Peripheral Blood Stem Cell Transplantation Research Articles

Higher Infused CD34+ Cell Dose Does Not Influence Clinical Outcomes in Allogeneic Peripheral Blood Stem Cell Transplantation Using Post-Transplant Cyclophosphamide in Children with High-Risk Leukemia

Background: The impact of infused graft cell dose on outcomes, including graft-versus-host disease (GVHD) and relapse, which have been major challenges in allogeneic hematopoietic stem cell transplantation (HSCT), remains unclear. Post-transplant cyclophosphamide (PTCy) has emerged as an effective and safe GVHD prophylaxis strategy, with improved GVHD incidence and relapse-free survival (RFS). Early practice of unmanipulated peripheral blood stem cell transplantation (PBSCT) using PTCy was commonly performed with a restriction on the CD34 + cell dose to minimize the risk of GVHD. However, recent studies demonstrated the protective effect of CD34 + cells on relapse, with no association with GVHD, thereby raising questions about the optimal cell dose. In this context, we aimed to study the impact of infused cell dose on outcomes in children with high-risk leukemia who underwent allogeneic PBSCT using PTCy. Methods: A retrospective analysis was conducted on 50 pediatric patients (median age at diagnosis : 9.3 years, range, 0.3-17.3) with hematologic malignancy (33 acute myeloid leukemia, 12 acute lymphoblastic leukemia, and 4 myelodysplastic syndrome/myeloproliferative neoplasm, 1 other) in first or second remission between 2019 and 2023. They received their first allogeneic PBSCT and donors included matched or mismatched unrelated donors (n=12) and haploidentical family donors (n=38). Conditioning was myeloablative, and PTCy-based GVHD prophylaxis (50mg/kg/day on days 3 and 4) was used for all patients. The patients were divided into three groups based on infused CD34 + cell dose: high dose group (>10 × 10 6/kg, N=10), intermediate dose group (5-10 × 10 6/kg, N=24), and low dose group (<5 × 10 6/kg, N=16). Results: The median age at HSCT was 11.6 years (range, 0.7-24.9). The median dose of infused CD34 + cells and CD3 + cells was 6.5 x 10 6/kg and 48.6 x 10 7/kg, respectively. There was a tendency for the mean dose of infused CD3 + cells to increase in the group with higher infused CD34 + cell dose: 47.6 x 10 7/kg for low dose group, 57.5 x 10 7/kg for intermediate dose group, and 73.4 x 10 7/kg for high dose group ( P=0.053). Patients receiving a higher dose of CD34+ cells had significantly shorter median time to neutrophil engraftment (13 days in high dose group vs. 14 days in intermediate dose group vs. 17 days in low dose group, P<0.001). The time to platelet engraftment was similar among the three groups. There was no difference among high dose, intermediate dose, and low dose groups in the cumulative incidence (CI) of day+100 grades II-IV acute GVHD and moderate to severe chronic GVHD (grades II to IV acute GVHD: 60.0% vs. 63.6% vs. 73.3% [ P=0.988], respectively; moderate to severe chronic GVHD: 22.2% vs. 29.2% vs. 25.0% [ P=0.961], respectively). With a median observation period of 20.4 months (range, 3.0-46.8) from transplant, RFS and overall survival (OS) showed a non-significant trend towards a higher survival rate in the high dose group compared to the other groups (RFS: 76.2% in high dose group vs. 62.1% in intermediate dose group vs. 62.6% in low dose group, P=0.694; OS: 88.9% in high dose group vs. 63.0% in intermediate dose group vs. 76.0% in low dose group, P=0.788). Conclusions: Higher number of infused CD34 + cell dose was associated with faster neutrophil engraftment. For patients in the high dose group (CD34 + cell dose > 10 x 10 6/kg with a relatively higher number of CD3 + cells), a non-significant trend toward a higher survival rate was observed, with no detrimental impact on GVHD. PBSCT in a pediatric patient from an unrelated or haploidentical adult donor may result in a high infused cell dose. Our findings suggest that restricting the number of infused CD34 + cell dose may not be necessary in the setting of allogeneic PBSCT with PTCy. Larger cohort studies are needed to confirm the potential benefits and drawbacks of a higher cell dose in children who receive PBSCT within a PTCy setting.

Scalp Cooling to Prevent Hair Loss in Multiple Myeloma Patients Undergoing Autologous Peripheral Blood Stem Cell Transplantation

The best outcomes for multiple myeloma progression-free and overall survival include the use of high-dose melphalan and autologous peripheral blood stem cell transplantation. Melphalan is given at a dose of 140 - 200 mg/m2 as a single dose two days before or in divided daily doses immediately prior to the reinfusion of stem cells. Melphalan causes nearly complete hair loss in all patients at these doses, (CTCAE v5 Grade 2). Hair typically falls out after 10-15 days and doesn't begin to grow back for 10-12 weeks. This outcome is widely expected and leads some patients to avoid doing an otherwise life sustaining procedure. In those that do proceed with the transplant, the alopecia can be emotionally harmful. Cryotherapy is commonly used to reduce melphalan side effects in the GI tract. Melphalan typically will cause diarrhea, nausea, and mouth sores yet a randomized trial done in 2006 showed that swallowing ice chips for 6 hours starting 30 minutes before the melphalan is given can reduce these unpleasant and potentially dangerous side effects by 60% (Lilleby et. al. 2006). We at Cedars-Sinai routinely have patients do oral cryotherapy for 3.5 hours starting 30 minutes prior to each dose of melphalan. This has reduced patient side effects substantially in our experience and is considered our standard of care. Chemotherapy drugs, such as melphalan, typically injure bone marrow, intestinal lining and other cells with high metabolism and rapid cell division. Hair follicles also have these properties and is likely why many chemotherapeutics cause hair loss when used. Scalp cooling has been used to prevent hair loss in many patients undergoing chemotherapy for solid tumors. For some women with breast cancer, this hair loss was reported to be more traumatizing than losing a breast to mastectomy (Zhang et. al. 2022). The use of cold caps during chemotherapy exposure time has helped reduce hair loss, presumably by causing vasoconstriction and reducing distribution of the drug to the hair follicle. This intervention has been effective even when drugs which have longer durations of circulation have been given. While there is a theoretical risk that scalp cooling may impair the killing of malignant cells in the scalp by the chemotherapy, there is no evidence of a heightened risk in studies. The penetration of the cold should not reach the skull bone where myeloma cells may reside and is generally to a depth of only a few millimeters. The toxicity of scalp cooling is minimal. In a study of 27 participants using scalp cooling for solid tumors, 96% reported that the procedure was worth the time, effort, cost, and discomfort and would recommend usage to others undergoing the same chemotherapy treatment (Sitarz et. al. 2022). While scalp cooling has been used to prevent hair loss in patients undergoing chemotherapy for solid tumors, no reports were found for its usage for multiple myeloma or other hematologic malignancies. Since melphalan has a much shorter half-life, (70 minutes), than most other chemotherapy drugs used for solid tumors, it is anticipated that scalp cooling will be more efficacious when used with this drug. In fact, after 5 hours the concentration of melphalan should only be 5% of that present immediately after administration. A 57-year-old patient with multiple myeloma undergoing high-dose chemotherapy with melphalan 200 mg/m2 opted to use the commercially available Penguin Cold Cap to prevent losing her hair. The device was started 60 minutes before and continued for 5 hours after the melphalan infusion was started at Day -2 and Day -1 prior to her autologous stem cell transplant. The procedure was well tolerated, and the patient had no signs of any hair loss after the stem cell transplant. Based upon this experience, a study was initiated to further assess the efficacy of scalp cooling with the Penguin Cold Cap device in multiple myeloma patients receiving autologous stem cell transplants. An update with results of this study will be presented at the meeting. A positive outcome may improve the percentage of people willing to undergo this life-sustaining procedure and improve the quality of life of those who do it.

