and growth factors was augmented. NK‐14 cell number was inversely correlated with the incidence of grade II‐IV acute graft versus host disease (GVHD). These findings reveal that robust reconstitution of immunoregulatory NK cells by day 14 after allo‐SCT is an important determinant of the clinical outcome, suggesting that NK cells may suppress the development of the T cell‐mediated alloreactive immune response through production of IL‐10.

Transplantation is an effective treatment of many clinical disorders, but the mechanisms that regulate immunological tolerance are uncertain and remain central to improving patient outcome. Hemopoietic stem cell transplantation (SCT) often establishes “mixed chimerism” in which immune cells from both the donor and patient coexist in vivo in a setting of immunological tolerance. We studied immune function in 69 patients within 2 months following SCT; 37 were fully donor and 32 displayed mixed chimerism. The proportion of T regulatory (Treg) cells was increased during mixed chimerism and comprised equal numbers of donor and host-derived regulatory cells. This was associated with a tolerogenic PD-L1+ profile on dendritic cells. Importantly, effector T cells from patients with mixed chimerism exhibited reduced cytotoxicity against host target cells in vitro, but this was restored following depletion of CD4+ Treg cells. These data show that Treg cells play a major role in sustaining immunological tolerance during mixed chimerism. These insights should help to guide novel interventions to improve clinical transplantation.

Key Points• A stem cell graft NK cell dose below 6.3 3 10 6 cells per kg associates with risk of disease relapse following T-cell-depleted allo-HSCT.• Clinical outcomes of patients undergoing allo-HSCT may be improved by setting an NK cell threshold within donor stem cell grafts.The graft-versus-leukemia (GVL) effect of allogeneic hemopoietic stem cell transplantation (allo-HSCT) is mediated by the donor immune system and acts to decrease the rate of disease relapse. Although studies of posttransplant immune reconstitution have identified correlates of clinical outcome, the number and profile of mature immune cells infused with the stem cell graft is also likely to be an important determinant and has been relatively poorly studied.We characterized immune cells within the stem cell graft of 107 patients who underwent T-cell-depleted allo-HSCT and related this to clinical outcome. The number of natural killer (NK) cells and T cells that were infused varied markedly between patients, but T-cell dosewas not an important factor in subsequent outcome. In contrast, the number of NK cells was a powerful determinant of the risk of disease relapse. Patients who received an NK cell dose below the median level of 6.3 3 10 6 cells per kg had a relapse rate of 40% at 2 years posttransplant compared with only 6% for those whose stem cell graft contained a dose above this value. Analysis of NK subsets showed that this effect was mediated primarily by the CD56 dim population of mature effector cells and that high-level expression of the activatory protein DNAM on donor NK cells was also strongly protective. These observations offer important insights into the mechanism of GVL and suggest that optimization studies of the number of NK cells within the stem cell graft should be considered as a means to reduce disease relapse.

Allogeneic stem cell transplantation (allo-SCT) can cure some patients with hematopoietic malignancy, but this relies on the development of a donor T cell alloreactive immune response. T cell activity in the first 2 weeks after allo-SCT is crucial in determining outcome, despite the clinical effects of the early alloreactive immune response often not appearing until later. However, the effect of the allogeneic environment on T cells is difficult to study at this time point due to the effects of profound lymphopenia. We approached this problem by comparing T cells at week 2 after allograft to T cells from autograft patients. Allograft T cells were present in small numbers but displayed intense proliferation with spontaneous cytokine production. Oligoclonal expansions at week 2 came to represent a substantial fraction of the established T cell pool and were recruited into tissues affected by graft-versus-host disease. Transcriptional analysis uncovered a range of potential targets for immune manipulation, including OX40L, TWEAK, and CD70. These findings reveal that recognition of alloantigen drives naive T cells toward a unique phenotype. Moreover, they demonstrate that early clonal T cell responses are recruited to sites of subsequent tissue damage and provide a range of targets for potential therapeutic immunomodulation.

