Prior allo-HSCT Research Articles

Impact of Previous Allogeneic Hematopoietic Stem Cell Transplantation on Chimeric Antigen Receptor (CAR) T Cell Treatment for Relapsed/Refractory Multiple Myeloma

BackgroundAnti-BCMA-directed chimeric antigen receptor (CAR) T cells are effective treatment for patients with refractory/relapsed multiple myeloma (RRMM). However, little is known about the impact of previous allogeneic hematopoietic stem cell transplantation (allo-HSCT) on lymphocyte collection for production of CAR T cells and subsequent treatment with CAR T cells. Patients and MethodsWe performed a retrospective analysis of cellular composition of lymphocyte collections, CAR T cell expansion and treatment outcomes of RRMM patients undergoing therapy with idecabtagene vicleucel (ide-cel) with and without history of allo-HSCT.27 patients (11/27 female) with median age 63 (range 39-75) years were analyzed. Five patients (19%) had the history of allo-HSCT median of 5.5 years before ide-cel. ResultsPrior to apheresis, the white blood cell, absolute lymphocyte counts, CD3+ cells and monocytes did not differ in patients with and without prior allo-HSCT. We also noticed no differences in the collected CD3+ yields or cellular compositions of lymphocyte collections.One year after ide-cel infusion, the progression-free survival and overall survival of patients with and without previous allo-HSCT did not differ with 60% and 45% respectively (P = .58) and 66.7% and 74% respectively (P = .84).The highest expansion of CAR T was detected between day 7 after infusion and showed no difference regarding previous allo-HSCT (P = .71).No graft-versus-host disease during the follow-up was detected. ConclusionOur data confirm that the treatment with ide-cel is feasible for patients with prior allo-HSCT. Furthermore, allo-HSCT did not influence cellular composition of lymphocyte collections, clinical outcome or in vivo expansion of ide-cel.

Efficacy and Tolerance of Brexucabtagene Autoleucel in Adults with Relapsed/Refractory B-Cell Precursor Acute Lymphoblastic Leukemia : A Graall Study from the Descar-T Registry

Background : Brexucabtagene autoleucel (brexu-cel) was recently approved for adult patients with relapsed/refractory (R/R) B-cell precursor acute lymphoblastic leukemia (BCP-ALL) based on the results of the ZUMA-3 phase 2 study. After a median follow-up of 39 months, brexu-cel showed a complete remission (CR)/CR with incomplete hematologic recovery (CRi) rate of 71% and a median overall survival of 26 months (Shah B, et al. ASCO 2023). In the present study, we aimed at investigating the efficacy and safety of brexu-cel in a real-life cohort of adult BCP-ALL patients included in the French early access program. Methods : In this Group for Research on Adult Acute Lymphoblastic leukemia (GRAALL) study, we performed an analysis of the DESCAR-T registry which collects real-life data of patients treated with CAR T-cells since July 2018 in France. All patients who underwent a leukapheresis with an intent to manufacture brexu-cel were included (N=80). Efficacy and safety analyses were performed in the 64/66 infused patients with available response assessment after infusion. The data cut-off was June 2023. The present study reports on best overall response, overall survival (OS), relapse-free survival (RFS), as well as immune effector cell-associated neurotoxicity syndrome (ICANS), and cytokine release syndrome (CRS) incidence and grading (according to ASTCT Consensus). Results : Between May 2019 and February 2023, 80 adults with R/R BCP-ALL from 22 French centers had a leukapheresis for brexu-cel. Among them, 14 patients (18%) were not infused because of death (8 pts), progression (1 pt), manufacturing failure (2 pts), or other causes (3 pts). Among the 64 infused patients with available response assessment, median age was 43.5 yrs (range, 22-69). A Philadelphia(Ph)-chromosome was found in 20/64 (31%). Patients had received a median of 3 (range, 1-6) prior lines of treatment including blinatumomab, inotuzumab ozogamicin and allogeneic hematopoietic stem cell transplantation (allo-HSCT) in 67%, 19% and 70% of patients respectively. Twelve patients (19%) had an active CNS disease (CNS2/3) prior to apheresis and 18/40 (45%) had bone marrow blasts ≥ 25% before lymphodepletion (LD). ECOG before infusion was ≥2 in 6/64 (9%) patients. All patients received fludarabine and cyclophosphamide as LD. Median time from apheresis to infusion was 40 days (range, 27-99). CRS and ICANS occurred in 48/64 (77%, grade 3+ in 6%) and 28/64 (45%, grade 3+ in 8%) of patients respectively and were reversible. A CR was achieved in 49/64 patients (77%) of whom 23/25 (92%) were MRD-negative. An older age, a prior allo-HSCT, and the occurrence of CRS were associated with significantly higher CR rates. The median follow-up was 13 months. Three patients were bridged to an allo-HSCT in continuous complete remission (second allo-HSCT for 2 of them). The median RFS and OS were 12.9 months and 15.6 months respectively (Figure). In patients who achieved a CR, median OS was 25.8 months (Figure). Patients with CNS involvement before leukapheresis had a significantly shorter RFS (HR 5.4, 95%CI 1.9-15.8, p=0.002) and OS (HR 3.3, 95%CI 1.4-8.2, p=0.008). Number of prior treatment lines, prior inotuzumab, prior blinatumomab, or pre-LD BM blast% were not associated with outcome. A better OS was observed in patients with prior allo-HSCT (HR .4, 95%CI 0.2-0.9, p=0.04). Conclusion : This multicenter real-life study confirms the efficacy and acceptable safety profile of brexu-cel in adult patients with R/R BCP-ALL. It also suggests that patients with CNS involvement, that were not eligible to ZUMA-3 study, have a limited benefit of brexu-cel when compared to other patients.

Gene-Edited Universal CD7 Chimeric Antigen Receptor T Cells for Pediatric T-Cell Acute Lymphoblastic Leukemia or Lymphoblastic Lymphoma

Background: T-cell acute lymphoblastic leukemia (T-ALL) and T-cell lymphoblastic lymphoma (T-LBL) are highly aggressive T-lineage malignancies characterized by an infiltration of immature T cells in the bone marrow (BM) and peripheral blood (PB) or extramedullary organ involvements. Effective treatments were elusive, and the long-term survival of patients with refractory/relapsed (R/R) T-ALL/LBL remains poor despite allogeneic hematopoietic stem cell transplantation (allo-HSCT). CAR-T therapies for T-cell malignancies remain underdeveloped due to the shared antigenicity between normal and malignant T cells. CD7 is highly expressed on the surface of T-ALL/LBL T cells and is considered a viable CAR-T therapeutic target. However, CD7-targeting immunotherapies may be compromised by T-cell fratricide and extermination. And one of the biggest challenges with autologous CAR-T cell therapy is to isolate a sufficient number of healthy T cells from malignant T cells. Thus, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR9-associated protein 9 (Cas9)-mediated gene ablation has been used to produce universal CD7-targeted CAR T cells (UCD7-CAR) from suitable healthy donors that no longer express CD7 and TCR. In vitro killing tests, animal tests, and phase 1 clinical trials have preliminarily verified the efficacy and safety of universal CD7 CAR-T cells. Here we investigated the safety and efficacy of the universal CD7 CAR-T therapy in phase 2 clinical trial(NCT05454241) for pediatric R/R T-ALL/LBL patients. Aims: To investigate the efficacy and safety of the universal CD7 CAR-T therapy for pediatric R/R T-ALL/LBL patients. Methods: Patients over three years of age whose disease failed ≥ 2 lines of therapies and had ≥ 80% CD7 expression were eligible, including those who relapsed within 12 months after complete response or relapsed more than 12 months after complete response and failed to achieve remission induced by one or more courses of standard treatment; and patients with recurrence after hematopoietic stem cell transplantation. A lymphodepletion regimen was administered to all patients using fludarabine (30 mg/m2 per day) and cyclophosphamide (500 mg/m2 per day) for three consecutive days (day -5 to day -3) before CAR-T infusion. Patients received one single infusion of UCD7-CAR T cells at a median dose of 2.0×10^6/kg. Consolidative allo-HSCT after remission was allowed after day 28 after UCD7-CART infusion at the discretion of the physician and patient preference. All surviving patients were followed until July 15, 2023; the median follow-up was 109 days (54 to 117 days). Results: Five eligible children, 1 with r/r T-LBL and 4 with r/r T-ALL, were enrolled between December 2022 and April 2023 (Table 1). The median age of the patients was 5 (4-11) years. One girl(Patient 04) had a history of allo-HSCT before enrollment. Patients were heavily pretreated with a median of 3(2-6) lines of therapies. At registration, the median proportion of blasts in 4 T-ALL patients was 47.275% (6.0%-56.0%) in BM by FCM along with CNS(n=2) or testis(n=1) involvement. In contrast, 1 T-LBL patient(patient 02) did not have BM blasts but with bulky mediastinal masses ≥7 cm in diameter. All five patients had no or mild CRS (no CRS, n=1; grade 1, n=3; grade 2, n=1), and most(n=4) did not show symptoms of neurotoxicity. Patient 04, who received a prior allo-HSCT approximately seven months before CAR-T therapy, had a Herpes virus 6 (HHV-6B) encephalitis on day 17 after CAR-T infusion, but no GVHD was observed. On day 28, 4 of 5 (80.0%) patients who had BM involvement achieved MRD-negative complete remission (CR; n=2) or CR with incomplete hematologic recovery (CRi; n=2); but patient 02 with bulky mediastinal masses did not have an obvious response. Until the cutoff date, patient 04 still kept a sustained MRD negative CR; patient 05 relapsed again 49 days after CAR-T infusion, and the other three patients received a subsequent allo-UCBT with a CR state. All the children are still alive. Conclusion:UCD7-CAR T therapy is a safe and highly effective pediatric T-ALL/LBL treatment. More patients and longer follow-ups are needed for validation.