Pre-Apheresis Prediction of CD34 + Cell Yield from Collecting Efficiency Is Not Reliable in Peripheral Blood Stem Cell Collection

Introduction Procurement of enough CD34 + cells (CD34 +) by apheresis is essential for the successful engraftment of peripheral blood stem cell transplantation (PBSCT). To determine the processed blood volume of apheresis to obtain a certain number of CD34 +, collecting efficiency 2 (CE2) is generally used, which is calculated from the total amount of CD34 + in the product (PBSC-CD34 +) divided by pre-apheresis CD34 + in the peripheral blood (PB-CD34 +) and by processed blood volume, and CE2 is determined beforehand from the accumulated data in each apheresis site. However, we sometimes experience cases in which collected amount of CD34 + are far from our expected values. It is probably because of the introduction of various CD34 + mobilization methods, new automated blood cell separators and protocols. Hence, we investigated thoroughly the kinetics of CD34 + in PBSC collection. Patients and Methods PBSC collections in 55 subjects, including 46 patients undergoing autologous PBSCT and 9 healthy allogeneic PBSCT donors, were analyzed prospectively. All patients were administered G-CSF 10 μg/day sc for 4 days and plerixafor 0.24 mg/kg sc at 22:30 on day 4, and PBSC collection was started from 9 am on day 5. Donors were given G-CSF 10 μg/day for 4 to 5 days until 2x10 6/kg (pt's body weight) CD34 + were collected. Apheresis was performed using Spectra Optia ® in CMNC mode. The apheresis time was adjusted depending on the CD34 + yield. CD34 + was analyzed by flow cytometry according to the ISHAGE protocol. Peripheral blood samples were obtained before, and every 1-1.5 hour after the start until the end of apheresis. Samples were also taken from the apheresis collection bag at the same timings as PB. Collecting efficiencies were calculated as follows: CE1(%) = [collected CD34 +]x100/([prePB-CD34 +]+[postPB-CD34 +])/2 x [processed blood volume]). CE0(%) = [collected CD34 +]x100/sum of ([prePB-CD34 +]+[postPB-CD34 +])/2 x [processed blood volume]) in each section (*CE0 was defined in this particular study). This study was conducted as a part of the prospective study, which was approved by the Ethics Committee of Keio University School of Medicine. Results More than 2x10 6/kg CD34 + were collected in the first day in 48 subjects (87%). The median processed blood volume and time was 5575 (range 3873-10903) mL and 185 (range 120-292) min, respectively. CE2 was calculated as a median 53% (range 20-88) from this cohort, but it varied markedly; CE2>70% in 6 cases, and <30% in 4. On the other hand, CE1 was median 65.5% (range 26.2-106.4%), and it also varied markedly; CE1>80% in 6 cases, and <40% in 7. CE1 and CE2 correlated strongly with each other (r=0.93), but CE1 was higher than CE2 in all cases but one; median 124(range 95-149) % (Fig.1). The main reason why CE1 was always higher than CE2 was probably because PB-CD34 + concentration was always declining during apheresis, which might be more influenced in plerixafor mobilization where CD34 + concentration changed in an hour-depending manner. In some apheresis cases with extremely low CE, it was revealed that cell aggregates containing myriads of platelets might have blocked the outlet of the collection kit, which was difficult to be recognized during apheresis. CE1 in each apheresis section also changed markedly during each apheresis and CE2 was not helpful for predicting optimal apheresis time (Fig. 2). In the first 10-20 minutes until the interphase formation, a real collection was not yet started so that CE1 in the first 1 hour became low. In the following sections, collection was supposed to become relatively steady, where CE would be influenced largely by interphase stability. In the last part of collection, CE tended to be relatively high for unknown reasons. CEs varied markedly during the whole collection periods. Conclusions Because multiple factors are associated with CE variability, CD34 + yields were sometimes far from the expected values calculated from prePB-CD34 + and CE2. Therefore, enumeration of CD34 + in the product during apheresis is recommended for secure and effective collections.

ABO Incompatibility Haploidentical Peripheral Blood Stem Cell Transplantation Combined with a Single Cord Blood Unit for Severe Aplastic Anemia Patients

Background: For young severe aplastic anemia (SAA) patients without HLA matched donors, haploidentical hematopoietic stem cell transplantation can be used as an alternative selection. The grafts of classic Beijing protocol in China is a combination of bone marrow and peripheral blood stem cell. For patients with major or minor blood type incompatibility, bone marrow stem cells need to undergo red blood cell or plasma removal treatment. There was rare reports about haploidentical peripheral blood stem cell combined with a single unrelated cord blood unit for ABO incompatibility haploidentical stem cell transplantation in SAA patients. Objective: To observe the efficacy of ABO incompatibility haploidentcial peripheral blood hematopoietic stem cell transplantation combined with a single unrelated cord blood unit for SAA patients. Method s : Fifty-five SAA patients underwent stem cell transplantation from August 2018 to February 2022 in the First Affiliated Hospital of Xi'an Jiaotong Univeristy were divided into two groups based on donor-recipient ABO compatibility, the donor-recipient ABO matched group（BM+PB group）using haploidentical bone marrow and peripheral blood stem cell as grafts, and donor-recipient ABO mismatched group（CB+PB group）, using unrelated cord blood and haploidentical peripheral blood stem cell as grafts. The differences of hematopoietic reconstitution, acute and chronic GVHD, CMV and EB virus infection, PFS, and OS between the two groups were compared. Result s : There were 30 cases in CB+PB group and 27 cases in the BM+PB group. Except for differences in donor-recipient ABO compatibility, the other characteristics of the two groups of patients were comparable((P>0.05). One patient in the BM+PB group had primary graft failure, while the rest of the patients were successfully implanted. There were no significant statistical differences in neutrophil,platelet and red blood cells recovery rates, the incidence of acute and chronic GVHD, CMV, EB virus infection, and PTLD between the two groups of patients(P>0.05). There was no significant statistical difference in OS between the two groups of patients(P>0.05)(Figure 1). Conclusion: For SAA patients with donor-recipient ABO incompatibility could use haploidentical peripheral blood cell combined with unrelated cord blood for transplantation which had compared outcome with haploidentcal bone marrow and peripheral blood cell transplantation.

