Six-Month Follow-up for Infectious Complications after Lymphodepletion and Application of CD19-Chimeric Antigen Receptor T (CAR-T) Cell Therapy

Background: In the past years, chimeric antigen receptor T (CAR-T) cell therapy targeting CD19 have been shown to be a new and effective treatment option in patients with relapsed/refractory non-Hodgkin lymphoma (NHL) and acute lymphoblastic leukemia (ALL). However, infections with severe and potentially life-threatening complications can be induced by either lymphodepleting chemotherapy and/or the infusion of CAR-T cells, while side effects such as cytokine release syndrome (CRS) might further complicate differential diagnosis. Methods: Infections and complications were evaluated during inpatient treatment as well as in a follow-up period of the first six months after dosing. Eighty-one dosings of CAR-T cells in seventy-three adult patients with either NHL (88%) or ALL (12%) were analyzed. Bacterial and viral pathogen were detected with blood cultures or examination of potential sources of infection such as catheter tips. Panel and serum testing for viral infection was carried out either as a screening or in case of suspicion, while fungal infections were diagnosed according to the 2008 revised European Organization for Research and Treatment of Cancer (EORTC) Consensus Group criteria to determine proven, probable and possible invasive fungal disease. Results: In 52 patients (64%, Table 1) fever was detected following lymphodepletion and CAR-T cell dosing . Microbiological or radiological findings were seen in 20% of cases. Of those, eight were of bacterial (10%), three of viral (4%), and five of fungal (6%) origin. Overall, more lines of therapy as well as more severe CRS were associated with early infection. Cytokine release syndrome was diagnosed in 41 patients (51%, Table 1), with a simultaneous detection in five bacterial (6%), two viral (2%), and five fungal (6%) infections (Figure 1). In the six months follow-up period seven patients with fever (9%) had microbiological or radiological findings, in most cases during the first 90 days after CAR T cell infusion (6 patients, 7%). Only one patient died of infection (pathogen: cytomegalovirus). Conclusions: Infections are common in CAR-T cell patients; therefore, fast and suitable identification and initiation of treatment are important in the heavily pretreated and immunocompromised patient population. While infectious complications are mostly manageable, the frequency of infectious complications in patients receiving CAR-T cell therapy underlines the value of standardized anti-infective prophylaxis and supportive therapy for reduction of morbidity and mortality. Figure 1 Figure 1. Disclosures Schubert: Gilead: Consultancy. Sauer: Pfizer: Consultancy, Speakers Bureau; Abbvie: Consultancy, Speakers Bureau; Matterhorn Biosciences AG: Consultancy, Other: DSMB/SAB Member; Takeda: Consultancy, Other: DSMB/SAB Member. Schmitt: Hexal: Other: Travel grant; TolerogenixX Ltd: Current Employment; Therakos/Mallinckrodt: Research Funding; Jazz Pharmaceuticals: Other: Travel grant. Müller-Tidow: Bioline: Research Funding; Pfizer: Research Funding; Janssen: Consultancy, Research Funding. Dreger: AbbVie: Consultancy, Speakers Bureau; AstraZeneca: Consultancy, Speakers Bureau; Bluebird Bio: Consultancy; BMS: Consultancy; Novartis: Consultancy, Speakers Bureau; Janssen: Consultancy; Gilead Sciences: Consultancy, Speakers Bureau; Riemser: Consultancy, Research Funding, Speakers Bureau; Roche: Consultancy, Speakers Bureau. Schmitt: Bluebird Bio: Other: Travel grants; MSD: Membership on an entity's Board of Directors or advisory committees; Novartis: Other: Travel grants, Research Funding; Hexal: Other: Travel grants, Research Funding; Kite Gilead: Other: Travel grants; Apogenix: Research Funding; TolerogenixX: Current holder of individual stocks in a privately-held company.

