Donor Lymphocyte Infusion Research Articles

In-vivo T-cell depleted reduced-intensity conditioned allogeneic haematopoietic stem-cell transplantation for patients with acute lymphoblastic leukaemia in first remission: results from the prospective, single-arm evaluation of the UKALL14 trial

SummaryBackgroundThe outcome of chemotherapy in patients older than 40 years with acute lymphoblastic leukaemia is poor and myeloablative allogeneic haematopoietic stem-cell transplantation (HSCT) has a high transplant-related mortality (TRM) in this age cohort. The aim of this study was to assess the activity and safety of reduced-intensity conditioned allogeneic HSCT in this patient population.MethodsThis was a single-arm, prospective study within the UKALL14 trial done in 46 centres in the UK, which recruited patients to the transplantation substudy. Participants in UKALL14 had B-cell or T-cell acute lymphoblastic leukaemia, were aged 25–65 years (BCR-ABL1-negative) or 18–65 years (BCR-ABL1-positive), and for this subcohort had a fit, matched sibling donor or an 8 out of 8 allelic matched unrelated donor (HLA-A, HLA-B, HLA-C, and HLA-DR). On June 20, 2014, the protocol was amended to allow 7 out of 8 matched unrelated donors if the patient had high risk cytogenetics or was minimal residual disease (MRD)-positive after the second induction course. Patients were given fludarabine, melphalan, and alemtuzumab (FMA; intravenous fludarabine 30 mg/m2 on days –6 to –2, melphalan 140 mg/m2 on day –2, and alemtuzumab 30 mg on day –1 [sibling donor] and days –2 and –1 [unrelated donor]) before allogeneic HSCT (aged ≥41 years patient pathway). Donor lymphocyte infusions were given from 6 months for mixed chimerism or MRD. The primary endpoint was event-free survival and secondary and transplantation-specific endpoints included overall survival, relapse incidence, TRM, and acute and chronic graft-versus-host disease (GVHD). This study is registered with ClinicalTrials.gov, NCT01085617.FindingsFrom Feb 22, 2011, to July 26, 2018, 249 patients (236 aged ≥41 years and 13 younger than 41 years) considered unfit for a myeloablative allograft received an FMA reduced-intensity conditioned HSCT. 138 (55%) patients were male and 111 (45%) were female. 88 (35%) participants received transplantations from a sibling donor and 160 (64%) received transplantations from unrelated donors. 211 (85%) participants had B-precursor acute lymphoblastic leukaemia. High-risk cytogenetics were present in 43 (22%) and another 63 (25%) participants were BCR-ABL1-positive. At median follow-up of 49 months (IQR 36–70), 4-year event-free survival was 46·8% (95% CI 40·1–53·2) and 4-year overall survival was 54·8% (48·0–61·2). 4-year cumulative incidence of relapse was 33·6% (27·9–40·2) and 4-year TRM was 19·6% (15·1–25·3). 27 (56%) of 48 patients with TRM had infection as the named cause of death. Seven (15%) of 48 patients had fungal infections, 13 (27%) patients had bacterial infections (six gram-negative), and 11 (23%) had viral infections (three cytomegalovirus and two Epstein-Barr virus). Acute GVHD grade 2–4 occurred in 29 (12%) of 247 patients and grade 3–4 occurred in 12 (5%) patients. Chronic GVHD incidence was 84 (37%) of 228 patients (50 [22%] had extensive chronic GVHD). 49 (30%) of 162 patients had detectable end-of-induction MRD, which portended worse outcomes with event-free survival (HR 2·40 [95% CI 1·46–3·93]) and time-to-relapse (HR 2·41 [1·29–4·48]).InterpretationFMA reduced-intensity conditioned allogeneic HSCT in older patients with acute lymphoblastic leukaemia in first complete remission provided good disease control with moderate GVHD, resulting in better-than-expected event-free survival and overall survival in this high-risk population. Strategies to reduce infection-related TRM will further improve outcomes.FundingCancer Research UK.

Increasing Role of Targeted Immunotherapies in the Treatment of AML.

Acute myeloid leukemia (AML) is the most common acute leukemia in adults. The standard of care in medically and physically fit patients is intensive induction therapy. The majority of these intensively treated patients achieve a complete remission. However, a high number of these patients will experience relapse. In patients older than 60 years, the results are even worse. Therefore, new therapeutic approaches are desperately needed. One promising approach in high-risk leukemia to prevent relapse is the induction of the immune system simultaneously or after reduction of the initial tumor burden. Different immunotherapeutic approaches such as allogenic stem cell transplantation or donor lymphocyte infusions are already standard therapies, but other options for AML treatment are in the pipeline. Moreover, the therapeutic landscape in AML is rapidly changing, and in the last years, a number of immunogenic targets structures eligible for specific therapy, risk assessment or evaluation of disease course were determined. For example, leukemia-associated antigens (LAA) showed to be critical as biomarkers of disease state and survival, as well as markers of minimal residual disease (MRD). Yet many mechanisms and properties are still insufficiently understood, which also represents a great potential for this form of therapy. Therefore, targeted therapy as immunotherapy could turn into an efficient tool to clear residual disease, improve the outcome of AML patients and reduce the relapse risk. In this review, established but also emerging immunotherapeutic approaches for AML patients will be discussed.