Salvage Autologous Peripheral Blood Stem Cell Transplantation after the Development of tMDS or AML in Multiple Myeloma Patients

Multiple Myeloma (MM) patients are often treated with high-dose chemotherapy and autologous stem cell transplantation (ASCT) for disease control. Lenalidomide is typically used as maintenance but results in an estimated 3.3% chance of developing a therapy-related myeloid neoplasm (TMN) typically myelodysplastic syndrome (MDS) or acute myelogenous leukemia (AML). This complication is often devastating with a median survival for those with a TMN of just 13 months. Over the past 6 years, 4 patients with multiple myeloma who developed a TMN were treated with a salvage ASCT using banked stem cells collected prior to their initial ASCT and before lenalidomide maintenance. None of these patients qualified for an allogeneic transplant. Melphalan 140 - 200 mg/m2 was used as conditioning prior to infusion of the peripheral blood stem cells, resulting in successful MDS/AML disease control. Case 1 = 61-year-old man with MM initially treated with CyBorD then transplanted in 2010. Post transplant treatment included lenalidomide maintenance, followed by a variety of salvage regimens over the next 7 years including thalidomide, carfilzomib, daratumumab and pomalidomide. He developed cytopenias evaluated by bone marrow biopsy in May 2017. This showed tMDS (Karyotype 47-48, XY, der (5)t(5:20)(q11.1;q11.1), +19, der(21:22)(q10:q10),+2~3mar[cp11]/46-48,idem,-der(5),+20[cp5]/46,XY[4]. FISH confirmed deletion 5q in 76% and loss of chromosome 5 in 6.5% of cells. NGS showed a frame shift mutation of TP53 at a variant allele frequency of 92.5%. He underwent a second ASCT in Aug 2017 and recovered normal hematopoiesis within three weeks. Unfortunately, he developed an aggressive relapse of his multiple myeloma 9 months later and succumbed from refractory multiple myeloma 14 months after the salvage transplant, without evidence of MDS. Case 2 = 72-year-old man with MM initially treated with CyBorD then an ASCT in May 2015. Lenalidomide maintenance was continued until October 2017 when he developed severe thrombocytopenia and circulating blasts. A bone marrow biopsy showed tMDS EB-1. Cytogenetics 46, XY t(3:21) (q26.2,q22) [18]/46, XY[2]. He received a second ASCT after melphalan 140 mg/m2 in Oct 2017 followed by recovery of normal blood counts. Bone marrow biopsy showed complete remission. He remains in remission from both the multiple myeloma and MDS almost 6 years later without any further therapy. Case 3 = 65-year-old man with MM treated with bortezomib + dexamethasone followed by ASCT in Aug 2012. He received maintenance lenalidomide for 4 years but then progressed. In Jan 2018 he developed pancytopenia and bone marrow biopsy demonstrated MDS with ringed sideroblasts. Cytogenetics were normal but NGS showed mutations of ASXL1, RUNX1, SF3B1, SETBP1 and DNMT3A. He underwent a second ASCT using his banked stem cells after melphalan 140 mg/m2 in Jan 2018 followed by full hematopoietic recovery. A repeat bone marrow biopsy in March 2022 showed persistent MDS harboring ASXL1, SF3B1, and DNMT3A mutations, but no detectable RUNX1 or SETBP1 abnormalities. His multiple myeloma remains in remission >5 years later. He receives only intermittent erythropoietin to maintain a Hgb of 11. Case 4 = 58-year-old man with MM initially treated with CyBorD followed by an ASCT in May 2014. He received lenalidomide maintenance but relapsed multiple times after 4 years ultimately complicated by renal failure requiring permanent dialysis. In March 2022 he developed pancytopenia. Bone marrow biopsy showed 15% blasts harboring del(5q), del(17p) and trisomy 8 by FISH. NGS demonstrated a mutation of ASXL1, and a copy number loss of TP53. Six months of decitabine did not improve his blood counts. In Dec 2022 he underwent a second ASCT after melphalan 140 mg/m2. A repeat bone marrow biopsy in Feb 2023 showed a complete morphological remission with a normal NGS. He is off all treatment 8 months post-transplant other than erythropoeitic support due to ongoing dialysis-dependent renal failure. The development of TMN is an uncommon but devastating event in patients with multiple myeloma after ASCT and lenalidomide maintenance. These patients responded well to a salvage ASCT using banked stem cells. This approach was well tolerated and provided durable hematopoietic recovery. Second ASCT using banked autologous stem cells should be considered in such patients who are not otherwise candidates for allogeneic transplantation.

Unrevealing Hematopoietic Reconstruction Discrepancies after Allo-UCBT and Allo-PBSCT at Single Cell Resolution

Umbilical cord blood (UCB) and G-CSF mobilizing peripheral blood stem cell (G-PBSC) are the main sources of hematopoietic stem cells for transplantation on clinic. Clinical data have shown that hematopoietic reconstruction in allogeneic cord blood transplantation (allo-UCBT) is significantly delayed compared with allogeneic peripheral blood stem cell transplantation (allo-PBSCT), suggesting that the cellular composition and reconstruction dynamics of UCB are significantly different from that of G-PBSC. Following on the heels of our recently study that found HSC/MPPs show differentiation bias to megakaryocytic-erythroid lineage and strong proliferation tendency, and defined a neutrophil progenitor population named S100A hi Neu2 which is inversely associated with the incidence of GVHD after allo-PBSCT (Yingying Huo et al, Science Immunology 2023), we next aimed to analyze the differences of hematopoietic reconstitution between allo-UCBT and allo-PBSCT and the causes of delayed hematopoietic reconstitution after allo-UCBT. In this study, we collected peripheral blood (PB) and bone marrow (BM) samples from 8 patients with bone marrow failure syndrome (BMFs) who received allo-UCBT (n=4) or allo-PBSCT (n=4) at different time points (d14, d21, d30, d60, d90, d180, d365) after transplantation. At the same time, UCB, G-PBSC and BM of normal children were collected as controls. Lin -CD34 + cells from BM, G-PBSC and UCB were separated by FACS for STRT-seq, the total nucleated cells (TNCs) of all samples were isolated for 10X transcriptome sequencing. We used 276628 hematopoietic cells to map the single cell transcriptome profiles of hematopoietic reconstruction by different transplantation methods and annotated 44 cell types. Compared with the G-PBSC, the immunogenicity of HSC/MPPs in Lin -CD34 + cells derived from UCB decreased, the proportion increased, and the differentiation bias of HSC/MPPs to monocytic and erythroid lineage was stronger, but the differentiation ability to myeloid and megakaryocytic lineage was decreased, the proportion of EBM, MEP and CMP decreased. For TNCs, the proportion of T cells and NK cells increased, and NK_CD56dim_CD16 had a stronger immune function. Compared with allo-PBSCT, the differentiation of HSC/MPPs and CMP into neutrophils in the early stage after allo-UCBT was weakened. The proportion of MEP cells decreased, and the differentiation ability of HSC/MPPs to MEP, HSC/MPPs and MEP to Mk was weakened. In summary, we found that the delayed reconstruction of neutrophils and platelets in patients with allo-UCBT are related to the nature of the graft, suggesting the importance of reasonable intervention of HSC derived from UCB to accelerate platelet implantation.

