Grade III-IV Acute Graft-versus-host Disease Research Articles

Casting Hope, Defying Odds: Unveiling the Impact of Haplo-Identical Stem Cell Transplant in Myeloid Malignancies - a Tertiary Cancer Care Center Experience

Background & Significance: Only 30% to 40% of patients in need of a curative stem cell transplant (SCT) could find a suitable matched sibling donor. For Indian patients, the likelihood of locating a 10/10 HLA identical unrelated donor within limited donor registries is approximately 14%. However, this probability has the potential to rise to 60% if registries with over 1,000,000 registered donors are available. 1,2 Consequently, there is an increasing inclination in India to perform haploidentical transplantations utilizing the post-transplantation cyclophosphamide (PTCY) platform developed by the Johns Hopkins group. 3 The outcomes of haploidentical stem cell transplantation (haplo-SCT) for the treatment of AML were enhanced in the 1990s with the introduction of a T-cell depletion (TCD) strategy followed by a myeloablative conditioning regimen. 4,5 In the last two decades, significant progress in haplo-SCT for hematological malignancies, especially AML, includes donor selection algorithms, improved grafts, GVHD prophylaxis, and enhanced immunologic recovery, benefiting patients. 6 Here, we present our experience of haplo-identical stem cell transplants in myeloid malignancies at our centre. Study design & Methods: We conducted a retrospective study at our site. Patients with myeloid malignancy who underwent haplo-identical stem cell transplant between Jan 2018 - Jan 2023 were included in the study and the follow-up was done till July 2023. Haplo-identical transplants done for diagnosis other than myeloid malignancy were excluded. The objectives of the study were to assess the non-relapse mortality [NRM] rate at day +100, relapse rate, graft-versus-host disease - free relapse-free survival [GRFS] and overall survival [OS] of the study cohort. GRFS was defined as a combined outcome including mortality from any cause, recurrence of malignancy, acute GVHD of grade 3 to 4, or chronic GVHD necessitating systemic immune suppression therapy. 7 Descriptive statistics (including median, mean, and range) were used to describe the central tendency and dispersion of variables. The probability of overall survival [OS] and graft versus host disease relapse free survival [GRFS] was estimated by the method of Kaplan and Meier. Probabilities of relapse or progression of malignancy, RRM, and day-100 NRM were summarized using cumulative incidence estimates All statistical analysis were done using statistical package for social science software (SPSS 21, IBM SPSS Statistics). Results: We have analysed 29 patients with various myeloid malignancies who have underwent haploidentical SCT from Jan 2018 to Jan 2023. There were 28 AML and 1 MDS patients. The median age was 35 (range, 16 - 59) and there were 22 males and 7 females. Conditioning intensity was myeloablative in 19 (65.5%), reduced intensity conditioning (RIC) in 8 (27.6%) and NMA in 2 (6.9%) patients. There were 10 (34.5%) patients in complete remission 1(CR1) and 19 (65.5%) in CR2. Hematopoietic Cell Transplantation-specific Comorbidity Index [HCT-CI] score was as low 11 (37.9%), intermediate 8 (27.6%) and high 10 (34.5%) patients respectively. Median time to neutrophil engraftment was 16 days (range, 12 - 25) and platelet engraftment was 17 days (range, 11 - 32). Median CD34 stem cell dose was 6.25 x 10*6/kg (range, 3.1 - 8.09) x 10*6/kg. Grade II-IV acute GVHD over first +100 days post SCT was observed in 6 (20.7) patients, and grade III-IV acute GVHD and chronic GVHD at follow up of one year was 3 (10.3) respectively. CMV reactivation by +100days was seen in 18 (62.06%) patients. Relapse was seen in 10 (34.5%) patients, out of which 2 patients are alive and 8 expired due to progressive disease. At median follow up of 13 months, OS is 60.3% (CI: 39.7% - 75.9%) and GRFS is at a median follow-up of 6 month was 51.2% (CI: 35.6% - 71%). Fig:1 NRM was 10.3% and 17.24% at +100 days and at last follow-up respectively. Fig:2 Conclusion: In conclusion, our study demonstrates favorable outcomes in terms of NRM (non-relapse mortality) with a low rate of 10.3% at 100 days after haploidentical SCT. The results also show promising overall survival (OS) and GVHD-free, relapse-free survival (GRFS) rates, supporting the potential of haploidentical transplants as an effective treatment option for myeloid malignancies. Further long-term follow-up and research are needed to validate and optimize these findings.

Fractionated Total Body Irradiation and Fludarabine Based Conditioning Regimen with Post-Transplant Cyclophosphamide (PTCy) for Mismatched Related and Unrelated Donors HCT for Acute Leukemia and MDS

Background: Allogeneic hematopoietic cell transplantation (alloHCT) remains the only curable treatment option for several hematological malignancies. Preparative and graft-versus-host disease (GVHD) prophylactic regimens combined with graft-versus-leukemia effect (GVL) are important in preventing graft rejection, disease relapse and GVHD; and subsequently impact the success of this life saving procedure. Choice of regimen depends on patient, donor/graft source and disease characteristics. Objectives: Assess the outcomes of patients who underwent haploidentical (haplo) or mismatched unrelated donor (MMUD) HCT with myeloablative conditioning (MAC) regimen using radiation in combination with fludarabine (FLU) with PTCy as higher intensity GVHD prophylaxis and evaluate the feasibility of a fludarabine and fractionated total body irradiation (FLU/FTBI)-based regimen in both donors. Study Design: Retrospective analysis to study the outcomes of patients receiving FLU/FTBI as myeloablative conditioning for mismatched (related or unrelated) donor HCT combined with post-transplant cyclophosphamide (PTCy) as GVHD prophylaxis. Results: One hundred and fifty-five consecutive patients undergoing HCT at City of Hope (COH) from January 2015 to December 2021 were included. Median age was 38 years (range 9-60) and 56.8% of patients were male and 97.5% had a Karnofsky performance status (KPS) ≥ 80. HCT comorbidity index was ≥ 3 in 36.1% cases and 29% with a disease risk index (DRI) of high/very high. Disease diagnosis included acute lymphoblastic leukemia (ALL) (46.5% of cases) and acute myeloid leukemia (AML) (36.1% of cases). The median donor age was 31-years with 67.1% haplo donors and 32.9% mismatched unrelated donors (MMUD). MMUD HCT led to faster neutrophil recovery (15 vs 16 days, p= 0.01) and platelet count recovery (18 vs 23 days, p= 0.029). Day 100 cumulative incidence of grade II-IV and III-IV acute GVHD had no statistical difference between the two cohorts. With a median follow-up of 24 months (range 3 to 81), 100-day and 1-year NRM was 1.9% and 8.5%, respectively. There was no difference in the NRM between MMUD and haplo (HR 0.92, CI (0.35,2.39), p=0.86). Two-year relapse rate and DFS were 11.8% and 76.9%, respectively. In this study, 7 out of 51 patients in the MMUD group and 17 out of 104 patients in the haplo group relapsed with no statistically significant difference between the groups (HR 0.82, CI: (0.35,1.97), p=0.67). At a median follow-up of 2 years, GRFS was 60% (95% CI 0.51- 0.67). There was no statistically significant difference in GRFS between the MMUD and haplo groups (HR 0.76, CI (0.44,1.32), p=0.33). Two-year OS was 80.1%. There were no DFS or OS differences between the MMUD and haplo groups. On multivariate analysis, age less than 40 and low to intermediate DRI showed a DFS benefit (p = 0.004 and 0.029 respectively). None of the demographic factors affected OS or GRFS. Disease risk index was the only factor on multivariate analysis affecting relapse rates with higher risk of relapse with higher DRI (p= 0.017) and extensive chronic GVHD risk (p= 0.014) with no impact on acute GVHD. Conclusions: FLU/FTBI followed by PTCy for GVHD prophylaxis is a well-tolerated myeloablative regimen in mismatched donors with acute leukemia or myelodysplastic syndrome (MDS) with low transplant related morbidity and mortality and has produced promising HCT outcomes.

Score to Guide Donor Choice in Haploidentical Stem Cell Transplant Using Post-Transplant Cyclophosphamide for Patients with Acute Myeloid Leukemia: A Study from the Acute Leukemia Working Party of the EBMT

Introduction: There is paucity of information to guide selection of the most appropriate stem cell donor for haploidentical (Haplo) hematopoietic stem cell transplant (HSCT). Patients and Methods: We retrospectively analyzed the characteristics of haploidentical family donors that may affect transplant outcomes in patients with acute myeloid leukemia (AML) who received graft-versus-host disease (GVHD) prophylaxis with postransplant cyclophosphamide (PTCy) registered in the EBMT database. The primary endpoint was GVHD and relapse-free survival (GRFS). Results: Overall, 2200 patients were included with a median age of 56 years (range, 18-75); 1742 (79%) were in complete remission and 1246 (56.6) received reduced intensity conditioning. Regarding donors, the median age was 37 years (range, 8-71), 820 (37%) were females of which 458 (21%) were used for male recipients, 1252 (57%) had positive CMV serostatus, 1631 (74%) donated peripheral blood (PB) and 1638 (75%) had ≥ 4/8 HLA mismatch with the recipient. 100-day acute GVHD grade II-IV and III-IV and 2-year chronic and chronic extensive GVHD were 28% (95% CI 26-30), 11% (95% CI 10-12), 33% (95% CI 31-35) and 14% (95% CI 12-15), respectively. After median follow-up of 24 months, the cumulative incidence of relapse and non-relapse mortality (NRM) and the probability of leukemia-free survival (LFS), overall survival (OS) and GRFS were 26% (95% CI 24-28), 22% (95% CI 20-24), 52% (95% CI 50-55), 57% (95% CI 55-60) and 41% (95% CI 39-43), respectively. In multivariable analysis, donor-related risk factors with a negative impact on GRFS were older age (HR 1.1; 95% CI 1.04-1.15), use of PB (HR 1.19; 95% CI 1.04-1.37), and female donors to male recipients (HR 1.25; 95% CI 1.09-1.43). We further developed a score that distinguished 4 groups with 0 (241), 1 (913), 2 (863) or 3 (183) donor-related risk factors. GRFS was 57% (95% CI 50-63), 43% (95% CI 39-46), 37% (95% CI 33-40), and 30% (95% CI 23-38), respectively (P < 0.001) (Figure 1). The score was also able to stratify risk groups for acute and chronic GVHD, NRM, LFS and OS. Conclusion: Donor variables have an important impact on AML patient's outcome after Haplo-HSCT using PTCy. With three simple donor characteristics, age, gender and stem cell source, we were able to generate a score that may help to select the most appropriate donor in clinical practice.