Pharmacologic Strategies for Post-Transplant Maintenance in Acute Myeloid Leukemia: It Is Time to Consider!

Simple SummaryAllogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative therapeutic procedure for patients with high risk acute myeloid leukemia. Its anti-leukemic activity is mainly derived from the intensity of the conditioning regimen used and the graft-versus-leukemia effect exerted by the donor T lymphocytes. Despite major progress in the allo-HCT procedure in recent years with the achievement of lower non-relapse mortality and long-term disease control. However, up to 45% of patients still experience relapse. Therapeutic strategies post-transplant aiming at preventing disease relapse are discussed in this review.Patients with high-risk acute myeloid leukemia are offered allogeneic hematopoietic cell transplantation (allo-HCT) in first remission to reduce risk of relapse. However, disease recurrence remains the major reason of allo-HCT failure, occurring in around 35–45% of patients, and leading to dismal outcomes. Strategies to reduce the risk of relapse are greatly needed, especially in the early post-transplant phase where the graft-versus-leukemia (GVL) effect is not yet activated. Some practices include the use of myeloablative conditioning regimens, close monitoring of measurable residual disease and donor chimerism, rapid tapering of immunosuppression, and implementation of pre-emptive strategies as the use of donor lymphocyte infusion. However, it’s time to consider prophylactic pharmacologic interventions post allo-HCT that aim at maintaining leukemic clones under control by both direct cytotoxic activity and by enhancing the GVL effect. In this current review, available data on drugs targeting epigenetic pathways like azacitidine, or actionable mutations like FLT3 and IDH1/2 inhibitors used as maintenance post allo-HCT, will be discussed.

A retrospective single-center analysis of G-CSF-mobilized donor lymphocyte infusion in hematologic malignancies after unmanipulated allogenic PBSCT.

To explore the efficacy and safety of G-SCF-mobilized donor lymphocyte infusion (DLI) for treatment of relapse of hematologic malignancies after allogeneic peripheral blood stem cell transplantation, we performed a retrospective analysis in a cohort of patients with morphologic (n = 36) or molecular (n = 22) relapse post transplantation. The 3-year post-DLI survival rates for therapeutic and preemptive DLI recipients were 16.7% and 33.3%, respectively. The occurrence of DLI-associated acute graft-versus-host disease predicted longer survival, whereas diagnosis of T cell acute lymphoblastic leukemia/lymphoma or myelodysplastic syndromes or early relapse after transplant (< 6months) predicted shorter survival after therapeutic DLI. Cumulative incidence of progression to hematologic relapse and non-relapse mortality after preemptive DLI were 46.8% and 29.1%, respectively. Active disease prior to transplant and early molecular relapse after transplant (< 4months) were the strongest predictors of non-relapse mortality after preemptive DLI. In conclusion, although therapeutic DLI had limited efficacy against T cell acute lymphoblastic leukemia/lymphoma or myelodysplastic syndromes or early post-transplant relapse, patients who developed DLI-associated acute graft-versus-host disease would benefit from this procedure in the setting of G-SCF-mobilized DLI. Furthermore, preemptive DLI could protect half of patients from hematologic relapse after transplantation with acceptable toxicity.

Hematopoietic stem cell transplantation for Wiskott-Aldrich syndrome: an EBMT Inborn Errors Working Party analysis

AbstractAllogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative treatment for patients affected by Wiskott-Aldrich syndrome (WAS). Reported HSCT outcomes have improved over time with respect to overall survival, but some studies have identified older age and HSCT from alternative donors as risk factors predicting poorer outcome. We analyzed 197 patients undergoing transplant at European Society for Blood and Marrow Transplantation centers between 2006 and 2017 who received conditioning as recommended by the Inborn Errors Working Party (IEWP): either busulfan (n = 103) or treosulfan (n = 94) combined with fludarabine ± thiotepa. After a median follow-up post-HSCT of 44.9 months, 176 patients were alive, resulting in a 3-year overall survival of 88.7% and chronic graft-versus-host disease (GVHD)-free survival (events include death, graft failure, and severe chronic GVHD) of 81.7%. Overall survival and chronic GVHD-free survival were not significantly affected by conditioning regimen (busulfan- vs treosulfan-based), donor type (matched sibling donor/matched family donor vs matched unrelated donor/mismatched unrelated donor vs mismatched family donor), or period of HSCT (2006-2013 vs 2014-2017). Patients aged <5 years at HSCT had a significantly better overall survival. The overall cumulative incidences of grade III to IV acute GVHD and extensive/moderate/severe chronic GVHD were 6.6% and 2.1%, respectively. Patients receiving treosulfan-based conditioning had a higher incidence of graft failure and mixed donor chimerism and more frequently underwent secondary procedures (second HSCT, unconditioned stem cell boost, donor lymphocyte infusion, or splenectomy). In summary, HSCT for WAS with conditioning regimens currently recommended by IEWP results in excellent survival and low rates of GVHD, regardless of donor or stem cell source, but age ≥5 years remains a risk factor for overall survival.