Phase II Trial of Reduced-Intensity Fludarabine, Melphalan, and Total Body Irradiation Conditioning Results in Favorable Outcomes with Haploidentical Donor Peripheral Blood Stem Cell Transplant

Introduction High risk hematologic malignancies are curable with allogeneic hematopoietic cell transplant (HCT). Haploidentical (haplo) HCT with post-transplant cyclophosphamide (PTCy) has improved access to transplant in patients lacking an HLA matched donor. However, traditional reduced-intensity conditioning (RIC) with fludarabine/cyclophosphamide/total body irradiation (TBI) for haplo HCT with PTCy is marred by high rates of relapse. This study seeks to optimize the RIC haplo HCT with PTCy platform in older adults with a slight intensification in conditioning and the use of peripheral blood stem cell (PBSCT) grafts in lieu of bone marrow grafts (BMT). Additionally, tacrolimus was substituted by sirolimus based on prior phase II data suggesting favorable rates of graft-versus-host disease (GVHD) after haplo PBSCT with PTCy (Bejanyan, Blood Adv. 2021). We hypothesized that this approach could successfully reduce the risk of relapse and improve disease-free survival (DFS) without substantially increasing non-relapse mortality (NRM). Methods: This single arm, single center phase II trial of haplo PBSCT used a RIC regimen consisting of Melphalan 70 mg/m 2 IV on day -6, fludarabine 30mg/m 2 IV daily on days -6 to -2, and TBI 200 cGy on day -1 (NCT04191187). Subjects received haplo PBSCT with a target dose of 5 x 10 6 CD34+ cells/kg and capped at 7 x 10 6 CD34+ cells/kg. GVHD prophylaxis consisted of PTCy 50 mg/kg on days +3 and +4, mycophenolate mofetfil (MMF) 1 gram three times daily from days +5 to +35, and sirolimus initiated at a target trough of 8-14 ng/mL on day +5 and tapered off between days +100 and +180. Eligibility criteria required a hematologic malignancy as the indication for allogeneic HCT and either age >55 years or a hematopoietic cell transplant comorbidity index (HCT-CI) > 3. The primary endpoint of this study is DFS with a hypothesis that the experimental regimen would have an 18 month DFS of 60% compared to a historic DFS of 40% and 90% power to reject the null hypothesis. Results: A total of 34 subjects were treated on the trial. The median age was 66 years (range: 31-74 years). The HCT-CI score was > 3 in 41%. Acute myeloid leukemia (AML, 44%) was the predominant indication for transplant followed by myelodysplastic syndromes (MDS, 29%). Nine patients (26%) were from underrepresented racial/ethnic minorities (those other than non-Hispanic white). Five patients (15%) received tacrolimus for GVHD prophylaxis before a protocol amendment changed the regimen to sirolimus for the remaining 29 patients (85%). The median follow-up time for 25 surviving patients was 28.5 months . The trial met the primary endpoint with 18-month DFS of 70.5% (90% CI > 59.1%, p=0.002). We observed no primary graft failure events. Neutrophil engraftment by day 30 was achieved in 30 patients (88%), and platelet engraftment by day 60 was achieved in 28 patients (82%). The cumulative incidence of grade II-IV acute GVHD at day 100 was 11.8% (95% CI: 3.6-25.1%). The cumulative incidence of moderate to severe chronic GVHD at 18 months was 9.1% (95% CI: 2.2-22.0%). At 18 months, the cumulative incidence of NRM was 17.7% (95% CI: 7.0-32.2%) and of relapse was 11.9% (3.7-25.4%). GVHD-free relapse-free survival at 18 months was 61.4% (95% CI: 42.9-75.5%) and the overall survival at 18 months was 73.3% (95% CI: 54.9-85.1%). Conclusion: In this completed phase II trial of fludarabine, melphalan 70 mg/m 2, TBI with haplo PBSCT and PTCy/sirolimus/MMF, the primary endpoint was met with an 18-month DFS that was superior to historical control. This was attributable to low rates of relapse without excessive NRM. Acute and chronic GVHD rates were favorable. Pharmacogenomic and pharmacokinetic correlative data is pending and will be included in the final presentation. These promising results merit further investigation to potentially establish this platform as a new standard approach to RIC haplo PBSCT.

Evaluation of Hematopoiesis and Disease Status in Patients with Hematologic Malignancies Using Whole-Body Bone Marrow Imaging with 18 F-FLT PET/MRI

Introduction Bone marrow examination is primarily focused on a limited region of the ilium, thereby inadequately assessing systemic hematopoiesis or residual tumor cells after therapy. Magnetic resonance imaging (MRI) of the spine can examine the fat marrow, but does not provide a direct assessment of hematopoietic cells. The use of the radiopharmaceutical 3‘-deoxy-3‘- 18F-fluorothymidine ( 18F-FLT) positron emission tomography (PET), which measures nucleic acid synthesis, can provide a quantifiable means of assessing hematopoietic cell proliferation. The combination of whole-body MRI and 18F-FLT PET may provide a more accurate assessment of whole-body bone marrow hematopoiesis in hematologic malignancies. Methods A prospective, open-label, exploratory study (UMIN000041491) was conducted to evaluate hematopoiesis using 18F-FLT PET/MRI imaging in patients planned for allogeneic hematopoietic stem cell transplantation. Subjects were patients over 20 years of age with hematologic malignancies who underwent 18F-FLT PET/MRI imaging before transplantation and at 50 and 180 days after transplantation. After an intravenous injection of 185 MBq 18F-FLT, patients were transferred to a simultaneous 3.0 T PET/MR scanner (Signa PET/MR; GE Healthcare, Waukesha, WI). The PET acquisition was performed in 3D mode with a 5.5 min/bed position (89 slices/bed) and a 24-slice overlap in 5 to 6 beds. The percentage of fat marrow was determined using MRI proton density fat fraction (PDFF) with a 1 cm 2 region of interest at 26 sites: cervical spine (C2-C7), thoracic spine (Th1-Th12), lumbar spine (L1-L5), and superior posterior iliac spine (two sites on each side). Similarly, the standardized uptake value (SUV) of 18F-FLT was measured. Results Thirteen patients with hematologic malignancies (8 with acute myeloid leukemia, 2 with acute lymphoblastic leukemia, and 3 with malignant lymphoma) were evaluated between August 2020 and April 2023. The median age of the patients was 46 years (range: 23 ~ 65). Seven patients underwent cord blood transplantation, while the remainder received peripheral blood stem cell transplantation. Prior to transplantation, all 13 patients underwent 18F-FLT PET/MRI scans. After transplantation, due to treatment-related death or worsening of the primary disease, 11 patients underwent scans on day 50, while 8 patients underwent scans on day 180, resulting in a total of 32 evaluable scans. In the 28 cases in hematologic remission at imaging, mean PDFF values were higher in the iliac (63.3% ± standard deviation 13.9) and lumbar (60.4% ± 14.9) than in the thoracic (47.2% ± 17.1) and cervical (37.5% ± 14.8) spines. Conversely, mean 18F-FLT SUV was higher in the thoracic (6.98 ± 2.31) and cervical (6.82 ± 2.03) than in the lumbar (5.06 ± 2.39) and iliac (3.95 ± 1.88) spine. This site-specific disparity in PDFF and 18F-FLT SUV was consistent both before and after transplantation. In all 32 cases, the median correlation coefficient between PDFF and 18F-FLT SUV was -0.60 (range: -0.92 ~ 0.17, Pearson's cumulative correlation coefficient), and 25 cases (78.1%) had a negative correlation coefficient below -0.4. Comparing the 12 cases with residual disease (4 cases with hematologic non-remission and 8 cases with hematologic remission but abnormal G-banding or quantitative polymerase chain reaction) with the 20 cases in complete remission, the correlation between PDFF and 18F-FLT SUV was significantly weaker in the residual disease group (-0.37 vs. -0.75, p<0.001, Mann-Whitney U test). When the correlation coefficient threshold was set at -0.57, the ROC curve for determining residual disease had an AUC of 0.86, a sensitivity of 83.3%, and a specificity of 85.0%. Discussion It is important to understand that the fat marrow and hematopoiesis degree in the iliac bone differs from that in the thoracic and cervical spine throughout the transplantation process, thereby influencing the disease status evaluation in hematological malignancies. The correlation between PDFF and 18F-FLT SUV, which is strong in cases of remission, weakens in cases of residual disease, even at the level of minimal residual disease. This discrepancy may reflect aberrant tumorigenic cell proliferation that differs from the norm. Thus, 18F-FLT PET/MRI was useful in understanding the hematopoietic and disease state of the systemic bone marrow in patients with hematologic malignancies.