Addition of Inotuzumab Ozogamicin to the Conditioning Regimen of Allogeneic Stem Cell Transplantation (allo-SCT) for Relapsed CD22 (+) Lymphoid Malignancies: Long-Term Survival Results

Background: Inotuzumab ozogamicin (InO) is a humanized antibody-drug conjugate that targets CD22+ B-cells. InO demonstrated antitumor activity and manageable toxicity in phase 1/2 trials for the treatment of B-cell non-Hodgkin lymphoma (NHL) as a single agent and in combination with rituximab. In order to improve outcomes in patients with relapsed CD22 (+) NHL, or chronic lymphocytic leukemia (CLL) who failed targeted therapies and were candidates for allo-SCT, we prospectively studied the addition of InO to our standard chemo-conditioning of BFR (bendamustine, fludarabine and rituximab-Khouri Blood 2014). Herein we report long-term survival outcomes. Methods: InO was infused intravenously (iv) on day -13 outpatient, with a dose cohort of 0.6, 1.2 or 1.8 mg/m2. Bendamustine 130 mg/m 2 iv daily on days -5 to -3 together with 30 mg/m 2 iv of fludarabine on days -5 to -3 were given prior to transplantation. Rituximab was given at a dose of 375 mg/m 2 iv on days -6, +1, and +8. Tacrolimus and mini-methotrexate were used for graft versus host disease (GVHD) prophylaxis. Results: The study included 26 patients. Median age was 59 (range, 26-70) years. Disease types: CLL [n=11 (27%) ; 64% with TP53 mutations (either alone, or with other mutations such as BTK, CDH2, ZMYM3); 22% with complex cytogenetics; 75% with unmutated IGHV; mantle cell lymphoma ( MCL) [n=8 (31%); 83% had Ki 67 >30%; 25% TP53 mutation; and 25% blastoid histology]; Follicularlymphoma (n=5, 19%), and diffuse large b cell ( DLBCL[n= 2; (8%)]. Median # prior treatments was 2.5 (range, 1-6). Patients with CLL/MCL were previously treated with ibritunib (n=10), venetoclax (n=5), idelalisib (n=2), nivolumab (n=1) and CAR T (n=1). At study entry, 18 (69%) patients were in CR, 7 (27%) in PR, and 1 (4%) had SD. Eleven (42%) received their transplants from matched sibling donors (MSDs) and 15 (58%) from matched unrelated donors (MUDs). The number of patients who received the 0.6, 1.2 or 1.8 mg/m2 of InO were 4, 2 and 20 patients, respectively. No DLT was observed. Forty-two percent of patients never experienced severe neutropenia and 77% never experienced platelet counts < 20K x 10 9/L. Only 1 patient developed veno-occlusive disease, confounded by the simultaneous manisfestation of hyper-acute GVHD related to prior nivolumab pre-alloSCT. Treatment-related mortality (TRM) at 2-years was 12%. With a median follow-up of 48.7 months (range, 3.6-82.8), the 5-year overall survival (OS) and progression-free survival rates (PFS) were 84% and 80%, respectively. Seven of 8 (87.5%) patients with PR/SD at study entry converted to CR after allo-SCT. There was no significant difference in OS or PFS by histology subtype. Patients who received a transplant from MSDs had OS and PFS rates of 100% v 79% ( P = .060) and 64% ( P = .032) for those who received MUDs, respectively (Figure 1). We compared results of this trial to a group of patients (n=56) with relapsed lymphoid malignancies who received allo-SCT at our center in a preceding prospective trial using BFR conditioning without InO and the same GVHD prophylaxis (clinicaltrials.gov #NCT00880815) which was previously published. There was no statistically significant difference in patients, disease (including histology, disease status pre-transplant) or transplant characteristics between the 2 groups. We found no statistically significant differences in engraftment times, incidence and grades of liver toxicity, TRM, risk of acute grade II-IV or III-IV GVHD. However, the study group containing InO had a higher incidence of extensive chronic GVHD (mainly de novo) than the control group (50% vs 25%, P = .019), respectively. There was a trend in patients with NHL to have a better 5-year OS (93% vs 68%) and 5-year PFS (93% vs 58%, Figure 2) in the study group vs the control groups. We did not observe such a trend in patients with CLL (5-year PFS 62% vs 59%): this could be related to small #patients, level of expression of CD22, more adverse mutations in the study group. Conclusions: Our results show that InO is safe when combined with an allo-SCT conditioning regimen and may improve survival outcomes in patients with CD22 (+) NHL. This needs to be validated in a larger number of patients. An ongoing trial at our center involves fractionating InO dose pre-and post-allo-SCT in patients with lymphoma or acute lymphoblastic leukemia receiving a reduced-intensity conditioning, and adding post-transplant cyclophosphamide to decrease the risk of GVHD.

Infusion of UM171-Expanded Cord Blood Led to Excellent Survival in Patients with High-Risk Leukemias: Results from Two Independent Phase II Studies

Background: Cord blood transplant (CBT) recipients experience delayed hematopoietic recovery and an increased risk of non-relapse mortality (NRM). UM171 is a small molecule that expands hematopoietic stem and progenitor cells (HSPC). An initial phase I-II clinical trial of a single UM171-expanded CBT was associated with low NRM and excellent long-term outcomes. (S Cohen et al. Lancet Haematology 2020). With the primary goal of generating increased numbers of HSPC to supplement a conventional single cord blood (CB) graft, we tested the same approach exclusively in high and very high-risk patients with acute leukemias/myelodysplastic syndromes (MDS). Methods: Between 2019 and 2022, two single independent prospective phase II studies were conducted in Montreal, at the Maisonneuve Rosemont Hospital and in Seattle, at the Fred Hutchinson Cancer Center. Primary objectives were safety/NRM and progression free survival at 2-years post-transplant. Only patients with high and very-high risk acute myeloid leukemia (AML), acute lymphoid leukemia (ALL) and MDS were eligible. Patients were required to have adequate organ function and comorbidity index as defined by the transplant center. Patients received a single UM171 7-day expanded and cryopreserved CB after either a myeloablative or mid-intensity conditioning regimen. All patients received tacrolimus and mycophenolate mofetil for GVHD prophylaxis. Results: A total of 52 patients were enrolled (31 in Montreal and 21 in Seattle) with 2 patients not receiving the UM171 expanded product and therefore removed from the final analysis. Patient's characteristics are shown in Table 1. The median age was 44 years (range 19-66) and weight 78 kg (range, 44-145). Twenty-eight patients (54%) were either in a no complete response (CR) status or in ≥CR2, ten (19%) were p53+ and 17 (33%) were second or third transplants. Forty patients (77%) received a 5/8 HLA-matched CB unit and the median of CD34+ cells infused was 4.7 10 6/Kg (0.9-7.5). All patients engrafted (ANC >500 10^ 9/L for 2 consecutive days) at a median of 17 days (range, 9-39 days). The median time to platelet recovery (>20 x 10^ 9/L) was 37 days (range 24-116). With a median follow-up of 24 months (range 0.7 - 39), the probability of 2-year overall survival (OS) and progression-free survival (PFS) was 67% (95% CI, 54-82) and 63% (95% CI, 50-79). OS for second/third transplants and p53+ patients was 64% (95% CI, 43-96) and 40 (95% CI, 19-86), PFS was 51 % (95% CI, 29-87) and 40 (95% CI, 19-86), respectively. At 2 years, the cumulative incidence of NRM was 19% (95% CI, 8-31) while the incidence of relapse was 18% (95% CI, 6-29). The incidence of grade II-IV and III-IV acute GVHD was 69% (95% CI, 56−82%) and 16% (95% CI, 6−27%). The rate of moderate/severe chronic GVHD was 7% (95% CI,1−15%) and translated in an incidence of a chronic-relapse-free-survival of 55% (95% CI, 42−72%). Of note, Kaplan-Meier analysis of all clinical outcomes showed no difference for patients treated in Montreal and Seattle, and results were similar for both centers (Figure 1). Conclusions: The results of 2 independent Phase II clinical studies demonstrated that infusion of a UM171 single CBT led to excellent clinical outcomes in patients with high and very-high risk malignancies including patients with p53+ mutation. We also observed encouraging results for patients undergoing second/third transplants (33% of the entire cohort). Clinical outcomes were similar between the two Transplant Centers. Based on these positive results, a multicenter randomized clinical trial is currently in the planning stage.

