CD19 CAR-T have emerged as a new standard treatment for relapsed/refractory (r/r) large B-cell lymphoma (LBCL). CAR-T real-world (RW) outcomes published to date suggest significant variability across countries. We provide results of a large national | 493 KUHNL et al.

The impact of bridging therapy (BT) on CD19-directed chimeric antigen receptor T-cell (CD19CAR-T) outcomes in large B-cell lymphoma (LBCL) is poorly characterised. Current practice is guided by physician preference rather than established evidence. Identification of effective BT modalities and factors predictive of response could improve CAR-T intention to treat and clinical outcomes. We assessed BT modality and response in 375 adult LBCL patients in relation to outcomes following axicabtagene ciloleucel (Axi-cel) or tisagenlecleucel (Tisa-cel). The majority of patients received BT with chemotherapy (57%) or radiotherapy (17%). We observed that BT was safe for patients, with minimal morbidity/mortality. We showed that complete or partial response to BT conferred a 42% reduction in disease progression and death following CD19CAR-T therapy. Multivariate analysis identified several factors associated with likelihood of response to BT, including response to last line therapy, the absence of bulky disease, and the use of Polatuzumab-containing chemotherapy regimens. Our data suggested that complete/partial response to BT may be more important for Tisa-cel than Axi-cel, as all Tisa-cel patients with less than partial response to BT experienced frank relapse within 12 months of CD19CAR-T infusion. In summary, BT in LBCL should be carefully planned towards optimal response and disease debulking, to improve CD19CAR-T patient outcomes. Polatuzumab-containing regimens should be strongly considered for all suitable patients, and failure to achieve complete/partial response to BT pre-Tisa-cel may prompt consideration of further lines of BT where possible.

Key Points• TNFRSF14 gene aberrations, common in FL, increase the ability of lymphoma cells to stimulate allogeneic T-cell responses.• TNFRSF14 lesions were associated with increased acute GVHD supporting stratified transplantation approaches in the allogeneic setting.Donor T-cell immune responses can eradicate lymphomas after allogeneic hematopoietic stem cell transplantation (AHSCT), but can also damage healthy tissues resulting in harmful graftversus-host disease (GVHD). Next-generation sequencing has recently identified many new genetic lesions in follicular lymphoma (FL). One such gene, tumor necrosis factor receptor superfamily 14 (TNFRSF14), abnormal in 40% of FL patients, encodes the herpes virus entry mediator (HVEM) which limits T-cell activation via ligation of the B-and T-lymphocyte attenuator.As lymphoma B cells can act as antigen-presenting cells, we hypothesized that TNFRSF14 aberrations that reduce HVEM expression could alter the capacity of FL B cells to stimulate allogeneic T-cell responses and impact the outcome of AHSCT. In an in vitro model of alloreactivity, human lymphoma B cells with TNFRSF14 aberrations had reduced HVEM expression and greater alloantigen-presenting capacity than wild-type lymphoma B cells. The increased immune-stimulatory capacity of lymphoma B cells with TNFRSF14 aberrations had clinical relevance, associating with higher incidence of acute GVHD in patients undergoing AHSCT. FL patients with TNFRSF14 aberrations may benefit from more aggressive immunosuppression to reduce harmful GVHD after transplantation. Importantly, this study is the first to demonstrate the impact of an acquired genetic lesion on the capacity of tumor cells to stimulate allogeneic T-cell immune responses which may have wider consequences for adoptive immunotherapy strategies. (Blood. 2016;128(1):72-81)

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IntroductionCOVID-19 has been associated with high morbidity and mortality in allogeneic hematopoietic stem cell transplant (allo-HCT) recipients.MethodsThis study reports on 986 patients reported to the EBMT registry during the first 29 months of the pandemic.ResultsThe median age was 50.3 years (min – max; 1.0 – 80.7). The median time from most recent HCT to diagnosis of COVID-19 was 20 months (min – max; 0.0 – 383.9). The median time was 19.3 (0.0 - 287.6) months during 2020, 21.2 (0.1 - 324.5) months during 2021, and 19.7 (0.1 – 383.9) months during 2022 (p = NS). 145/986 (14.7%) patients died; 124 (12.6%) due to COVID-19 and 21 of other causes. Only 2/204 (1%) fully vaccinated patients died from COVID-19. There was a successive improvement in overall survival over time. In multivariate analysis, increasing age (p<.0001), worse performance status (p<.0001), contracting COVID-19 within the first 30 days (p<.0001) or 30 – 100 days after HCT (p=.003), ongoing immunosuppression (p=.004), pre-existing lung disease (p=.003), and recipient CMV seropositivity (p=.004) had negative impact on overall survival while patients contracting COVID-19 in 2020 (p<.0001) or 2021 (p=.027) had worse overall survival than patients with COVID-19 diagnosed in 2022.DiscussionAlthough the outcome of COVID-19 has improved, patients having risk factors were still at risk for severe COVID-19 including death.

