SAFETY AND EFFICACY FINDINGS OF AUTO1, A FAST-OFF RATE CD19 CAR, IN RELAPSED/REFRACTORY B-CELL NON-HODGKIN'S LYMPHOMA (B-NHL), AND CHRONIC LYMPHOCYTIC LEUKEMIA (CLL) / SMALL LYMPHOCYTIC LYMPHOMA (SLL)

Background: We have previously described AUTO1, a CD19 CAR with a fast off-rate CD19 binding domain, designed to reduce CAR T-cell immune toxicity and improve engraftment. Its clinical activity has been tested in r/r paediatric and adult B-ALL (Ghorashian S et al., Nat Med 2019;Roddie C et al., JCO 2021). This data confirms the intended function of the receptor, with low levels of CRS/ICANS and long-term engraftment of CAR T-cells observed in both patient groups. Aims: We have initiated testing of AUTO1 in the setting of B-NHL and CLL/SLL (NCT02935257). Methods: Manufacturing: CAR T-cell products were generated using a semi-automated closed process from non-mobilised patient leukapheresate. Study design: Subjects ≥ 16y underwent lymphodepletion with fludarabine (30mg/m x3) and cyclophosphamide (60mg/kg x1) prior to AUTO1 infusion, with the exception of the DLBCL cohort who additionally received a single dose of pembrolizumab (200mg) on day -1 to potentiate CAR-T expansion. AUTO1 dose varies based on the indication. Split dosing of 230 x106 CD19 CAR T-cells at day 0 and day 9 is employed in the CLL cohort. A single dose of 200 x106 CD19 CAR T-cells is delivered to patients with B-NHL. Study endpoints include feasibility of manufacture, grade 3-5 toxicity and remission rates at 1 and 3 months. Results: As of 8th February 2022, we enrolled 23 patients: 11 low grade NHL (LG-NHL:7 with FL and 3 with MCL), 7 DLBCL and 5 CLL. Apheresis was successful in all 23 patients and product manufacture was successful in 22 (pending in the last). 19 patients were infused: 10 with LG-NHL, 6 with DLBCL and 3 with CLL. 1 CLL patient was pending infusion at time of data cut-off and 2 patients died pre-infusion: 1 MCL patient, from COVID-19 and 1 CLL patient, from intracerebral haemorrhage. Patients treated with AUTO1 had a median age of 60 years (range 39-79), had received a median of 3 prior lines of treatment (range 2-8). Grade 1 CRS was reported in 6/19 and Grade 2 CRS in 3/19. No ICANS was observed in the B-NHL and CLL cohorts. CAR engraftment was observed in 13/13 patients evaluated by qPCR with ongoing persistence in 12/13 patients at last follow-up. In the LG-NHL and DLBCL cohorts 10/10 and 4/5 evaluable patients respectively were in CMR by 18FDG PET-CT post-treatment. Responses were ongoing in 9/10 LG-NHL at 12 months and in 4/4 DLBCL at months 1, 3, 3 and 6. In the CLL cohort, 2/3 evaluable patients achieved MRD negative remission in the bone marrow with residual small volume lymph nodes by CT at 6 and 3 months of follow-up respectively. 1 CLL patient did not engraft and had SD at month 1. Summary/Conclusion: AUTO1 has a tolerable safety profile in patients with r/r B-NHL and CLL despite high disease burden. Early data shows excellent complete remission rates and excellent CAR engraftment/expansion. Additional patients, updated data and longer follow up will be presented.