Background Treatment of transformed follicular lymphoma (TFL) remains undefined and there is no consensus on the role of consolidation after induction chemotherapy. Outcomes for TFL in the pre-rituximab era were poor with a reported median overall survival (OS) of only 1.7 years1. This study investigates whether R-CHOP is an effective therapy for patients with TFL and which patient factors present at transformation help to predict outcome. Methods 1900 lymphoma diagnoses from January 2000 - June 2012 were retrospectively screened and identified 60 patients with transformed indolent lymphoma. 40 eligible patients with histologically confirmed TFL were identified for this study. Overall survival (OS) and progression-free survival (PFS) were the primary study end-points. Results The median follow up time for the cohort was 66 months (interquartile range (IQR) - 25-92 months) and the median age at diagnosis of TFL was 60 years (52-68 years). The majority (60%) of the cohort had high-grade (HG) transformation subsequent to diagnosis of follicular lymphoma (asynchronous TFL) with a median time to transformation of 48 months (24-78 mo). 32.5% of patients were simultaneously diagnosed with follicular lymphoma (FL) and HG disease (synchronous TFL). In a minority (3%), FL was diagnosed after HG disease. Univariate analysis revealed no significant relationship between outcome and patient age, sex or disease stage. However, patients with an elevated LDH (defined as >1.5x the upper limit of normal) at the time of diagnosis had a significantly reduced OS (5 mo vs 86 mo; p=0.003) and PFS (2.25 mo vs 56 mo; p=0.02). When compared with synchronous TFL, patients with asynchronous TFL had a reduced median survival (9 mo vs 67 mo; p=0.03) and PFS (7 mo vs 67 mo; p=0.003). When multivariate analysis is performed, elevated LDH and asynchronous TFL remain significant factors in determining PFS (p=0.021 and p=0.008 respectively). However, only elevated LDH remains a significant factor in determining OS (p=0.002). 25/40 patients were treated with R-CHOP for TFL, with the remaining 15 either treated palliatively: steroids and etoposide (n=8), radiotherapy (n=1); with CHOP (n=4) or another R-chemo (n=2; R-ESCHAP; R-CVP). All R-CHOP treated patients were rituximab naïve. Of the 25 patients treated with R-CHOP: 20 were treated with R-CHOP alone, 2 received R-CHOP and another chemotherapy, 1 had R-CHOP and autograft and 2 received R-CHOP and allograft. In our cohort, R-CHOP treated patients had a 5-year OS of 62%, a median OS of 86 months (31-120 months) and PFS of 56 months (14-86 months). This represents a marked improvement in outcome compared to historic data, which showed a 5-year OS of 33% for TFL patients treated with CHOP alone2. The patients treated with R-CHOP alone (without further chemotherapy, autograft or allograft) had a similar outcome with a median OS of 86 months (37-120 months) and median PFS of 56 months (11-86 months). Conclusion Our results demonstrate the excellent outcomes achieved with R-CHOP alone in rituximab naïve patients with transformed follicular lymphoma. Patients with TFL presenting with synchronous disease and non-elevated LDH have significantly improved outcomes. In such patients, we may consider reserving consolidation with autograft or allograft for the future. 1. Al-Tourah, A. J. et al. Population-based analysis of incidence and outcome of transformed non-Hodgkin’s lymphoma. Journal of clinical oncology : official journal of the American Society of Clinical Oncology26,5165–9 (2008). 2. Al-Tourah, A. J. et al. Addition of Rituximab to CHOP Chemotherapy Significantly Improves Survival of Patients with Transformed Lymphoma. Blood (ASH Annual Meeting Abstracts)110, (2007). Disclosures: Chaganti: Roche: Membership on an entity’s Board of Directors or advisory committees, Receipt of travel grant Other.