A Prospective Randomized Clinical Trial Comparing a Calcineurin-Free Gvhd Prophylaxis Regimen with Post-Transplant Cyclophosphamide and Abatacept to Methotrexate and Tacrolimus

Background: Chronic Graft Versus Host Disease (GVHD) is one of the major causes of mortality and morbidity after an allogeneic stem cell transplantation. We hypothesized that we could induce post-transplant tolerance by using the combination of post-transplant cyclophosphamide (PTCy) and abatacept (CTLA4Ig) for GVHD prophylaxis. PTCy can eliminate most host-reactive donor T cells. Abatacept (CTLA4Ig) blocks the costimulatory signals given to naïve T cells during immune reconstitution, thus favoring an anergic phenotype and promoting tolerance towards recipient derived antigens. CTLA4Ig gives an activating signal to NK cells and has therefore the ability to preserve the graft-versus-tumor effect. Methods: We conducted a prospective randomized clinical trial. Patients with hematologic malignancies in need of an allogeneic transplant and with an 8/8 matched related or unrelated donor were randomized 1:1 to tacrolimus and methotrexate for GVHD prophylaxis (SOC arm) or PTCy on days +3 and +4 followed by abatacept on an extended schedule: days +5, +14,+28, +56, +84, +112, +140 and +168 (Aba arm). Patients were stratified by conditioning regimen (myeloablative vs reduced intensity) and donor type (matched sibling vs matched unrelated donor). They received peripherally collected stem cells. The primary endpoint was moderate and severe chronic GVHD at 1 year and the secondary endpoints overall chronic GVHD, Grade II-IV and III-IV acute GVHD rate, overall (OS), disease-free (DFS), and GVHD-relapse-free-survival (GRFS) at on year, transplant related mortality and infection rate. The study stopped enrolling on the SOC arm when abatacept was approved for GVHD prophylaxis and the institutional SOC changed to include abatacept. Results: 40 patients were treated on this study, 25 of which on the aba arm. There were two cases of secondary graft failure (one on each arm) that were excluded from further analysis other than OS. The trial met its primary end point: Kaplan-Meier estimates of moderate/severe cGVHD were 0% on the aba and 65.8% on the SOC arm (p < 0.0001). GRFS was 58.3% in the aba and 21.4% in the SOC arm (p=0.043). There were no treatment related deaths on the aba and two on the SOC arm. There was no statistically significant difference in the rates of OS (92% aba, 80% SOC, p=0.28), DFS (62.5% aba, 85.7% SOC, p=0.103) and infection. Grade III-IV acute GVHD rate was 4.1% on the aba and 20% on the SOC arm (p=0.132), whereas Grade II-IV 12.5% on aba and 35.7% on SOC (p=0.117). There were no cases of acute GVHD of the gut or liver on the aba arm. Overall chronic GVHD rate (including mild) was 9.1% on the aba and 74% on the SOC arm (p<0.0001). Conclusions: The calcineurin inhibitor-free combination of PTCy and abatacept for GVHD prophylaxis is feasible, well tolerated and associated with a very low rate of chronic GVHD and a favorable GRFS rate.

Updated Findings of a Phase II Study of Ruxolitinib Pre-, during- and Post-Hematopoietic Stem Cell Transplantation for Patients with Primary or Secondary Myelofibrosis

Background: Despite tremendous progress in the treatment of myelofibrosis in the last decade, the only curative therapy remains allogeneic hematopoietic cell transplantation (HCT). There are now three FDA-approved JAK inhibitors (JAKi) to treat symptomatic splenomegaly and constitutional symptoms in myelofibrosis, although these agents do not prevent disease progression. Discontinuation of JAKi before (pre) HCT is challenging as patients can experience return of symptoms. Thus, ruxolitinib is often continued during HCT in an off-label fashion; however, little is known about the safety and efficacy of this approach. Furthermore, there is increasing use of ruxolitinib after (post) HCT, following its approval in treating refractory graft-versus-host disease (GVHD). Methods: We previously reported the interim results of a phase II, multicenter, investigator-initiated trial investigating ruxolitinib given pre-, during- and for 1-year post-HCT for patients with primary or secondary MF (NCT03427866). Here we present the results of the study with full accrual of 43 patients. The primary endpoint was 1-year GVHD-free, relapse-free survival (GRFS). Secondary endpoints included overall (OS) and progression free survival (PFS), engraftment, and incidence of acute and chronic GVHD. Patients were treated with reduced intensity conditioning with fludarabine (30mg/m 2/d x 5 days) and melphalan (100 or 140mg/m 2 x 1). Patients received peripheral blood stem cell grafts from either 7/8 or 8/8 HLA-matched donors. GVHD prophylaxis consisted of standard tacrolimus and methotrexate. Results: 44 patients with myelofibrosis were enrolled and 43 underwent HCT between 9/2018 and 5/2023. Median age was 66 (range 46-75), 37% were female (n=16), and most patients had DIPSS intermediate-2/high risk (n=36), 60% (n=27) were receiving ruxolitinib prior to enrolling on the study. Most (n=35) received 8/8 matched unrelated transplants and had measurable splenomegaly by either ultrasound or CT (n=40) prior to HCT. At baseline, 25 patients had JAK2 mutation, 8 had CALR and 5 had MPL mutations, 13 patients had ASXL1 mutations (Figure 1). No differences in outcomes were observed by pre-HCT mutational status. At day 100, all but one patient had undetectable mutations by next generation sequencing. The most common grade 3/4 hematologic adverse events (AE) were anemia (n=12), thrombocytopenia (14), neutropenia (n=11). Non-hematologic grade 3/4 events included hypertriglyceridemia (n=3). Median time to neutrophil engraftment was 15 days (range 4-38), one patient did not engraft. Median time to platelet (>20x10 9) engraftment was 25 days (range 11-145). At day 30, 2 patients had a donor-cell chimerism below 90% (one ultimately relapsed) and at day 100, 2 patients had chimerism below 90 (one ultimately relapsed). With a median follow up among survivors of 13 months (range 0.7 - 26), 1-year GRFS was 74%. OS, PFS and cumulative incidence of NRM and disease relapse were, 86%, 79%, 10%, and 10%, respectively (Figure 2). The cumulative incidence of grade III-IV acute GVHD at 6 months was 2.4%. Only one patient had grade IV acute GVHD. One year moderate/severe chronic GVHD was 11%In univariable analysis, thrombocytopenia of <40 x 10 9/L pre-HCT was associated with worse OS (1-yr OS: 64% vs 92%, p=0.008). Splenomegaly (defined as >17 cm) was associated with worse PFS (1-yr PFS: 100% vs 64%, p=0.046). There was an improvement in OS in patients that received ruxolitinib and achieved response pre-HCT compared to those that did not but this did not achieve statistical significance (1-yr OS 100% vs 74%, p=0.054). Discussion: This study is the first, multicenter trial to test ruxolitinib use pre-, during- and post-HCT in patients with myelofibrosis. Our results demonstrate safety and feasibility of this approach. Favorable rates of engraftment were observed with ongoing ruxolitinib administration even through hematopoietic nadir. We continue to demonstrate favorable outcomes of PFS, OS and GRFS with a low incidence of severe acute and chronic GVHD. Our results strongly support the use of ruxolitinib in the peri- and post-transplant setting for patients with myelofibrosis undergoing HCT.

A Phase I Trial of Activated Donor-Derived Marrow Infiltrating Lymphocytes to Treat Relapsed Hematologic Malignancies after Allogeneic Transplantation with Post-Transplantation Cyclophosphamide As Graft-Versus-Host Disease Prophylaxis

Background: Donor lymphocyte infusion (DLI) or a second allogeneic transplant (HCT) are the only curative treatments for hematologic malignancies relapsing after initial HCT. Both approaches lack significant efficacy and may cause considerable toxicity. Post-transplant cyclophosphamide (PTCy) used as graft-versus-host disease (GVHD) prophylaxis eliminates alloreactive T cells and enriches for tumor-specific T cells in the bone marrow. We hypothesized that expanded, donor-derived marrow infiltrating lymphocytes (alloMILs) collected post-HCT could restore antitumor immunity in relapsed recipients without the additional GVHD and toxicity seen with DLI or second HCT. Methods: We conducted a phase I dose-escalation trial (NCT02342613) of expanded alloMILs to treat bone marrow infiltrating hematologic malignancies relapsing after HCT with PTCy. Key inclusion criteria were age ≥ 18 years; relapsed hematologic malignancy ≥ 6 months after HLA matched or mismatched HCT with PTCy; donor CD3 + chimerism ≥ 30% in the peripheral blood; and lack of immunosuppressant use for 2 weeks prior to alloMILs harvest. Enrolled patients underwent salvage chemotherapy prior to or after alloMILs harvest to control the disease during the expansion process. Harvested bone marrow mononuclear cells were co-incubated with anti-CD3/CD28 beads and IL-2 for 7 to 14 days until the target CD3 + dose was reached. Given the differential risk of GVHD with matched versus mismatched DLI, dosing progressed from 1 x 10 7 to 5 x10 7 CD3 + cells/kg for matched HCT recipients and 1 x 10 6 to 5 x10 7 CD3 + cells/kg for mismatched HCT recipients. The primary endpoint was the feasibility of the product, defined as: successful harvest; expansion; infusion; and absence of grade III-IV acute GVHD for 90 days after infusion. Evaluation for HLA loss was performed using next-generation sequencing (NGS) of HLA loci. Single cell RNA sequencing (scRNAseq) was performed using 10x Genomics technology, Cell Ranger (v6.0.2), and Seurat (v4.3.0). Results: Thirty-two patients enrolled and underwent bone marrow harvest. Two patients were inaspirable, and five patients were not expanded due to low cell counts or high tumor volume. Twenty-five patients underwent alloMILs expansion, of which five failed to expand. Twenty patients received an infusion and six received a second infusion. Of the twenty patients receiving an infusion, eleven had multiple myeloma (MM) or plasma cell leukemia; five had acute myeloid leukemia (AML); one had chronic myeloid leukemia in blast phase; and three had chronic lymphocytic leukemia. Harvest, expansion, and infusion were well tolerated with minimal adverse events. No patient developed acute or chronic GVHD after infusion. Dosing advanced to the highest level of 5 x10 7 CD3 + cells/kg in both the mismatched and matched HCT cohorts. At day 60, the overall response rate (composite of complete (CR) and partial responses) was 40 percent (8/20) in the entire cohort; 33.3 percent (2/6) in the myeloid cohort (Figure 1A); 30 percent (3/10 evaluable patients) in the MM cohort; and 66.7 percent (2/3) in the lymphoid cohort. One MM patient achieved sustained > 2 years long CR and one AML patient is in ongoing CR, both of whom received alloMILs with no or minimal disease followed by maintenance therapy. HLA loss analysis was performed on pre-expansion samples from three AML patients receiving a mismatched HCT and alloMILs. Both non-responders in this cohort had loss of the host mismatched HLA haplotype. ScRNAseq on pre-expansion samples from ten AML patients, eleven MM patients, and four AML patients in remission after HCT (control) yielded 197 522 total cells and 32 587 CD8 + T cells. CD8 + T cells expressing a senescent-like gene signature previously associated with dysfunctional tumor killing in AML patients (Mazziotta et al ASH 2022) were associated with non-response primarily in AML patients (observed log2 fold change -2.48 compared with responders; FDR = 0.0017) (Figure 1B). Conclusions: AlloMILs demonstrated feasibility, a favorable safety profile, and early evidence of clinical activity in patients with measurable residual disease. The maximum dose of 5 x10 7 CD3 + cells/kg was reached, and no patient developed acute or chronic GVHD. HLA loss and CD8 + T cell senescence may be associated with non-response in AML patients. A clinical trial utilizing alloMILs as maintenance therapy for patients with measurable residual disease is in development.