Third-Generation Chimeric Antigen Receptor (CAR) T Cells in Patients with Relapsed/Refractory Acute Lymphoblastic Leukemia (ALL) and Non-Hodgkin Lymphoma (NHL) - Results from the Heidelberg Trial 1 (HD-CAR-1 trial)

Introduction Chimeric antigen receptor (CAR) T cell (CART) therapy has shown to be a new and very promising therapeutical method in patients with relapsed or refractory (r/r) acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphoma (NHL). The investigator-initiated Heidelberg-CAR-T-cell-trial 1 (HD-CAR-1) evaluates both efficacy and safety of escalating doses of 3 rd-generation CD19-directed CARTs comprising CD28 and 4-1BB as costimulatory molecules in patients with r/r ALL and NHL. Leukapheresis, manufacturing, administration, patient monitoring and follow-up were all conducted in-house at the Heidelberg University Hospital. Methods Treatment was conducted with escalating doses of autologous 3 rd-generation CARTs after lymphodepletion with fludarabine (90 mg/m 2) and cyclophosphamide (1,500 mg/m 2) in patients with r/r acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), or Non-Hodgkin's lymphoma (NHL), with subtype including diffuse large B-cell lymphoma (DLBCL), transformed follicular lymphoma (tFL) or mantle cell lymphoma (MCL). Treatment efficacy as well as occurrence of toxicities, such as cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), infections or cytopenia, were evaluated. Following prior results regarding dose-dependent efficacy and excellent toxicity profile with dose levels (DL) I, II and III (10 6, 5×10 6 and 20×10 6 CARTs/m 2), a trial amendment was approved for treatment of patients with higher CART doses (DL IV, V and VI: 5x10 7, 10x10 7 and 20x10 7 CARTs/m 2). Results Overall, screening was performed for 32 patients. Two patients were considered screening failures due to rapidly progressive disease (PD) and uncontrolled hepatitis B infection, respectively; leading to 30 patients enrolled in the study. The HD-CAR-1 product was given to 27 patients (12 patients with ALL, four with CLL, four with MCL, five with DLBCL, and two with FL) in different dose levels (six patients with DL I, six patients with DL II, eight patients with DL III, 5 patients with DL IV, 2 patient with DL V). The CART product was not given to two patients due to PD and lethal septic complication, respectively. Severe CAR-T toxicity was rare, as only two patients developed CRS ≥ III°. Both patients received treatment with tocilizumab, while one was additionally treated with steroids. No ICANS ≥ III° were reported in the study. 54% of patients achieved a complete response (CR) with an overall response rate (ORR) of treated patients of 65%. In a subgroup response analysis, an ORR of 92% (83% CRs) with 50% of all patients achieving MRD-negative CR was seen in ALL patients. In the NHL/CLL cohort, an ORR of 43% and a CR rate of 29% were observed. Figure 1 displays OS and PFS results till the end of study (EOS, day +90). Conclusion Academic CART production was feasible for all enrolled patients. Patients responded clinically to treatment and CARTs displayed a highly favorable safety profile. Overall, HD-CAR-1 accounts for clinical evaluation of 3 rd generation CARTs. Figure 1 Figure 1. Disclosures Schubert: Gilead: Consultancy. Schmitt: TolerogenixX Ltd: Current Employment; Hexal: Other: Travel grant; Jazz Pharmaceuticals: Other: Travel grant; Therakos/Mallinckrodt: Research Funding. Müller-Tidow: Pfizer: Research Funding; Janssen: Consultancy, Research Funding; Bioline: Research Funding. Dreger: Riemser: Consultancy, Research Funding, Speakers Bureau; Janssen: Consultancy; BMS: Consultancy; Gilead Sciences: Consultancy, Speakers Bureau; AbbVie: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; AstraZeneca: Consultancy, Speakers Bureau; Bluebird Bio: Consultancy; Roche: Consultancy, Speakers Bureau. Schmitt: MSD: Membership on an entity's Board of Directors or advisory committees; TolerogenixX: Current holder of individual stocks in a privately-held company; Kite Gilead: Other: Travel grants; Bluebird Bio: Other: Travel grants; Novartis: Other: Travel grants, Research Funding; Hexal: Other: Travel grants, Research Funding; Apogenix: Research Funding.

The First Real-World Experience with Betibeglogene Autotemcel (beti-cel) Gene Therapy Treatment for Transfusion-Dependent β-Thalassemia (TDT)