Outcomes After Donor Lymphocyte Infusion in Patients With Hematological Malignancies: Donor Characteristics Matter

In the context of T-cell depletion, failing to achieve full donor chimerism (FDC) entails higher risk of graft loss and disease relapse. Donor lymphocyte infusion (DLI) is an adoptive immunotherapy for mixed chimerism (MC) or relapsed disease after reduced-intensity conditioning allogeneic hematopoietic stem cell transplantation (HSCT). Nevertheless, little is known of factors associated with attaining FDC or disease remission. We carried out a retrospective study with 100 adult patients to identify patient and donor factors that can predict achievement of FDC and disease remission and describe complications after DLI. Indications for DLI were T-cell MC in 61 patients and relapsed disease in 39 patients. Forty patients (65.6%) with MC attained T-full donor chimerism (T-FDC), with higher responses seen in patients whose donors were female (81.5% versus 52.9%, P = .004) and cytomegalovirus negative (76.5% versus 52%, P = .004). However, only patients with younger donors (<30 years old) compared to older donors (94.4% versus 53.5%, P = .013) and those attaining unfractionated whole blood (UWB) FDC after DLI (76.6% versus 28.6%, P < .001) had a survival benefit and subsequently a better graft-versus-host disease (GvHD)–free/relapse-free survival. Nineteen of 39 patients (48.7%) with relapsed disease achieved remission after DLI. In this cohort, attaining T-FDC impacted favorably in disease control (76.7% versus 12.5%, P = .012) and improved survival (45.5% versus 12.5%, P = .007). In the whole population, the cumulative incidence of acute GvHD (aGvHD) at day 100 after DLI was 23%, and chronic GvHD (cGvHD) at 1 year after DLI was 22%. In the whole population, donor age was also a determining factor for aGvHD, because patients with younger donors had a lower incidence of aGvHD (8% versus 36%, P = .021). The cGvHD was more likely to occur in patients who converted to T-FDC (34% versus 10.3%, P = .025). Donor characteristics are increasingly considered when deciding approaches for HSCT. Donor age should be considered when planning HSCT, as well as doses and scheduling of DLI. As per our experience, this should be done alongside T/UWB chimerism to achieve the maximal clinical benefit with less associated toxicity. Selection of younger male donors from stem cell registries can minimize the risk of GvHD and improve survival.

Optimization of Donor Lymphocyte Infusion for AML Relapse After Allo-HCT in the Era of New Drugs and Cell Engineering.

Donor lymphocyte infusion (DLI) is a key strategy for the treatment of AML relapse after allogeneic hematopoietic cell transplantation (allo-HCT) and has been used for either prophylactic, pre-emptive, or therapeutic purposes. However, the prognosis of these patients remains dismal even after DLI infusion (2-year overall survival, ~25%), and the efficacy is achieved at the cost of toxicities such as graft-versus-host (GVH) disease. Attempts to optimize DLI efficacy and safety, such as dose/timing modification and the use of cytoreduction, before DLI have been performed previously. Recently, a great number of novel targeted and immunomodulatory agents have emerged. Some of them, such as hypomethylating agents, FLT3 and Bcl-2 inhibitors, have been used in combination with DLI, aiming to enhance the graft-versus-leukemia effect. Moreover, manipulation of the DLI graft through cell selection (e.g., donor NK cells) or cell engineering (donor CAR-T cells) has shown potentially superior anti-tumor effects but less GVH effect than conventional DLI in clinical trials. This review summarizes the recent advances on the use of DLI for the prophylaxis/treatment of AML relapse and discusses future strategies which may further improve the treatment efficacy.

Advances in Allogeneic Cancer Cell Therapy and Future Perspectives on "Off-the-Shelf" T Cell Therapy Using iPSC Technology and Gene Editing.