Naturally Selected CD7-Targeted Chimeric Antigen Receptor (CAR)-T Cell Therapy for Refractory/Relapsed Acute Myeloid Leukemia: Phase I Clinical Trial

Introduction Refractory or relapsed (r/r) acute myeloid leukemia (AML) is associated with a relatively poor prognosis, even in patients who undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT), emphasizing the critical need for novel therapies. Approximately 30% of AML patients express CD7 on their leukemic blasts and malignant progenitor cells. Naturally selected CD7 CAR-T (NS7CAR-T) therapy has shown significant efficacy with a favorable safety profile in T-cell lymphoid malignancies. In a phase I clinical study (https://clinicaltrials.gov NCT04938115), we investigated the safety and efficacy of CAR-T therapy for treating r/r AML patients with CD7-positive disease. Methods Peripheral blood mononuclear cells were obtained from either the patients themselves (n=9) or the transplant donor (n=1) in cases of relapse post-transplant. T-cells were then purified using CD3+ magnetic beads. The second-generation CD7CAR with a 4-1BB costimulatory domain was manufactured following the manufacturer's protocol. Before the CAR-T cell infusion, bridging therapies were permitted for patients with rapid disease progression. All patients received intravenous fludarabine (30mg/m 2/d) and cyclophosphamide (300mg/m 2/d) lymphodepletion chemotherapy for three consecutive days (Day -5 to Day -3). The median time from leukapheresis to CAR-T cell infusion was 15 days. Results Between June 2021 and January 2023, we enrolled 10 patients with CD7-positive r/r AML (CD7 expression >50% with good intensity) and administered NS7CAR-T cell infusions, with 4 receiving a low dose (5×10 5/kg) and 6 receiving a medium dose (1×10 6/kg). Table 1 displays the characteristics of the enrolled patients, revealing a median age of 34 years (7-63 years) and median bone marrow (BM) blasts percentage by flow cytometry (FCM) of 17.0% (2.0-72.7%) at enrollment. One patient presented with diffuse extramedullary disease (EMD). Before enrollment, patients had undergone a median of 9 (range: 3-17) prior lines of therapy. Seven patients had a history of allo-HSCT and the median interval period from the prior transplant to relapse was 12.5 months (3.5-19.5 months). Following infusion, the median peak of circulating NS7CAR-T cells was 2.72×10 5 copies/μg (0.671~5.41×10 5 copies/μg) genomic DNA, which occurred around Day 21 (Day 14 - Day 21) based on q-PCR, with 64.68% (40.08%~92.02%) occurring on Day 17 (Day 11 - Day 21) according to FCM. The median transduction efficiency of the products was 95.6% (70.4%-98.5%). At four weeks post NS7CAR-T cell infusion, 7/10 (70%) patients achieved complete remission (CR) in BM, and 6 of them attained minimal residual disease (MRD)-negative CR. Three patients showed no remission (NR), including 1 with EMD who had partial remission (PR) based on PET-CT evaluation on Day 35. All NR patients were found lost CD7. The median observation time was 178 days (28-752 days). Among the 7 patients who achieved CR, 3 who relapsed from prior transplants underwent consolidative 2 nd allo-HSCT about 2 months after CD7 CAR T-cell infusion. Two patients remained in leukemia-free survival on day 752 and day 315, respectively, while 1 patient died on day 241 due to transplant-related mortality. Among the other 4 patients without consolidative allo-HSCT, 3 relapsed on day 47, day 83, and day 115, respectively (all 3 patients were found to have CD7 loss), and 1 patient died from lung infection. Post-infusion, the majority of patients (80%) experienced mild cytokine release syndrome (CRS), with 7 displaying grade I and 1 having grade II CRS, while 2 patients (20%) experienced grade III CRS. None of the patients had neurotoxicity. Among the 7 patients with prior allo-HSCT, 1 who had a relapse approximately 100 days after prior allo-HSCT developed mild skin graft-versus-host disease following CAR-T therapy. Conclusion Our study highlights the NS7CAR-T therapy as a promising approach for achieving a favorable initial CR in CD7-positive AML patients, even in those who have undergone extensive prior treatments and experienced relapse post allo-HSCT. It potentially could serve as a bridging therapy before transplant. CD7 loss is a major issue either in NR patients or relapsed patients. The safety profile of NS7CAR-T therapy was manageable. However, to comprehensively assess the efficacy of NS7CAR-T in treating CD7-positive AML, further data from a larger cohort of patients and longer follow-up time are essential.

CD19 CAR T cells are an effective therapy for posttransplant relapse in patients with B-lineage ALL: real-world data from Germany.

Patients with precursor B-cell acute lymphoblastic leukemia (pB-ALL) who have relapsed after allogeneic hematopoietic stem cell transplantation (allo-HSCT), have relapsed more than once, or are resistant upfront have a dismal prognosis. CD19-targeted chimeric antigen receptor (CAR) T cells have evolved as potent immune therapies. Tisagenlecleucel (Tisa-cel) is a commercially available autologous CD19-directed CAR T-cell product. We performed a retrospective study inviting all CAR T-cell centers in Germany to participate. Eighty-one patients with pB-ALL were included. Twenty-eight days after CAR T-cell infusion, 71 patients (87.7%) were in complete response, and 8 (9.9%) were in nonremission. At 2 years, the probabilities of event-free survival (pEFS), relapse-free survival (pRFS), and overall survival (pOS) were 45.3%, 51.7%, and 53.2%, respectively. pEFS was not different in patients without (n= 16, 55.0%) vs with prior allo-HSCT (n= 65, 43.4%). In patients treated after allo-HSCT, the time to relapse after allo-HSCT was a strong predictor of outcome. Patients relapsing within 6months of allo-HSCT had a disappointing pEFS of 18.4% (pOS= 16.0%); the pEFS for those relapsing later was 55.5% (pOS= 74.8%). Our study provides real-world experience in pediatric, adolescent, and young adult patients with ALL treated with Tisa-cel, where most patients were treated after having relapsed after allo-HSCT. A total of 45.3% were rescued with a single dose of Tisa-cel. Our novel finding that patients with ALL after allo-HSCT had by far a better pEFS if relapse occurred beyond 6months might be helpful in clinical decision-making and motivates studies to uncover the reasons.

Haploidentical Hematopoietic Stem Cell Transplant Plus Add-Back NK Cells in Pediatric High-Risk ALL

Introduction: Natural killer (NK) lymphocytes are cells of innate immunity that protect against tumor and infections. NK cells recognize self and non-self HLA class I ligands, are regulated by a balance between activator and inhibitory signals through surface receptors, and can interact with HLA class I molecules on target cells. Killer-cell Immunoglobulin-like Receptors (KIRs) are inhibitory molecules expressed on NK cells and belong to the immunoglobulin superfamily. KIRs function to "educate" NK cells in effective defense against unhealthy self/non-self cells and tolerance against healthy self cells. NKs are thought to play a key role in preventing early relapse of hematologic malignancies, virus infection and graft versus host disease (GvHD) after haploidentical hematopoietic stem cell transplantation (haplo-HSCT).In B-/T-cell alpha/beta depleted haplo-HSCT, donor-versus-recipient allo-reactive NK cells can exert an efficient graft versus leukemia (GvL) effect, mediated by inhibitory KIRs where the HLA ligand is missing on recipient cells. Donor NK cells after haplo-HSCT are "immature" and not effective as the mature NKs. These immature NK cells are CD56bright, are derived from CD34+ stem cells, and mature to a CD56dim phenotype. The mature CD56dim NK cells are characterized by acquisition of KIRs, CD16 and CD57 in mature stages, which have functional significance in targeting and medicating their cytolytic activity. Based on these considerations, we performed haplo-HSCT with donor NK cell add-back to provide mature, functional immunological surveillance against tumor (MRD) and virus reactivation, which can frequently occur in manipulated haplo-HSCT for pediatric acute lymphoblastic leukemia (ALL). Methods: We evaluated the alloreactive effect of donor-derived NK cells in three pediatric high-risk ALL who underwent B-/T-cell alpha/beta depleted haplo-HSCT followed by donor NK infusion. Patients' characteristics are summarized in the Table. All 3 patients were male; median age was 13 months. Patients 1 and 2 had infant ALL, and patient 3 had refractory-relapsed (r/r) ALL. All patients received a median of 3 lines chemotherapy. Patient 1 received a prior allo-HSCT. Patients 1 and 2 received chemo-based conditioning regimens consisting of thyotepa, and fludarabine; In addition, patient1received treosulfan, and patient 2 received busulfan. Treosulfan was given to patient 1, due to less toxicity profile given prior allo-HSCT. Patient 3 received Total Body Irradiation (TBI), thyotepa, and fludarabine. All patients received rituximab and letermovirfor EBV and CMV prophylaxis, respectively, for all patients. Mother was Donor for all patients. Median CD34+, CD19+, CD3+-alpha/beta cell dose was 8.8, 0.05, 0.41 x 106/kg, respectively. NK cell allo-reactivity was tested by evaluating KIR genotyping and KIR/KIR-ligand mismatch in graft-versus-host direction. All three patients present KIR/KIR-ligand mismatch. Results: Engraftment was day +13, +14 and +19 for ANC, and +14, +18 and +17 for PLT (for both >20K and >50K), for patients 1, 2 and 3, respectively. NK cell number were monitored on day +7, +14, +21 and +28 (data pending). Patients received NK cell infusion on day 30 +/- 2 days. No infusion reactions were observed. MedianNK infused were 256x106/kg. None of the patients developed CMV, EBV or ADV reactivation. Patient 2 developed Grade 2 acute GvHD (skin) treated with steroids. No Grade GvHD 3-4 was observed. Median follow up was 58 days. All patients had full donor chimerism at day 30 ±2. All patients are currently in hematological CR; patient 1 converted to positive MRD at nine months from transplant. Conclusion: Alloreactive NK cell add-back infusion after B-/T-cell alpha/beta depleted haplo-HSCT could represent an effective option to improve transplant outcome and prevent virus reactivation. These NK cells may improve efficacy by enhancing GvL and could contribute to maintain the "disease control" through immunologic surveillance in high-risk ALL. Indeed, NK killing, which is higher in mature NK cells, depends on acquisition of sequential phenotypic maturation. Thus, infusion of mature donor NK cells may help to maintain control of MRD and virus reactivation through immunologic surveillance. Although our preliminary observations seem to be promising, this hypothesis should be confirmed in clinical trial of a larger number of patients. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

A Novel Universal CD7-Targeted CAR-T Cell Therapy for Relapsed or Refractory T-Cell Acute Lymphoblastic Leukemia and T-Cell Lymphoblastic Lymphoma

Background Universal CAR-T (UCAR-T) using gene-editing techniques has attracted significant attention due to its prompt availability for patients. To date, there are only a few clinical case reports of universal CAR-T therapy for T-cell malignancies. Here, we explored the efficacy and safety of CD7-targeted UCAR-T (RD13-01) cells for relapsed or refractory (R/R) T-cell acute lymphoblastic leukemia (T-ALL) and T-cell lymphoblastic lymphoma (T-LBL) in a phase I clinical trial (NCT04620655). Methods RD13-01 is an allogeneic, healthy donor-derived, and CRISPR/Cas9-edited anti-CD7 CAR-T cell product. RD13-01 consists of a CAR with a CD7-binding single-chain variable fragment (scFv), a 4-1BB costimulatory domain, CD3ζ signaling domain, a γc intracellular domain, in addition to an NK inhibitory (NKi) ligand containing an EC1-EC2 extracellular domain of E-cadherin fused to a CD28 co-stimulatory domain. The CAR and the NKi ligand are linked by an F2A self-cleaving peptide. Intravenous fludarabine (25-30 mg/m2/d), cyclophosphamide (300mg/m2/d) and etoposide (100 mg/m2/d) were given to all patients on Day -6 to Day -3 prior to CD7 UCAR-T cell infusion. Results Between December 2020 and May 2022, 10 patients (7 males, 3 females), 7 with T-ALL and 3 with T-LBL were enrolled. Median patient age was 16.5 years (range: 2-27 years). Patients had a median of 4.5 (2-6) prior lines of therapies. Two patients relapsed from a previous allogeneic hematopoietic stem cell transplant (allo-HSCT) within 6 months. In addition, 3 patients who showed no response (NR) to prior autologous CD7 CAR-T therapy were also included. Patient characteristics are shown in Table 1. Four patients harbored high-risk genotypes including STIL-TAL1, TP53, BCR-ABL, and others. By morphology, the median bone marrow (BM) blasts at enrollment were 60% (4%-96.5%). Of the eight patients with peripheral blood (PB) blasts, the median blasts were 27% (9%-85%). At enrollment, 8 patients had extramedullary disease (EMD) including 3 with central nervous system (CNS) involvement (1 CNS-1, 2 CNS-3), 3 with diffuse involvement, and 3 had localized EMD. The median transfection efficiency of the RD13-01 product was 64.6% (range: 59.0%-91.2%). A single dose of CD7 UCAR-T cells were infused to the first 3 enrolled patients at 0.5-1×107 cells/kg. Subsequently, 6 patients received a medium dose of 2×107cells/kg, and 1 received a high dose of 4×107cells/kg. By the cut-off date of July 11, 2021, the median observation time was 153 days (range: 28-315 days). On day 28 post infusion, 8/10 (80%) patients achieved complete remission (CR) in BM/PB, and 7 of the 8 patients were minimal residual disease (MRD) negative. Notably, the 3 patients who had failed prior autologous CD7 CAR-T therapy achieved CR. The first enrolled 2 patients who received the low dose showed NR and withdrew on day 28. Among the 7 patients with EMD, 4 achieved EMD CR at the median day 30, 1 had progression disease (PD) and 2, with NR in BM, withdrew prior to EMD evaluation. With a median time of 47 days (40-67 days) following infusion, 6 patients in CR (including 1 MRD +CR) underwent consolidation allo-HSCT, and 4/6 remained progression-free longest up to 315 days. However, 2/6 relapsed without CD7 lost on day 186 and day 200, respectively, and subsequently died. In addition, 1 CR patient died from bacterial infection on day 35. One PD patient received salvage transplantation and died from relapse on day 150. Post infusion, 9/10 patients experienced grade I cytokine release syndrome (CRS) and 1/10 had grade 3 CRS. Only 1 patient with CNS-3 experienced grade 3 neurotoxicity. By qPCR, CD7 UCAR-T cells reached a median peak level of 1.43×106 copies /μg genomic DNA (1.11×105~4.33×106)copies /μg genomic DNA, which occurred on day 12 (7-24 days). The median peak of circulating CD7 UCAR-T was 47.6% (0.01%~83.9%) occurring on day 7 (6-19 days), as measured by flow cytometry (Figure.1). Conclusions Our phase I trial showed that the allogeneic "off-the-shelf” RD13-01 product was safe and dose-dependently effective in treating patients with heavily pretreated T-ALL/LBL, including those with EMD and prior allo-HSCT, those who already failed autologous CD7 CAR-T therapy, and who could not manufacture autologous CAR-T from the patient's own PB due to high blasts in PB and those with rapid disease progression. Long-term observation and more patients are needed to further evaluate the safety and efficacy of CD7 UCAR-T cells. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Clinical experience with venetoclax in patients with newly diagnosed, relapsed, or refractory acute myeloid leukemia

BackgroundDiagnosis of acute myeloid leukemia (AML) is associated with poor outcome in elderly and unfit patients. Recently, approval of the BCL-2 inhibitor venetoclax (VEN) in combination with hypo-methylating agents (HMA) led to a significant improvement of response rates and survival. Further, application in the relapsed or refractory (r/r) AML setting or in context of allogeneic stem cell transplantation (alloHSCT) seems feasible.Methods and patientsFifty-six consecutive adult AML patients on VEN from January 2019 to June 2021 were analyzed retrospectively. Patients received VEN either as first-line treatment, as subsequent therapy (r/r AML excluding prior alloHSCT), or at relapse after alloHSCT. VEN was administered orally in 28-day cycles either combined with HMA or low-dose cytarabine (LDAC).ResultsAfter a median follow-up of 11.5 (range 6.1–22.3) months, median overall survival (OS) from start of VEN treatment was 13.3 (2.2–20.5) months, 5.0 (0.8–24.3) months and 4.0 (1.5–22.1) months for first-line, subsequent line treatment and at relapse post-alloHSCT, respectively. Median OS was 11.5 (10–22.3) months from start of VEN when subsequent alloHSCT was carried out. Relapse-free survival (RFS) for the total cohort was 10.2 (2.2 – 24.3) months. Overall response rate (composite complete remission + partial remission) was 51.8% for the total cohort (61.1% for VEN first-line treatment, 52.2% for subsequent line and 42.8% at relapse post-alloHSCT). Subgroup analysis revealed a significantly reduced median OS in FLT3-ITD mutated AML with 3.4 (1.9–4.9) months versus 10.4 (0.8–24.3) months for non-mutated cases, (HR 4.45, 95% CI 0.89–22.13, p = 0.0002). Patients harboring NPM1 or IDH1/2 mutations lacking co-occurrence of FLT3-ITD showed a survival advantage over patients without those mutations (11.2 (5–24.3) months versus 5.0 (0.8–22.1) months, respectively, (HR 0.53, 95% CI 0.23 – 1.21, p = 0.131). Multivariate analysis revealed mutated NPM1 as a significant prognostic variable for achieving complete remission (CR) (HR 19.14, 95% CI 2.30 – 436.2, p < 0.05). The most common adverse events were hematological, with grade 3 and 4 neutropenia and thrombocytopenia reported in 44.6% and 14.5% of patients, respectively.ConclusionDetailed analyses on efficacy for common clinical scenarios, such as first-line treatment, subsequent therapy (r/r AML), and application prior to and post-alloHSCT, are presented. The findings suggest VEN treatment combinations efficacious not only in first-line setting but also in r/r AML. Furthermore, VEN might play a role in a subgroup of patients with failure to conventional chemotherapy as a salvage regimen aiming for potential curative alloHSCT.

First-in-Human Clinical Study of a Novel CD7-Targeted Chimeric Antigen Receptor (CAR)-T Cell Therapy for Refractory/Relapsed Mixed Phenotype Acute Leukemia (MPAL)

IntroductionMixed phenotype acute leukemia (MPAL) is a rare subtype of acute leukemia with features of both acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). The blast cells of MPAL express multilineage immunophenotypic markers and may have a shared B/T/myeloid phenotype. CD7 is expressed by the leukemic blasts and malignant progenitor cells of approximately 30% of AML patients. MPAL is usually associated with a relatively poor prognosis which is even worse compared to either AML or ALL, and even among patients that undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT), underscoring the need for new therapies for these patients. CAR-T cell therapy has shown to be efficacious with a tolerable safety profile in a subset of hematological malignancies. Here, we explored the safety and efficacy of CAR-T therapy in treating refractory/relapsed (r/r) MPAL patients with CD7-positive in a phase I dose-escalation clinical study (https://clinicaltrials.gov NCT04938115).MethodsPeripheral blood (PB) mononuclear cells were obtained from patient themselves or patient transplant donors for those who relapsed post-transplant by leukapheresis. T-cells were purified using CD3+ magnetic beads or CD4+ and CD8+ magnetic beads. The second-generation CD7 CAR with a 4-1BB costimulatory domain was manufactured per the manufacturer's protocol. This phase I dose escalation study was initiated to explore the safety and efficacy of CD7 CAR-T in treating patients with MPAL. Prior to the CAR-T cells infusion, patients received systemic bridging chemotherapy due to rapid disease progression and then all patients received intravenous fludarabine (30mg/m 2/d) and cyclophosphamide (300mg/m 2/d) (FC) lymphodepleting chemotherapy for 3 consecutive days (Day -5 to Day -3). The median time from leukapheresis to CAR-T cell infusion was 14 days.ResultsFrom Nov. 2020 to June 2021, 5 adult acute leukemia patients with CD7-positive (4 MPAL, 1 FLT3-mutated AML) were enrolled and infused with CD7 CAR T-cells, one with a low-dose (1.5×10 5/kg), 2 with a medium dose (5.0×10 5/kg), and 3 with a high dose infusion (1.0×10 6/kg). The median transduction efficiency of products was 70.4% (range: 32.0%-96.9%). As of July 30, 2021 cut-off date, the median observation time was 37 days (range: 35-232 days). Characteristics of enrolled patients are shown in Table 1. The median age was 33 years (range: 21-37 years), and the median bone marrow (BM) blasts percentage by morphology was 28.0% (range: 2.5-51.5%) at enrollment. Four patients had prior allo-HSCT history including one who had extramedullary disease (EMD) who relapsed following a 2 nd transplant and had also received CD19 CAR-T cell therapy prior to enrollment in the current trial. The median interval period from prior transplant to CD7 CAR-T cell infusion was 16 months (range: 8-23 months). Following infusion, the median peak of circulating CD7 CAR-T cell was 1.17×10 5copies/μg (0.651~7.04×10 5copies/μg) genomic DNA which occurred around Day 21 (Day14 - Day21) and 59.2% (4.28%~74.58%) occurring on Day18 (Day11-Day21) by q-PCR and flow cytometry respectively (Fig.1).Four weeks post CD7 CAR-T cell infusion, 4/5 patients achieved complete remission (CR) or CR with incomplete blood recovery (CRi) in BM and all achieved minimal residual disease (MRD)-negative CR. One patient who relapsed post 2 nd transplant, also with EMD, achieved CR in BM, however, remission was not achieved in EMD through PET-CT evaluation on Day 35.One MRD-negative CR patient subsequently underwent consolidative allo-HSCT 120 days post CD7 CAR T-cell infusion and has remained in MRD-negative CR. Other 3 patients without consolidative allo-HSCT remained in MRD-negative CR till the last follow-up. All 5 patients developed cytokine release syndrome (CRS)-three of 5 patients had grade I CRS, one patient had grade II and one patient had grade III CRS. None of the patients had neurotoxicity. Among the 4 patients who had prior allo-HSCT, 1 developed grade I graft-versus-host disease post CAR-T therapy.ConclusionThis study demonstrated that CD7-targeted CAR-T therapy offers an opportunity to achieve CR for CD7-positive MPAL patients even for those who relapsed post-transplant. Safety was manageable, however, more data on additional patients and longer observation times are needed to further evaluate the efficacy of CD7 CAR-T products. [Display omitted] DisclosuresBa: SenlangBio: Current Employment.

High Effectiveness and Safety of Anti-CD7 CAR T-Cell Therapy in Treating Relapsed or Refractory (R/R) T-Cell Acute Lymphoblastic Leukemia (T-ALL)

BackgroundCompared with the substantial efficacy of chimeric antigen receptor T-cell (CAR-T) therapy that has achieved in B-ALL, whether CAR-T therapy is effective and safe for patients with T-ALL is still being explored in early stage clinical trials. Here, we present outcomes from our phase 1 clinical trial of CD7-targeting CAR-T (CD7CAR) cells therapy for R/R T-ALL (NCT04572308).MethodsPeripheral blood (PB) mononuclear cells were obtained by leukapheresis. T cells were separated and transduced with lentivirus. The second-generation CD7CAR is composed of an anti-CD7 single-chain antibody, a IgG4 hinge region, a CD28TM transmembrane domain, an intracellular co-stimulatory domain of 4-1BB and CD3ζ, and the truncated EGFR protein linked by T2A. All patients received intravenous fludarabine (30 mg/m 2/d) and cyclophosphamide (300 mg/m 2/d) for 3 days prior to CD7CAR infusion.ResultsSeventeen R/R T-ALL patients were enrolled between December 2020 and June 2021. Characteristics of patients are shown in Table 1. Data from 14 patients with a median age of 17 years (range: 3-42 years) were available for evaluation. The rest 3 patients were withdrawn from study within 14 days due to rapid disease progression. High-risk subtype patients enrolled including 1 with Ph-positive T-ALL and 3 with early T-cell precursor (ETP)-ALL. Seven of the 14 patients also had high-risk genotypes, namely SIL-TAL1, EZH2, TP53, RUNX1, BCR-ABL, JAK1 and JAK3. At enrollment, the median percentage of bone marrow (BM) blasts was 11.53% (range: 0.18%-65.03%), and 5 of 14 patients had extramedullary involvements, including optic nerve involvement (N=2), central nervous system leukemia (N=3), diffuse extramedullary involvements (N=2), and bulky lymph nodes in the neck (N=1). Patients were heavily pretreated with a median of 5 prior lines of therapies (range: 3-8 lines) and three relapsed from prior allogeneic hematopoietic stem cell transplantation (allo-HSCT).CD7CAR-T cells were 100% successfully manufactured with a transfection efficiency of 93.8% (range: 59.6%-99.9%). Twelve of 14 participants received bridging chemotherapy. A single dose of CD7CAR-T cells was infused to patients, with 2 receiving a low-dose (0.5x10 5 cells/kg), 11 receiving a medium dose (1-1.5x10 6 cells/kg) and 1 receiving a high-dose (2x10 6 cells/kg).By the data cutoff date (July 12, 2021), the median follow-up time was 105 days (range: 32-206 days, Fig.1A). By day 28 post infusion, 92.9% (13/14) of patients achieved complete remission (CR, N=4) or CR with incomplete hematological recovery (CRi, N=9) in their BM, with all 13 patients achieving minimal residual disease (MRD) negative CR/CRi. Additionally, 4/5 patients with extramedullary involvement also achieved extramedullary remission at a median of day 32 (range: 28-90 days) post infusion. Consolidation allo-HSCT was permitted at the treatment physician's discretion and the patient's preference. A total of 11/14 patients were bridged to consolidation allo-HSCT at a median of 57 days post CD7CAR infusion, of which 9 patients have remained MRD-negative CR/CRi. One patient who had allo-HSCT prior to CD7CAR infusion died following a second haplo-HSCT due to acute graft-versus-host disease. Of the other 3 patients who were not bridged to allo-HSCT, 1 patient relapsed on day 28 due to rapid disease progression after initial CRi on day 14. Thirteen of 14 patients experienced mild CRS (Grade ≤2). One patient had Grade 3 CRS. The median time to onset of CRS was 1 day (range: 0-11 days), with a median duration of 14 days (range: 3-25 days). Neurotoxicity (Grade 1) occurred in only 1 patient.After infusion, the median peak of CAR-T copy number was 2.38 ×10 5copies/µg DNA (range: 0.2-6.67 ×10 5 copies/µg DNA), which occurred on day 20 (range: 10-42 days, Fig.1B). Importantly, CD7CAR persisted well in PB at a median of 52.5 days (range:20-120 days) at last evaluation regardless of transplantation status. Maximum proportion of CD7CAR-T cells proliferation reached 84.95% by flow cytometry (Fig.1C).ConclusionsOur results demonstrate that CD7CAR therapy is safe and highly effective in treating patients with heavily pretreated R/R T-ALL, including those with extramedullary involvements, a history of prior allo-HSCT or with high-risk subtypes. More patients and a longer observation time are needed to further evaluate the potential beneficial advantages and side effects of CD7CAR therapy for T-ALL patients. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Granulocyte Transfusions for Neutropenic Patients Receiving Allogeneic Hematopoietic Stem Cell Transplantation

Background: Granulocyte transfusion (GTX) have been used to prevent or treat life-threatening infection in patients with severe neutropenia, especially after allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, there remains the paucity of data about clinical benefit of GTX after allo-HSCT.Material and methods: We retrospectively analyzed the transplant outcomes of allo-HSCT patients who underwent GTX in our institution between 2012 and 2016. Overall survival (OS) was estimated by Kaplan-Meier and were compared using the log-rank method. The cumulative incidences of neutrophil engraftment, non-relapse mortality (NRM), relapse, and acute graft-versus-host disease (aGVHD) were evaluated using Gray's method. Pearson's correlation coefficient was used to analysis relationship between transfused granulocyte cells and absolute white blood cells (WBC) increment.Results: A total of 13 patients received 40 times GTX after allo-HSCT. Median interval between allo-HSCT and the first GTX was 10.5 (range, -8 to 80) days. Seven patients who had infection prior allo-HSCT were received GTX as a planned strategy (planned-GXT group) and 6 patients who suffered from infection after allo-HSCT were treated with GTX (non-planned GXT group). Median age of patients was 58 (range, 30-68) and the underlying disease was predominantly acute myeloid leukemia. Average number of transfused granulocyte was 0.70 (range, 0.10 - 1.61) x 109/kg and median transfusion per patient was 2 (range, 1-6). Median WBC increment one day after GTX was 515 (range, 20-5,090)/μl and WBC increment was significantly correlated with infused granulocyte dosage (p = 0.0054). Average C-reactive protein at GTX and one day after GTX were 11.36mg/dl and 11.01mg/dl, respectively. Neutrophil engraftment rate at 60 days after allo-HSCT was 53.8%. Overall survival (OS) at day 28 and 1 year after GTX were 84.6% and 15.4%, respectively. The incidence of 1-year NRM, 1- year CIR, grade II to IV aGVHD, and grade III to IV aGVHD were 69%, 15%, 39%, and 31%, respectively. Regarding survival, the planned GTX group showed relatively higher OS than the non-planned GTX group (1-y OS, planned GTX group vs. non-planned GXT group, 28.6% vs. 0%, p = 0.062). Infection was the leading cause of death (n = 4), but no patient died by primary infection during neutropenia. Engraftment failure (n =2), organ failure (n = 2), recurrence of underlying disease (n = 2) and acute graft-versus-host disease (n = 1) were followed.Conclusions:Successful WBC increment by GTX might prevent to progress infection during neutropenia period without severe adverse event. Patients with uncontrolled infection before allo-HSCT could get the benefits from GTX as a planned strategy. GTX provide the chance for patients with prior history or active infection to receive allo-HSCT. [Display omitted] DisclosuresNishimori:Toko Pharmaceutical Industries: Other: Investigational drug is provided free of charge.. Maeda:Toko Pharmaceutical Industries: Other: Investigational drug is provided free of charge.

Lung transplantation for late-onset non-infectious chronic pulmonary complications of allogenic hematopoietic stem cell transplant

BackgroundLate onset non-infectious pulmonary complications (LONIPCs) following allogenic hematopoietic stem cell transplantation (allo-HSCT) confer a significant mortality risk. Lung transplantation (LTx) has the potential to provide survival benefit but the impact of prior allo-HSCT on post-LTx outcomes is not well studied.MethodsThis retrospective, single-centre cohort study assessed the post-LTx outcomes of adults with LONIPCs of allo-HSCT. Outcomes of LTx for LONIPCs were compared to propensity-score matched LTx controls (n = 38, non-HSCT) and recipients of re-LTx (n = 70) for chronic lung allograft dysfunction (CLAD).ResultsNineteen patients underwent DLTx for LONIPCs of allo-HSCT between 2003 and 2019. Post-LTx survival was 50% at 5-years. Survival to 1-year post-LTx was similar to matched controls (p = 0.473). Survival, conditional on 1-year survival, was lower in the allo-HSCT cohort (p = 0.034). An increased risk of death due to infection was identified in the allo-HSCT cohort compared to matched controls (p = 0.003). Compared to re-LTx recipients, the allo-HSCT cohort had superior survival to 1-year post-LTx (p = 0.034) but conditional 1-year survival was similar (p = 0.145).ConclusionThis study identifies an increased risk of post-LTx mortality in recipients with previous allo-HSCT, associated with infection. It supports the hypothesis that allo-HSCT LTx recipients are relatively more immunosuppressed than patients undergoing LTx for other indications. Optimisation of post-LTx immunosuppressive and antimicrobial strategies to account for this finding should be considered.

Blinatumomab as first salvage versus second or later salvage in adults with relapsed/refractory B-cell precursor acute lymphoblastic leukemia: Results of a pooled analysis.

Background Blinatumomab is a BiTE® immuno‐oncology therapy indicated for the treatment of patients with relapsed or refractory (r/r) B‐cell precursor (BCP) acute lymphoblastic leukemia (ALL).AimsTo assess the efficacy and safety of blinatumomab as first salvage versus second or later salvage in patients with r/r BCP ALL.Materials & MethodsPatient‐level pooled data were used for this analysis. In total, 532 adults with r/r BCP ALL treated with blinatumomab were included (first salvage, n = 165; second or later salvage, n = 367).ResultsCompared with patients who received blinatumomab as second or later salvage, those who received blinatumomab as first salvage had a longer median overall survival (OS; 10.4 vs. 5.7 months; HR, 1.58; 95% CI, 1.26–1.97; P < .001) and relapse‐free survival (10.1 vs. 7.3 months; HR, 1.38; 95% CI, 0.98–1.93; P = .061), and higher rates of remission (n = 89 [54%] vs. n = 150 [41%]; odds ratio, 0.59; 95% CI, 0.41–0.85; P = .005), minimal residual disease response (n = 68 [41%] vs. n = 118 [32%]), and allogeneic hematopoietic stem cell transplant (alloHSCT) realization (n = 60 [36%] vs. n = 88 [24%]), and alloHSCT in continuous remission (n = 33 [20%] vs. n = 52 (14%]). In a subgroup analysis, there was no apparent effect of prior alloHSCT on median OS in either salvage group. The safety profile of blinatumomab was generally similar between the groups; however, cytokine release syndrome, febrile neutropenia, and infection were more frequent with second or later salvage than with first salvage.DiscussionIn this pooled analysis, the logistic regression analyses indicated greater benefit with blinatumomab as first salvage than as second or later salvage, as evident by the longer median OS, longer median RFS, and higher rates of remission.ConclusionOverall, blinatumomab was beneficial as first salvage and as second or later salvage, but the effects were favorable as first salvage.

1087. Evaluation of Risk Factors for Infection among Patients Receiving Ibrutinib

BackgroundIbrutinib is a small-molecule inhibitor of Bruton tyrosine kinase (BTK) approved for various B-cell malignancies and cGVHD. Rates of serious infection—defined as requiring hospitalization or parenteral antimicrobials— and invasive fungal infection (IFI) in patients on ibrutinib are as high as 11.4% and 4.2% respectively (Varughese T, et al. Clin Infect Dis 2018;67(5):687-92), which may be related to off-target inhibition of interleukin-2-inducible T-cell kinase or macrophage function.MethodsWe retrospectively reviewed infection complications in patients receiving ibrutinib at our institution between 06/01/2014 and 08/31/2019, including patients who received single-agent or combination ibrutinib. In this study, serious infection was defined as above, or a diagnosis of pneumonia regardless of hospitalization or parenteral antimicrobial therapy. Logistic regression was used to identify risk factors.ResultsBaseline characteristics of 134 included patients are in Table 1. Infection and serious infection occurred in 96 (72%) and 48 (36%) patients, respectively. When pneumonia was not included as a criterion for serious infection, the serious infection rate was 22%. Prior allogeneic stem cell transplant (allo-HSCT) (OR 4.50; 95% CI 1.19 – 17.00) and corticosteroid use (OR 5.42; 95% CI 1.49 – 19.82) were significant risk factors for serious infection without pneumonia (Table 2).Of 37 patients (28%) who received primary HSV/VZV prophylaxis with acyclovir, there was one case of suspected herpes zoster infection (3%). IFI developed in 7 patients (5%): 5 with Pneumocystis jirovecii pneumonia (PJP), 1 with invasive aspergillosis, and 1 with a filamentous fungus, species unknown. Other identified organisms are detailed in Figure 1. Classical risk factors for IFI, including diabetes, allo-HSCT, and concurrent corticosteroid use, were not significant predictors in this group.Table 1. Baseline Characteristics Table 2. Risk Factor Analysis Figure 1. Identified Organisms in Serious Infection ConclusionSerious infections developed at a higher rate than previously reported in the literature, with IFI rates similar to those previously described. Prior allo-HSCT and steroid use were found to be risk factors for serious infection without pneumonia. Treating physicians should have a high index of suspicion for pneumonia, IFI, and PJP in this population.Disclosures All Authors: No reported disclosures

Pseudo-Allogeneic CAR-T Therapy after Allogeneic Stem Cell Transplantation in Relapsed/Refractory B-Cell NHL

Introduction Chimeric antigen receptor T-cell (CAR-T) therapy has emerged as a powerful therapy for relapsed and refractory (R/R) B-cell malignancies. A growing body of research suggests that CAR-T therapy can be safe and effective in patients who have previously received allogeneic hematopoietic stem cell transplantation (alloHSCT). "Pseudo-allogeneic" CAR-T therapy refers to manufacture of engineered T-cells collected from an alloHSCT recipient exhibiting 100% donor chimerism. This CAR-T approach poses theoretical risks due to alloreactivity and increased CAR-T toxicity. Most studies to date in this area have enrolled patients with leukemia. We present here a single-center experience with pseudo-allogeneic CAR-T following alloHSCT in 6 patients with large B-cell lymphoma (LBCL). Patients and Methods Patients with R/R LBCL who underwent treatment with axicabtagene ciloleucel (axi-cel) CAR-T after prior alloHSCT were identified. All patients underwent lymphodepletion with cyclophosphamide and fludarabine prior to CAR-T infusion. CAR-T toxicities, namely cytokine release syndrome (CRS) and immune effector-cell associated neurotoxicity syndrome (ICANS) were graded in accordance with the 2019 American Society for Transplantation and Cellular Therapy (ASTCT) consensus grading. Results Six patients who underwent axi-cel CAR-T due to post-alloHSCT R/R LBCL were identified. All patients had stage ≥II disease. At the time of CAR-T apheresis, all patients had ≥95% donor chimerism and were off immunosuppression, without evidence of GVHD. Manufacturing failure occurred in only one patient (case 2) due to low viability and upon second apheresis, manufacture was successful. All 6 pseudo-allogeneic CAR-T therapy patients tolerated infusion and did not show increased incidence or severity of CRS or ICANS compared to our center's experience with standard CAR-T patients, with only one patient experiencing greater than grade 2 toxicity. Three of six patients developed graft-versus-host disease (GVHD); however, one case was in the setting of PD-1 blockade and two were isolated cutaneous manifestations. There was no incidence of severe GVHD. All three cases of GVHD underwent CAR-T within ten months after alloHSCT, whereas the three patients without GVHD were &amp;gt;1 year post-HSCT at time of CAR-T. Two cases who had donor lymphocyte infusions prior to CAR-T did not develop GVHD. In terms of efficacy, three patients achieved a complete remission. There was no perceptible relationship between the development of GVHD and the response to CAR-T. Four of six had cytopenias at day 30 after CAR-T, with only two exhibiting persistent cytopenias at day 90. Lastly, in this small sample size, no differences were seen in incidence of GVHD or treatment response between haploidentical, matched-related, and matched-unrelated alloHSCT donors. Conclusion In our experience, pseudo-allogeneic CAR-T therapy following alloHSCT appears to be a safe and well-tolerated treatment modality for R/R B-cell lymphoma. The efficacy of this modality will need to be borne out in further studies. Disclosures No relevant conflicts of interest to declare.

Feasibility, and Efficacy of Donor-Derived cd19-Targeted Car t-Cell Therapy in Refractory/Relapsed(r/r)b-Cell Acute Lymphoblastic Leukemia (b-all) Patients

Backgrounds As CAR T-cell therapy is a highly personalized therapy, process of generating autologous CAR-T cells for each patient is complex and can still be problematic, particularly for heavily pre-treated patients and patients with significant leukemia burden. Here, we analyzed the feasibility and efficacy in 37 patients with refractory/relapsed (R/R) B-ALL who received CAR T-cells derived from related donors. Patients and Methods From April 2017 to May 2020, 37 R/R B-ALL patients with a median age of 19 years (3-61 years), were treated with second-generation CD19 CAR-T cells derived from donors. The data was aggregated from three clinical trials (www.clinicaltrials.gov NCT03173417; NCT02546739; and www.chictr.org.cn ChiCTR-ONC-17012829). Of the 37 patients, 28 were relapsed following allogenic hematopoietic stem cell transplant (allo-HSCT) and whose lymphocytes were collected from their transplant donors (3 HLA matched sibling and 25 haploidentical). For the remaining 9 patients without prior transplant, the lymphocytes were collected from HLA identical sibling donors (n=5) or haploidentical donors (n=4) because CAR-T cells manufacture from patient samples either failed (n=5) or blasts in peripheral blood were too high (&amp;gt;40%) to collect quality T-cells. The median CAR-T cell dose infused was 3×105/kg (1-30×105/kg). Results For the 28 patients who relapsed after prior allo-HSCT, 27 (96.4%) achieved CR within 30 days post CAR T-cell infusion, of which 25 (89.3%) were minimal residual disease (MRD) negative. Within one month following CAR T-cell therapy, graft-versus-host disease (GVHD) occurred in 3 patients including 1 with rash and 2 with diarrhea. A total of 19 of the 28 (67.9%) patients had cytokine release syndrome (CRS), including two patients (7.1%) with Grade 3-4 CRS. Four patients had CAR T-cell related neurotoxicity including 3 with Grade 3-4 events. With a medium follow up of 103 days (1-669days), the median overall survival (OS) was 169 days (1-668 days), and the median leukemia-free survival (LFS) was 158 days (1-438 days). After CAR T-cell therapy, 15 patients bridged into a second allo-HSCT and one of 15 patients (6.7%) relapsed following transplant, and two died from infection. There were 11 patients that did not receive a second transplantation, of which three patients (27.3%) relapsed, and four parents died (one due to relapse, one from arrhythmia and two from GVHD/infection). Two patients were lost to follow-up. The remaining nine patients had no prior transplantation. At the time of T-cell collection, the median bone marrow blasts were 90% (range: 18.5%-98.5%), and the median peripheral blood blasts were 10% (range: 0-70%). CR rate within 30 days post CAR-T was 44.4% (4/9 cases). Six patients developed CRS, including four with Grade 3 CRS. Only one patient had Grade 3 neurotoxicity. No GVHD occurred following CAR T-cell therapy. Among the nine patients, five were treated with CAR T-cells derived from HLA-identical sibling donors and three of those five patients achieved CR. One patient who achieved a CR died from disseminated intravascular coagulation (DIC) on day 16. Two patients who achieved a CR bridged into allo-HSCT, including one patient who relapsed and died. One of two patients who did not response to CAR T-cell therapy died from leukemia. Four of the nine patients were treated with CAR T-cells derived from haploidentical related donors. One of the four cases achieved a CR but died from infection on day 90. The other three patients who had no response to CAR T-cell therapy died from disease progression within 3 months (7-90 days). Altogether, seven of the nine patients died with a median time of 19 days (7-505 days). Conclusions We find that manufacturing CD19+ CAR-T cells derived from donors is feasible. For patients who relapse following allo-HSCT, the transplant donor derived CAR-T cells are safe and effective with a CR rate as high as 96.4%. If a patient did not have GVHD prior to CAR T-cell therapy, the incidence of GVHD following CAR T-cell was low. Among patients without a history of transplantation, an inability to collect autologous lymphocytes signaled that the patient's condition had already reached a very advanced stage. However, CAR T-cells derived from HLA identical siblings can still be considered in our experience, no GVHD occurred in these patients. But the efficacy of CAR T-cells from haploidentical donors was very poor. Disclosures No relevant conflicts of interest to declare.

PRS14 THE ECONOMIC BURDEN OF BRONCHIOLITIS OBLITERANS SYNDROME (BOS) IN ALLOGENIC HEMATOPOIETIC STEM CELL TRANSPLANT (ALLOHSCT) PATIENTS WITH MEDICARE COVERAGE

Bronchiolitis Obliterans Syndrome (BOS) is a rapidly progressive obstructive airway disease characterized by T-cell mediated inflammation and fibrosis which leads to respiratory failure and death with a 5 year survival of 13% in allogenic HSCT (alloHSCT). This study characterized healthcare resource use and costs in alloHSCT Medicare patients who developed BOS. The data source for this retrospective longitudinal study was the Medicare Limited Dataset; study timeframe was 01/01/2010-12/31/2017. Study participants were age-eligible (>=65yrs) and disability-eligible (<65yrs) fee-for-service beneficiaries with an index BOS diagnosis (ICD-9: 491.8, 491.9, 515, 516.34, 561.8; ICD-10: J41.8, J42, J84.09, J84.89, and J84.115), and prior alloHSCT. Outcome measures were patient characteristics, costs paid by Medicare, and healthcare resource utilization in patients who survived at least 1 year. Analyses were repeated for patients who survived 2 and 3 years. Among 2,022 patients, 41% were female; mean age was 62.1yrs (SD:12.5); 42.6% (N=861) were <65yrs. Mean per-patient costs in the first post-BOS diagnosis year were $47,737 (SD:66,300). Among those who survived, costs declined to $22,782 (SD:48,920; N=1,436) in year 2 and $12,519 (SD:35,195; N=939) in year 3. Inpatient admissions averaged $27,842 (SD:51,770) per-patient in the first year post-diagnosis, decreasing to $11,239 (SD:34,761) in year 2 and $6,499 (SD:23,856) in year 3. Mean per-patient hospitalization rates in the first post-diagnosis year were 1.6 (SD: 2.0), declining to 0.7 (SD:1.6) in year 2 and 0.4 (SD:1.2) in year 3. Mean length of hospital stay 21.2 (SD:29.1), 17.8 (SD:31.3) and 16.4 (SD:19.8) days in years 1,2, and 3, respectively. More than 2 in 5 Medicare alloHSCT patients who develop BOS are age <65 disability-eligible patients. Inpatient costs underlie approximately half of the economic burden of BOS over time. The yearly decline in costs reflects decreasing hospitalization rates and may reflect survival of healthier patients.

Largest Single Center Experience Using Dual T-Cell Depletion with ATG and Ptcy for Gvhd Prophylaxis in Peripheral Blood RIC Allo-HSCT

Introduction: Dual T-cell depletion with ATG and PTCy combined with cyclosporine (CsA) in peripheral blood (PB) reduced intensity conditioning (RIC) allo-HSCT results in an impressive control of clinically relevant GVHD. We aim to share the largest and unique single center experience using this novel GVHD combination in allo-HSCT for hematological malignancies. Methods Between October 2015 and April 2019, 365 consecutive adult recipients underwent PB RIC allo-HSCT. Conditioning regimen consisted on fludarabine, busulfan and 200 cGy of total body irradiation. For GVHD prophylaxis all cases received ATG, PTCy (50mg/kg/24h x 2 doses on day +3 and +4) and CsA since day +5. Two hundred fifty-nine (71%) recipients, transplanted between 2015 and May 2018, received a total dose of 4.5mg/kg of rabbit-ATG (given on day -3,-2 and -1). In May 2018, the protocol was reviewed and refined decreasing the dose of ATG to a total of 2mg/kg (given on day -3 and -2). A total of 106 (29%) recipients received the lowered dose of ATG. Data was collected retrospectively and updated on July 2019. Cumulative incidence (Cum.Inc) of GVHD, CMV and EBV reactivation analysis was assessed accounting relapse and death as competing events. The multivariate analysis for OS and RFS was controlled by the following significant variables in the univariate analysis: age at transplant, disease risk index (DRI) (low and moderate v's high and very high), Karnofsky performance status (&gt;80% v's ≤80%), HCT-CI score ≥3 and donor type. Results Baseline characteristics and main post-transplant information and outcome are summarized in Table 1 and 2. The cum.Inc of grade II-IV and grade III-IV at day +100 was respectively 14% (95 confidence interval (CI) 11.1-18.4) and 4.7% (95% CI 2.8-7.2). The cum.Inc of moderate and severe chronic GVHD at 1 year was 13% (95% CI 9.7-16.8). ATG dose and donor type did not influence acute/chronic GVHD rates (Table 3). The cum.Inc of CMV and EBV reactivation at day +180 was comparable between the two cohorts that received different dose of ATG (P&gt;0.05). However, in the cohort that received a lower dose of ATG (2mg/kg), no CMV disease was documented and the percentage of probable or proven EBV-post-transplant lymphoprolipherative disease (P/P-PTLD) was only 3.7%. The percentages of CMV disease and P/P-PTLD in the group that received a dose of ATG of 4.5 mg/kg were respective 4.6% and 8.8%. Overall survival (OS), relapse-free survival (RFS), non-relapse mortality (NRM) and the cumulative incidence (cumInc) of acute GVHD of the entire cohort and according to the ATG dose are shown in the Table 2 and the Table 3. OS and RFS curves of all 365 patients and stratified according to donor type are shown in the Plots 1 to 4. In the multivariate analysis, age at transplant [(HR 1 (95% CI 1.01-1.02); P=0.046], high and very high DRI score [HR 1.8 (95% CI 1.2-3.6); P=0.001], KPS ≤80% [HR 1.8 (95% CI 1.2-2.7); P=0.001], and HCT-CI score ≥3 [HR 1.4 (95% CI 1.01-2.09); P=0.042] were significant risk factors for worse OS. Donor type was not a significant parameter for OS (P&gt;0.05). In the multivariate analysis of risk factors for RFS, high DRI score [HR 1.7 (95% CI 1.2-2.4); P=0.002], and a KPS ≤80% prior allo-HSCT [HR 2 (95% CI 1.4-2.8); P&lt;0.001] were significant risk factors for worse RFS. To receive grafts from a 10/10 MUD was a significant parameter for better RFS [HR 0.6 (95% CI 0.4-0.9); P=0.046]. Conclusions Dual T-cell depletion with ATG and PTCy provides an impressive control of GVHD with acceptable relapse rates using PB stem cell grafts independently of the donor type. This observation suggests that the present combination overcomes the HLA-barrier and its effect on GVHD. Acute GVHD rates are effectively controlled with a dose of ATG of only 2mg/kg when it is combined with PTCy and CsA. Further investigations need to be done to better define the efficacy of a lower dose of ATG controlling chronic GVHD in this setting. Further investigations and refinements need to be done to improve survival rates in those recipients with higher DRI score and worse KPS ≤80% prior transplantation. Disclosures Michelis: CSL Behring: Other: Financial Support. Mattsson:Gilead: Honoraria; Therakos: Honoraria; Celgene: Honoraria.

Pivotal Safety and Efficacy Results from Transcend NHL 001, a Multicenter Phase 1 Study of Lisocabtagene Maraleucel (liso-cel) in Relapsed/Refractory (R/R) Large B Cell Lymphomas

Pivotal Safety and Efficacy Results from Transcend NHL 001, a Multicenter Phase 1 Study of Lisocabtagene Maraleucel (liso-cel) in Relapsed/Refractory (R/R) Large B Cell Lymphomas

Health-Related Quality of Life of Blinatumomab for Relapsed or Refractory B-Cell Precursor Acute Lymphoblastic Leukemia in a Randomized, Open-Label Phase 3 Study (TOWER): A Subgroup Analysis By Prior Allogeneic Hematopoietic Stem Cell Transplantation

Background In the phase 3 TOWER study, patients with relapsed or refractory (r/r) Ph– B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) who received blinatumomab had longer overall survival and improved health-related quality of life (HRQoL) versus patients who received standard of care chemotherapy (SOC). Because ALL patients who relapse from previous hematopoietic stem cell transplantation (HSCT) have poorer prognosis, we analyzed the HRQoL of TOWER patients with or without prior allogeneic HSCT (alloHSCT). Methods Adults (n=405) with r/r Ph– BCP ALL were randomized 2:1 to 2 cycles of induction blinatumomab (n=271) or SOC (n=134), followed by up to 3 consolidation cycles; 12 months of maintenance was allowed. AlloHSCT was allowed after cycle 1. HRQoL was assessed in cycle 1 (days 8, 15, and 29) using the EORTC QLQ-C30 Questionnaire. For global health status and functioning scales, a higher score indicates better HRQoL; for symptom scales/items, a lower score indicates better HRQoL. Time to deterioration analyses assessed the treatment effect based on a 10-point deterioration (clinically significant threshold) from baseline. Results Of 342 evaluable patients (blinatumomab, n=247; SOC, n=95); 114 (blinatumomab, n=85; SOC, n=29) and 228 (blinatumomab, n=162; SOC, n=66) did and did not, respectively, have prior alloHSCT. In those with no prior alloHSCT, changes in global health status were minimal for blinatumomab and SOC (Figure 1). In contrast, in patients with prior alloHSCT, global health status modestly improved in the blinatumomab group but worsened by ≥10 points at all time points for SOC, indicating clinically meaningful deterioration. Changes in functioning scales were minimal in the blinatumomab arm, both with or without prior alloHSCT, except for relatively improved emotional scores in patients with prior alloHSCT. In contrast, SOC patients had worsening in most functioning scales, regardless of prior alloHSCT status. This effect was most marked in those with prior alloHSCT, in whom physical, role, and social functioning deteriorated by ≥10 points. Similar patterns were observed for symptom scales/items: while blinatumomab was associated with improved or less worsening in symptom scores versus SOC, most symptom scores worsened in the SOC arm, especially in patients with prior alloHSCT, for whom all symptoms (except dyspnea) deteriorated by ≥10 points. Compared with SOC, blinatumomab was associated with a delayed time to clinically meaningful deterioration, particularly in patents with prior alloHSCT (Figure 2). Conclusions In patients with r/r Ph– BCP ALL, blinatumomab was associated with improved HRQoL compared with SOC, regardless of whether patients had received prior alloHSCT. Notably, however, the HRQoL benefit of blinatumomab was most pronounced among patients with prior alloHSCT.