Safety and Efficacy of AUTO1, a Fast-Off Rate CD19 CAR in Relapsed/Refractory B-Cell Non-Hodgkin's Lymphoma (B-NHL) and Chronic Lymphocytic Leukaemia (CLL)

INTRODUCTION We have previously described AUTO1, a CD19 CAR with a fast off-rate CD19 binding domain, designed to reduce CAR-T immune toxicity and improve engraftment. Its clinical activity has been tested in r/r paediatric and adult B-ALL. Cumulatively, this data confirms the intended function of the receptor, with low levels of CRS/ICANS and long-term engraftment of CAR T-cells observed in both patient groups. Recently, CAR-T therapy has been explored in indolent lymphomas such as follicular (FL) and mantle cell lymphoma (MCL), but a high incidence of toxicity including Grade 3-4 ICANS has been reported. We have initiated testing of AUTO1 in the setting of indolent and high-grade B-NHL and CLL (NCT02935257). METHODS Manufacturing: CAR T-cell products were generated using a semi-automated closed process from non-mobilised leukapheresate. Study design: Subjects ≥ 16y underwent lymphodepletion with fludarabine (30mg/m 2 x3) and cyclophosphamide (60mg/kg x1) prior to AUTO1 infusion, with the exception of the DLBCL cohort who additionally received a single dose of pembrolizumab (200mg) on day -1 to potentiate CAR-T expansion. AUTO1 dose varies based on the indication. Split dosing of 230 x10

Early safety and efficacy findings of auto1 (cat19), a fast-off rate cd19 car, in relapsed / refractory indolent b cell lymphomas

Background: We have previously described AUTO1 (CAT19), a CD19 CAR with a fast off-rate CD19 binding domain, designed to reduce CAR T-cell immune toxicity and improve engraftment. Its clinical activity has been tested in r/r paediatric and adult B-ALL. Cumulatively, this data confirms the intended fucntion of the receptor, with low levels of CRS/ ICANS and long-term engraftment of CAR T-cells observed in both patient groups. Recently, CAR therapy has been explored in indolent lymphomas such as follicluar (FL) and mantle cell lymphoma (MCL), but a high incidence of toxicity inluding Grade 3-4 ICANS has been reported. Aims: We have initiated testing of AUTO1 (CAT19) in the setting of indolent B-cell lymphoma (NCT02935257). Methods: Manufacturing: CAR T-cell products were generated using a semi-automated closed process from non-mobilised leucapheresate. Study design: subjects>/=16y underwent lymhpodepletion with fludarabine (30mg/m2 x3) and cyclophosphamide (60mg/kg x1) followed by a single CAR T-cell infusion of 200 x10

Steroid Use, Advanced Stage Disease and ≥3 Lines of Prior Chemotherapy Are Associated with a Higher Risk of Infection Following CD19 CAR T-Cell Therapy for B-NHL: Real World Data from a Large UK Center