The impact of Coronavirus disease 2019 (COVID-19) on outcomes in patients with cancer remains unclear. Acute Myeloid Leukemia (AML)/high-risk myelodysplasia (MDS) are common hematological malignancies resulting in profound immunosuppression, which is exacerbated by intensive and less-intensive chemotherapy. Importantly, venetoclax based regimens have been increasingly used during the pandemic as a strategy to reduce patient hospitalization however, there is little information concerning the impact of such regimens on COVID-19 infection rates. We therefore opened a prospective clinical study (PACE), at the start of the current pandemic in April 2020 to characterize the risk of COVID-19 infection in patients with AML/MDS-EB2 receiving intensive or non-intensive treatment, including patients treated with venetoclax-based regimens. The primary aim was to determine the incidence of COVID-19 in patients with AML /MDS-EB2 including both, prior to study entry and during treatment until 4 weeks after the last cycle of treatment. Secondary aims were to: characterize the presentation of COVID-19; define the severity and type of both non-COVID-19 and COVID-19 infections; and undertake an exploratory analysis to quantify the incidence of COVID-19 infection in patients receiving (less-intensive) venetoclax based regimens. All analysis conducted to date has been descriptive. 211/230 recruited patients had full treatment histories available, of whom 116 patients received intensive chemotherapy and 95 low intensity regimens. 48 patients received a venetoclax-based regimen. The median age of the non-intensive treatment arm was 72 years; (range 19.1-86.5) and of the intensive arm was 59 years (range 16.1-76.1). There were more cases of secondary AML and relapsed disease in the non-intensive arm as compared to the intensive arm. 25/226 evaluable patients tested positive for COVID-19 as defined by positive SARS-CoV2 PCR test, 10 with a prior diagnosis at study entry and 15 tested positive during the study. The incidence of COVID-19 infection for patients with AML/MDS-EB2 was 11.1% (90%CI: 7.8%-15.1%) (Table). A lower proportion of patients (n=6/91 6.6%) undergoing non-intensive treatment suffered COVID-19 as compared to those undergoing more intensive chemotherapy regimens (n=19/116, 16.4%). Specifically, only 3/48 (6.3%) patients undergoing a venetoclax regimen were infected with SARS-CoV2. The most common presenting symptoms of COVID-19 in this study, regardless of the intensity of chemotherapy, was fever and cough with 6/25 patients asymptomatic. The risk of death at 30 days following study entry in patients who had prior COVID-19 infection or who contracted COVID-19 during this period was 13.6%, compared to 3.9% in the overall cohort without COVID-19 infection. There was a lower incidence of non-COVID-19 related infections in patients receiving venetoclax-based regimens, n=43 infections in 24 (50.0%) of patients; with 313 infections in 94 (81%) of intensively treated patients. The overall occurrence of non-COVID-19 infection in the non-intensive arm was 87 infections in 50 (54.9%) patients. Our multi-center study provides real-world estimates for the incidence and presentation of COVID-19 infection in a cohort of patients with AML/MDS-EB2, and indicates a higher risk of death at 30 days in patients with prior COVID-19 infection prior to, or during treatment. Venetoclax based, and other non-intensive, regimens, increasingly implemented during the pandemic, to minimize patient exposure and reduce usage of hospital beds, appeared to be associated with a low incidence of COVID-19. Further follow-up will be required to understand the long-term impact of this strategy. Analysis of immune responses to COVID-19 infection and vaccination is on-going. Acknowledgments: This study was funded by Cure Leukaemia under the Trials Acceleration Program (TAP), and grants from BMS and Blood Cancer UK. Figure 1 Figure 1. Disclosures Loke: Novartis: Other: Travel; Janssen: Honoraria; Amgen: Honoraria; Pfizer: Honoraria; Daichi Sankyo: Other: Travel. Knapper: Pfizer: Consultancy, Speakers Bureau; Astellas: Ended employment in the past 24 months, Speakers Bureau; Jazz: Consultancy, Speakers Bureau; Novartis: Consultancy, Research Funding, Speakers Bureau. Khan: Abbvie: Honoraria; Astellas: Honoraria; Takeda: Honoraria; Jazz: Honoraria; Gilead: Honoraria; Novartis: Honoraria. Dillon: Amgen: Other: Research support (paid to institution); Astellas: Consultancy, Other: Educational Events , Speakers Bureau; 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; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: educational events; Jazz: Other: Education events; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Research Support, Educational Events; Shattuck Labs: Membership on an entity's Board of Directors or advisory committees. Culligan: AbbVie Ltd: Honoraria, Speakers Bureau; Celgene Ltd: Honoraria, Speakers Bureau; Gilead: Honoraria, Speakers Bureau; Jazz Pharma: Honoraria, Speakers Bureau; Takeda UK Ltd: Honoraria, Speakers Bureau. McMullin: Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Other: clinical trial support, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; AbbVie: 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, Speakers Bureau; AOP Orphan: Research Funding, Speakers Bureau. Murthy: Abbvie: Other: support to attend educational conferences.. Craddock: Novartis Pharmaceuticals: Other: Advisory Board ; Celgene/BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding.