Doses Of Donor Lymphocyte Infusions Research Articles

Randomized Trial of Prophylactic Donor Lymphocyte Infusion with Positively Selected CD4+ T Cells after HLA-Identical Allogeneic Stem Cell Transplantation

Introduction Allogeneic stem cell transplantation (alloSCT) can cure patients with hematological malignancies by T-cell mediated alloreactivity against patient hematopoiesis, the graft-versus-leukemia (GvL) effect. GvL can coincide with graft-versus-host disease (GvHD) when donor T cells target non-hematopoietic tissues. Increase of donor chimerism in bone marrow (BM) or peripheral blood (PB) after alloSCT indicates GvL response. After T-cell depleted alloSCT, donor lymphocyte infusion (DLI) can restore GvL. Dose and timing of DLI influence the degree of alloreactivity. Low dose of unmodified DLI as low as 0.3x10 6 T cells/kg 3 months after alloSCT appeared not to cause GvHD. (Zouwen et al. Ann Hematol, 2023) We hypothesized that infusion of a higher dose of purified CD4+ donor T cells would not cause GvHD, while inducing GvL by selective targeting of the MHC class II positive hematopoietic cells. Method A randomized controlled phase 2 trial was conducted in patients with hematological malignancies after HLA-identical sibling alloSCT with alemtuzumab added to the graft. Patients without GvHD or relapse were randomized at 2.5 months for prophylactic DLI with 1.0x10 6/kg CD4+ T cells (CD4+ DLI) 3 months after alloSCT or conventional care without DLI (CC). Both groups were eligible for prophylactic unmodified DLI at 6 months. Cumulative incidence (CI) of GvHD requiring immunosuppressive treatment 3 months after randomization was the primary endpoint. Changes in the trajectory of chimerism in BM and subsets in PB (CD4+ T cells, CD8+ T cells, NK cells, B cells and monocytes) were compared by means of mixed effects beta regression as secondary endpoints. Results 66 patients were included (table 1). CI of GvHD did not differ between groups (CD4+DLI: 6.1% vs CC: 9.1%, Gray's test p>0.9). Relapse was comparable (CD4+DLI: 15% vs CC: 12%), although heterogeneity of diseases prevented a formal comparison. In the CD4+ DLI group, BM chimerism was full donor (FD, >95% donor) at baseline in 23/33 patients, while 10/33 had mixed chimerism (MC, ≤95%). In the CC group, 23/33 were FD and 10/33 MC. Some patients with MC at baseline converted to FD in both groups (CD4+ DLI: 1/10 vs CC: 1/10). Changes in BM chimerism did not differ between CD4+ DLI and CC (p = 0.9). Chimerism of B cells, NK cells and monocytes in PB resembled bone marrow chimerism with most patients being FD at baseline. Changes in chimerism did not differ between CD4+ DLI and CC (p = 1.0, 0.5 and 0.9 for B cells, NK cells and monocytes respectively). In the CD4+ DLI group, 25/30 evaluable patients were MC in the CD4+ T-cell subset in PB at baseline. 3 month after randomization 7/25 had converted to FD, 17/25 remained MC and 1/25 was unevaluable. Of the 17 patient who remained MC, CD4+ donor chimerism increased (absolute increase >5%) in 13, decreased (>5%) in 2 and was stable in 2. In the CC group, 26/32 were MC in CD4+ T cells at baseline, of which 6 converted to FD, 18 remained MC and 2 were unevaluable. Of the 18 patients remaining MC, CD4+ chimerism increased in 5, decreased in 9 and remained stable in 4. The CD4+ donor chimerism increased significantly after CD4+ DLI compared to CC (p = 0.01) (Figure 1). In the CD4+ DLI group, 23/29 evaluable patients were MC in the CD8 subset at baseline. 7/23 converted to FD, 15/23 remained MC and 1 was unevaluable. Of these 15 MC patients at 3 months, 9 had increasing, 5 stable and 1 decreasing donor chimerism after 3 months. In CC, 22/31 were MC at baseline. 4/22 converted to FD at 3 months and 17/22 remained in MC. Of the 17 MC patients, 6 had increasing, 3 decreasing and 8 stable chimerism. The CD8+ donor chimerism increased significantly in the CD4+ DLI group compared to CC (p = 0.03). Conclusion CD4+ selected DLI at a dose of 1x10 6 CD4+/kg 3 months after HLA identical T-cell depleted alloSCT did not cause GvHD. Chimerism in BM leukocytes, B cells, NK cells or monocytes did not indicate GvL mediated by CD4+ DLI, possibly because most patients were already FD at baseline. CD4+ and CD8+ T-cell donor chimerism increased significantly after CD4+ DLI, suggesting a GVL-effect - earlier demonstrated in vitro for 4 selected patients. (Van Balen et al. Front Immunol, 2018) However, most patients did not convert to FD in the T-cell compartment, suggesting the GvL-effect of CD4+ DLI was limited. We considered this GvL-effect insufficient to prevent relapse and stress the importance of CD8+ donor T cells as main drivers of alloreactivity after DLI following HLA-identical alloSCT.

Risk-Adapted Donor Lymphocyte Infusion after Hematopoietic Cell Transplant in Pediatric and Young Adult Patients Is Associated with Low Risk of Graft Versus Host Disease

Introduction: Donor lymphocyte infusion (DLI) is a form of adoptive immunotherapy administered to enhance the graft-versus-leukemia (GVL) effect after an allogeneic hematopoietic cell transplantation (HCT). DLI is frequently chosen for its ease of administration and low risk of graft ablation as compared with other chemotherapeutic options in patients experiencing mixed chimerism (MC) or disease relapse. But in patients with acute leukemia experiencing relapse, clinical responses are seen in fewer than 20-30%. Success is also limited by the occurrence of acute and chronic graft-versus-host disease (GVHD). We had previously described our risk-adapted strategy of administering DLIs based on chimerism and donor source (Rujkijyanont P, et al. Blood Cancer J 2013). To determine the efficacy and toxicity of DLIs and to identify potential factors influencing the outcomes, we conducted a retrospective single center study including patients who received DLIs after HCT. Methods: We collected data on all HCTs and conventional DLIs that had been administered to patients from 1993 to 2022 for any indication at our center. Each HCT was considered as an independent event. Numeric variables were represented by median and range and compared using the Wilcoxon-Mann-Whitney test. Categorical variables were compared using the Fisher exact test. Competing-risk regression models using the Fine-Gray method were developed to evaluate risk factors for acute GVHD and chronic GVHD. Death and relapse were considered as competing risk events for these GVHD outcomes. Follow-up data were censored at subsequent HCT, 2 years after the first DLI, 5 years after transplant, or the last follow-up. Logistic regression analysis was performed to assess factors associated with the response to DLI within 180 days after the first DLI. Results: During the study period, 236 patients received 252 HCTs followed by DLIs (median age at HCT 9.2 [range 0.2-25.1] years). An additional 743 patients received 806 HCTs with no subsequent DLI (median age at HCT 10.3 [range 0.1-27.2] years). Dosing most frequently used was 1 × 10 5, 1 × 10 6 and 1 × 10 7 CD3+ cells/kg, for haploidentical donor (HAPLO), matched unrelated donor (MUD) and matched sibling donor (MSD) recipients, respectively. Initial doses were occasionally lower based on risk of GVHD and were escalated as tolerated and based on response. After receiving DLI, 19.4% developed acute GVHD, and 9.2% developed chronic GVHD with no significant differences observed between MSD, MUD and HAPLO recipients. After adjusting for donor source, longer duration between HCT and DLI was associated with a significantly decreased risk of both acute (HR 0.97 P<0.001) and chronic GVHD (HR 0.98 P=0.04). A higher CD3+ cell dose was also significantly associated with an increased risk of acute GVHD (HR 1.03 P<0.001) but not chronic GVHD (HR 0.96 P=0.12). The overall response rate after DLI for treating MC or graft failure was 45.2% for MSD, 32.6% for MUD and 41.4% for HAPLO recipients. Logistic regression analysis revealed leukemia patients had a higher response rate after receiving a DLI for mixed chimerism from MSD (OR=19.5 P=0.002) and HAPLO (OR=9.03 P=0.042), but not from MUD HCT (OR=0.65 P= 0.57), compared to patients with non-malignant disorders. We also evaluated the response to DLI for frank disease relapse in 15 patients. The response rate after DLI for disease relapse was 50% (1/2) for MSD, 44.4% (4/9) for HAPLO, but 0% (0/4) for MUD recipients. Conclusions: In our analysis, the incidence of GVHD was not higher in pediatric and young adult HCT recipients who received DLI as compared to those who did not. Overall, the risk of developing acute and chronic GVHD after DLI was low and comparable between different donor sources. The risk of GVHD decreased further away from HCT and increased with higher DLI dose. The response rate for treating MC and disease relapse remains less than 50%. Thus, DLIs may be safely administered to pediatric and young adult patients after HCT. The therapeutic effect may be modulated by adjusting the dose, timing and frequency of DLI administration.

Donor Lymphocyte Infusion for Prophylaxis and Treatment of Relapse in Pediatric Hematologic Malignancies after Allogeneic Hematopoietic Stem Cell Transplant.

Donor lymphocyte infusion (DLI) is effective for managing patients with hematologic malignancies after allogeneic hematopoietic stem cell transplant (HSCT). However, few studies have explored its optimal use in pediatric populations. Herein, we report our single-center experiences of DLI and factors for predicting its outcomes. This retrospective study included pediatric patients who had received DLI (between June 1998 and December 2022) after allogeneic HSCT. Data regarding patient characteristics, preDLI disease status, and DLI characteristics were collected. The primary outcomes were overall survival (OS), event-free survival (EFS), and graft-versus-host-disease (GVHD) development. The study cohort comprised 17 patients with acute leukemia, 3 with chronic leukemia, and 3 with lymphoma. Prophylactic, preemptive, and therapeutic DLI were used in 7, 7, and 9 patients, respectively. Patients' median age and DLI dose were 9 years and 4.6 × 10 7 CD3 + cells/kg, respectively. The 5-year OS, EFS, and non-relapse mortality were 43.5%, 38.3%, and 13.3%, respectively. Approximately 39% of the patients developed Grade III or IV acute GVHD, whereas moderate/severe chronic GVHD (cGVHD) occurred in 30% of the evaluable patients. Patients' disease status before HSCT (p = 0.009) and DLI (p = 0.018) were the key factors influencing EFS. The implementation of a dose escalation schedule was associated with a marginal reduction in the risk of moderate/severe cGVHD (p = 0.051). A DLI dose of ≥5 × 10 7 CD3 + cells/kg was significantly associated with a high moderate/severe cGVHD risk (p = 0.002) and reduced OS (p = 0.089). Patients' disease status before HSCT and DLI may help predict EFS. The use of DLI as a prophylactic and preemptive modality leads to a favorable 5-year EFS. To safely deliver DLI in children, clinicians must maintain vigilant monitoring and prepare patients in advance when escalating the dose to ≥5 × 10 7 CD3 + cells/kg.

Adoptive Immunotherapy via Donor Lymphocyte Infusions following Allogeneic Hematopoietic Stem Cell Transplantation for Myelofibrosis: A Real-World, Retrospective Multicenter Study

Allogeneic hematopoietic cell transplantation (allo-HCT) remains the only curative option for Myelofibrosis (MF). Relapse however remains a significant problem in up to 20-30% of cases. Donor Lymphocyte Infusions (DLI) represent a potentially effective strategy for relapse prevention and management, but optimal timing based on measurable residual disease (MRD)/chimerism analyses and regimen choice remain undetermined. We performed a retrospective 'real world' analysis of a multicentre cohort of MF allo-HCT patients from 8 European transplant centres who received DLI between 2005-2022. Response was assessed using IWG-MRT defined response criteria, and survival endpoints were estimated using the Kaplan-Meier estimator and log-rank test. The study included 28 patients with a median age of 58 years and a Karnofsky performance status of >80. The majority of patients had DIPPS-plus Intermediate-2 or high-risk disease at the time of allo-HCT. In vivo T cell depletion was utilised in 20 (71.2%) cases, with 19/20 patients receiving anti-thymocyte globulin (ATG). Indication for DLI was either 'pre-emptive' (n=15), due to a decrease in recipient chimerism (n=13) or molecular relapse (n=2), or 'therapeutic' (n=13) for clinician-defined haematological/ clinical relapse. No patient received DLI prophylactically. Median time to DLI administration was 23.4 months post allo-HCT. Of the 16 patients receiving >1 dose of DLI, 12 were part of a planned escalating dose regimen. Median follow-up from time of 1st DLI administration was 55.4 months. Response rates to DLI were CR (n=9), PR (n=1), and clinical improvement (n=6). Chimerism levels improved in 16 patients, and stable disease was reported in 5 patients. No response or progression was reported in 7 patients. DLI-induced aGVHD was reported in 11 (39%) cases, grade 3/4 (n=7;25%). Median overall survival from time of 1st DLI was 62.6 months, and the cumulative incidence of relapse/progression after 1st DLI was 30.8% at 6 months. This study highlights that good response rates can be achieved with DLI even after frank relapse in some patients within a cohort where other treatment options are very limited. More prospective studies are warranted to identify the optimal DLI regimen and timing to improve patient outcomes.

Low incidence and morbidity of Epstein-Barr virus reactivation following donor lymphocyte infusions.

Low incidence and morbidity of Epstein-Barr virus reactivation following donor lymphocyte infusions.

Prophylactic Donor Lymphocyte Infusion in Patients after Allogeneic Stem Cell Transplantation with Post-Transplant Cyclophosphamide Is Associated with Low Relapse Risk and Excellent Survival in Patients below 65 Years with Acute Myeloid Leukemia and High-Risk Myelodysplasia

BackgroundPost-transplant cyclophosphamide (PTCy) effectively prevents graft-versus-host-disease (GVHD) in allogeneic stem cell transplantation (alloSCT) with matched related and matched unrelated donors resulting in low risk of non-relapse mortality (NRM) (<10%). However, PTCy-alloSCT is associated with high relapse rates of approximately 20-30% after 1 year and 30-40% after 2 years (Gooptu et al. Blood 2021, Ruggeri et al. J Hemat Oncol 2018). Prophylactic donor lymphocyte infusion (DLI) may reduce relapse, although it may increase the risk of GVHD. AimTo provide evidence for reduction of relapse and improvement of survival by combining allogeneic SCT with PTCy and subsequent standardized prophylactic donor lymphocyte infusions (DLI) in a cohort of patients with acute myeloid leukemia (AML) and high risk myelodysplasia (MDS). Patients and MethodsSixty-five patients with AML (n=50) or high risk MDS (n=15) received myeloablative (n=15) or reduced-intensity (n=50) alloSCT with a matched related (n=8) or 9/10 (n=19) or 10/10 (n=38) matched unrelated donor. Based on modified ELN criteria, 10 AML patients were intermediate risk and 40 poor risk. GVHD prophylaxis consisted of PTCy, mycophenolate until day +30, and tacrolimus tapered from +70 (related or 10/10 unrelated) or day +90 (9/10 unrelated). All patients were planned to receive DLI at 6 months after transplantation at a dose of 3 x 10^6 CD3+ cells/kg in related and 1.5 x 10^6 CD3+ cells/kg in unrelated alloSCT. In poor risk patients (poor risk AML and high risk MDS) additional low dose DLI (0.3 or 0.15 x 10^6 CD3+ cells/kg in related and unrelated alloSCT, respectively) was planned one month after tacrolimus tapering (i.e. 3-4 months after alloSCT). In poor risk patients with a sensitive molecular or immunophenotypical minimal residual disease (MRD) marker (<0.1%) low dose DLI was not administered but MRD monitored; only in case of MRD positivity at 2 or 4 months additional low dose DLI was given. ResultsOf the 65 patients, 49 received standard dose DLI at 6 months after alloSCT (75%), either as a first dose at 6 months (40%), or as a second DLI after a low dose DLI at 3-4 months after alloSCT (35%). Reasons for not receiving standard dose DLI were NRM (5%), GVHD (9%), relapse (9%) and donor-related (2%). Of the 22 poor risk patients with a sensitive MRD marker, 15 received the first DLI at 6 months; 6 received both low dose DLI and 6 month DLI because of MRD positivity at 2 or 4 months after alloSCT; one patient did not receive prophylactic DLI because of systemic relapse at day 105. With a median follow up of 400 days (range 183-814), 12 patients developed systemic relapse. Most relapses (67%) occurred very early after transplant (median 110 days, range 63 to 165 days), before low dose DLI could be effectively given. These early relapses occurred significantly more in patients >= 65 years (88%) than <65 years (p=0.01 Fisher's exact). Overall survival at 1 year was 95% (95% CI 89-100%) in patients <65 (n=42), significantly higher than the 68% (95% CI 49-95%) in patients >=65 (n=23) (p=0.01). Relapse rate at 1 year was 5% (95% CI 1-15%) in patients <65, significantly lower than the 37% (95% CI 25-58%) in patients >=65 (p=0.001). Grade 2-4 acute and chronic GVHD incidence at 1 year was low (6% (95% CI 2-14%) and 11% (2.5-25%), respectively). Survival at 1 year was similar (p=0.35) in poor risk patients without MRD marker (80%, 95% CI 67-96%), poor risk with MRD marker (95%, 95% CI 87-100%) and intermediate risk (86%, 95% CI 63-100%). For these groups relapse risk was also similar: 18% (95% CI 7-33%), 16% (95% CI 3-36%) and 11% (95% CI 5-41%), respectively. ConclusionsThis study is the first to demonstrate feasibility of prophylactic DLI after PTCy-alloSCT with a low associated risk of GVHD. The observed low incidence of relapse at 1 year after transplantation (5%) of patients aged <65 years appears to be substantially less than the reported risk without pre-planned DLI (20-30%). Although the value of early DLI administration (around 3-4 months) is still unclear, standard dose DLI administration at 6 months appears feasible in intermediate risk patients and poor risk patients with sensitive MRD markers. Early relapses after alloSCT, at a time point before early DLI could be effective, caused the inferior survival of patients aged >= 65 years. The results of this study can serve as a reference for designing future prophylactic cellular interventions in the PTCy-alloSCT setting. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Targeting Molecular Remission with Donor Lymphocyte Infusions Shows Excellent Outcomes for Persistent or Relapsed Myelofibrosis after Stem Cell Transplantation

About 10-30% of myelofibrosis patients who undergo allogeneic hematopoietic cell transplantation will eventually experience relapse within 5 years. While significant improvement has been achieved in stratifying patients according to their risk for posttransplant mortality, preventing and treating relapse remains an unmet clinical need. Notably, no standard of care exists for treatment of relapsed myelofibrosis. On option in the transplant setting (mainly established in CML and AML) is transferring donor T cells to reinforce a graft-versus-leukemia (GVL) effect targeting the recurring malignant cells. Previous small sample studies also indicated a strong graft-versus-myelofibrosis effect of donor lymphocyte infusion (DLI). Additionally, molecular monitoring posttransplant may further help to target outcomes and identify cohorts with distinct risk for and outcome after relapse receiving DLI. Here, we evaluated the largest cohort to date of myelofibrosis patients receiving DLI. The aim of this study was to induce molecular complete remission (CR) and to evaluate associations with overall outcomes. Patients were eligible to receive DLI if they were free of GVHD and immunosuppressive therapy. If no GVHD or response occurred within 6 weeks, another escalating dose (half-log) of DLI was administered. Highly sensitive chimerism and molecular monitoring with developed driver mutation-specific PCRs for JAK2, CALR and MPL was done every month (until day 360 posttranspant) and with routine visites thereafter We present results of 57 genetically annotated myelofibrosis patients who received donor lymphocyte infusion (DLI) for persistent disease (n=20), molecular relapse (n=17), or hematologic relapse (n=20), aiming to achieve molecular complete remission (CR). A total of 143 DLI procedures were given (range, 1-5 cumulative DLIs). Median CD3+ starting dose of first DLI was 1 x106 (range, 1 x105-1 x107), escalated by half-log after at least 6 weeks if no response nor graft-versus-host disease occurred. Overall molecular CR rate was 70% (n=38) and seemed to be higher for patients who received first DLI for molecular relapse (88%, 15 out of 17). For each DLI, molecular CR was achieved in 40% (23 out of 57) after first, in 44% (17 out of 39) after second, in 32% (8 out of 25) after third, in 470% (7 out of 15) after fourth, and in 43% (3 out of 7) after fifth DLI. In terms of acute GVHD, 15 overall cases occurred after a total number of 143 procedures (11%) and appeared to be associated with response. Of 22 patients who achieved initial molecular CR after first DLI, 11 patients (50%) received subsequent DLIs, of whom 4 patients initially received first DLI for hematological relapse, 4 patients for molecular relapse, and 3 patients for disease persistence. Relapses after first DLI were hematological in 8 patients (73%) and molecular in 3 patients (27%), and second DLI was given within a median of 10 weeks (range, 6-323 weeks) from first DLI. Of those, 9 patients could be eventually converted with subsequent DLIs into durable molecular CR (82%) with a median of 7 years after last DLI. Overall outcome was driven by response to first DLI. Five-year overall survival after first DLI was 85% (95% CI, 67-100%) for patients with molecular CR versus 52% (95% CI, 33-71%) for patients with less than molecular CR. Achievement of molecular CR after first DLI was associated with 78% reduced risk of death (P=0.02). All patients who relapsed after initial molecular CR after first DLI (50%, n=11) were alive at last follow-up. Multivariable analysis on overall survival and disease-free survival, adjusting for time-dependent and continuous effects of total number of DLIs, showed significantly reduced risk of death for patients with molecular CR after first DLI (with patients achieving less than molecular CR as reference), with hazard ratio of 0.22 (95% CI, 0.06-0.80; P=0.02). Similar results were retrieved for risk of death or relapse/disease persistence after last DLI, with a hazard ratio of 0.14 (95% CI, 0.05-0.39; P<0.001). No significant effect of number of DLIs or indication for first DLI were identified. Targeting molecular CR after DLI is essential to achieve excellent long-term survival in persistent or relapsed myelofibrosis, and DLI together with molecular monitoring should be standard of care for relapsed myelofibrosis. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Phase I Trial of CD8-Depleted Human Leukocyte Antigen (HLA) Mismatched Unrelated Donor Lymphocyte Infusion (DLI) to Achieve Remissions in Myelodysplastic Syndrome (MDS) and Secondary Acute Myeloid Leukemia (sAML)

Background Hypomethylating agents (HMAs) are the standard of care in higher risk MDS, yielding a median survival of 12-18 months. After HMA failure or progression to sAML. median survival is only 4-6 months. We developed a novel cellular therapy using HLA mismatched, unrelated, CD8-depleted, CD4+ DLI to induce remission in patients with MDS and sAML who have not previously undergone allogeneic hematopoietic cell transplant (HCT). The DLI is intentionally class II HLA mismatched to activate donor CD4+ T cells which then provide immunologic "help" to reverse recipient immune exhaustion and, thus, promote a potent antitumor response (Symons. BBMT. 2008). Further, HLA mismatched donors are easily identified and allow the potential for an "off the shelf" product. By depleting CD8+ T cells, it is intended that the DLI does not engraft, thus negating the risk of graft-versus-host disease (GVHD). Instead, this therapy is intended to induce remission as a bridge to curative allogeneic HCT. Methods This completed phase I trial enrolled patients with MDS refractory to at least 4 cycles of HMA or sAML at the Moffitt Cancer Center from 2020-2022. Patients who received prior allogeneic HCT were excluded. DLI donors were selected from a pre-existing pool of unrelated donors at the New York Blood Center (NYBC) on the basis of class II HLA mismatch, CMV compatibility, and ABO compatibility. Patients were treated with induction chemotherapy as chosen by their primary physician. In parallel, donors underwent leukapheresis at the NYBC and the cell product was shipped to the Moffitt Cancer Center. The DLI was depleted of CD8+ T cells using the CliniMACS® system with CliniMACS® CD8 reagent in the Moffitt Cell Therapy Laboratory. HLA-mismatched CD4+ DLI was infused fresh within 24-36 hours after completing induction chemotherapy. The trial followed a 3+3 design to determine the recommended phase II dose (RP2D) of DLI where dose level (DL) 1 was 1x106 CD4 cells/kg, DL2 was 1x107 CD4 cells/kg, and DL3 was 5x107 CD4 cells/kg. Dose limiting toxicities (DLTs) were defined as grade 2-4 acute GVHD, grade 3-4 cytokine release syndrome (CRS), grade 2-4 infusion reactions, aplasia beyond 56 days in the presence of detectable donor chimerism, or grade 4 organ toxicity by CTCAE 5.0. Mechanistic studies were pursued to evaluate markers of immune tolerance, cytokine profiles, and confirm the DLI did not engraft. Results Nine patients (8 sAML, 1 MDS) were treated. All patients had progressed through at least one prior line of therapy (Table 1). The median age was 66. All AML patients had adverse risk disease by ELN risk stratification including 4 patients with TP53 mutation and complex cytogenetics. The MDS patient had very high-risk disease by R-IPSS. A suitable donor was identified for all patients despite a donor pool of only 30 donors. Cell collections, shipments, and processing for all patients were successful with all products achieving <3% CD8+ T cells and >70% cell viability. No patients experienced DLTs at any dose level. One patient at DL3 experienced grade 2 CRS that resolved with tocilizumab. There were no cases of grade 3-4 CRS nor GVHD (Table 2). Complete remission (CR) was achieved in 2/3 (66%) patients at DL3, 1/3 (33%) patients at DL2, and 0/3 (0%) patients at DL1. All 3 patients who reached CR proceeded to allogeneic HCT. At the time of marrow recovery post-treatment, donor DNA in the blood and marrow was no longer detectable in any of the patients. Patients who achieved CR (n=3) had significantly higher levels of IL6 on day +1 (p=0.01) and a trend towards higher levels of IL2, IL15, IFN-gamma, and TNF-alpha in the first 7 days after DLI compared to patients who did not achieve CR. Conclusions Induction chemotherapy followed by CD8-depleted HLA mismatched, unrelated donor DLI was feasible and well tolerated with no DLTs, confirming the RP2D of 5x107 CD4 cells/kg. At DL3, 2 of 3 patients achieved CR, including one with TP53 mutation and complex cytogenetics, which is generally resistant to induction chemotherapy and compares favorably to 20-30% historical CR rates with chemotherapy alone in those pts. Mechanistic studies correlated increased post-treatment cytokine levels with depth of remission. Assessment of markers of immune tolerance are pending and will be presented at the conference. Based on these promising results, this novel cellular therapy is being investigated now in a phase II clinical trial at the Moffitt Cancer Center. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Alterations of Peripheral Blood T Cell Subsets following Donor Lymphocyte Infusion in Patients after Allogeneic Stem Cell Transplantation

Donor lymphocyte infusion (DLI) after allogeneic stem cell transplantation (alloSCT) is an established method to enhance the Graft-versus-Leukemia (GvL) effect. However, alterations of cellular subsets in the peripheral blood of DLI recipients have not been studied. We investigated the changes in lymphocyte subpopulations in 16 patients receiving DLI after successful alloSCT. Up to three DLIs were applied in escalating doses, prophylactically for relapse prevention in high-risk disease (n = 5), preemptively for mixed chimerism and/or a molecular relapse/persistence (n = 8), or as part of treatment for hematological relapse (n = 3). We used immunophenotyping to measure the absolute numbers of CD4+, CD8+, NK, and CD56+ T cells and their respective subsets in patients’ peripheral blood one day before DLI (d-1) and compared the results at day + 1 and + 7 post DLI to the values before DLI. After the administration of 1 × 106 CD3+ cells/kg body weight, we observed an overall increase in the CD8+ and CD56+ T cell counts. We determined significant changes between day − 1 compared to day + 1 and day + 7 in memory and activated CD8+ subsets and CD56+ T cells. Applying a higher dose of DLI (5 × 106 CD3+ cells/kg) led to a significant increase in the overall counts and subsets of CD8+, CD4+, and NK cells. In conclusion, serial immune phenotyping in the peripheral blood of DLI recipients revealed significant changes in immune effector cells, in particular for various CD8+ T cell subtypes, indicating proliferation and differentiation.

Donor Lymphocyte Infusion Is a Feasible Way to Improve Survival in Patients with Acute Myeloid Leukemia and Myelodysplastic Syndromes Who Relapse after Allogeneic Stem Cell Transplantation

Introduction: Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative treatment in patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) yet the major cause of death remains relapse after transplantation which occurs in 30-70% of patients for whom the prognosis is dismal. Since the 1990's donor lymphocyte infusion (DLI) has been proven able to induce remission after allo-HSCT and the use of therapeutic DLI at relapse has widely increased. The immunological mechanism in DLI is primarily T-cell-mediated graft-versus-leukemia (GVL) effect driven by genetic differences between donor and recipient in minor and major histocompatibility antigens. DLI treatment at relapse can additionally reverse T-cell exhaustion and increase T-cell receptor diversity, both of which are GVL-enhancing mechanisms. Risks and complications with DLI-treatment are primarily graft-versus-host disease (GVHD). Though dose escalation schedules have been suggested to increase the GVL-effect while minimizing the risk of GVHD, uniform therapeutic algorithms are still lacking, treatment is often individually scheduled, and outcome results are often disappointing with reported 2-year overall survival rates at 14-29% in AML relapse patients (Greiner J, Götz M, Bunjes D, Hofmann S, Wais V. Immunological and Clinical Impact of Manipulated and Unmanipulated DLI after Allogeneic Stem Cell Transplantation of AML Patients. J Clin Med. 2019;9(1):39). During the last decade, treatment with the hypomethylating agent azacitidin (Aza) has become another potential treatment in patients with myeloid malignancies. Immunological mechanisms of GVL in Aza-treatment for relapse include epigenetically reactivation of pro-apoptotic pathways and demasking of tumor-antigens while increased expression of regulatory T-cells protects from GVHD. In recent years DLI and Aza have been used for synergistical effect post-HSCT relapse both in patients who are un-fit to receive high-dose cytoreductive therapy as well as consolidation after reinduction. The aim of this analysis is to report results of retrospective single center-study of patients treated with DLI +/- Aza over a period of twenty years.Methods: Between 2001 and 2020 50 adult patients with relapse after allo-HSCT for AML(n=38) or MDS (n=12) were treated with DLI at the Department of Hematology, Transplant Unit, at Rigshospitalet, Copenhagen University Hospital, table 1. Only patients free from active GVHD were selected as DLI-candidates. Median follow-up time was 57 (1-170) months. Reinduction with high-dose chemotherapy was administered in 35 (70%) of patients prior to DLI and 34 (68%) patients were in complete morphological remission (CR) before DLI. DLI-products were unmanipulated and obtained from leukapheresis of unstimulated peripheral blood in matched related or unrelated donors of the original stem cell graft. Patients received a median of 3 (1-5) doses of DLI with median total doses of 6,1x10 7 (5x10 6- 4,65x10 8) CD3 postive T-cells per kg. Aza was used together with DLI from 2012 and administrered in 28 (56%) patients with a median of 6 (2-20) cycles. Reported outcomes are overall survial (OS) and relapse-free survival (RFS) in patients in CR prior to DLI.Results: At end of follow-up 20 patients were alive, 11 of these in CR and 2 in partial remission. In 7 patients, DLI was discontinued due to the development of GVHD after 1-2 doses, 6/7 of these patients had unrelated donors. Overall, 2 (4%) patients died from GVHD after DLI. Seven patients received a second HSCT after DLI treatment and were censored at this date in survival analyses. Figure 1a+b shows OS in all patients (n=50) and RFS in patients in CR prior to DLI (n=34). 2-year OS was approximately 59% and 5-year OS was 20%. 2-year RFS was approximately 32% and 5-year RFS was 8%. None of the analyzed baseline factors showed significant associations to the probability of OS, table 2, or RFS (data not shown). Reinduktion before first DLI and increasing doses of transplanted CD3 T cell per kg showed trends towards superior survival probability but failed to reach significant levels, possibly due to the limited patient number.Conclusion: Treatment vith DLI +/- Aza is effective and safe as relapse-treatment after allo-HSCT in myeloid diseases. In selected patients, a short-term (2-year) overall survival of 59% is achieved, and 20% of the patients remain long term survivors. [Display omitted] DisclosuresFischer-Nielsen: A.F.N. is employee and shareholder of StemMedical A/S, a biotech company working with cell-enriched fat grafting.: Current Employment, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company.

Prophylactic or Preemptive Low-Dose Azacitidine and Donor Lymphocyte Infusion to Prevent Disease Relapse following Allogeneic Transplantation in Patients with High-Risk Acute Myelogenous Leukemia or Myelodysplastic Syndrome

Because of the persistently high rates of relapse of patients with high-risk acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS) following allogeneic hematopoietic stem cell transplantation (allo-HSCT), post-transplantation maintenance therapy has been proposed. We previously initiated a Phase II trial in which epigenetic therapy was combined with immunotherapy in an attempt to reduce disease relapse. In that study, low-dose azacitidine (AZA) and escalating doses of donor lymphocyte infusion (DLI) were given as post-allo-HSCT maintenance treatment. In the present study, we retrospectively analyze a larger cohort of patients receiving post-transplantation maintenance therapy and provide updates on some patients of the earlier study. The objectives of the present study were to analyze the cumulative incidence of relapse (CIR), overall survival (OS), and progression-free survival (PFS) and the incidence of acute and chronic graft-versus-host disease (GVHD) of patients with high-risk AML or MDS receiving post-transplantation maintenance treatment with AZA with or without DLI. We retrospectively analyzed 77 patients (54 with AML, 23 with MDS) considered at high risk based on either their genomic or clinical status at transplantation. Following allogeneic transplantation, they received at least 1 cycle of prophylactic or preemptive low-dose AZA with or without escalating doses of DLI to prevent disease relapse. Almost one-half of the patients (47%) were able to receive the full 12 cycles of scheduled AZA, and a majority (79%) received at least 1 DLI. With a median follow-up of 24 months, 19 patients (25%; 16 with AML, 3 with MDS) relapsed, at a median of 9.8 months (range, 4 to 58.6 months), giving a 22% CIR at 24 months. OS and PFS at 24 months were 70.8% and 68.3%, respectively. The cumulative incidences of grade II-IV acute GVHD and chronic GVHD were 27.4% and 45%, respectively. Only a minority of patients (11%) required delayed administration of AZA. These findings confirm that AZA-DLI maintenance is both tolerable and effective in reducing the risk of post-transplantation relapse.

Escalated dose donor lymphocyte infusion treatment in patients with primary immune deficiencies after HSCT with reduced-intensity conditioning regimen

Objective/BackgroundMixed chimerism is a major concern after allogenic hematopoietic stem cell transplantation (HSCT) using a reduced-intensity conditioning (RIC) regimen in primary immunodeficiencies (PIDs). A donor lymphocyte infusion (DLI) escalating dose regimen has been developed with the aim of reducing toxicity while preserving efficacy. However, the graft-versus-host disease (GvHD) development remains the most common and adverse effect of DLI and continues to be a limiting factor in its application, especially nonmalignant diseases such as PIDs. We prospectively evaluated PID patients after HSCT using RIC in Children s Medical Center, who were candidates for an escalating dose of DLI for MC from 2016 to 2018. MethodsWith the median follow-up of 16.4 months, 12 patients (nine males and three females) with a median age of 3.72 years received DLI. The median number of DLI was 3.2 (range, 1–5), the maximum and total dose of DLIs administered per patient were 3.6 × 107 (range, 1–5) cells/kg CD3+ and 9.3 × 107 (range, 1–15) cells/kg CD3+ cells, respectively. ResultsMedian donor chimerism at baseline before the DLIs was 41% (range, 11–73%), patients received DLIs at a median of 105 (range, 37–230) days and 52 (range, 3–168) days after the HSCT and onset of the MC, respectively. At the final assessment, six (54.5%) patients improved after DLIs at a median of 47.3 days. ConclusionPID patients may benefit from DLI with an escalating dose regimen, but the GvHD development remains a concern during the DLI, and the optimum dose and frequency must be standardized.

Low Dose Donor Lymphocyte Infusion (DLI) Is Effective As Prophylactic Therapy for Mixed Chimerism in the Setting of In-Vivo T Cell Depleted Allogeneic Hematopoietic Cell Transplantation

Introduction: Donor lymphocyte infusion (DLI) has been used as a preemptive therapy for those with mixed donor chimerism (MDC) or in the presence of minimal residual disease or as salvage therapy for relapse of disease post allogeneic stem cell transplantation (allo SCT). The efficacy of DLI and the ease of therapy are balanced by the potential for significant toxicity with 100-day DLI-related mortality rate approaching 20%. A number of strategies have been employed in an effort to avoid the major complication of DLI, namely Graft-versus-host disease (GVHD). These strategies include the use of escalating doses of T cells (1 x 10 6 - 1 x 10 8/ kg) and manipulations of the T cells prior to infusion. We conducted a retrospective study of the prophylactic role of low dose DLI (< 5 x 10 6 /kg) in patients with mixed chimerism in the setting of in-vivo T cell depleted allo SCT.Methods: We identified 33 consecutive patients who underwent allo SCT with T cell depletion conditioning regimen with a minimum of 100-day post-transplant follow up. Five patients qualified for our study. MDC was defined by CD3 or CD33 subsets <=95% of the donor and trending down in two or more consecutive samples measured at 100-day or beyond. Full donor chimerism (FDC) was > 95% of CD3 or CD33 subsets. We adopted two myelo-ablative and 1 reduced intensity conditioning with in-vivo T cell depletion in all regimens. Myelo-ablative regimens: Fludarabine 30 mg IV day -8 to day -4 and Busulfan 3.2 mg IV from day -5 to day -2. GVHD prophylaxis consisted of anti-thymocyte globulin for a total dose of 7.5 mg/kg IV from day -4 to day -2 and tacrolimus starting day -1 (FB-ATG regimen). Carmustine 300 mg/ m2 IV day -6, Cytarabine 400 mg/ m2 and etoposide 200mg/ m2 IV on day -5 to day -3, melphalan 140 mg/ m2 IV on day -2. GVHD prophyalxis consisted of alemtuzumab 20 mg IV on day -5 to day -2 and tacrolimus starting day -1 (BEAM-C regimen). Reduced intensity regimen consisted of Fludarabine 30mg/m2 on day -6 to day -2 and melphalan 140 mg/ m2 on day -2. GVHD prophylaxis consisted of alemtuzumab 20 mg IV daily from day -8 to day -5 and tacrolimus starting day -1 (FMC regimen). Demographic, disease and transplant variables were collected.Results: The median age was 52 (range: 28-57) years. There was 1 patient each with diagnoses of T-cell Acute Lymphoblastic Leukemia, Acute Myelogenous Leukemia, Relapsed Hodgkin Lymphoma, Chronic Lymphocytic Leukemia, and Chronic Myelomonocytic Leukemia. Three patients had received FMC regimen and 1 each received FB-ATG and BEAM-C regimen. All five patients had MDC in CD3 subset and FDC in CD33 subset pre-DLI. The median CD3 chimerism pre-DLI was 21% (9%-81%). None of the patients were diagnosed with acute or chronic GVHD pre-DLI. The median time to DLI infusion was 6 (3-9.5) months. The median CD3 dose of the DLI was 3 (range: 3-10) x 106 /kg. The median time for conversion of MDC to FDC was 3 (2-7.5) months. All 5 patients converted to FDC in CD3 subset. One out of five patients needed a second DLI (CD3 cell dose: First DLI 3 x 106 /kg and second DLI 10 x 106 /kg) due to persistent MDC in CD3 subset (Table 1). One patient (20%) developed steroid responsive acute GVHD of the skin, GI and liver (grade III) following DLI (CD 3 dose 3 x 106 /kg) and this has evolved into extensive cGVHD which is under partial remission. At 1 year follow up: none relapsed and the OS was 100%.Conclusion: Low dose DLI (CD 3 dose starting at 3-4 x 106 /kg) is highly effective (80%) as a prophylactic therapy for conversion of MDC to FDC with minimal risk of GVHD in the setting of in-vivo T cell depleted allo SCT. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Targeted Therapy in FLT3-ITD Positive Myeloid Sarcoma: Proof of Principle