Background Beti-cel ex vivo gene therapy integrates a modified HBB gene into hematopoietic stem cells of patients with TDT, aiming to enable lifelong, stable production of functional adult hemoglobin (Hb). The efficacy and safety of the treatment have been demonstrated in a total of 63 patients treated across 4 clinical trials (HGB-204,-HGB-205, HGB-207, and HGB-212). Here, we present the first patient who received beti-cel outside of the clinical trial setting, a 14-year-old male with a β 0/β + (IVS-1-6) genotype. Methods Following hematopoietic stem cell collection via granulocyte-colony stimulating factor plus plerixafor mobilization and apheresis, CD34+ cells were transduced with the BB305 lentiviral vector encoding HbA T87Q. The patient received hypertransfusion before mobilization and conditioning, maintaining a pre-transfusion Hb level of >11 g/dL. Six days prior to beti-cel infusion, single-agent busulfan myeloablation was initiated (16 single doses at 0.8 mg/kg body weight; 3.2 mg/kg/24 h) with concomitant clonazepam (see Table for treatment timeline). Ursodeoxycholic acid therapy was continued as hepatic veno-occlusive disease (VOD) prophylaxis through inpatient treatment. Results The patient was diagnosed with TDT at the age of 2 years in his home country and has been treated in Germany since the age of 9. Regular transfusion therapy was initiated soon after diagnosis (Table). Aged 9, the patient was started on desferasirox for iron elimination therapy. His annualized red blood cell (RBC) transfusion volume was 174 ml/kg in 2018 and 185 ml/kg in 2019, maintaining his pre-transfusion Hb at or above 9 g/dl. No HLA-related donor was available for allogeneic transplant. At informed consent, the patient was 13 years old and met the eligibility criteria for beti-cel treatment as outlined in the summary of product characteristics (SmPC). The patient was physically fit, with a 90% Lansky score and regular participation in school sports, but reported physical limitations when running extensively. The patient underwent a thorough assessment before admission (Table), which did not reveal any remarkable abnormalities except TDT-related splenomegaly and signs of slight iron overload (liver iron content, 2.0 mg/g dry weight [normal range, 0.17-1.8]). On 11/Feb/2021, the patient was infused with 5.1 × 10 6 CD34+ cells/kg. The patient received 4 RBC and 8 platelet transfusions following infusion until Day 13 and 27, respectively (Table). Neutrophil and platelet engraftment occurred on day 27 post beti-cel infusion. The patient was discharged from inpatient treatment the same day, in excellent general condition, with 90% Lansky score, Hb of 8.2 g/dl, a reticulocyte count of 9.3%, a total white cell count of 1.55/nl, a neutrophil count of 0.75/nl, and a platelet count of 24/nl. At last follow-up (+100 days), the patient felt well and exhibited normal exercise tolerance. He has received neither red blood cell nor platelet transfusions or chelation therapy since discharge. Total Hb was 11.8 g/dl (Table). Granulocytes and lymphocytes had recovered to normal levels. The patient showed continued, albeit slowly improving, thrombocytopenia (platelet count, 31/nl [29/nl at +60 days]), consistent with previous observations after beti-cel therapy. Myeloablation and beti-cel infusion were tolerated well. Adverse events post infusion were febrile neutropenia, elevated C-reactive protein levels, pruritus, gingivitis, mild mucositis, and vertigo, consistent with the SmPC. At +23 and +26 days, the patient experienced transient subjective hearing loss (quickly resolved). No VOD events occurred. Conclusions This is the first real-world patient with TDT treated with beti-cel therapy. The treatment regimen had a tolerability profile consistent with that of mobilization, apheresis, and busulfan myeloablation, matching clinical trial observations. Following treatment, this 14-year-old patient reached a total Hb of 11.8 g/dL at +100 days without requirement of red cell transfusions and continues to exhibit prolonged but slowly improving and asymptomatic thrombocytopenia. Figure 1 Figure 1. Disclosures Schmitt: TolerogenixX Ltd: Current Employment; Therakos/Mallinckrodt: Research Funding; Hexal: Other: Travel grant; Jazz Pharmaceuticals: Other: Travel grant. Schmitt: Bluebird Bio: Other: Travel grants; Novartis: Other: Travel grants, Research Funding; TolerogenixX: Current holder of individual stocks in a privately-held company; Apogenix: Research Funding; MSD: Membership on an entity's Board of Directors or advisory committees; Hexal: Other: Travel grants, Research Funding; Kite Gilead: Other: Travel grants. Kulozik: Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy, Honoraria; BioMedX: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; bluebird bio, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

Th22 and Tfh Cell Elevation Is Associated with Clinical Response of Photopheresis Therapy in Patients with Steroid-Refractory/ Resistant Graft-Versus-Host Disease (GvHD)