Allogeneic haematopoietic stem-cell transplantation remains the only curative treatment for relapsed/refractory acute myeloid leukaemia (AML) and high-risk myelodysplasia but has previously been limited to patients who achieve remission before transplant. New sequential approaches employing T-cell depleted transplantation directly after chemotherapy show promise but are burdened by viral infection and require donor lymphocyte infusions (DLI) to augment donor chimerism and graft-versus-leukaemia effects. T-replete transplantation in sequential approaches could reduce both viral infection and DLI usage. We therefore performed a single-arm prospective Phase II clinical trial of sequential chemotherapy and T-replete transplantation using reduced-intensity conditioning without planned DLI. The primary endpoint was overall survival. Forty-seven patients with relapsed/refractory AML or high-risk myelodysplasia were enrolled; 43 proceeded to transplantation. High levels of donor chimerism were achieved spontaneously with no DLI. Overall survival of transplanted patients was 45% and 33% at 1 and 3 years. Only one patient developed cytomegalovirus disease. Cumulative incidences of treatment-related mortality and relapse were 35% and 20% at 1 year. Patients with relapsed AML and myelodysplasia had the most favourable outcomes. Late-onset graft-versus-host disease protected against relapse. In conclusion, a T-replete sequential transplantation using reduced-intensity conditioning is feasible for relapsed/refractory AML and myelodysplasia and can deliver graft-versus-leukaemia effects without DLI.

Background Axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tisa-cel) CD19 CAR-T therapies are licensed in the UK for relapsed/refractory large B-cell lymphoma (LBCL). Corticosteroids for CAR-T toxicity were administered to 28% and 10% of patients in ZUMA-1 and JULIET respectively, but real-world steroid use is reported to be much higher (Nastoupil et al, JCO 2020), with concerns that this may adversely impact on OS and PFS following CAR-T. Analysis of real-world datasets may facilitate the identification of modifiable risk factors for toxicity. Here, we report the UK experience of CAR-T toxicity and its management in 341 LBCL patients with a focus on predictors for corticosteroid use and the impact of steroids on OS/PFS post CAR-T therapy. Methods Data were collected in 10 UK centres from January 2019 to April 2021. CRS/ICANS were graded prospectively (ASTCT). Low (LG) and high-grade (HG) CRS/ICANS were classified as grade 1-2 and 3-5 respectively. Hyper-acute CRS was defined as onset within 24 hours of cells. Steroid cumulative dosing for CAR-T toxicity was calculated as dexamethasone equivalent up to day 30. Product selection was at the discretion of the treating physician. Toxicity management in the UK follows EBMT and ASCT guidance. Results A total of 341 patients received axi-cel (n=261) and tisa-cel (n=80) with a median follow-up of 14.8 (3.4-30) and 13.9 (range 7.5-27) months. Median age was 59 (range 18-80), 61% were male (M=207, F=134) and 79% received bridging therapy (BT). HG CRS, hyperacute CRS and HG ICANS with axi-cel (8.8%; 38%; 21% respectively) and with tisa-cel (7.5%; 26%; 5% respectively) were observed, with incidence of HG ICANS post axi-cel lower than published reports. Risk factors for HG CRS were age<65yrs (p=0.014), LDH pre-lymphodepletion (LD) (p=0.04) and ECOG>0 at infusion (0.001); and hyper-acute CRS was associated with stable (SD) or progressive disease (PD) after BT (p=0.036). On multivariate analysis (MVA), ECOG >0 (OR 3.4, 95% CI 1.3-9.1, p=0.015) and SD/PD post BT (OR 1.8, 95% CI 1.03-3.3, p=0.039) were predictive of HG CRS and hyper-acute CRS respectively. Risk factors for HG ICANS were age<65yrs (0.03), ECOG>0 (p=0.009), SD/PD post BT (p=0.011), extranodal disease (p=0.02) and LDH>normal on Day 0 (p=0.02). By MVA, LDH>normal on Day 0 (OR 3.8, 95% CI 1.4-10.5, p=0.009) was predictive of HG ICANS. Steroids were used in 44% (n=115) of axi-cel treated patients, administered at day 6 (median; range 1-22), at a median dose of 165mg (range 10-2182) over a median of 8 days (range 1-86). Anakinra was given as an adjunctive agent for high-grade ICANS (n=26, 10%), CRS (n=10, 4%) or HLH (n=3, 1%) at a median of day 8 (range 5-43) for a median of 6 days (range 1-16). 18% of tisa-cel patients (n=14) received steroids, administered at day 4 (median; 2-26) at a median dose of 95mg (range 10-220) over a median of 4 days (range 1-8). Tocilizumab was used in 74% and 48% of axi-cel and tisa-cel patients respectively. Clinical factors associated with steroid use included ECOG>0 (OR 1.8, 95% CI 1.2-5.6, p=0.002), and the emergence of SD/PD post BT (OR 1.7, 95% CI 1.02-2.8, p=0.04). SD/PD post BT also predicted for higher total steroid dose (>median; OR 1.7, 95% CI 1.1-2.9, p=0.03), and prolonged (>1 week) administration (OR 1.8, 95% CI 1.1-2.9, p=0.03) (Table 1). The impact of clinical parameters including toxicity and steroids on PFS and OS post-CAR-T were assessed. Adjusted for age, sex, ECOG and LDH>normal pre-LD, HG ICANS (but not HG CRS) was associated with worse OS (HR 2.4, 95% CI 1.3-4.4, p=0.004). 100 day NRM was 3.5% for the whole cohort. Median OS was not reached. In contrast to other published series, early steroid use (HR 1.0, 95% CI 0.6-1.6, p=0.99), higher total doses (HR 1.2, 95% CI 0.7-1.9 p=0.6) and prolonged (>1 week) steroid exposure (HR 1.3, 95% CI 0.8-2.2, p=0.25) were not associated with worse OS. Early steroid use (HR 0.7, 95% CI 0.3-1.6, p=0.4), higher doses (HR 0.5, 95% CI 0.2-1.2, p=0.13) and prolonged exposure (HR 0.9, 95% CI 0.4-2.0, p=0.8) also had no significant impact on PFS. Conclusion Patients who are refractory to BT or with other markers of high disease burden at infusion are more likely to require steroids for CAR-T toxicity, with axi-cel associated with more HG ICANS and cumulative steroid exposure than tisa-cel. Despite this, steroid use for CAR-T toxicity did not negatively impact on PFS or OS. Rates of HG ICANS with axi-cel were comparatively lower in this UK dataset. Figure 1 Figure 1. Disclosures Sanderson: Kite, a Gilead Company: Honoraria; Novartis: Honoraria. Kuhnl: Kite: Honoraria; Novartis: Research Funding. Menne: Kite/Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grant, Research Funding, Speakers Bureau; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Honoraria, 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, Other: Travel grants; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grants; Astra Zeneca: Research Funding; Jazz: Other: Travel grants; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel grants; Bayer: Other: Travel grants; Kyowa Kirin: Other: Travel grants; Daiichi Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Atara: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Other: Honoraria for Lectures; Roche: Other: Honoraria for Lectures. Chaganti: Celgene-BMS: Consultancy, Honoraria, Other: Travel support; Takeda: Consultancy, Honoraria, Other: travel support, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Other: Travel support, Research Funding, Speakers Bureau; Kite, a Gilead Company: Consultancy, Honoraria, Other: Travel support, Research Funding, Speakers Bureau; Atara Bio: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Research Funding; Incyte: Honoraria, Speakers Bureau. Nicholson: Novartis: Consultancy, Other: Conference fees; Kite, a Gilead Company: Other: Conference fees, Speakers Bureau; BMS/Celgene: Consultancy; Pfizer: Consultancy. Latif: Takeda UK: Speakers Bureau; Astellas: Consultancy, Honoraria, Speakers Bureau; Abbvie: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Novartis,: Consultancy, Honoraria; Daiichi Sankyo: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Kite: Consultancy, Honoraria, Speakers Bureau. Jones: Janssen: Consultancy; Kite/Gilead: Honoraria; Novartis: Honoraria. Sharplin: Kite Gilead: Honoraria; Novartis: Other: Travel Support. Jalowiec: Kite Pharma Gilead Sciences': Honoraria, Speakers Bureau. Roddie: Novartis: Consultancy; Celgene: Consultancy, Speakers Bureau; Gilead: Consultancy, Speakers Bureau. OffLabel Disclosure: Anakinra for CAR-T toxicity management

Background: Chimeric antigen receptor-modified T-cells targeting CD19 (CAR-T19) are licensed for treating relapsed/refractory diffuse large B-cell lymphoma and B-acute lymphoblastic leukemia. Predicting treatment responses and toxicity (e.g., cytokine release syndrome and neurotoxicity) remains a big challenge. CAR-T19 monitoring could increase our understanding of treatment responses and be of relevance to patient management. A robust method for accurate CAR-T19 detection is therefore extremely desirable.Methods: An assay that uses fluorochrome-conjugated human recombinant soluble CD19 was tested against two commercially available CAR-T19 therapies and a CAR-T19 cell line developed in-house. Precision, concordance, and analyte stability were tested using peripheral blood obtained from CAR-T19-treated patients and controls. Results:The assay showed good accuracy, and had a limit of blank for whole blood samples of 0.13%. Reproducibility and inter-operator concordance were satisfactory (CVs <15%). The assay distinguished CAR-T19 from reactive T-cells in cerebrospinal fluid (CSF) from patients with suspected immune effector cell-associated neurotoxicity syndrome (ICANS), and was adapted to study memory T-cell compartments in treated patients. Conclusion:The assay enabled routine monitoring of CAR-T19 in blood and CSF samples. Despite profound cytopenia in many lymphoma patients, results were obtained regularly from only 4 ml of blood. The assay can be adapted easily to characterize the memory and exhaustion status of CAR-T19 and native T-cells. Importantly, it does not rely on CAR construct specificity; thus, it can be used to detect any CD19-targeted CAR cell. Finally, our validation process can serve as a blueprint for other fluorochrome proteins used to detect CAR cells.