Outcome of Multiple Myeloma Patients Undergoing Allogeneic Stem Cell Transplant with Post-Transplant Cyclophosphamide - a Single Center Experience

Objective: The survival of multiple myeloma (MM) patients has improved significantly in the past decade with the development of new effective treatments including immunomodulators, monoclonal antibodies, and chimeric antigen receptor T cell (CAR-T) therapy. However, to date, none of the available treatments is curative for MM. In high-risk and relapsed patients, allogeneic stem cell transplant (allo-SCT) achieved long term survival in carefully selected MM patients. Here, we report our experience in MM patients who received allo-SCT at Thomas Jefferson University Hospital (TJUH). We aim to define the role of allo-SCT in the new era of MM treatment. Method: We retrospectively analyzed data of 57 MM patients who received allo-SCT at TJUH from 1996-2023. We used EZR software to analyze post-transplant outcomes including overall survival (OS) and disease-free survival (DFS) with Kaplan Meier method. Cumulative incidence (CI) calculated by EZR was used to determine relapse rate (RR) and non-relapse mortality (NRM). Median time to neutrophil and platelet engraftment was analyzed by Excel 2022. Results: The median age was 53 years old (range from 34-68 years old); 29 females and 28 males. Mean follow up time was 57.9 months (range from 0 to 253.6 months). Thirty-two patients received reduced intensity conditioning, 11 patients received myeloablative conditioning regimen, and 5 patients received non-myeloablative conditioning regimens. Thirty-one patients received matched related donor (MRD), 3 patients received matched unrelated donor (MUD), 21 patients received haploidentical (HI), and 2 patients received mismatched unrelated donor stem cell grafts. Time to neutrophil and platelet engraftment data was available for 33 and 29 patients, respectively. The median time to neutrophil engraftment was 12 days (range from 3-23 days). and the median time to platelet engraftment was 16 days (range from 6-51days). The 3-year and 5-year probabilities of OS were 53.2% (95% confidence interval is 38.7% to 65.7%) and 48.3% (95% confidence interval is 33.9% to 61.3%) respectively. The 3-year and 5-year probability of DFS were 37% (95% confidence interval is 21.6% to 52.5%) and 26.2% (95% confidence interval is 12.6% to 42%) respectively. Since 2009, most of the patients (33/36) in this study received post-transplant cyclophosphamide. Thus, we compared the OS for patients who received allo-SCT before 2009 and after 2009. The 5-years OS was 28.6% (95% confidence interval is 7.8% to 42.5%) and 62.7% (95% confidence interval is 43% to 77.2%) for patients who received allo-SCT before 2009 and after 2009 respectively (P=0.029). Among 43 patients with available relapse date data, the CI of relapse at 3 years was 36.9% (95% confidence interval 21.5%-52.4%) and the CI of NRM at 3 years was 26.1% (95% confidence interval 14%-39.9%). Thirty-five patients were evaluable for acute graft versus host disease (GVHD). Nine patients developed grade I-IV acute GVHD (25.7%) and 2 patients experienced grade III-IV acute GVHD (5.7%). Four out of 35 evaluable patients experienced chronic GVHD (11.4%): 2 patients had mild to moderate scleroderma, one patient had severe chronic skin GVHD and one had severe lung chronic GVHD. For 36 patients received allo-SCT after 2009, 3 died from relapse, 3 patients died from infection, 2 died from GVHD, 2 from unknown cause, one from brain bleeding, one from non-infectious pulmonary failure and one from acute heart failure. Conclusion: In MM patients with high-risk feature or relapsed/refractory disease, allo-SCT can be curative for approximately a third of the patients. Post-transplant cyclophosphamide coupled with contemporaneous MM treatments significantly increased the survival of allo-SCT MM patients in the modern era.

Reduced Intensity Haploidentical Bone Marrow Transplantation in Adults with Severe Sickle Cell Disease: BMT CTN 1507

Background: Allogeneic hematopoietic stem-cell transplantation has curative potential for sickle cell disease (SCD). Event-free survival (EFS) in children with SCD is >90% after a bone marrow transplant (BMT) from a myeloablative matched sibling donor (MSD). Unfortunately, <15% of patients with SCD have MSD, and myeloablative conditioning can be prohibitively toxic in adults with SCD. Reduced intensity HLA-haploidentical BMT with post-transplant cyclophosphamide (PTCy) has been shown in small studies to expand the donor pool with encouraging results. Still, concerns about graft failure and graft-versus-host disease (GVHD) persist. We present the results of a Blood and Marrow Transplant Clinical Trials Network (BMT CTN) 1507, multi-center single-arm, phase-II, prospective clinical trial (clinicaltrials.gov #NCT03263559) of haploidentical-BMT with PTCy to estimate EFS at 2-years in adults with severe SCD. Pediatric stratum data is not included in the data presentation and will be available in 2-years. Study Design and Methods: Eligibility: SCD patients aged 15.00-45.99 years with prior stroke, recurrent ACS or pain, chronic transfusion regimen, or tricuspid valve regurgitant jet velocity (TRJV) ≥2.7 m/sec were eligible. Participants were required to have an HLA-haploidentical first-degree relative donor, willing and able to donate bone marrow. The primary objective was EFS (survival without primary or secondary graft failure or second infusion of stem cells) at 2 years after haploidentical-BMT. Secondary objectives included determining the impact on clinical and laboratory manifestations of SCD and other transplant outcomes at 2 years post haploidentical-BMT. The protocol was opened for enrollment on 10/5/2017, completed accrual on 01/6/2021, and data are current as of 8/2023. Preconditioning with hydroxyurea (HU) 30mg/kg/day (Day-70 to Day-10); Conditioning regimen included Thymoglobulin (rATG), Thiotepa, Fludarabine, Cyclophosphamide, and Total Body Irradiation (TBI). GVHD prophylaxis included PTCy, sirolimus, and mycophenolate mofetil, figure. Results: A total of 54 eligible participants enrolled from 19 sites; 42 (78%) proceeded to transplant. Amongst enrolled participants, 59.3% are male, 92.6% are Black, and 3.7% are Hispanic. 10 participants started HU but did not proceed to BMT, and 2 did not start HU or proceed to BMT. Reasons included donor issues (n=4), withdrawal of consent (n=2), insurance coverage (n=2), death (n=1), and other (n=3). 38/42 (90%) participants completed the study as planned; 2 participants withdrew consent, and 2 were lost to follow-up. The median age was 22.8 years at enrollment; 47/54 (87%) of enrolled participants had Hemoglobin SS disease, 40/54 (74.1%) had a Lansky/Karnofsky score of 90-100 at baseline, and 41/54 (75.9%) had an HLA match score of 4/8. Recurrent vaso-occlusive pain episodes (38.9%), acute chest syndrome (16.8%), and overt stroke (16.7%) were the most common indications for transplant. Only 13 (31%) participants achieved the intended 30 mg/kg/day dosing of HU preconditioning. Estimated 2-year EFS is 88% (95% CI: 73.5%, 94.8%); all except one qualifying event occurred within 12 months. The 2-year overall survival (OS) post-HU was 93.0% (95% CI: 79.8%, 97.7%), and the 2-year OS post-transplant was 95.0% (95% CI: 81.5%, 98.7%); 2 (4.8%) participants had primary graft failure, and 1 (2.4%) had secondary graft failure before day +100. The cumulative incidence of grades II-IV acute GVHD at day 100 was 26.2% (95% CI: 14.0%, 40.2%), and grades III-IV acute GVHD at day 100 was 4.8% (95% CI: 0.9%, 14.4%). There were two deaths in the first year post-BMT (1 -organ failure; 1-ARDS), none in the second year; 33 (78.6%) participants reported at least one re-admission post-BMT, mainly due to either bacterial infection (n=41) or viral reactivation (n=36), table. Conclusion: This multi-center phase-II trial of a reduced intensity haploidentical-BMT in adults with SCD shows durable donor engraftment at 2-years with low mortality. The 2-year EFS and OS are comparable to that reported after MSD myeloablative BMT. These results support haploidentical BMT with PTCy as a suitable and tolerable curative therapy for adults with SCD and severe end-organ toxicity such as stroke and pulmonary hypertension, a population typically excluded from participating in myeloablative gene therapy and gene editing trials.

Post-transplant сyclophosphamide after matched donor hematopoietic stem cell transplantation in children with acute leukemia.