The concept of allogeneic cell therapy was first presented over 60 years ago with hematopoietic stem cell transplantation. However, complications such as graft versus host disease (GVHD) and regimen-related toxicities remained as major obstacles. To maximize the effect of graft versus leukemia, while minimizing the effect of GVHD, donor lymphocyte infusion was utilized. This idea, which was used against viral infections, postulated that adoptive transfer of virus-specific cytotoxic T lymphocytes could reconstitute specific immunity and eliminate virus infected cells and led to the idea of banking third party cytotoxic T cells (CTLs). T cell exhaustion sometimes became a problem and difficulty arose in creating robust CTLs. However, the introduction of induced pluripotent stem cells (iPSCs) lessens such problems, and by using iPSC technology, unlimited numbers of allogeneic rejuvenated CTLs with robust and proliferative cytotoxic activity can be created. Despite this revolutionary concept, several concerns still exist, such as immunorejection by recipient cells and safety issues of gene editing. In this review, we describe approaches to a feasible “off-the-shelf” therapy that can be distributed rapidly worldwide. We also offer perspectives on the future of allogeneic cell cancer immunotherapy.

Donor lymphocyte infusion after haploidentical hematopoietic stem cell transplantation for acute myeloid leukemia

Although haploidentical donor lymphocyte infusion (DLI) is a valid treatment option for relapsed acute myeloid leukemia (AML), the incidence and risk factors for graft-versus-host disease (GVHD) and the efficacy of haploidentical DLI have not been fully evaluated. We retrospectively analyzed the outcomes after haploidentical DLI for 84 patients with AML using a nationwide database and additional questionnaires. The median number of DLI cycles and infused CD3+ cell dose was 1 and 1.0 × 106/kg, respectively. The infused CD3+ cell count of 5.0 × 105/kg or higher was associated with acute GVHD (grade II-IV, 32.1% vs. 10.5%, p = 0.03; grade III-IV, 21.4% vs. 5.3%, p = 0.10). Patients who developed grade III-IV acute GVHD more frequently succumbed to treatment-related mortality (46.7% vs. 15.8% at 1 year, p = 0.002), although the relapse-related mortality was significantly low (40.0% vs. 72.2% at 1 year, p = 0.025). The overall response to DLI was significantly higher in the preemptive DLI group (47.4%) than in the therapeutic group (13.9%, p = 0.002). In the multivariate analysis, preemptive DLI was the predictive factor for overall response (odds ratio, 5.58; p = 0.003). Our results indicated the substantial risk of acute GVHD after haploidentical DLI with CD3+ cell count of 5.0×105/kg or higher and the favorable outcomes after preemptive DLI.

Preemptive Immunotherapy for Minimal Residual Disease in Patients With t(8;21) Acute Myeloid Leukemia After Allogeneic Hematopoietic Stem Cell Transplantation.

In patients with t(8;21) acute myeloid leukemia (AML), recurrent minimal residual disease (MRD) measured by RUNX1-RUNX1T1 transcript levels can predict relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT). This study aimed to compare the efficacy of preemptive interferon (IFN)-α therapy and donor lymphocyte infusion (DLI) in patients with t(8;21) AML following allo-HSCT. We also evaluated the appropriate method for patients with different levels of RUNX1-RUNX1T1 transcripts. In this retrospective study, consecutive patients who had high-risk t(8;21) AML and received allo-HSCT were enrolled. The inclusion criteria were as follows: (1) age ≤65 years; (2) regained MRD positive following allo-HSCT. MRD positive was defined as the loss of a ≥4.5-log reduction and/or <4.5-log reduction in the RUNX1-RUNX1T1 transcripts, and high-level, intermediate-level, and low-level MRDs were, respectively, defined as <2.5-log, 2.5−3.5-log, and 3.5−4.5-log reductions in the transcripts compared with the pretreatment baseline level. Patients with positive RUNX1-RUNX1T1 could receive preemptive IFN-α therapy or DLI, which was primarily based on donor availability and the intentions of physicians and patients. The patients received recombinant human IFN-α-2b therapy by subcutaneous injection twice a week every 4 weeks. IFN-α therapy was scheduled for six cycles or until the RUNX1-RUNX1T1 transcripts were negative for at least two consecutive tests. The rates of MRD turning negative for patients with low-level, intermediate-level, and high-level RUNX1-RUNX1T1 receiving IFN-α were 87.5%, 58.1%, and 22.2%, respectively; meanwhile, for patients with intermediate-level and high-level RUNX1-RUNX1T1 receiving DLI, the rates were 50.0% and 14.3%, respectively. For patients with low-level and intermediate-level RUNX1-RUNX1T1, the probability of overall survival at 2 years was higher in the IFN-α group than in the DLI group (87.6% vs. 55.6%; p = 0.003). For patients with high levels of RUNX1-RUNX1T1, the probability of overall survival was comparable between the IFN-α and DLI groups (53.3% vs. 83.3%; p = 0.780). Therefore, patients with low-level and intermediate-level RUNX1-RUNX1T1 could benefit more from preemptive IFN-α therapy compared with DLI. Clinical outcomes were comparable between preemptive IFN-α therapy and DLI in patients with high-level RUNX1-RUNX1T1; however, they should be further improved.