Retrospective Study of Allogeneic Hematopoietic Stem Cell Transplantation for Relapse or Refractory Peripheral T-Cell Lymphoma at Toranomon Hospital and Toranomon Hospital Kajigaya

[Background] Relapsed or refractory peripheral T-cell lymphoma (R/R PTCL) is known to have a poor prognosis. Although new medications have been introduced in recent years, allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only curative treatment for R/R PTCL. We review the results of allo-HSCT for PTCL at our institution. [Methods] We performed a retrospective analysis of R/R PTCL patients who underwent first allo-HSCT at our hospital from February 2011 and April 2023. The primary endpoint was OS, which was defined as the time from allo-HSCT to death from any cause or the last follow-up. The secondary endpoints included progression-free survival (PFS), relapse/progression incidence (RI) and non- relapse mortality (NRM). PFS was defined as the time from allo-HSCT to relapse/progression, death, or the last follow-up. OS and PFS were estimated by the Kaplan-Meier method and multivariate Cox proportional hazard models. The cumulative incidence of relapse and NRM were investigated with a competing risk analysis using Gray's test and multivariable Fine and Gray competing risk regression. [Results] During the study period, a total of 44 patients received first allo-HSCT for PTCL (ALK positive ALCL: 2, ALK negative ALCL: 2, AITL: 10, PTCL-NOS: 21, CTCL: 7, HSTL: 2). The median follow-up months of survivors was 51.6 (range, 2.6-141.6). The median age of patients at transplantation was 50 years (range, 17-70). Clinical stage I/II at diagnosis was 10 cases, and clinical stage III/IV was 34 cases. Prognostic Index for PTCL(PIT) was score 1 in 20 cases, score 2 in 20 cases and score 3 in 3 cases. Hematopoietic Cell Transplantation-specific Comorbidity Index (HCT-CI) ≧ 2 was 21 cases. Performance Status (PS) 0-1 was 32 cases and PS 2-4 was 12 cases. Primary induction failure (PIF) was 28 cases and relapse after first remission (REL) was 16 cases, including 5 cases of relapse after autologous stem cell transplantation. Median number of chemotherapy regimens received before allo-HSCT was 3 (range, 1-8). Clinical stage at transplantation was CR/PR in 23 patients and SD/PD in 21 patients.The majority, thirty-two had received unrelated cord blood transplantation (CBT), six did unrelated bone marrow transplantation (uBMT), and 6 did related peripheral blood stem cell transplantation (rPBSCT). Thirty-two patients received myeloablative conditioning (MAC), eighteen of which included total body irradiation (TBI) and 15 of which included busulfan (BU). Twelve patients received reduced-intensity conditioning (RIC) . Regarding the primary endpoint, the 4-year OS after allo-HSCT was 53.3%. The 4-year PFS, RI and NRM were 50.4%, 20.7% and 28.8%, respectively. The 4-year OS of CBT, uBMT and rPBSCT patients was 55.2%, 66.7% and 33.3%, respectively. The 4-year OS of REL and PIF patients was 79.1% and 39.5%, respectively (p<0.01). The 4-year OS of MAC and RIC was 49.5% and 64.3%, respectively (p=0.58). The 4-year OS of patients with TBI was superior to patients without TBI (71.1% vs 40.3%, p=0.05). The 4-year OS of CR/PR patients at transplant was superior to SD/PD patients (67.1% vs. 42.9%, p=0.05). In the univariate analysis, PS 0-1, HCT-CI 0-1, REL, CR/PR patients at transplant, patients with TBI and patients without BU were favorable prognostic factors. In the multivariable analysis, REL was associated with better OS (p=0.01, HR 0.16; 95% CI: 0.04-0.65). Except for 3 patients who died from transplant complications before engraftment, 41 patients achieved neutrophil engraftment, with a median engraftment date of 19 days (range, 11-31 days) after transplantation. Twenty-seven patients had acute GVHD (Grade I: 3, Grade II: 13, Grade III: 8, Grade IV: 3), and 11 patients had chronic GVHD. Eleven patients relapsed after transplant, and the median time from transplant to relapse was 26.3 months (range, 0.6-87.1 months). Three patients survived at the last follow up, and the median follow-up time of survivors from relapse was 430 days (range, 12-1301). [Conclusion] Our data indicated good results of allo-HSCT for R/R PTCL, and significantly better in relapse after first remission patients.

Azacitidine Combined with Interferon α for Preemptive Treatment of AML/MDS after Allogeneic Peripheral Blood Stem Cell Transplantation：a Prospecitive Phase II Study

Objective : this study investigated the efficacy and safety of azacitidine and interferon α preemptive treatment in the post-transplant in patients with AML/MDS. Methods: between Octorber 1, 2019 and July 31, 2022, a total of 49 patients aged 17 to 62 years were enrolled into this prospective clinical study of post-transplant azacitidine combined with interferon α preemptive treatment. Patients with minimal residual disease (MRD) positive and / or mixed chimerism were scheduled to receive azacitidine, given as 32 mg/m 2 per day subcutaneously for 5 days, and interferon α 3 million units/m 2 per day from 8th day and continued for 28th day for 1 cycle. Results: patients who acquired treatment response were 34 (69.4%), of which turned MRD-negative and obtained complete chimerism were 22 (44.9%) and 5 (10.2%) at 1 cycle, respectively. Median follow-up time after preemptive intervention was 440(range, 45 to 927) days. Cumulative incidences of relapse (CIR) and no relapse mortality (NRM) were 36.7% and 4.1%, respectively. Probabilities of event-free survival (EFS) and overall survival (OS) were 55.1% and 71.4%, respectively. The most common adverse events were graft-versus-host disease (GVHD) (38.8%), liver toxicity (46.9%) and neutropenia (28.6%). Conclusion: these data support the notion that azacitidine combined with interferon α is better used as the preemptive therapy against relapse tendency for patients after allo-HSCT performed for AML/MDS. Side effects were mainly GVHD, reversible cytopenia and hepatic toxicity. This prospective trial in the post-transplant setting was feasible and safe but challenging. This trial was registered at www.clinicaltrials.gov as#NCT04078399.