The data on post-transplant cyclophosphamide (PTCy) in pediatric acute leukemia after matched allo-HSCT are limited to case series. The present study aimed to assess the results of PTCy-based GVHD prophylaxis in a large cohort of children with acute leukemia after matched allo-HSCT. A retrospective analysis of 190 pediatric patients with acute leukemia who had a first allograft between 2008 and 2020 from a matched sibling donor (MSD) or matched unrelated donor (MUD) was carried out. In the MSD setting, GVHD prophylaxis consisted of PTCy alone (n=28) for the study group, and calcineurin inhibitor (CNI)±antimetabolite (n=30) for the control group. In MUD setting, most patients in the study group received GVHD prophylaxis with PTCy+CNI+mycophenolate mofetil (n=42, 66.7%) or PTCy+CNI+sirolimus (n=12, 19%). All patients (n=69) in the control group received ATG+CNI+antimetabolite. After MUD allo-HSCT, the incidences of acute GVHD grade III-IV and moderate/severe chronic GVHD were significantly lower in the PTCy group compared to control (6.6%vs. 35.0% and 12.7%vs. 47.1%, respectively, p<.0001). Five-year GVHD-free, relapse-free survival (GRFS) after MUD allo-HSCT was higher in the PTCy group compared to control (35.1%vs. 7.3%, p<.0001). At the same time, there was no significant difference between both groups after MSD allo-HSCT. In pediatric acute leukemia, PTCy-based GVHD prophylaxis for MUD allo-HSCT is a feasible and effective option that results in a low incidence of GVHD. Compared to the ATG-based approach, PTCy provides better control of GVHD in children. In pediatric allo-HSCT from MSD, PTCy demonstrates comparable effectiveness to conventional GVHD prophylaxis.

Allogeneic Hematopoietic Stem Cell Transplantation in Elderly Patients: The Experience of the Spanish Group of Hematopoietic Transplantation and Cell Therapy (GETH-TC)

Introduction Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is associated with significant toxicity and high risk of related mortality in older patients, especially when myeloablative conditioning is used. However, the upper limit of age for this procedure is not clearly defined. The aim of the study is to evaluate the safety and effectiveness of allo-HSCT in a cohort of elderly patients transplanted in Spain, considering non-relapse mortality (NRM), cumulative incidence (CI) of relapse, overall survival (OS) and progression-free survival (PFS). As secondary objectives, we evaluate the potential toxicity of allo-HSCT analyzing the days from infusion to hospital discharge, the number of readmissions within the first year, the CI of graft-versus-host disease (GvHD) and GVHD-free/relapse-free survival (GRFS). Finally, we also looked for prognostic factors significantly impacting OS. Methods We retrospectively analyzed 529 patients ≥65 years of age undergoing a first allo-HSCT between 2011 and 2020 in 17 Spanish centres, regardless of the indication and characteristics of transplantation. Subanalyses were performed according to chronological age (65-69 vs ≥70 years of age) and conditioning intensity (myeloablative vs non-myeloablative). Results Median age was 67.2 years (range 65.0-82.5) and 54 patients were ≥70 years. The most frequent indication was acute leukemia in 260 patients (49.1%). Clinical characteristics are shown in Table 1. Patients ≥70 years were more frequently male and had a lower HCT-CI than patients &amp;lt;70, without any other differences in patients' or transplant characteristics. The median follow-up was 51.2 months (range 9.3-139.6). At 1- and 4-years post-transplant, NRM were 24.3% (95%CI 21-28) and 32.0% (95%CI 28-36), CI of relapse were 21.4% (95%CI 18-25) and 29.1% (95%CI 25-33), OS were 61.2% (95%CI 57-65) and 43.4% (95%CI 39-48) and PFS were 54.3% (95%CI 50-58) and 38.9% (95%CI 35-43), respectively (Figure 1). No differences were found according to age group 65-69 vs ≥70 ( p=0.822, p=0.835, p=0.648 and p=0.743, respectively). Patients who had received myeloablative conditioning had lower CI of relapse (at 4 years post-transplant 19.3% vs. 30.7%, p=0.030), with no differences in NRM ( p=0.308), OS ( p=0.440) or PFS ( p=0.261). Regarding the duration of allo-HSCT admission, 486 patients were discharged alive, with a median number of hospital days from infusion to discharge of 22 (range 8-142). There were no differences based on age group ( p=0.635) or conditioning intensity ( p=0.606). Among 486 patients who were primary discharged, 320 (66.0%) needed a new readmission during the first-year post-transplant, with a median of 1 (range 0-6) up to day +100 and 2 (range 1-10) up to day +365. There were also no differences according to age ( p=0.789 and p=0.779, respectively) or conditioning intensity ( p=0.264 and p=0.818, espectively). Acute GvHD occurred in 265 patients (58.2%), 205 (45.1%) grades I-II and 60 (13.2%) grades III-IV. The CI of acute GvHD grades II-IV and grades III-IV at day +100 was 43.5% and 16.9%, respectively. A total of 174 patients (38.2%) developed chronic GvHD, 66 (14.6%) mild, 49 (10.8%) moderate and 56 (12.4%) severe. The CI of moderate-severe chronic GvHD at 1 and 2 years was 18.2% and 22.4%, respectively. According to age group, there were no differences in the CI of acute GvHD grades II-IV ( p=0.920), acute GvHD grades III-IV ( p=0.853) or chronic moderate-severe GvHD ( p=0.798). At 1- and 4-years after allo-HSCT, GRFS were 37.6% (95%CI 33-42) and 23.7% (95%CI 20-28), with no differences by age group ( p=0.569) or conditioning intensity ( p=0.707). In multivariate analysis, ECOG pretransplant ≥1 (HR 1.32, 95%CI 1-1.7; p=0.028), HCT-CI ≥3 (HR 1.34, 95%CI 1.1-1.7; p=0.016), high/very high DRI (HR 1.62, 95%CI 1.3-2.1; p&amp;lt;0.001) and no development of chronic GvHD (HR 2.99, 95%CI 2.3-3.9; p&amp;lt;0.001) were associated with worse OS. Age, gender, previous lines of treatment or autologous HSCT, donor type, stem cell source, conditioning intensity and development of acute GvHD did not influence OS. Conclusions Allo-HSCT is effective and safe at ages over 65 years, or even 70 years old. Myeloablative conditioning regimen may offer a lower risk of relapse without increasing toxicity. In our experience, ECOG, HCT-CI, DRI and chronic GvHD are more relevant parameters for post-transplant survival than chronological age.

Flares of Acute Graft-Versus-Host Disease: Mount Sinai Acute Gvhd International Consortium (MAGIC) Study

[Background] The current standard first-line treatment for acute graft-versus-host disease (GVHD), systemic high-dose steroids, induces clinical responses in a majority of patients. Flares of GVHD after initial improvement often occur during tapering or discontinuation of immunosuppression. There is no consensus regarding the definition of GVHD flare and little has been published regarding its natural history. [Methods] We retrospectively evaluated clinical data and blood samples from 968 allogeneic hematopoietic cell transplantation (HCT) recipients from 23 Mount Sinai Acute GVHD International Consortium (MAGIC) transplant centers who achieved complete response (CR) or very good partial response (VGPR) within 4 weeks of acute GVHD treatment between 2014 and 2021. VGPR was defined as the complete resolution of acute GVHD manifestations except residual stage 1 skin disease. Flares were defined as a recurrence of acute GVHD after achievement of CR/VGPR if (1) patients had an increased symptom severity of at least 1 organ stage; (2) received intensified treatment (increase in steroid dose ≥ 0.25 mg/kg or initiation of additional systemic immunosuppression); and (3) had no prior history of primary disease relapse or donor lymphocyte infusion preceding the flare. Serum samples obtained at the time of CR/VGPR and at the time of flares were analyzed for ST2 and REG3α concentrations that generated MAGIC algorithm probabilities (MAPs) resulting in previously validated Ann Arbor (AA) scores (1, 2, and 3). [Results] The median recipient age at HCT was 55 years (range: 0 to 79); 18.6% of patients had grades III-IV acute GVHD before CR/VGPR. The median maximum daily dose of corticosteroids before CR/VGPR was 1 mg/kg methylprednisolone equivalent (range, 0.1 to 3.2 mg/kg). Flares developed within 6 months following CR/VGPR in 210/968 (21.7%) patients with a median onset of 28 days (range: 2 to 448). Symptom severity at the onset of flare symptoms varied widely (grade I: 22%; grade II: 38%; grade III-IV: 41%) and the development of a flare was associated with a five-fold increase in NRM (hazard ratio [HR], 4.84 [95% CI, 3.19-7.36], P &amp;lt; 0.001) when considered as a time-dependent covariate in a multivariate regression model. The large majority of non-relapse deaths after flares (54/71, 76%) were due to acute GVHD or complications from its treatment. The AA scores at the time of first CR/VGPR successfully stratified patients for risk of six-month NRM (AA1: 5%, AA2: 11%, AA3: 34%, P &amp;lt; 0.001) (Figure A). Increasing AA score at CR/VGPR was also associated with significantly increased risk of GVHD flares (Figure B). Not only did the risk of flare increase with each rising AA score, but the number of patients with severe (grade III/IV) symptoms at flare onset also increased (AA1: 34%, AA2: 43%, AA3: 54%). We next generated a multivariate regression model of risk factors for the development of flares. High AA scores at the time of CR/VGPR (AA2: HR, 1.81 [95% CI, 1.32-2.48], P = 0.001; AA3: HR, 3.14 [95% CI, 1.98-4.98], P &amp;lt; 0.001), HCT from HLA mismatched unrelated donor (HR, 1.74 [95% CI, 1.00-3.02], P = 0.049), and interestingly, rapid achievement of CR/VGPR from the time of initial treatment (≤14 days) (HR, 1.84 [95% CI, 1.21-2.80], P = 0.004) were all identified as significant risk factors. Meanwhile, no other transplant, GVHD, or treatment characteristics associated with the development of flares including maximum GVHD severity, maximum steroid dose, and use of additional immunosuppressive agents other than steroids before CR/VGPR. AA scores measured at the onset of flare symptoms in 98 patients also predicted six-month NRM (AA1, 6%; AA2, 19%; AA3 42%, P = 0.01). [Conclusion] Despite advances in treatment, flares of GVHD symptoms following excellent (CR/VGPR) responses still occur in over one fifth of patients in current practice and are associated with a five-fold increase in six-month NRM. AA scores from serum biomarkers predict outcomes despite the absence of symptoms, suggesting that MAGIC biomarkers detect subclinical damage to GI crypts that can drive later recrudescence of clinical GVHD. Measurement of the MAP at the time of response to GVHD treatment may thus help to risk-stratify tapering strategies of immunosuppressive therapy.

Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation in Vexas Syndrome: A Systematic Review and Meta-Analysis

Introduction: Vacuoles, E1 enzyme, X-linked, Autoinflammatory, Somatic (VEXAS) syndrome presents as an auto-inflammatory disorder with overlapping hematological and rheumatological features. It is caused by mutation in UBA1 and is often refractory to treatment. Corticosteroids and Janus Kinase (JAK) inhibitors are being used for symptomatic treatment. Here, we review the literature for the outcomes of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with VEXAS Syndrome. Methods: Following the preferred reporting items for systemic reviews and meta-analysis (PRISMA) guidelines, a comprehensive literature search was performed on three databases (PubMed, Cochrane Register of Controlled Trials, and Clinicaltrials.gov) using MeSH terms and keywords for “VEXAS Syndrome” AND “treatment” from the date of inception to May 31, 2023. Our search produced 100 results, and duplicates were removed. After excluding irrelevant and review articles during primary and secondary screening, six studies were included which mentioned the outcomes of allogeneic hematopoietic stem cell transplantation in adult VEXAS syndrome patients. Inter-study variance was calculated using the Der Simonian-Laird Estimator. 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). Results: A total of 18 patients from six studies reporting the outcomes of allogeneic HSCT in VEXAS syndrome patients were included for this systematic review and meta-analysis. (Table 1) The median age of the participants was 59.5 years (43-69) and all the patients were male. The median follow-up time was 11.6 months (0.4-67). Manifestations of the disease included myelodysplastic syndrome (MDS) 38.9% (n=7), refractory inflammatory symptoms 16.7% (n=3), transfusion dependent disease 16.7% (n=3), myelofibrosis (MF) 5.6% (n=1), MDS plus MF 5.6% (n=1), systematic lupus erythematosus 5.6% (n=1), multiple myeloma 5.6% (n=1), and IgG4-related disease 5.6% (n=1). Donor type was matched unrelated 50% (n=9), matched related 33.3% (n=6), mismatched unrelated 11% (n=2), and the donor type was unknown for one patient. The source of stem cells was peripheral blood and bone marrow in 83.3% (n=15) and 5.6 % (n=1) of the patients, respectively, while it was not reported for 11% (n=2) of the patients. The pooled overall survival (OS) at a median of 6 (0.4-67) months was 93.3% (95% CI 0.67-0.1, I 2=0%, p=0.64, n=18). The incidence of acute graft versus host disease (GvHD) grade I-II, acute GvHD grade III-IV, and chronic GvHD was 17% (n=3), 11% (n=2), and 11% (n=2), respectively. Among the 3 patients who died, one patient expired due to sepsis, multiorgan failure, and cardiac arrest, second patient due to infection, and the third patient due to severe hypoxic pneumonia. Conclusion: Allogeneic HSCT has shown promising results in treating patients with VEXAS syndrome with good overall survival and acceptable incidence of graft versus host disease. However, considering the small sample size more studies should be done to consolidate these findings.

Addition of Myeloablative Doses of Total Marrow Irradiation (TMI) to Myeloablative Fludarabine/Busulfan Conditioning for Allogeneic HSCT in Patients with High-Risk AML, CML, or Myelodysplastic Syndrome: A Phase II Clinical Trial

In allogeneic hematopoietic stem cell transplantation (HSCT) for high-risk myeloid disorders, the intensity of the conditioning regimen correlates with the risk of relapse, but its benefit may be offset by its risk of toxicity. The addition of increasing doses of TMI to myeloablative conditioning was previously shown to have acceptable toxicity in a phase I trial by our group (PMID 25234438), but the efficacy of this strategy remains uncertain. From 2017 to 2023, 31 patients with high-risk acute myeloid leukemia (AML, n=20) or myelodysplastic syndrome (MDS, n=5), or chronic myeloid leukemia (CML, n=3) in accelerated phase or blast crisis, were enrolled into a prospective phase II clinical trial of allogeneic HSCT using myeloablative TMI at 9Gy in combination with standard myeloablative fludarabine (160 mg/m2) and targeted IV busulfan (daily exposure of AUC 4800 μM*min over 3 hours) (FluBu4) chemotherapy. TMI was delivered by using volumetric modulated arc therapy (VMAT) at 1.5Gy twice per day for 3 days for a total of 9Gy. The primary objective of the trial was to achieve &amp;gt;50% Disease-Free Survival (DFS) at 1 year. Here, we report the results on 28 patients who received the TMI-based transplant, whereas among the remaining 3, 1 had not started the conditioning yet and 2 became ineligible due to progression of disease and deterioration of performance status, respectively. The study included patients with matched related donors (MRD, n=9) receiving TMI/FluBu4 as a preparative regimen and patients with matched unrelated (MUD, n=13) or 1-antigen mismatched unrelated (MMUD, n=6) donors receiving conditioning with TMI/FluBu4 + rabbit anti-thymocyte globulin (rATG). Graft-versus-host disease (GVHD) prophylaxis was with methotrexate and tacrolimus, and palifermin was used to prevent severe mucositis. Patients' gender ratio was 16 female/12 male; race was Caucasian in 17 patients, African American in 4, Latino in 7; and median age was 53 years (range: 20-68). The median HCT-Comorbidity Index (HCT-CI) was 3 (range: 0-7). All 20 AML patients were at high risk of relapse because of adverse cytogenetic or molecular profile at diagnosis (n=13), or in second complete remission (CR2) (n=2), or with active disease at the time of transplant (n=5). All patients received peripheral blood stem cells (PBSC) (median CD34+ cell dose: 8.5 x 10 6/kg, range: 2.4-19.9) and fully engrafted. The median time to absolute neutrophil count (ANC) and platelet engraftment was 14 (range: day 9-22) and 15 (range: day 9-43) days, respectively. Grade 3-4 extramedullary toxicities were: mucositis in 57% (n=16), nausea/vomiting in 11% (n=3) and diarrhea in 7% (n=2) of the patients. Acute GVHD grade III-IV was seen in 3 patients (10%). Moderate/severe chronic GVHD was observed in 10 patients (36%). With a median follow-up of 1315 days (range: 158-1925 days) for patients alive, the overall 1 year and current overall survival were 73% and 64%, respectively. GVHD-Free Relapse-Free Survival (GRFS) at 1-year was 54%. Of 5 AML patients transplanted with active disease, 3 were alive and in remission at 1 year and at current date, while 2 died of relapsed disease. Of 28 patients in the study, 6 relapsed/progressed (21%) and 5 of them died of the disease (18%); whereas 5 patients (18%) died of transplant-related mortality (TRM) (2 deaths from septic shock, 1 from disseminated toxoplasmosis, 1 from idiopathic pneumonia and 1 from unknown causes). Kaplan Meyer curves for Overall Survival (OS) and DFS are shown in Figure 1 and 2, respectively. Addition of myeloablative TMI at 9Gy to standard myeloablative targeted FluBu4 was well tolerated and achieved very encouraging results in a group of patients with myeloid malignancies at high risk of relapse (clinicaltrials.gov Identifier: NCT03121014).

Diagnostic Performance and Clinical Impacts of Metagenomic Sequencing after Allogeneic Hematopoietic Stem Cell Transplantation

Background: Metagenomic Next-Generation Sequencing (mNGS) is a rapid, non-culture-based, and high-throughput technique for pathogen diagnosis. Despite its numerous advantages, only a few studies have investigated its use in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Methods: We conducted a retrospective analysis of 404 mNGS tests (343 infectious episodes) performed on 264 patients following allo-HSCT. We assessed the analytical performance and clinical utility of mNGS for clinical impacts. Results: Metagenomic sequencing demonstrated a significantly higher rate of positive microbiological findings as compared to conventional microbiology tests (CMT) (334/404 (82.7%) vs. 159/404 (39.4%), P&amp;lt;0.001). For the 343 infectious episodes, the sites of infection among the three groups were shown in Figure 1. We observed differences in microbial detection rates of both CMT and mNGS among the three groups. The highest detection rate was seen in group B, followed by group C and A, as shown in the mNGS testing (A-68.7%, B-96.1%, C-78.8%, P&amp;lt;0.001) and CMT (A-24.1%, B-53.9%, C-42.6%, P&amp;lt;0.001), respectively. Our results indicated that Klebsiella, Escherichia, and Pseudomonas spp. were the most-frequently isolated bacterial species after allo-HSCT, which were more likely to be present in patients of pre-engraftment group than others. We compared the detection rates of bacteria and fungi in infectious episodes with and without GVHD. The detection rate of bacteria was significantly higher in GVHD cases, irrespective of the diagnostic method used (mNGS, GVHD vs no-GVHD 37.3% vs. 22.2%, P=0.008; CMT, GVHD vs no-GVHD 20.6% vs. 9.5%, P=0.011). The highest detection rate was observed in cases with Grade Ⅲ-Ⅳ acute GVHD. Similarly, the same trend was seen in fungal detection, although the differences were not statistically significant. Nonetheless, when only Aspergillus spp. and Mucorales were considered, cases with GVHD exhibited higher detection rates than those without GVHD ( Aspergillus:11.8% vs. 5.1%, P=0.048; Mucorales: 5.9% vs. 1.3%, P=0.035). Among the 404 mNGS tests, 377 of which underwent microbiological culture within 48 hours of sample collection, and the positive rate of culture was 10.1% (38/377). Using culture results as reference, the sensitivity and specificity of mNGS were 97.4% and 64.4%, respectively. Using all relevant tests as reference (CMT), the sensitivity and specificity of mNGS were 86.7% and 26.8%, respectively (Table 1). A total of 44.8% (181/404) of mNGS tests had a positive impact on etiological diagnosis (Table S1), and 24.3% (98/404) led to proper antibiotic adjustment. Further analysis was conducted on cases having positive or negative CMT results. In the positive CMT group, 21.0% (85/404) of mNGS tests had a positive impact, primarily because it detected more microorganisms that were considered pathogens by clinicians. In the negative CMT group, 23.8% (96/404) of mNGS test showed a positive impact, as it provided etiological clues. In 20.3% (82/404) of cases, the microorganisms reported by mNGS were not considered pathogenic by clinical assessment. In terms of antibiotic adjustment, mNGS tests yielded positive effects in 11.9% (48/404) and 12.4% (50/404) of cases in the positive and negative CMT groups, respectively. The positive impact of mNGS was more evident in non-plasma samples, such as BALF and cerebrospinal fluid (Figure 3 D). For pathogen diagnosis, the positive impact was 62.7% in non-plasma samples versus 41.2% in plasma samples ( P=0.001). For antibiotic adjustment, the positive impact was 40.3% in non-plasma samples compared to 21.1% in plasma samples ( P=0.002). Furthermore, mNGS showed greater benefits in etiological diagnosis for patients with multi-site infections compared to those with single-site infections or fever of unknown origin (61.6% vs. 42.5% and 19.2%, respectively, P=0.001). Conclusion: Metagenomic sequencing had great potential for pathogen diagnosis in patients undergoing allo-HSCT. With improved methodologies and cost reduction, mNGS can serve as a valuable tool in addition to CMT. .