Hypomethylating Agent-Based Combination Therapies to Treat Post-Hematopoietic Stem Cell Transplant Relapse of Acute Myeloid Leukemia

Allogeneic stem cell transplantation still represents the best curative option for most patients with acute myeloid leukemia, but relapse is still dramatically high. Due to their immunologic activity and safety profile, hypomethylating agents (HMAs) represent an interesting backbone for combination therapies. This review reports mechanism of action, safety, and efficacy data on combination strategies based on HMAs in the setting of post-allogeneic stem cell transplant relapse. Several studies highlighted how HMAs and donor lymphocyte infusion (DLI) combination may be advantageous. The combination strategy of HMA with venetoclax, possibly in association with DLI, is showing excellent results in terms of response rate, including molecular responses. Lenalidomide, despite its well-known high rates of severe graft-versus-host disease in post-transplant settings, is showing an acceptable safety profile in association with HMAs with a competitive response rate. Regarding FLT3 internal tandem duplication (ITD) mutant AML, tyrosine kinase inhibitors and particularly sorafenib have promising results as monotherapy and in combination with HMAs. Conversely, combination strategies with gemtuzumab ozogamicin or immune checkpoint inhibitors did not show competitive response rates and seem to be currently less attractive strategies. Associations with histone deacetylase inhibitors and isocitrate dehydrogenase 1 and 2 (IDH1/2) inhibitors represent new possible strategies that need to be better investigated.

Prevention and Treatment of Acute Myeloid Leukemia Relapse after Hematopoietic Stem Cell Transplantation: The State of the Art and Future Perspectives.

Allogeneic hematopoietic stem cell transplantation (HSCT) for high-risk acute myeloid leukemia (AML) represents the only curative option. Progress has been made in the last two decades in the pre-transplant induction therapies, supportive care, selection of donors and conditioning regimens that allowed to extend the HSCT to a larger number of patients, including those aged over 65 years and/or lacking an HLA-identical donor. Furthermore, improvements in the prophylaxis of the graft-versus-host disease and of infection have dramatically reduced transplant-related mortality. The relapse of AML remains the major reason for transplant failure affecting almost 40–50% of the patients. From 10 to 15 years ago to date, treatment options for AML relapsing after HSCT were limited to conventional cytotoxic chemotherapy and donor leukocyte infusions (DLI). Nowadays, novel agents and targeted therapies have enriched the therapeutic landscape. Moreover, very recently, the therapeutic landscape has been enriched by manipulated cellular products (CAR-T, CAR-CIK, CAR-NK). In light of these new perspectives, careful monitoring of minimal-residual disease (MRD) and prompt application of pre-emptive strategies in the post-transplant setting have become imperative. Herein, we review the current state of the art on monitoring, prevention and treatment of relapse of AML after HSCT with particular attention on novel agents and future directions.

Azacitidine and donor lymphocytes infusions in acute myeloid leukemia and myelodysplastic syndrome relapsed after allogeneic hematopoietic stem cell transplantation from alternative donors.

Introduction:Azacitidine (AZA) either single-agent or with donor lymphocytes infusions (DLI) has been used as a salvage treatment for acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) relapsing after allogeneic hematopoietic stem cell transplantation (HSCT). To date, the majority of data come from patients relapsed after HSCT from full-matched donors.Methods:We report a multicenter, collaborative, retrospective analysis of 71 patients with hematologic (n = 40, 56%) and molecular relapse (n = 31, 44%) of myeloid neoplasms after HSCT from alternative donors (mismatched unrelated, n = 39, 55%; haploidentical, n = 29, 41%) consecutively treated at three European centers with AZA ± DLI.Results:Median time from HSCT to relapse was 9 months. Additional DLI were given to 33 patients (46%). After a median of four cycles, overall response rate (ORR) was 49% and complete response (CR) rate was 38%. CR lasted for a median of 17 months (range 5–89 months). Median follow-up in the entire cohort was 11 months (range 1–115 months). Event-free survival (EFS) and overall survival (OS) at 1 year were 26% and 53%, respectively. Treatment of molecular relapse granted higher CR rate (65% versus 15%; p = 0.0001), 1-year EFS (43% versus 13%; p = 0.006), and 1-year OS (79% versus 34%; p < 0.001) compared to hematologic relapses. Addition of DLI resulted in significantly higher responses and longer 1-year EFS and OS (Mantel–Byar test, p = 0.004 and p = 0.002, respectively). When applied to our cohort, the APSS-R score confirmed its ability to stratify patients into distinct prognostic groups with significantly different response rates (p = 0.0005) and survival (p < 0.0001). Treatment was well tolerated, with the incidence of late acute and chronic graft-versus-host disease of 27% and 18%, respectively.Conclusion:AZA ± DLI proved feasible and effective in AML and MDS relapsing after HSCT from alternative donors. Despite modest efficacy among hematologic relapses, pre-emptive treatment with AZA ± DLI fared better in molecular relapse. Additional DLI contributed to improving efficacy and ensuring longer survival.