T-Cell Depletion with Both Reduced Dose Anti-Thymocyte Globulin and Reduced Dose Post-Transplant Cyclophosphamide in Haploidentical Peripheral Blood Stem Cell Transplantation for Acute Leukemia and Myelodysplatic Syndrome

Graft-versus-host disease (GVHD) prophylaxis in allogeneic hematopoietic stem cell transplantation from HLA haplo-identical familial donor (haplo-HSCT) is based on in vivo T-cell depletion with either anti-thymocyte globulin (ATG) or post-transplant cyclophosphamide (PTCy). ATG has made significant contributions to enabling haplo-HSCT. However, the benefit of ATG may be often mitigated by higher risk of viral reactivation, including cytomegalovirus (CMV) and Epstein-Barr virus (EBV) due to a slower immune reconstitution. PTCy revolutionized HLA-mismatched HSCT and rapidly became the standard-of-care. However, it also has problems due to a cytokine release syndrome (CRS) -like symptoms and excessive cytotoxicity leading to the risk of acute cardiotoxicity and the possibility of alleviated graft-versus-leukemia effect. Considering a demand for more optimal in vivo T-cell depletion, we tried to combine both ‘lower-dose’ ATG and ‘lower-dose’ PTCy before and after stem cell infusion, respectively, hoping they can mitigate their individual limitations while maintaining the effectiveness of in vivo T-cell depletion. We retrospectively included 60 adults with acute leukemia or myelodysplastic syndrome who underwent haplo-HSCT following busulfan (3.2 mg/kg/day for 4 days as myeloablative and for 2 days as reduced intensity conditioning) and fludarabine (a total of 160 mg/m 2) between January 2019 and June 2023. Among them, 32 received a novel combination of ATG (a total of 3.0, 3.5, or 4.0 mg/kg depending on the absolute lymphocyte count level on days -3) and PTCy (50mg/kg on day +3 and 30mg/kg on day +4) compared to 28 patients who received ATG only (2.5 mg/kg/day from days -3 to -1, a total of 7.5 mg/kg) as in vivo T-cell depletion. Most patients received cyclosporine and mycophenolate mofetil as GVHD prophylaxis. The median follow-up duration for all patients was 8 months (median 9 months in the ATG/PTCy group and 7.5 months in the ATG group, respectively; P = 0.744). Baseline characteristics including age, sex, disease status, modified EBMT score, and the intensity of conditioning, were well-balanced except slightly higher infused CD34+ cells in the ATG/PTCy group (median 5.2 vs. 4.7 x 10 6/kg, P = 0.042). The cumulative incidence of acute GVHD at day +100 and moderate to severe chronic GVHD at 1 year were significantly lower in the ATG/PTCy group compared to the ATG group, respectively [grades II-IV acute GVHD: 20.4% (95% confidence interval [CI], 4.3-33.8%) vs. 48.4% (95% CI, 25.2-64.4%), P = 0.014; grades III-IV acute GVHD: 7.5% (95% CI, 0-17.1%) vs 31.1% (95% CI, 10.5-46.9%), P = 0.019; and moderate to severe chronic GVHD: 9.5% (95% CI, 0-21.2%) vs. 60% (95% CI, 23.3-79.1%), P = 0.007]. The ATG/PTCy group had a tendency of less incidence and severity of the haplo-fever. Multivariate analysis showed a significantly higher GRFS (hazard ratio 0.35, P = 0.002) and OS (hazard ratio 0.4, P = 0.014) for an ATG/PTCy group. The use of dual T-cell depletion with the reduced dose ATG in combination with the reduced dose PTCy showed a significantly superior early transplant outcome over with ATG of 7.5 mg/kg in terms of both GVHD and survival outcomes.

Post Transplant Cyclophosphamide (PTCY) in Peripheral Blood Stem Cell Transplant Results in Successful Engraftment and Substantially Low Frequency of Chronic Graft Versus Host Disease (GvHD), without Impaired Cellular Immune Reconstitution

The Post-Transplant Cyclophosphamide (PTCY) approach was first studied in the haploidentical transplant setting, and it resulted in high percentages of engraftment and reduced frequency of acute and mainly chronic GvHD as well as non-relapsed mortality. PTCY is now increasingly being used in HLA-partially and fully matched unrelated, as well as matched related donors. The aim of this study was to investigate the impact of PTCY on the incidence of chronic GvHD, disease relapse and infections because of possible cellular immune impairment. Fifty-one consecutive patients who underwent allogeneic hematopoietic stem cell transplant from an unrelated donor were studied. PTCΥ was administered on days +3 and +4 post-transplant at a dose of 50 mg/kg/day. Additional GvHD prophylaxis included tacrolimus and mycophenolate mofetil starting on day +5. In patients with no evidence of GvHD, immunosuppression was gradually tapered, and eventually stopped by day +90. We evaluated the safety and efficacy of PTCY, focusing on toxicity, engraftment, aGvHD and cGvHD frequency, relapse, non-relapse mortality, survival and immune reconstitution. We performed 51 unrelated donor transplants with PTCY from January 2021 to May 2023 in patients with a median age of 52 (18-69) years. The indication for transplant was AML/MDS (n=36), NHL/CLL, (n=2), pMF (n=2), CML (n=2) και ALL (n=9). Disease risk index (DRI) was intermediate for most patients (34/51), 7 had low and 10 had high DRI. Thirty-seven patients received myeloablative conditioning and 14 reduced-intensity. Overall, three patients were transplanted from a matched sibling, 36 from an 8/8 matched unrelated donor and 12 from an 7/8 HLA-matched unrelated donor. All patients received a peripheral blood graft with a median CD34+ cell dose of 6.97×10e6/kg (3.27-15.82). The most common toxicities observed were mucositis (n=34), diarrhea (n=40), vomit (n=12), liver toxicity (n=3) and acute kidney injury (n=4) - which in all cases were grade Ι-ΙΙ. Engraftment, defined as neutrophils >500/μl, was achieved in 46 cases in a median of 16 (13-27) days. Three patients died before day +28 due to NRM and two additional patients with myelofibrosis and MDS respectively had primary graft failure. The cumulative incidence of aGvHD, grade ΙΙ-IV at 100 days was 46.7% (95%CI: 34.1-63.8). However, aGvHD, grade ΙΙΙ-IV was only 3.9% (95%CI: 1.0-15.5). The cumulative incidence of cGvHD at 18 months was 13,4% (95%CI: 5.8-31.0), with only one case of extensive cGvHD. In a median follow-up of 14.5 (1-28) months, disease free (DFS) was 76,8% (95%CI: 65.5-90.0) at 18 months and overall survival (OS) was 76.3% (95%CI: 64.9-89.8) and 71.6% (95%CI: 58.6-88.3) respectively. There was no statistically significant difference in survival rates for patients who received an HLA mismatched and those who received an HLA-matched unrelated-donor transplant. cGvHD-Relapse-Free Survival was 63.5% (95%CI: 50.3-80.1). Two patients died of their disease and non-relapse mortality was 19.1%. Specifically, 6 patients died of Infections, 1 due to primary graft failure, 1 due to heart failure, and 1 due to Idiopathic Pulmonary Syndrome. Immune reconstitution at month 6 was 420 cells/ul (20-2225) and 179 (13-594) for CD8 and CD4 respectively. At month 12 CD8 and CD4 were 552 (55-3002) and 364 (60-787). 31 viral infections were documented in 28 patients (Respiratory viruses n=13, BKV n=11, CMV n=7). In regard with opportunistic infections, 2 patients had fungal infections and 1 patient atypical mycobacterium. We used PTCY for GvHD prophylaxis in mismatched, full-matched unrelated and matched sibling donor transplants with peripheral blood stem cell graft. This approach was well tolerated. Engraftment was documented in most patients, with a low incidence of grade III-IV aGvHD. Importantly cGvHD, which is the most important barrier in unrelated donor transplant, was substantially low with this method. Cellular immune reconstitution was adequate for CD8 but somewhat impaired for CD4. However, the incidence of viral and opportunistic infections was not increased. Overall, there are implications that PTCY may revert the negative impact of HLA mismatch on the outcomes of unrelated donor transplantation, while it is also a viable option for MUD and MSD transplant.