Comparison of Non-Relapse Mortality after Haploidentical Hematopoietic Stem Cell Transplantation with Post-Transplant Cyclophosphamide Versus Single Umbilical Cord Blood Transplantation for Hematologic Disease

Introduction: Unrelated cord blood transplantation (UCBT) and haploidentical stem cell transplantation with post-transplant cyclophosphamide as graft-versus-host disease (GVHD) prophylaxis (PTCy-haplo) are alternative options for patients with hematologic disease lacking a human leukocyte antigen (HLA)-matched donor. Non-relapse mortality (NRM) after UCBT may vary depending on the cord blood CD34+ cell count, but no study has accounted for CD34+ cell count when comparing the outcomes after UCBT and PTCy-haplo. Therefore, we analyzed transplant outcomes after UCBT and PTCy-haplo in patients with hematologic disease from data of a nationwide registry that included cord blood CD34+ cell count. Methods: Patients with hematologic disease receiving first UCBT or PTCy-haplo between 2014 and 2020 were identified from the nationwide registration data of the Japanese Data for Hematopoietic Cell Transplantation. Acute GVHD-related mortality was defined as death caused primarily by GVHD or occurred secondary to GVHD, and infection-related mortality as death due to graft failure or infection but not acute GVHD. Patients treated by UCBT were stratified by the median CD34+ cell count for comparison (0.84 × 10 5/kg). Results: A total of 7,499 patients were enrolled and classified into 3 groups: PTCy-haplo (n = 1,142), UCBT with high CD34+ cell count (UCB-H; ≥ 0.84 × 10 5/kg, n = 3,185), and UCBT with low CD34+ cell count (UCB-L; &amp;lt; 0.84 × 10 5/kg, n = 3,172). Patients in the PTCy-haplo group were slightly younger than UCB-H and UCB-L patients (median age: 54 vs. 56 and 55 years). The PTCy-haplo group also included a greater proportion of males than the UCB-H group (62.4% vs. 50.0%) but not the UCB-L group (64.2%). A greater proportion of PTCy-haplo patients had a PS score of 0 (53.2% vs. 46.2% and 45.6%), a hematopoietic cell transplantation-specific comorbidity index of 0 (57.6% vs. 52.7% and 54.4%) and donor-specific anti-HLA antibody (2.7% vs. 1.0% and 1.6%), received reduced-intensity conditioning (58.0% vs. 40.5% and 41.6%), calcineurin inhibitor with mycophenolate mofetil (88.5% vs. 38.6% and 38.4%), and underwent transplantation in the later period (82.0% vs. 54.6% and 50.7%). There were no significant differences in disease-risk index between groups. At 2 years post-transplantation, NRM and overall survival (OS) were significantly better in the PTCy-haplo group than the UCB-H and UCB-L groups (NRM: 18.8% vs. 21.6% and 25.3%, P &amp;lt; 0.001; OS: 56.2% vs. 53.3% vs. 49.6%, P &amp;lt; 0.001). Neutrophil engraftment rate at 42 days was also significantly higher in the PTCy-haplo group than the UCB-H and UCB-L groups (93.7% vs. 87.5% and 82.9%, P &amp;lt; 0.001). The PTCy-haplo group less frequently developed grade II-IV (26.4% vs. 37.3% and 34.4%, P &amp;lt; 0.001) and III-IV acute GVHD (7.0% vs. 12.2% and 10.5%, P &amp;lt; 0.001). While neither the differences in NRM nor that in OS remained significant between PTCy-haplo and UCB-H groups in multivariable analysis (NRM: hazard ratio [HR], 1.18, 95% confidence interval [CI], 0.99-1.41, P = 0.073; OS: HR, 1.05, 95% CI, 0.94-1.17, P = 0.42), significant differences were maintained between PTCy-haplo and UCB-L groups (NRM: HR, 1.35, 95% CI, 1.13-1.61, P = 0.001; OS: HR, 1.12, 95% CI, 1.00-1.26, P = 0.042). Regarding the cause-specific mortality, infection-related mortality was also significantly lower in the PTCy-haplo group compared to UCB-H and UCB-L groups (8.1% vs. 11.1% and 13.6%, P &amp;lt; 0.001) while GVHD-related mortality did not differ among groups (5.0% vs. 5.2% and 4.9%, P = 0.69). Conclusion: UCBT-H resulted in similar NRM and OS as patients receiving PTCy-haplo, whereas outcomes were worse in UCBT-L. These findings indicate that high CD34+ cell count in cord blood is a critical criterion for alternative donor selection.

Outcome of Allogeneic Stem Cell Transplantation in FLT3-TKD-Mutated AML - a Study on Behalf of the Acute Leukemia Working Party of the EBMT

Introduction The overall prognostic impact of point mutations in the tyrosine-kinase domain 1 of FLT3 (FLT3-TKD mut) in patients (pts) with acute myelogenous leukemia (AML) remains controversial. Furthermore, co-occurrence of FLT3-TKD mut and mutated nucleophosmin-1 (NPM1 mut) was shown to have a favorable prognostic impact on AML pts receiving conventional chemotherapy. However, little is known about the outcome of AML pts with FLT3-TKD mut with or without co-occurring NPM1 mut treated with allogeneic stem cell transplantation (alloSCT). Patients and Methods This is a retrospective study of the acute leukemia working party (ALWP) of the European Society for Blood and Marrow transplantation (EBMT) investigating the outcome of adult AML pts with FLT3-TKD mut with or without NPM1 mut after first alloSCT using matched sibling (MSD), unrelated (UD) or haploidentical (haplo) donors between 2005 and 2022. All patients were in first or second complete remission (CR1 of CR2). Information on cytogenetic risk was necessary for inclusion. No ex-vivo T-cell depletion (TCD) was allowed. The primary endpoint was leukemia-free survival (LFS) at two years after alloSCT. Secondary endpoints were overall survival (OS), cumulative incidence of relapse (RI), non-relapse mortality (NRM), acute and chronic graft-versus-host disease (GVHD) and GVHD-free, relapse free survival (GRFS). One hundred and eighty-two adult AML pts with FLT3-TKD mut were identified, of which 74 (40.7%) had a co-occurring mutation in NPM1. Median age was 55.1 years (range 18.6-79.1) and 46.7% were male. Median follow-up was 21.4 months [IQR 13.6-28.1]. 78% of the pts were in CR1. Cytogentic risk was favorable, intermediate and adverse in 12.6%, 75.3% and 12.1% of pts, respectively. Additional FLT3 internal tandem duplication (FLT3-ITD) was present in 25.8% of pts. Information on measurable residual disease (MRD) was available for 68.7% of pts, being positive in 48% of these. Karnofsky performance score was &amp;lt; 90% in 21.1%, and hematopoietic cell transplantation-specific comorbidity index (HCT-CI) was &amp;gt;=3 in 28.1% of pts. 69.6% of pts were cytomegalovirus (CMV) positive. Conditioning was myeloablative in 52.8% and reduced intensity in 47.2% of pts. Stem cell donors were MSD, UD and haplo in 25.8%, 55.5% and 18.7% of cases. Stem cell source was bone marrow in 10.4%, peripheral blood in 87.4% and both in 2.2%. In-vivo TCD was performed in 59.2% of pts. GVHD prophylaxis was calcineurin inhibitor-based in 92.2% of pts. Results Engraftment was achieved in 99.4% of pts with a day-60 absolute neutrophil count (ANC) &amp;gt;0.5 x 10 9/L of 97.7% [95% CI: 93.7-99.2]. Day-180 rates of acute GVHD (aGVHD) grade II-IV and grade III-IV were 26.2% (95% CI:19.9-32.9) and 8.1% (95% CI:4.6-12.8), respectively. At two years, rates of total chronic GVHD (cGVHD) and extensive cGVHD were 30% (95% CI: 22.5-38) and 16.6% (95% CI:10.6-23.7), respectively. Two-year LFS and OS were 66.1% (95% CI: 57.6-73.2) and 74% (95% CI: 65.4-80.8), respectively. Two-year RI, NRM and GRFS were 22.5% (95% CI:16-29.8), 11.4% (95% CI: 7-17), and 51.1% (95% CI: 42.4-59.1), respectively. Cause of death was original disease in 47.5%, infection in 27.5%, GVHD in 22.5% and non-SCT related in 2.5% of cases. In univariate analysis the only factor with significant impact on LFS was donor type (haplo [n=34] vs. others, p=0.006). For GRFS, patient CMV negativity (p=0.014) and in-vivo TCD (p=0.01) were significant. Interestingly, co-occurring mutations in FLT3 (FLT3-ITD) or NPM1 were not identified as having a significant impact on LFS or GRFS. Moreover, MRD status before alloSCT was also not shown to have a significant impact on these outcomes. In multivariate analysis of LFS and GRFS, only donor type (haplo [n=34] vs. others) was shown to be significant for both endpoints, hazard ratio (HR) 2.54; 95% CI: 1.4-4.6; p=0.002, and HR 2.01; 95% CI: 1.18-3.41; p=0.01, respectively. Conclusion Acknowledging the limitations of our retrospective study in this rare entity results are encouraging given the high-risk population (median age 55.1 years, CR2 in 22%, co-occurring FLT3-ITD in 25.8%, positive MRD in 48%, HCT CI &amp;gt;=3 in 28.1%). LFS, OS and GRFS rates were 66.1%, 74% and 51.1%, respectively, and both RI and NRM were comparably low with rates of 22.5% and 11.4%, respectively. No positive prognostic impact of co-occurring mutations in FLT3-TKD and NPM1 was detected, unlike what was found for conventional chemotherapy.