INTRODUCTIONAcute myeloid leukemia (AML) with FMS-like tyrosine kinase 3 (FLT3) mutation is a poor prognosis disease, with a high rate of relapse and poor OS, even after allogeneic hematopoietic cell transplantation (alloHCT).In recent years FLT3 inhibitors have emerged in the treatment of FLT3-ITD AML both as monotherapy and in combination with standard chemotherapy; they were used both during induction therapy and in relapsed or refractory disease. They have also been used as maintenance therapy after transplantation.FLT3 inhibitors act by blocking the proliferative boost due to FLT3-ITD.Some of these drugs are approved for the treatment of solid cancers such as hepatocellular carcinoma, renal cell carcinoma and differentiated thyroid carcinoma.We report the case of a patient with FLT3-ITD-positive AML whose disease relapsed after alloHCT as a myeloid sarcoma and who was successfully treated with Sorafenib.CASE REPORTA 54-year old male was diagnosed with AML with a normal karyotype and FLT3-ITD and NPM1 mutations. A molecular complete response (CR) was observed after “3+7” induction therapy. A consolidation therapy with Citarabine was administered and then alloHCT was performed. Conditioning was tBu-Flu and donor was an HLA-identical sibling. Cyclosporine and short term Methotrexate were used as Graft Versus Host Disease (GVHD) prophylaxis.No sign of acute GVHD occurred, molecular CR was confirmed at bone marrow evaluation at day +100, thereafter CSPA was tapered.Nine months after alloHCT a left pectoral subcutaneous nodule appeared. The biopsy consisted with myeloid sarcoma; molecular analysis revealed that sarcoma was FLT3-ITD positive. Meanwhile many sarcomas quickly appeared in different areas of the body and patient referred tingle in his right leg. A CT-PET scan showed pathological uptake in cervical lymph nodes, in subcutaneous and muscular lesions at left upper limb, right hip, thighs, and at right tibia bone. At the same time bone marrow exam confirmed molecular CR and full donor chimerism.Immunosuppression was stopped and he was admistered Sorafenib 200 mg twice for day in off-label use 11 months after alloHCT. Superficial lesions and right leg tingle decreased within 7 days and no lesion was detected by physical examination after 10 weeks of therapy; CT-PET scan after 8 weeks showed partial remission.Sorafenib was increased to 400 mg twice for day and the expected side effects occurred, namely diarrhoea and palmar-plantar erythrodysesthesia.After four months of therapy with Sorafenib, he was treated with donor lymphocyte infusion (DLI), the drug was continued and no clinical manifestation of GVHD appeared. He received a second dose of DLI after seven weeks from the first dose.After 23 weeks of Sorafenib treatment and two dose of DLI, sarcomas localization continued to slowly decrease, bone marrow exam confirmed molecular CR and full donor chimerism, and patient was in good physical condition, with limited oral chronic GVHD.CONCLUSIONOur observation is the proof of Sorafenib activity even in FLT3-ITD myeloid sarcoma, and of his ability to reach extramedullary tissue and to be effective against sarcoma myeloblasts. This experience suggest to look for FLT3 mutation in myeloid sarcoma tissue and to consider therapy with FLT3-inhibitors, alone or in association with chemotherapy. DisclosuresNo relevant conflicts of interest to declare.

Efficacy of Donor Lymphocyte Infusion in CD34+ Selected Allogeneic Hematopoietic Stem Cell Transplant for Myeloid and Lymphoid Malignancies: A Single Center Experience

Introduction Donor lymphocyte infusion (DLI) has been used to prevent or treat relapse after allogeneic hematopoietic stem cell transplantation (alloHCT) since the 1990s. Retrospective series have reported variable efficacy (CML up to 60%, ALL 0% in some series) with rates of DLI-associated graft-versus host disease (GVHD) of 40-60%. DLI's ability to potentiate graft versus leukemia effects and GVHD are thought to be primarily T Cell mediated, and T cell chimerism, repertoire, and exhaustion may have important influence on outcomes.The use of ex-vivo T cell depleted CD34 selected alloHCT has been shown to provide similar survival to unmodified grafts but with lower acute and chronic GVHD, and is now being studied in a randomized trial exploring calcineurin inhibitor free GVHD prevention regimens (BMT CTN 1301). There is however limited data on DLI in this context. Here we describe safety and efficacy outcomes of DLI in recipients of CD34 selected alloHCT.Methods This retrospective study included all CD34 selected alloHCT recipients at our center who received DLI from January 2005 to January 2016 for treatment or prevention of relapse. We excluded patients with multiple myeloma as these results have been reported elsewhere. Primary outcomes were maintenance or achievement of disease remission, and change in whole bone marrow and peripheral T Cell chimerism over time. A loess smoothed curve was used to visually display changes in chimerism over time and to provide time point chimerism estimates.Results 58 patients received DLI for frank relapse (n=20), minimal residual disease (MRD, n=11), or for relapse prevention in the context of mixed marrow or peripheral blood chimerism (n=27). AML (40%) and MDS (29%) were the most common diagnoses, and most patients (74%) had intermediate disease risk index (Table 1). All patients received peripheral blood stem cell grafts and myeloablative conditioning. Median DLI dose was 0.5 x 106 CD3 cells/kg (0.01-10.0) with 86% of patients receiving doses between 0.1 and 1.0 x 106 CD3 cells/kg. DLI was most often given once (67%), with some patients having 2 (21%) or > 2 treatments (12%). Of the 20 patients who received DLI for frank relapse, 3 (15%) achieved remission, and of the 11 patients who received DLI for minimal residual disease, 8 (73%) achieved remission. Of the 27 patients with mixed chimerism treated with preventive DLI, remission was maintained in 22 (81%). Achieving or maintaining remission was not independently associated with underlying diagnosis, use of adjunctive hypomethylating agents or stem cell boost, or DLI dose or frequency in this cohort. DLI resulted in an average whole bone marrow donor chimerism increase after DLI, regardless of DLI indication (9% at 90 days; Fig 1). T Cell donor chimerism also increased after DLI, with a more pronounced increase in patients treated for relapse (50%) than those treated for relapse prevention (12%; Fig 1). Prior to DLI, rates of grade II-IV and III-IV acute GVHD were 10 and 3% respectively, and no patients had moderate or severe chronic GVHD. All GVHD had resolved prior to DLI administration. After DLI we observed 2 episodes (3%) of late acute grade II-IV GVHD (both grade III skin), and 4 episodes (7%) of moderate-severe chronic GVHD with median onset of 99 and 80 days post DLI, respectively (range 44-401).Conclusions DLI given after CD34+ selected alloHCT was associated with GVHD rates that were substantially lower than reported in other DLI contexts. Disease response to DLI was higher in MRD positive patients than for those with frank relapse (15 vs 73%), suggesting that regular MRD assessment and prompt DLI administration may be an effective relapse prevention strategy in MRD positive patients. The low relapse rate observed in patients with mixed chimerism receiving preventive DLI (19%) was not substantially different than historical relapse rates observed in CD34+ selected patients at our institution, so does not yet provide a convincing signal to explore DLI for relapse prevention in the absence of MRD. In summary, DLI given after T Cell depleted alloHCT was associated with low rates of GVHD and may be an effective strategy to prevent frank relapse in MRD positive patients after alloHCT. Acknowledging the inherent limitations of our small sample size, our observations suggest broader exploration of this safe and potentially effective strategy is warranted. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Outcomes with preemptive donor lymphocyte infusions after allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia and myelodysplastic syndromes: A systematic review and meta-analysis.