The HLA-B Leader MM Genotype Has a Negative Impact on Outcomes in HLA-B One Antigen Mismatched and HLA-B Matched Cord Blood Transplantation without Anti-Thymocyte Globulin: Analysis of the Japanese Society for Transplantation and Cellular Therapy

Background: The dimorphism at position -21 of exon 1 in HLA-B gives rise to leader peptides featuring either methionine (M) or threonine (T) as the second residue in the processed leader peptide (HLA-B leader). The cell surface abundance of HLA-E is positively correlated with the copy number of −21M HLA-B. In hematopoietic cell transplantation (HCT), the MM genotype in the recipients is associated with worse outcomes after HLA-matched and mismatched unrelated bone marrow and peripheral blood stem cell transplantation compared with TT (Kanaya M, et al. ASH Annual Meeting 2021, Petersdorf EW et al. Lancet Haematol. 2020 and Blood. 2020). Eurocord/EBMT study revealed HLA-B leader mismatch in HLA-B mismatched combination is associated with relapse and non-relapse mortality (NRM) risks after cord blood transplantation (CBT) (Petersdorf EW et al. Haematologica 2021). Notably, approximately 70% of patients in the literature administrated anti-thymocyte globulin (ATG) for graft-versus-host disease (GVHD) prophylaxis. The impacts of HLA-B leader dimorphism on the outcomes of CBT still needed to be elucidated more. Particularly, we were interested in the significance of HLA-B leaders in CBT without an ATG, then we conducted a retrospective study to elucidate it. Methods: Clinical data of 10,569 patients who underwent single-unit CBT for acute myeloid leukemia (AML, n=5,518), myelodysplastic syndrome (MDS, n=1,483), acute lymphoblastic leukemia (ALL, n=2,020), and lymphoma (n=1,548) between 2008 - 2021 were provided by the Japanese Data Center for Hematopoietic Cell Transplantation. HLA-A, -B, -C, and -DRB1 typing was performed at least at the antigen level. The leader genotype is defined based on the two HLA-B allotypes. All patients were not used ATG for GVHD prophylaxis. Study outcomes were overall survival (OS), cumulative incidences of relapse, NRM, and grade II-IV acute GVHD (aGVHD). Multivariable Cox regression analysis including covariables; disease risk index (DRI), myeloablative/reduced-intensity conditioning, presence of total body irradiation as a conditioning regimen, short-term methotrexate or mycophenolate mofetil for GVHD prophylaxis, recipient cytomegalovirus serostatus. All statistical analyses were performed with EZR. Results: The median patient's age was 53 (range 0-88) years. The numbers of patients with HLA-B leader TT, MT, and MM genotype were 7,639 (72.3 %), 2,707 (25.6 %), and 223 (2.1 %), respectively. To classify HLA-B match/mismatch status, we stratify “HLA-B one locus mismatched (GVH direction)” and HLA-B matched (no GVH direction mismatch)“. First, we focused on HLA-B one antigen mismatched (HLA 5/6 antigen matched, n = 1172) setting as shown in the previous literature. Recipient MM genotype showed significantly worse OS and relapse in the multivariate analysis compared to MT or TT genotype (Tx) (Figure) (OS: hazard ratio [HR] 0.543 [95% CI, 0.311 - 0.947]; p = 0.032, relapse: [HR] 2.863 [95% CI, 1.330 - 6.165]; p = 0.007). Recipient MM didn't relate to relapse and grade II-IV aGVHD. Next, we explored the impacts of HLA-B leaders in HLA-B antigen-matched CBT (3/6 - 6/6 matched, n = 3995). Donor MM genotype demonstrated a negative impact for OS and NRM, not relapse and aGVHD, compared to Tx donor (Figure) (OS: [HR] 0.738 [95% CI, 0.542 - 1.000]; p 0.050, NRM: [HR] 1.695 [95% CI, 1.097 - 2.621]; p = 0.018). Especially, OS and NRM of donor MM genotype were significantly inferior to Tx in HLA 6/6 matched (n = 914) CBT (OS: [HR] 0.311 [95% CI, 0.187 - 0.518]; p < 0.001, NRM: [HR] 3.216 [95% CI, 1.931 - 5.356]; p = 0.034). Conclusions: ATG would affect immune dynamics strongly in CBT via in-vivo T cell depletion, yet the current study demonstrated the HLA-B leader was still a significant risk factor in CBT without ATG for the first time. Recipient MM genotype in HLA-B one locus mismatched (HLA 5/6 matched) and donor MM genotype in HLA-B matched were the risk factors for worse CBT outcomes. We concluded MM genotype donors would be avoided to decrease NRM in HLA-B matched CBT. The precise mechanism of negative impact in CBT outcomes in patients or donor MM genotype remains to be clarified, however, we assume higher level HLA-E expression may be crucial in terms of NKG2A inhibitory signaling to T cells/NK cells and T-cell direct recognition for peptide/HLA-E complex in CBT.

Clofarabine and High-Dose Melphalan Reduced Intensity Conditioning Regimen with Methotrexate-Based GvHD Prophylaxis

Introduction: Reduced-intensity conditioning (RIC) allogeneic stem cell transplant (allo-SCT) remains a curative option for elderly and/or unfit patients with hematologic malignancies. Fludarabine-containing regimens make up the cornerstone of RIC regimens, however, during the nation-wide fludarabine shortage in 2022, many institutions used fludarabine-free RIC regimens out of necessity though data was extremely limited. Clofarabine is a second-generation purine analog with more potent anti-leukemic activity and a different adverse effect profile compared to fludarabine. We report our experience with clofarabine-based RIC conditioning for adult patients with non-Hodgkin's lymphoma (NHL) and myeloid malignancies. Methods: In this retrospective single-center matched cohort study at Stanford Health Care, we compared adult RIC allo-SCT patients receiving clofarabine and melphalan (CloMel) with a matched cohort receiving fludarabine and melphalan (FluMel) from January 1, 2022 to December 31, 2022. CloMel consisted of clofarabine 30 mg/m 2 on days -6 to -2 followed by melphalan 140 mg/m 2 on day -1, while FluMel consisted of fludarabine 30 mg/m 2 on days -5 to -2 followed by melphalan 140 mg/m 2 on day -1. Clofarabine dose adjustments were made in patients with renal dysfunction according to the following institutional guidelines based on creatinine clearance (CrCl): 22.5 mg/m 2 for CrCl 60 to 79 mL/min, 15 mg/m 2 for CrCl 30 to 59, and avoiding clofarabine for CrCl less than 30 mL/min. Dose modifications for fludarabine and melphalan due to renal dysfunction were at the discretion of the care team. Patients received graft versus host disease (GvHD) prophylaxis with tacrolimus and methotrexate. Efficacy and safety outcomes were assessed. Data were analyzed using Mann-Whitney U and chi-square tests. Results: We identified 9 matched pairs for a total of 18 patients. Most patients received an allo-SCT for a myeloid malignancy (8 patients with AML, 8 patients with MDS, and 2 patients with NHL). All patients received a peripheral blood stem cell transplant, with 89% receiving a matched unrelated donor and 11% receiving a matched related donor transplant. Baseline characteristics were balanced between groups. There was no difference in time to neutrophil engraftment (mean 14 vs 14 days; p=0.42), time to platelet engraftment (mean 16 vs 24 days; p=0.33), or 100% donor whole blood chimerism (71% vs 78%; p=0.32) at 6 months in the CloMel and FluMel groups, respectively. No statistically significant difference was observed for the number of patients who experienced acute (2 vs 0; p=0.13) and chronic GvHD (0 vs 4, p=0.09) at 6 months between groups. At 6 months, 2 patients in the CloMel group and no patients in the FluMel group experienced early non-relapse mortality (p=0.13). Both patients who died experienced acute renal failure secondary to conditioning chemotherapy with a median onset of renal dysfunction 6 days after initiation of clofarabine, followed by sepsis and multi-organ failure. Both patients required initiation of external renal replacement therapy and ultimately passed 12 days and 29 days post-transplant, prior to engraftment. Notably, both patients had a history of kidney dysfunction prior to transplant, one patient with chronic kidney disease (CKD) stage 3 and the other patient with lymphomatous involvement of the kidneys, and received appropriate clofarabine renal dose adjustments per institutional standards. Conclusion: CloMel demonstrated similar efficacy outcomes at 6 months and represents a feasible alternative to FluMel as a RIC regimen. However, given the notable occurrence of renal failure and early death in the CloMel arm, careful consideration and particular caution in administering to patients with a prior history of renal disease is recommended.