Outcomes after Bone Marrow Versus Peripheral Blood Stem Cell Matched Unrelated Donor Hematopoietic Stem Cell Transplantation

Background: Matched unrelated donors (MUD) have become an acceptable alternative donor for patients requiring potentially curative hematopoietic stem cell transplantation (HSCT) and lacking a matched sibling donor. Patients may undergo a bone marrow (BM) or peripheral blood stem cell (PBSC) graft, with previous studies showing similar survival outcomes. However, BM grafts have shown a lower incidence of chronic graft-versus-host disease (GVHD) but a higher relapse rate and slower engraftment. We aimed to compare the outcomes of BM versus PBSC in patients undergoing MUD HSCT. Methods: For this retrospective single-center study, we included all (n=276) adult MUD HSCT recipients at the University of Kansas Medical Center who had at least one year of follow-up (August 2016 to July 2021). We conducted a bivariate analysis using chi-squared and ANOVA tests. The Kaplan-Meier and regression analyses were also performed. Data analyses were conducted using SPSS version 28. Statistical significance was considered at p&amp;lt;0.05. Results: Our study included 276 MUD patients including 110 PBSC (40%) and 166 BM (60%) grafts. The median age was 55 (range 21-77) years, and 158 patients (57%) were males. Eighteen patients (6%) were ethnic minorities, and 89 (32%) patients had a Karnofsky performance status of ≥90%. 118 (43%) patients had a hematopoietic cell transplantation-specific comorbidity index of 3 or higher. Hematologic diseases included acute myeloid leukemia (n=119, 43%), myeloid disorders (n=77, 28%), acute lymphoblastic leukemia (ALL) (n=35, 13%), Lymphoma (n=15, 5%), and others (n=30, 11%). Sixty-two percent of patients were in complete remission at the time of transplantation, and patients not in remission included myelodysplastic syndrome, myelofibrosis, and lymphoma patients. Reduced-intensity conditioning (RIC, n=162, 58%) and myeloablative conditioning (MAC) (n=114, 41%) were used. The median follow-up was 55 (21-73) months. Overall survival (OS) was not reached in either BM or PBSC MUD HSCT group, while a median disease-free survival of 45 and 49 months was noted in PBSC and BM groups respectively (p=0.915). We observed similar rates of relapse (25% vs 27%, p=0.413), one-year overall survival (75% vs 72%, p=0.679), one-year disease-free survival (63% vs 62%, p=1.00), and one-year non-relapsed morality (NRM, 23% vs 21%, p=0.779) after PBSC or BM graft. Bone marrow graft recipients had delayed engraftment of neutrophils (20 days vs 16 days, p&amp;lt;0.001) and platelets (&amp;gt;20 K/uL: 24 days vs 16 days, p&amp;lt;0.001; &amp;gt;50 K/uL: 28 days vs 18 days, p=0.006) compared to PBSC recipients. Bone marrow graft recipients had similar rates of grade II-IV acute GVHD (50% vs 52%, p=0.714) and grade III-IV GVHD (12% vs 11%, p=0.847), but lower rates of 1-year chronic GVHD (39 % vs 55%, p=0.014) compared to PBSC recipients. In the subgroup analysis stratified by conditioning intensity, faster engraftment of neutrophils (median 16 vs 21 days, p&amp;lt;0.001) and platelets (&amp;gt;20 K/uL: 18 days vs 27 days, p&amp;lt;0.001; &amp;gt;50 K/uL: 18 days vs 33 days, p&amp;lt;0.001) was observed with PBSC as compared to BM graft in myeloablative transplant recipients, while there was no statistically significant association with the rates of acute or chronic GVHD, NRM, Relapse, DFS, and OS after a PBSC or BM graft. Among the RIC transplant recipients, faster neutrophil engraftment (mean 17 vs 20 days, p&amp;lt;0.001) and higher 1-year extensive chronic GVHD (52% vs 32%, p=0.015) were observed with PBSC compared to BM graft whereas no statistically significant difference was noted in platelet engraftment, acute GVHD, NRM, Relapse, DFS, and OS after a BM or PBSC graft. Conclusions: Allogeneic matched unrelated donor hematopoietic stem cell transplant recipients had similar rates of overall and disease-free survival, relapse, non-relapse mortality, and acute GVHD after a bone marrow or peripheral blood stem cell graft; however, delayed neutrophil and platelet engraftment with a lower incidence of chronic GVHD was noted after a bone marrow graft compared to peripheral blood stem cell graft.

Itacitinib for Prevention of Graft-Versus-Host Disease and Cytokine Release Syndrome with T-Cell Replete Peripheral Blood Haploidentical Transplantation

Introduction: Haploidentical peripheral blood allogeneic hematopoietic cell transplantation (PB haplo-HCT) can be complicated by graft-versus-host disease (GVHD) and cytokine release syndrome (CRS). Acute GVHD rates are higher with PB grafts compared with bone marrow, affecting 35-45% of patients and outcomes are poor in steroid refractory cases. Severe CRS occurs in 10-15% of patients receiving PB haplo-HCT and is associated with high non-relapse mortality and one-year overall survival between 25-30%. As interferon-γ and IL-6 are important mediators in both acute GVHD and CRS, we hypothesized that JAK1 inhibition with itacitinib could prevent these toxicities without impairing engraftment. Here we report outcomes from our study of itacitinib with haplo-HCT (NCT03755414). Methods: Patients with AML, MDS, ALL, or NHL in remission undergoing PB haplo-HCT were treated with itacitinib 200 mg/day on days -3 through +100 (first 20 patients) or 180 (second 22 patients), followed by a taper. Myeloablative and reduced intensity conditioning were allowed. GVHD prophylaxis was tacrolimus, mycophenolate mofetil, and post-transplant cyclophosphamide. Primary outcomes were incidence of primary graft failure and incidence of grade III-IV acute GVHD. Secondary outcomes included incidence and severity of CRS, relapse, GRFS, and overall survival. Results: Forty-two patients were enrolled and underwent transplantation on study between November 2019 and December 2022, median days of follow up was 453 days (range 142-1259). The patient population had a median age of 60 years (20 - 73 years) with the majority of patients having AML (AML 60%, ALL 21%), MDS 10%, MF 5%, NHL 4%). All patients with AML, MDS, or ALL were in a complete morphologic remission, although 45% had disease by either cytogenetics, next generation sequencing, or measurable residual disease assay (flow cytometry for AML/MDS, NGS for ALL). There were no cases of grade III-IV acute GVHD. The cumulative incidence of grade II acute GVHD on day 100 was 17.3% (95% CI, 7% - 31%), day 180 was 20.5% and day 365 was 20.5%. There were no cases of severe CRS with 90% of patients having grade 1 CRS and 10% having no CRS. No anti-IL6R or steroid therapy was used. There were no cases of primary graft failure. The cumulative incidence of relapse at 1 year was 10% (95% CI, 3% to 22%) and at 2 years was 14% (95% CI, 5% to 29%). In patients who survived without relapse to day 100, the 1-year cumulative incidence of moderate or severe chronic GVHD was 5% (95% CI 1% - 17%). The refined GRFS at day +180 was 85% (95% CI 69% - 93%) and at day +365 was 79% (95% CI 62% - 89%). Overall survival at 180 days 87% (95% CI 72% - 94%) and at 1 year was 80% (95% CI 63% - 90%). Analysis of peripheral blood mononuclear cells at day +28, +60, and +100, revealed that patients on itacitinib, compared with control haplo-HCT patients, had lower numbers of CD4 and CD8 central memory T cells, lower numbers of CD4 and CD8 naïve T cells, and higher numbers of classical monocytes, nonclassical monocytes, and both myeloid and plasmacytoid dendritic cells. In itacitinib treated patients, T-cell subsets expressed lower LAG3 and PD-1 and higher TIGIT, while monocytes expressed higher HLA-DR, CD80, and CD86. Conclusions: Itacitinib with PB haplo-HCT was safe with low rates of acute and chronic GVHD, without increased risk of relapse or transplant related mortality. Severe CRS was not seen in this trial, and no anti-IL6 or steroid therapy was used. The addition of Jak inhibition to standard PtCy based GVHD prophylaxis was associated with encouraging rates of GRFS and OS on this pilot and expansion study. Patients on itacitinib have unique immune reconstitution characteristics both in terms of PBMC counts and signaling markers within subsets.