Effect of Donor Lymphocyte Infusion From Two Types of Donors on Mixed Chimerism With Secondary Graft Failure After Allogeneic Hematopoietic Stem Cell Transplantation

Mixed chimerism (MC) and secondary graft failure (SGF) with recipient- or donor-type chimerism is a major obstacle in allogeneic hematopoietic stem cell transplantation (HSCT). Donor lymphocyte infusion (DLI) can eradicate minimal residual disease or be used to rescue a hematologic relapse, being able to induce durable remissions after HSCT. This study aimed to analyze the efficacy and immune mechanism of DLI from the original and alternative donor for patients of mixed donor chimerism with SGF. The alternative donor refers to the candidate relative donor who did not initially provide stem cells and includes HLA-matched sibling donor or HLA-haploidentical donor. We conducted a retrospective study of 246 patients with a median age of 37 (9-58) years who had regularly detected MC, complete donor chimera (CC), and regulatory T cells (Treg). The median diagnosis time of SGF was 69 (39-141) days after transplantation. Sixteen patients with SGF received DLI from the alternative donor, including 3 patients who chose DLI from the original donor with no initial response and 13 patients who directly chose DLI from the alternative donor. Sixteen patients with SGF existed mixed chimerism synchronously and the rate calculated overall chimerism of MC was 63% (range 42%-85%) after transplantation. The proportion of Treg decreased significantly in SGF patients from a median of 2.66% ± 0.80% to 0.93% ± 0.57% at a time point after transplantation (P = .02). The DLI of the alternative donor in 14 patients achieved complete response and MC gradually convert to CC state, simultaneously there was significant increase in the Treg fraction (SGF versus complete response: 0.93% ± 0.57% versus 3.61% ± 0.82% [P = .01]). For the clinical nonresponders from 2 types of donors, there was no significant change in MC and Treg cells. The OS and disease-free survival at 2 years after DLI were 69.7% ± 3.19% and 61.3% ± 4.80%, respectively. DLI from the alternative donor may be an effective treatment for MC with SGF, and the mechanism is closely related to the activation of Treg cells level.

The Two-Step Allogeneic Stem Cell Transplantation Approach Results in Rapid Engraftment and Excellent Outcomes in Patients with Lymphoid Malignancies

The 2-step graft engineering approach has been the main platform for allogeneic hematopoietic cell transplantation (allo-HCT) at Thomas Jefferson University since 2005. We have previously described separating donor lymphocyte infusion followed by cyclophosphamide for bidirectional tolerization from CD34-selected hematopoietic grafts in haploidentical and matched related donors. Here we analyzed 60 patients with high-risk lymphoid malignancies who underwent a 2-step allo-HCT between 2008 and 2020. The majority of patients received haploidentical stem cell grafts (82%), and 20% of patients received matched related donor stem cell grafts. The patients underwent allo-HCT for diffuse large C cell lymphoma (n=17; 28%), chronic lymphoblastic leukemia (n=10; 17%), follicular lymphoma (n=8; 13%), and Hodgkin lymphoma (n=7; 12%). Eight patients (13%) had received prior high-dose chemotherapy. Thirty patients (50%) had a Hematopoietic Cell Transplantation Comorbidity Index ≥3, and 20 patients (33%) had a Center for International Blood & Marrow Transplant Research Revised Disease Risk Index of high risk or very high risk. The median patient age was 56 years (range, 24 to 75 years). Neutrophils engrafted at a median of 11 days (range, 9 to 16 days), and platelets engrafted at a median of 16 days (range, 13 to 37 days). With a median follow-up of 6 years, the 3-year probability of overall survival was 62.9% (95% confidence interval [CI], 49.3% to 73.8%), and that of disease-free survival was 60.2% (95% CI, 46.4% to 71.6%). The cumulative incidence of relapse at 3 years was 11.9% (95% CI, 5.2% to 21.6%). The cumulative incidence of nonrelapse mortality at 3 years was 30.1% (95% CI, 1.91% to 42.0%). The cumulative incidence of grade II-IV acute graft-versus-host disease (GVHD) at 1 year was 45% (95% CI, 32.2% to 57.0%), and that of grade III-IV acute GVHD at 1 year was 5% (95% CI, 1.3% to 12.6%). The cumulative incidence of cGVHD at 3 years was 15.2% (95% CI, 7.5% to 25.4%). The 2-step approach achieved excellent outcomes in high-risk lymphoid malignancies, with rapid neutrophil and platelet recovery.