e19014 Background: Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative therapy for acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) but relapse and graft versus host disease (GVHD) remain the most common challenges. Donor lymphocyte infusion (DLI) is the infusion in which lymphocytes from the original stem cell donor are infused, after the transplant, to augment an anti-tumor response or to ensure that the donor stem cells remain engrafted. In this systematic review and meta-analysis, we focused at outcomes of preemptive DLI in AML and MDS. Methods: Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines (PRISMA) PubMed, CINAHL, Cochrane, and Clinical trials.gov were searched. We included 8 out of 214 articles, excluding duplicates and non-relevant articles. The quality of the included studies was evaluated using NIH quality assessment tool. Proportions along with 95% Confidence Interval (CI) were extracted to compute pooled analysis using the ‘meta’ package by Schwarzer et al. in the R programming language (version 4.16-2) to report the efficacy of preemptive DLI. We pooled the experimental arms results of the included trials using the inverse variance method and logit transformation. Between studies, the variance was calculated using Der Simonian-Laird Estimator. Results: We identified 222 patients who received preemptive DLI. Median age, time since transplant and DLI dose were 48 (32-58) years, 82 (7-160) days and 1.4 million cells/kg respectively. CR and PR were 43% (95%CI 0.14-0.78, I293%, n= 127) and 61% (95%CI 0.40-0.78, I262%, n= 81) respectively. After median follow up of 46 months, non-relapsed mortality (NRM) was 52% (95%CI 0.38-0.65, I249%, n = 121). OS was reported 72% (95%CI 0.62-0.80, I20%, n= 100). Acute and chronic GVHD incidence after DLI was 20% (95% CI 0.13-0.29, I24%, n= 105) and 25% (95% CI 0.08-0.56, I2=79%, n=101) respectively (Table). Conclusions: Preemptive DLI significantly improves OS with a low incidence of acute and chronic GVHD. However, NRM was seen in more than half of all the patients and prospective studies are needed to evaluate safety of preemptive DLI. Outcomes with preemptive DLI (n= 222).[Table: see text]

Donor lymphocyte infusions after first allogeneic hematopoietic stem-cell transplantation in adults with acute myeloid leukemia: a single-center landmark analysis

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is potentially curative for acute myeloid leukemia (AML). The inherent graft-versus-leukemia activity (GvL) may be optimized by donor lymphocyte infusions (DLI). Here we present our single-center experience of DLI use patterns and effectiveness, based on 342 consecutive adult patients receiving a first allo-HSCT for AML between 2009 and 2017. The median age at transplantation was 57 years (range 19–79), and the pre-transplant status was active disease in 58% and complete remission (CR) in 42% of cases. In a combined landmark analysis, patients in CR on day +30 and alive on day +100 were included. In this cohort (n=292), 93 patients received cryopreserved aliquots of peripheral blood-derived grafts for DLI (32%) and median survival was 55.7 months (2-year/5-year probability: 62%/49%). Median survival for patients receiving a first dose of DLI “preemptively,” in the absence of relapse and guided by risk marker monitoring (preDLI; n=42), or only after hematological relapse (relDLI; n=51) was 40.9 months (2-year/5-year: 64%/43%) vs 10.4 months (2-year/5-year: 26%/10%), respectively. Survival was inferior when preDLI was initiated at a time of genetic risk marker detection vs mixed chimerism or clinical risk only. Time to first-dose preDLI vs time to first-dose relDLI was similar, suggesting that early warning and intrinsically lower dynamics of AML recurrence may contribute to effectiveness of preDLI-modified GvL activity. Future refinements of the preemptive DLI concept will benefit from collaborative efforts to diagnose measurable residual disease more reliably across the heterogeneous genomic spectrum of AML.

Haploidentical CD45RA-Negative Donor Lymphocyte Infusions Are Feasible, Safe and Associated with Clinical Benefit

<h3>Introduction</h3> Donor T-cell reconstitution following hematopoietic cell transplantation (HCT) is critical for infection and leukemic control. Donor lymphocyte infusions (DLI) provide additional donor T cells, but may cause graft-versus-host-disease (GVHD) from alloreactive T-cells. As GVHD risk increases with increasing HLA-mismatch, conventional haploidentical DLI doses are often limited to 1 × 10⁵ T cells/kg. Since the majority of alloreactive T cells reside in the naïve (CD45RA-positive) subset, CD45RA-depleted DLI may provide a diverse lymphocyte repertoire to aid in infection and leukemic disease control, with decreased GVHD risk. Herein, we report on feasibility, safety, and early efficacy of escalating doses of haploidentical memory DLI. <h3>Methods</h3> Donors underwent leukapheresis without mobilization; 2 total blood volumes were collected. Depletion of CD45RA-positive cells was performed using the CliniMACS device (Miltenyi Biotec). DLI dosing typically started at 1 × 10⁵ T cells/kg, with dose escalation every 4 weeks based on clinical need. <h3>Results</h3> All donors collected successfully in one attempt. Following CD45RA-depletion, median residual T cell dose was 45 × 10⁶/kg and CD45RA-positive T cell dose was <0.001 × 10⁶/kg (>3.9 log depletion), allowing multiple doses to be stored for future use (Figure 1). Twelve patients received a total of 29 DLIs (median infusions=2, range 1–5; Figure 2). Indications for DLI included detectible leukemia (6), mixed chimerism (6), and lymphopenia/viral infection (3); 3 recipients had multiple indications. First DLI was infused a median of 101.5 days post-HCT (range 41-356). Twenty-three doses had no detectible CD45RA-positive T cells (<0.001 × 10⁶/kg) and 6 contained 0.001-0.002 × 10⁶ CD45RA-positive T cells/kg. No infusion related acute adverse events occurred. One patient developed acute GVHD (clinical grade IV, stage 3 skin/stage 4 gut), 21 days post-DLI (dose=1 × 10⁵ T cells/kg). After DLI, the majority of patients showed some clinical response (chimerism improvement/stability, decreased viral load, and/or rise in peripheral CD3 count). Eradication of detectable leukemia however was not successful, with all 6 patients eventually having disease progression (1 rapid progression; 5 frank relapse 2–6 months after first DLI). With median length of follow-up after last DLI of 243 days (range 20-924), no patients have developed chronic GVHD. <h3>Discussion</h3> CD45RA-depletion is feasible and effective in removing naïve donor T-cells. Haploidentical CD45RA-depleted DLIs were well tolerated and associated with low incidence of acute GVHD, even with T-cell doses as high as 10 × 10⁶/kg. The majority of patients showed clinical benefit from DLI, with the exception of leukemia disease control. We are currently further investigating the efficacy and safety of CD45RA-depleted DLI as part of a prospective clinical haploidentical HCT trial.

Prophylactic or Preemptive Low-Dose Azacitidine (AZA) and Donor Lymphocyte Infusion (DLI) Prevent Disease Relapse Following Allogeneic Transplantation in High Risk Acute Myeloid Leukemia and Myelodysplastic Syndrome