In patients with steroid-refractory/resistant graft-versus-host disease (GvHD), extracorporeal photopheresis (ECP) has been identified as a promising therapeutic strategy due to its safety profile and convincing clinical response rates. While previous studies have reported on the role of Th1, Th2 and Treg cells in ECP therapy, further comprehensive analysis of T helper cells is necessary to provide better understanding of the underlying mechanisms. In this study, we thus investigated the influence of long-term ECP treatment on both Th cells as well as on immune checkpoint molecules and apoptosis. Overall, we investigated 27 patients with GvHD treated by ECP therapy, containing 13 patients with acute GvHD and 14 patients with chronic GvHD. 10/13 (76.9%) of aGvHD and 9/14 (64.3%) of cGvHD patients clinically responded to ECP therapy. Three (23.1%) patients reached CR and seven (53.8%) patients achieved PR under ECP treatment in patients with aGvHD, while in patients with cGvHD CR was achieved in one (7.1%) and PR in eight (57.1%) patients. Stabilization of disease was observed in five (35.7%) patients. On an immunological level, aGvHD, cGvHD and healthy donors (HD) patients showed different profiles of Th populations. In GvHD patients, significantly higher levels for Th2 (aGvHD vs. HD: 36.26% vs. 13.88%, p = 0.014; cGvHD vs. HD: 30.71% vs. 13.88%, p = 0.026), Th17 (aGvHD vs. HD: 19.21% vs. 7.49%, p = 0.038), Th22 (aGvHD vs. HD: 1.22% vs. 0.11%，p = 0.011; cGvHD vs. HD: 0.64% vs. 0.11%, p = 0.012) and GM-CSF + Th cells (aGvHD vs. HD: 1.15% vs. 0.14%, p = 0.022; cGvHD vs. HD: 0.84% vs. 0.14%，p = 0.012) and clearly lower levels for T follicular helper (Tfh) cells including Th1- (aGvHD vs. HD: 0.37% vs. 2.04%, p = 0.002; cGvHD vs. HD: 1.28% vs. 2.04%, p = 0.03) and Th2-like cells (aGvHD vs. HD: 1.17% vs. 4.19%, p = 0.033) were observed in comparison to HDs. This suggests Th cells account for a crucial role in GvHD pathogenesis. ECP therapy was able to accelerate recovery of Tfh cells, including Th1- (Time point 1 vs. Time point 2 in aGvHD: 0.37% vs. 0.97%, p = 0.028), Th2- (T1 vs. T2 in aGvHD: 1.17% vs. 1.35%, p = 0.049; T1 vs. T2 in cGvHD: 2.08% vs. 3.15%, p = 0.048) and Th17-like Tfh cells (T1 vs. T2 in aGvHD: 1.82% vs. 2.70%, p = 0.034), facilitating immune reconstitution after allo-HSCT and thereby alleviating GvHD. Clinical response in aGvHD patients was strongly associated with elevation of Th22 cells by ECP therapy showing 51% upregulation (T1 vs. T2: 0.86% vs. 1.3%，p=0.007). In addition, we also found that the expression of the Fas receptor on effector T cells could be further upregulated with ECP treatment (T1 vs. T2 in cGvHD: 49.65% vs. 56.46%, p = 0.011), which increases the susceptibility of these effectors T cells to Fas-mediated apoptosis. This could lead to the elimination of these overactivated effector T cells and the perseverance of immunological tolerance by triggering activation-induced cell death. In addition, a reduction of Tim-3-expressing effector T cells, which are associated with the severity of GvHD, with ECP therapy (T1 vs. T2 for aGvHD: 18.09% vs. 15.10%, p = 0.044) was discovered. In conclusion, ECP therapy exerts immunomodulatory effects by promoting balanced immune reconstitution and inducing immune tolerance, making it an attractive and promising treatment option for patients with GvHD. Disclosures Schubert: Gilead: Consultancy. Hegenbart: Alnylam: Honoraria; Akcea: Honoraria; Janssen: Consultancy, Research Funding; Prothena: Research Funding; Pfizer: Consultancy, Honoraria. Schönland: Prothena: Honoraria, Other: Travel grants; Takeda: Honoraria, Other: Travel grants; Pfizer: Honoraria; Janssen: Honoraria, Other: Travel grants, Research Funding; Sanofi: Research Funding. Müller-Tidow: Pfizer: Research Funding; Bioline: Research Funding; Janssen: Consultancy, Research Funding. Dreger: Riemser: Consultancy, Research Funding, Speakers Bureau; Bluebird Bio: Consultancy; Roche: Consultancy, Speakers Bureau; AbbVie: Consultancy, Speakers Bureau; BMS: Consultancy; AstraZeneca: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Janssen: Consultancy; Gilead Sciences: Consultancy, Speakers Bureau. Schmitt: MSD: Membership on an entity's Board of Directors or advisory committees; Hexal: Other: Travel grants, Research Funding; Kite Gilead: Other: Travel grants; TolerogenixX: Current holder of individual stocks in a privately-held company; Bluebird Bio: Other: Travel grants; Novartis: Other: Travel grants, Research Funding; Apogenix: Research Funding. Schmitt: Therakos/Mallinckrodt: Research Funding; TolerogenixX Ltd: Current Employment; Jazz Pharmaceuticals: Other: Travel grant; Hexal: Other: Travel grant.