Time‐dependent analysis of adoptive immunotherapy following sequential FLAMSA‐reduced intensity conditioning and allogeneic hematopoietic stem cell transplantation in patients with high‐risk myeloid neoplasia

Prophylactic donor lymphocyte infusions (DLI) are part of the sequential FLAMSA-reduced intensity conditioning (RIC) regimen to cure high risk myeloid neoplasia with allogeneic hematopoietic stem cell transplantation (HSCT). Although DLI themselves carry significant risks, their prophylactic use has not been analyzed in a time-dependent manner. One hundred and fourteen patients underwent FLAMSA-RIC HSCT between 2013 and 2020. Next to Kaplan-Meier estimation of overall, disease-free, and graft-versus-host relapse-free survival (OS, DFS, GRFS), cumulative incidences of relapse and death in remission were calculated in a competing risk model. Additionally, the contribution of prophylactic and preemptive DLI as time-dependent covariates was assessed using a time-varying model toward DFS (Simon-Makuch method, Mantel-Byar test). At 2years, OS was 45.2% [95% CI 36.7-55.7%], DFS 31.8% [95% CI 24-42.2%] and GRFS 11.3 [95% CI 6.5-19.8]. Neither prophylactic nor preemptive DLI showed a significant influence on DFS when considered time-dependent covariates (Mantel-Byar, p=.3). This was further corroborated in competing risk analysis with DLI as time-dependent covariates. Both prophylactic and preemptive DLI miss significance in their impact on survival within a high-risk cohort in a time-varying model. Controlled trials to address the impact of postgrafting immunotherapy approaches are needed.

Treatment of AML Relapse After Allo-HCT

With advances in allogeneic hematopoietic stem cell transplant (allo-HCT), disease relapse has replaced transplant-related mortality as the primary cause of treatment failure for patients with acute myeloid leukemia (AML). The efficacy of allo-HCT in AML is a consequence of a graft-versus-leukemia (GVL) effect that is mediated by T lymphocytes, and unique mechanisms of immune evasion underlying post-allo-HCT AML relapses have recently been characterized. Relapsed AML following allo-HCT presents a particularly vexing clinical challenge because transplant-related toxicities, such as graft-versus-host (GVHD) and infections, increase the risk of treatment-related morbidity and mortality. In general, the prognosis of relapsed AML following allo-HCT is poor with most patients failing to achieve a subsequent remission and 2-year survival consistently <15%. The two factors that have been found to predict a better prognosis are a longer duration of post-transplant remission prior to relapse and a lower disease burden at the time of relapse. When considered in combination with a patient’s age; co-morbidities; and performance status, these factors can help to inform the appropriate therapy for the treatment of post-transplant relapse. This review discusses the options for the treatment of post-transplant AML relapse with a focus on the options to achieve a subsequent remission and consolidation with cellular immunotherapy, such as a second transplant or donor lymphocyte infusion (DLI). While intensive reinduction therapy and less intensive approaches with hypomethylating agents have long represented the two primary options for the initial treatment of post-transplant relapse, molecularly targeted therapies and immunotherapy are emerging as potential alternative options to achieve remission. Herein, we highlight response and survival outcomes achieved specifically in the post-transplant setting using each of these approaches and discuss how some therapies may overcome the immunologic mechanisms that have been implicated in post-transplant relapse. As long-term survival in post-transplant relapse necessarily involves consolidation with cellular immunotherapy, we present data on the efficacy and toxicity of both DLI and second allo-HCT including when such therapies are integrated with reinduction. Finally, we provide our general approach to the treatment of post-transplant relapse, integrating both novel therapies and our improved understanding of the mechanisms underlying post-transplant relapse.

Antibody-drug conjugates plus Janus kinase inhibitors enable MHC-mismatched allogeneic hematopoietic stem cell transplantation.

Despite the curative potential of hematopoietic stem cell transplantation (HSCT), conditioning-associated toxicities preclude broader clinical application. Antibody-drug conjugates (ADCs) provide an attractive approach to HSCT conditioning that minimizes toxicity while retaining efficacy. Initial studies of ADC conditioning have largely focused on syngeneic HSCT. However, to treat acute leukemias or induce tolerance for solid organ transplantation, this approach must be expanded to allogeneic HSCT (allo-HSCT). Using murine allo-HSCT models, we show that pharmacologic Janus kinase 1/2 (JAK1/2) inhibition combined with CD45- or cKit-targeted ADCs enables robust multilineage alloengraftment. Strikingly, myeloid lineage donor chimerism exceeding 99% was achievable in fully MHC-mismatched HSCT using this approach. Mechanistic studies using the JAK1/2 inhibitor baricitinib revealed marked impairment of T and NK cell survival, proliferation, and effector function. NK cells were exquisitely sensitive to JAK1/2 inhibition due to interference with IL-15 signaling. Unlike irradiated mice, ADC-conditioned mice did not develop pathogenic graft-versus-host alloreactivity when challenged with mismatched T cells. Finally, the combination of ADCs and baricitinib balanced graft-versus-host disease and graft-versus-leukemia responses in delayed donor lymphocyte infusion models. Our allo-HSCT conditioning strategy exemplifies the promise of immunotherapy to improve the safety of HSCT for treating hematologic diseases.