Introduction: Despite therapeutic advances in recent years, disease relapse is still observed in up to 50-60% of the patients (pts) receiving allogeneic transplantation for high risk AML and MDS. In an initial Phase II trial of 30 pts treated with prophylactic low-dose AZA and escalated doses of DLI to prevent relapse, we reported that such prophylactic treatment can be safely administered and compared favorably to patients receiving no post-transplant maintenance. We here update 16 pts from our center, included in that protocol, as well as a larger cohort of additional patients treated with combined epigenetic and cellular therapy and the resultant effect on their event-free survival and their overall survival. Patients and methods: Fifty-nine pts (median age 59 yrs (range, 37-70); 30 M/29 F), comprising 40 pts with AML and 19 pts with MDS, were treated. Among the AML pts (ELN classification FAV n=2, INT n=17, ADV n=21), high risk criteria were as follows: 15 had complex karyotypes, 7 Flt3-ITD, 1 MECOM (EVI1) rearr., 3 monosomies, 2 t(9;11), and 1 t(11;19)); 9 were in CR≥2, 4 were refractory, and 13 had 2ary AML to MDS/chemotherapy/or MPS. Among the MDS pts, high risk criteria included 6 pts with complex caryotypes, 2 monosomies, 1 MECOM (EVI1) rearr., and 4 had 2ary MDS. IPSS-R median was 5.5 (3 - 7.5). MDS pre-transplant status included 7 CR1, 1 CR2, 5 PR, 1 relapse, 4 upfront, and 1 refractory. The therapeutic protocol administered to the initial 16 pts consisted of AZA, starting between d56 and d100 post-transplant, at a dose of 32 mg/m²/d SC, for 5 consecutive days, every 28 days, for up to a total of 12 cycles followed by DLI commencing after 3 cycles of AZA and 4 weeks following discontinuation of immunosuppressive prophylaxis. Two additional DLI were scheduled every 8 weeks following the 1st DLI. The doses of DLI 1, 2 and 3 were, respectively, 5x106, 1x107, and 5x107 CD3+ cells/kg for matched related donor (MRD), and 1x106, 5x106, and 1x107 CD3+ cells/kg for unrelated donor (UD). In the extended patient cohort, presented here, we slightly modified the schedule: DLI could be given earlier (after one or two cycles of AZA) and haploidentical pts could receive AZA/DLI as well, with DLI at the escalated doses of 1x105, 5x105, and 1x106 CD3+ cells/kg. Immunosuppression included cyclosporine A (CsA) in case of MRD, CsA and mycophenolate mofetil (MMF) in case of UD or haplo. MMF was progressively reduced during the first 2 months. CsA was tapered starting at day 60-100 post-transplant. Patients could start AZA while they were still receiving CsA. The conditioning regimens consisted of MAC for 5 pts, RIC for 46 pts and sequential for 8 pts. Donors were MRD, MUD, UD 9/10, and haplo for 20, 30, 1 and 8 pts respectively. Results: The median number of cycles AZA was 7 (range 1-12), 17 pts received 12 cycles of AZA, while 42 pts (71%) received at least one DLI. The median number of DLI was 1 (range 0-4), 15 pts received ≥ 3 DLI. The median time for the first post-transplant AZA injection was 83 days (range 56-145 d) and the median time post-transplant for those pts who received a first DLI was 148 days (range 78-245 d). The median pt-follow-up was 17 months (range 2-83). Eight pts (13%) relapsed (7 AML and 1 MDS). The cumulative incidence of relapse and NRM at 1 year was 12% and 11.5% respectively. Fifteen pts (25%) died. Causes of death included relapse in 6 pts, infection in 7 pts, myocardial infarction in 1 pt, and GvHD in 1 pt. Overall survival and event free survival for the entire group at 2 years was 71% (95% CI 54-82%) and 67% (95% CI 50-80%) respectively. The cumulative incidence of acute GvHD grade 1-4 and chronic GvHD were 32% (95% CI 16-49%) and 39% (95% CI 20-58%). Among the 8 pts who developed grade 3 acute GvHD, 4 occurred in pts who had received DLI. One pt died from grade 4 digestive GvHD post-AZA alone. Conclusion: We conclude that, despite their very high risk disease, prophylactic/preemptive low-dose AZA and DLI can be readily and safely administered with an acceptable incidence of subsequent GvHD to the AML and MDS pts described here. Significantly, in the poor-prognosis pts under study, the incidence of relapse is lower than expected. Furthermore, considering the immune escape mechanisms prophylactic or pre-emptive either AZA or DLI might be associated to additive non-cross reactive interventions, such as checkpoint inhibitors, in order to further decrease disease relapse and increase overall survival. Disclosures Peterlin: Jazz Pharma: Consultancy; Astellas: Consultancy; Daiichi-Sankyo: Consultancy; AbbVie Inc: Consultancy. Orvain:Novartis: Honoraria; Incyte: Honoraria. Chevallier:Jazz Pharmaceuticals: Honoraria; Daiichi Sankyo: Honoraria; Incyte: Consultancy, Honoraria.

PB2350 EFFICACY AND SAFETY OF POST HEMATOPOIETIC STEM CELL TRANSPLANTATION DONOR LYMPHOCYTE INFUSION IN PATIENTS WITH ACUTE LEUKEMIA. RETROSPECTIVE ANALYSIS IN OUR CENTER

Background:Relapse of acute leukemia (AL) after allogenic hematopoietic stem cell transplantation (alloHSCT) worsens patients’ prognosis. Donor lymphocyte infusion (DLI) may be an effective therapy in these patients.Aims:Our objective was to asses the efficacy and safety of DLI in three different settings after alloHSCT: therapeutic (relapse or progression), pre‐emptive (positive minimal residual disease or mixed chimerism) and prophylactic (patients at high risk of relapse).Methods:Retrospective analysis of 30 patients with AL who received DLI after alloHSCT from 2000 to 2018. Patients in 2nd or further complete remission (CR), positive MRD or adverse cytogenetics were considered at high risk for relapse. Median age was 37 years (5‐71). Twenty one patients were males. The baseline characteristics of the patients are shown in table 1.Twenty two patients had a matched donor (14 related, 8 unrelated), 5 patients received a mismatched graft and 3 patients a haploidentical graft. Fourteen patients received DLI therapeutically, 11 pre‐emptive and 5 as prophylaxis. At DLI, only one patient had mild chronic graft versus host disease. All patients were off immunosuppresive therapy at DLI. Seven patients received reinduction chemotherapy before the DLI.Fifty eight doses of DLI were administered, with a median of 1 (1‐5) dose per patient. The maximum infused dose varied, depending on the type of donor and degree of HLA disparity: 5,4 (1 ‐15,3), 4,2 (1‐10), 1,9 (0,2‐4,6) and 0,5 (0,2‐1) × 10^7/kg in matched related donor, matched unrelated donor, missmatch and haploidentical, respectively. The dose was higher in the therapeutic group. Median time until triggering event of DLI (relapse, appearance of MRD or loss of chymerism) was 132 days (21‐547) and median time from alloHSCT until first DLI was 179 days (38‐771)Leukemia Free Survival (LFS) and overall survival (OS) were calculated using de Kaplan‐Meier (KM) method and compared using the log‐rank test. The median follow‐up was calculated with the inverse of KM. SPSS software was used for the data analysis.Results:Nine out of 14 patients in the therapeutic group reached CR and 1 PR. Among 11 patients in pre‐emptive group, 5 reached CR. Four out of 5 patients in the prophylactic group remained in CR. The median follow up after DLI was 65 (IC 95% 16,3 to 113,6) months. Median OS and LFS for the entire cohort were 14 (IC 95%, 3, 9 to 24,1) and 9 (IC 95%, 1,1 to 16,9) months, respectively.Median OS and LFS in the therapeutic group were 7 (CI 95%, 1, 5‐12,5) and 4 (CI 95%, 0‐12,5) months, respectively. Median OS and LFS in the pre‐emptive group, were 14 (CI 95% 7, 7‐20,3) and 5 (CI 95%, 0‐38) months, respectively. In the prophylactic group, the median OS (p = 0,029) and LFS (p = 0,01) were not reached. The LFS probability at 1, 2 and 3 years was 80% (IC 95%, 77 to 82).Patients in CR after DLI (n = 14) had a median LFS of 17 months (IC 95% 5,5 to 28)After DLI, 14 (46,7%) patients developed GvHD: grade III‐IV acute GvHD in 2 (6,7%) and moderate‐severe chronic GvHD in 5 (16,6%). Two patients with chronic GvHD died of related complications. The causes of death were: relapse (n = 13), severe infection (1), demyelinizing neuropathy (1) and 2 unknown.Summary/Conclusion:Our data suggest that prophylactic DLI could improve LFS in high risk patients. Therapeutic and pre‐emptive DLI was useful in a subgroup of patients with relapsed leukemia or positive MRD. More than half of relapsed patients reached CR after DLI. DLI was a safe treatment, GVHD being the most frequent complication but with a low incidence of severe forms.image