Background: Tisagenlecleucel (Tisagen) and Axicabtagene Ciloleucel (Axicel) CD19 CAR T-cell products are licensed in the UK for adults with relapsed/refractory high-grade B-cell Non-Hodgkin's lymphoma (B-NHL). Infection rates for the first 30 days post CAR T range from 23% (Hill et al, Blood 2018) to 42% (Park et al, Clin Infect Dis 2018) with a predominance of early bacterial infections. Infection etiology is multifactorial, including pre-existing immunosuppression, poor marrow reserve, concomitant disease, delayed cytopenias and lymphodepletion. CRS has been shown to be an independent risk factor and associated treatment (Tocilizumab, steroids) may contribute. Risk assessment is limited by heterogenous cohorts in published reports and practice variations in use of prophylactic antibiotics and intravenous immunoglobulin (IVIG). To determine incidence and outcome of infection with licensed CAR T-cell products, we conducted a retrospective review at UCLH, London, UK. Methods: Electronic medical records were used to collect data on patients treated with Tisagen/Axicel from May 2019 to July 2020. Infections at ≤28 days and >28days following infusion were recorded. Infections were defined as a positive microbiological/virology result in conjunction with clinical symptoms. Invasive fungal infections were classified according to revised EORTC criteria. Infections were graded as severe (requiring systemic treatment) or life threatening (hypotension/organ support). Results: Sixty adults with B-NHL received Tisagen (n=19) or Axicel (n=41). Patients did not receive prophylactic antibiotics. IVIG was given for hypogammaglobulinaemia with recurrent infections (n=4). Within 28 days of infusion, 44 episodes of infection occurred in 28 patients (47%). Post day 28 (range 29-452), 19 episodes occurred in 9 patients (15%). Severe (n=9) and life-threatening (n=7) infection occurred in 15% and 12% of patients respectively, with two infections resulting or contributing to death (3.3%). Infections were bacterial (56%), respiratory viral (24%), other viral (14%) and fungal (6%). Six (10%) developed viral reactivations;CMV (n=1), BK virus in blood or urine (n=2), HHV6 (n=1) or AdV (n=2). PCR proven JC virus causing progressive multifocal leukoencephalopathy was reported in 1 patient at day 116. Only one late COVID-19 infection occurred despite the program remaining operational throughout lockdown. There was no association between early infection and CRS severity (p=0.43), or use (p=0.94) and dose of Tocilizumab (p=0.54). With regard to pre-treatment variables, advanced disease at time of infusion (≥stage 3) was associated with higher risk of any infection (OR 4.2, 95% CI 1.3- 13.4, p=0.016) and lines of prior therapy (≥3) with higher risk of early infection (OR 3.0, 95% CI 1.0-8.9, p=0.048). Steroid treatment was associated with a higher risk of early (and overall) infection (OR 3.0. 95% CI 1.0-8.6, p=0.048). A diagnosis of ICANS was associated with infection beyond day 30 (p=0.021). In multivariate analyses, steroid use (p=0.03) and ≥3 lines of prior therapy (p=0.021) were associated with infection ≤28 days of infusion. Steroid use (p= 0.049) and stage pre infusion (p=0.023) were associated with higher risk of any infection. Conclusion: In this real world analysis of B-NHL patients treated with Tisagen or Axicel, 47% developed early infection at ≤28 days. Severe or life-threatening infection occurred in 27% of patients. Multivariate analysis confirms significant association with (1) steroid exposure (2) ≥stage 3 disease and (3) ≥3 lines of previous therapy. There was no overt association with Tocilizumab use or CRS severity. Unlike other centers, our cohort did not receive prophylactic antibiotics or IVIG. Patients with advanced disease are high risk for CRS, ICANS and infectious complications. Risk modification strategies include bridging optimization to reduce disease burden pre CAR T with infectious prophylaxis from referral until at least 3-6 months post-infusion. In this analysis, steroids represent a significant ri k and efforts should be made to wean doses swiftly. The use of steroid sparing agents such as Anakinra may be important (clinical trial results awaited). In ≥ stage 3 disease or heavily pre-treated patients, there may be a role for prophylactic antibiotics but this should be explored within a clinical study with consideration of local antimicrobial resistance patterns. Disclosures: Neill: Novartis: Other: Funded attendance at academic conferences;Celgene: Other: Funded attendance at academic conferences. Townsend: Roche, Gilead: Consultancy, Honoraria. Ardeshna: Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees;Beigene: Membership on an entity's Board of Directors or advisory committees;Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees;Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees;ADC Therapeutics: Membership on an entity's Board of Directors or advisory committees;Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees;Sanofi, Genzyme, AstraZeneca: Speakers Bureau;University College London (UCL)/UCL Hospitals (UCLH) Biomedical Research Unit: Other: Supported by this organisation. Cwynarski: Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support, Speakers Bureau;Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees;Atara: Consultancy, Membership on an entity's Board of Directors or advisory committees;Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau;KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support, Speakers Bureau;Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support, Speakers Bureau;Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel Support. Peggs: Autolus: Consultancy. Roddie: Celgene: Honoraria;Gilead: Honoraria;Novartis: Honoraria. O'Reilly: Gilead: Honoraria;Novartis: Honoraria, Other: Travel support.