Donor memory-like NK cells persist and induce remissions in pediatric patients with relapsed AML after transplant

AbstractPediatric and young adult (YA) patients with acute myeloid leukemia (AML) who relapse after allogeneic hematopoietic cell transplantation (HCT) have an extremely poor prognosis. Standard salvage chemotherapy and donor lymphocyte infusions (DLIs) have little curative potential. Previous studies showed that natural killer (NK) cells can be stimulated ex vivo with interleukin-12 (IL-12), -15, and -18 to generate memory-like (ML) NK cells with enhanced antileukemia responses. We treated 9 pediatric/YA patients with post-HCT relapsed AML with donor ML NK cells in a phase 1 trial. Patients received fludarabine, cytarabine, and filgrastim followed 2 weeks later by infusion of donor lymphocytes and ML NK cells from the original HCT donor. ML NK cells were successfully generated from haploidentical and matched-related and -unrelated donors. After infusion, donor-derived ML NK cells expanded and maintained an ML multidimensional mass cytometry phenotype for >3 months. Furthermore, ML NK cells exhibited persistent functional responses as evidenced by leukemia-triggered interferon-γ production. After DLI and ML NK cell adoptive transfer, 4 of 8 evaluable patients achieved complete remission at day 28. Two patients maintained a durable remission for >3 months, with 1 patient in remission for >2 years. No significant toxicity was experienced. This study demonstrates that, in a compatible post-HCT immune environment, donor ML NK cells robustly expand and persist with potent antileukemic activity in the absence of exogenous cytokines. ML NK cells in combination with DLI present a novel immunotherapy platform for AML that has relapsed after allogeneic HCT. This trial was registered at https://clinicaltrials.gov as #NCT03068819.

Haploidentical transplantation has a superior graft-versus-leukemia effect than HLA-matched sibling transplantation for Ph- high-risk B-cell acute lymphoblastic leukemia.

Background:Compared with human leukocyte antigen (HLA)-matched sibling donor (MSD) transplantation, it remains unclear whether haploidentical donor (HID) transplantation has a superior graft-versus-leukemia (GVL) effect for Philadelphia-negative (Ph–) high-risk B-cell acute lymphoblastic leukemia (B-ALL). This study aimed to compare the GVL effect between HID and MSD transplantation for Ph– high-risk B-ALL.Methods:This study population came from two prospective multicenter trials (NCT01883180, NCT02673008). Immunosuppressant withdrawal and prophylactic or pre-emptive donor lymphocyte infusion (DLI) were administered in patients without active graft-versus-host disease (GVHD) to prevent relapse. All patients with measurable residual disease (MRD) positivity posttransplantation (post-MRD+) or non-remission (NR) pre-transplantation received prophylactic/pre-emptive interventions. The primary endpoint was the incidence of post-MRD+.Results:A total of 335 patients with Ph– high-risk B-ALL were enrolled, including 145 and 190, respectively, in the HID and MSD groups. The 3-year cumulative incidence of post-MRD+ was 27.2% (95% confidence interval [CI]: 20.2%–34.7%) and 42.6% (35.5%–49.6%) in the HID and MSD groups (P = 0.003), respectively. A total of 156 patients received DLI, including 60 (41.4%) and 96 (50.5%), respectively, in the HID and MSD groups (P = 0.096). The 3-year cumulative incidence of relapse was 18.6% (95% CI: 12.7%–25.4%) and 25.9% (19.9%–32.3%; P = 0.116) in the two groups, respectively. The 3-year overall survival (OS) was 67.4% (95% CI: 59.1%–74.4%) and 61.6% (54.2%–68.1%; P = 0.382), leukemia-free survival (LFS) was 63.4% (95% CI: 55.0%–70.7%) and 58.2% (50.8%–64.9%; P = 0.429), and GVHD-free/relapse-free survival (GRFS) was 51.7% (95% CI: 43.3%–59.5%) and 37.8% (30.9%–44.6%; P = 0.041), respectively, in the HID and MSD groups.Conclusion:HID transplantation has a lower incidence of post-MRD+ than MSD transplantation, suggesting that HID transplantation might have a superior GVL effect than MSD transplantation for Ph– high-risk B-ALL patients.Trial registration:ClinicalTrials.gov: NCT01883180, NCT02673008.