Recruitment of NK Cells during Autologous Apheresis Allows Efficient NK Cell Collection for Immunotherapy

Background: Natural killer (NK) cell-based immunotherapies are emerging as a new, cutting-edge, promising cancer treatment. NK cells have been used to generate autologous as well as allogenic chimeric antigen receptor NK (CAR-NK) cells, and are currently being tested in multiple clinical trials. The advantage of these cells over CAR-T cells is that they show a superior toxicity profile, less on-target/off-tumor effects, and their toxicity mechanism could be independent of CAR. Additionally, allogenic CAR-NK cells are less immunogenic and cause less graft versus host disease in comparison to CAR-T cells. NK-cell collection during apheresis is the first step in the production of CAR-NK-cells. Efficient collection of NK-cells is paramount to successful manufacture of a CAR-NK cell product. Here, we present our single-center experience on individualized high-flow autologous lymphocyte apheresis in heavily pre-treated patients who qualified for a CAR-T treatment. In this abstract, we demonstrate data on NK-cell collections that derived from our research on T-cell collections. Study design and methods: In this retrospective, descriptive study, we compared collection efficiencies (CE%), absolute efficiencies (AE; absolute yield) and relative efficiencies (RE; AE/total number of absolute circulating pre-apheresis cells) for NK- and T-cell collections. Recruitment of cells was assumed if RE>1. The analysis was performed for 9 heavily pre-treated diffuse large B-cell lymphoma patients who underwent autologous T-cell collections for CAR-T treatment between October 2018 and November 2019. These 9 patients were chosen because the data on pre-apheresis NK- and T-cell concentrations, and harvest NK- and T-cell yield, were available for them. For calculation of CE% a standard formula was used (Figure 1, A). Results: A total of 9 high-flow lymphocyte collections achieved the cell yield of 1x10 9 cells for T- cells and 88% (n=8) achieved the cell yield of 1x10 9 cells for NK-cells. The median pre-apheresis cell concentration for NK-cells was 0.21 x10 9/L (range 0.05 - 0.29) and for T-cells was 0.69 x10 9/L (0.11 - 2.09). The median average blood flow was 77 ml/min (49 - 132), the median processed blood volume was 13.51L (7.35 - 31.17), while the median ratio of processed blood volume to total blood volume was 2.57 (1.46 - 6.67). The median AE for NK-cells with 1.58x10 9 (0.55 - 5.9) was markedly lower but not statistically significant (p=0.14) than that of T-cells with 5.5x10 9 (1.88 - 18.41). The CE of NK-collections was median 89% (29 - 125), while the CE of T-cell collections was median 68% (31 - 93) and they were not statistically different (p=0.605). The same was observed for RE which was 3.04 (0.63 - 4.31) for NK-cells and 1.91 (0.68 - 4.52) for T-cells with no statistically significant difference (Independent-Samples Mann-Whitney U Test, p=0.836). Figure 1 presents the differences in AE (B), CE (C) and RE (D) between NK- and T-cell collections. Conclusions: During high-flow lymphocyte apheresis, NK- as well as T-cells are recruited, as in the majority of collections the cell yield is greater than the absolute circulating pre-apheresis cell count (when RE was > 1). Thus, the origin and immunophenotype of these NK- and T-cells should be subject of further investigation. CE for NK- and T-cells are similar and high enough to perform efficient cell collections of both cell types for immunotherapy. Figure 1 Figure 1. Disclosures Jalowiec: Kite Pharma Gilead Sciences': Honoraria, Speakers Bureau. Daskalakis: Amgen: Other: Travel grant; Roche: Other: Travel grant; Gilead: Membership on an entity's Board of Directors or advisory committees, Other: Travel grant; Celgene/BMS: Consultancy, Other: Travel grant; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Travel grant; NovoNordisk: Other: Travel grant.