Haploidentical Hematopoietic Stem Cell Transplantation with Post-Transplant Cyclophosphamide in the Chilean National Health System. a Single Center Study

Haploidentical peripheral blood stem cell transplantation with post-transplant cyclophosphamide (Haplo-PTCy) is the most common transplantation modality in low-and-middle-income countries (LMIC). Registry data has shown comparable outcomes when using haploidentical donors versus Matched Unrelated Donors (MUD) in patients with acute leukemias. In the Chilean Public Health System Haplo-PTCy was incorporated in 2016 for adults up to 60 years old. We analyzed all adult patients who received an Haplo-PTCy at Hospital del Salvador, in a prospective registry study between 2016 and 2021. The primary outcome was overall survival (OS). Secondary outcomes were event-free survival (EFS), cumulative incidence of relapse, and incidence of grade II-IV acute graft-versus-host disease (aGVHD) at day +100. Overall survival and EFS were estimated using the Kaplan-Meier method. The cumulative incidence of relapse was calculated using relapse as the primary event and death without relapse as a competing event. Acute GVHD is shown as absolute incidence at day +100. All statistical analyses were performed with R. This study was done in compliance with the Helsinki Declaration and was approved by the Institutional Review Board. Eighty-five Haplo-PTCy were performed in 82 patients (Table 1). Three-second Haplo-PTCy were excluded from this analysis. The median age was 25 years (range, 15-51), and 65% were male. Ninety-four percent of patients had a neoplastic disease (77/82), and the most common diagnosis was acute lymphoblastic leukemia (57%). Forty-seven percent proceeded to transplant in the first complete response. Most of the patients (76%) presented a low hematopoietic cell transplantation (HCT)-specific comorbidity index. Conditioning was mostly myeloablative (96%). The median dose of CD34+ cells infused was 8.1 x 106/kg (range, 2.4-10.0). No patient needed a desensitization regimen. Cytokine release syndrome (CRS) was common (86%) but no grade 3 CRS was observed. Primary graft failure was observed in one patient (1.2%). Poor graft function was observed in 11 patients (13%). Five patients (6.1%) died before engraftment. The incidence of grade II-IV aGVHD at day +100 was 29% (grade IV was not observed). With a median follow-up of 33 months (range 0-84), the estimated 3-year OS and EFS were 68.3% (95% CI 59-79%) and 64.6% (95% CI 55-76%), respectively (Figure 1). In patients with neoplastic disease (n=77), the 3-year cumulative incidence of relapse was 23% (95% CI 15-33%). Haplo-PTCy is feasible in LMIC. This cohort of cases, mostly young patients with neoplastic disease, shows encouraging survival with an acceptable aGVHD and relapse incidence.

Fluoroquinolone-Resistant Enterobacteriaceae Prevalence for Patients Undergoing Autologous Hematopoietic Stem Cell Transplantation (aHSCT) in the Treatment of Multiple Myeloma (MM)

Background: Fluoroquinolones (FQL) are commonly used in antimicrobial prophylaxis in immunocompromised cancer patients (pts) during prolonged neutropenia. A possibly high and increasing proportion of pts harboring FQL-resistant Enterobacteriaceae (FRE) challenges the assumption that prophylaxis with FQLs is still of benefit in preventing sepsis. Previous studies reported that colonization of FRE in allogeneic transplant patients may be an infection risk factor (cf. Satlin et al. Clin Infect Dis 202;73:1257-65). This prospective study aims to determine the prevalence of FRE in defined pt populations in two metropolitan areas treated with dose-intense melphalan with autologous peripheral blood stem cell (PBSC) transplantation, and to determine the possible clinical effects of FRE in the host microbiome on transplant outcomes. Methods: Pts eligible for this prospective, ongoing study have a diagnosis of MM and are undergoing autologous PBSC transplantation after conditioning with dose-intense melphalan 200 mg/m 2 at Hackensack University Medical Center (HUMC) and MedStar Georgetown University Hospital (MGUH). Peri-rectal swabs are scheduled before chemotherapy mobilization of PBSC given with FQL prophylaxis, before transplant admission with initiation of antimicrobial prophylaxis, at time of hospital discharge, and 3 months after aHSCT. Prophylaxis is discontinued with fever or hospital discharge. Blood cultures are obtained at time of fever (>38 °C) with adjustments in antibiotics per standard of care. A central catheter is placed for venous access in all patients throughout their transplant course. Pts are discharged after achieving neutrophil (ANC) engraftment and control of conditioning regimen toxicities. Bacterial cultures from perirectal swabs (fresh or frozen for shipping) were purified on CHROMagar™ Orientation Plates and grown in the presence of ≥5 ug/ml ciprofloxacin to select for quinolone-resistant organisms. Results: To date, 39 pts are evaluable (Table 1). PBSC were mobilized using filgrastim/plerixafor (G-Moz) or cyclophosphamide/etoposide/dexamethasone (CDE) followed by filgrastim with levofloxacin prophylaxis. The quantity of CD34+ cells infused is in Table 1. All pts achieved ANC engraftment at a median of 10.8 days (range 9-14) and were hospitalized for a median of 13 days (range 11-24). 37/39 pts collected swabs before transplant admission (and swabs were obtained at discharge for the other 2 pts). 13/37 (35%) admission swabs demonstrated FRE colonization (Table 2). 6/33 swabs at time of discharge were positive for FRE including for 4 pts negative for FRE on transplant admission with a total of 17/39 pts (44%) showing FRE colonization at some point during the transplant admission. Samples collected at 3 months after transplantation for 24 pts reaching that timepoint showed FRE colonization for 4 pts including 2 pts not previously testing positive at time of transplantation. 27/107 samples tested positive for FRE and 21/39 pts (54%) had at least one FRE positive culture. Seven pts (20%) developed neutropenic fever but no pt experienced a blood-stream infection (BSI). One pt developed Clostridium difficile colitis during the period of neutropenia. One pt tested positive for MRSA colonization at admission but did not develop fever or BSI. One pt was readmitted after initial hospital discharge for evaluation of fever without a source of infection determined. Ten pts (5 FRE colonized during transplant course) were given prednisone for persistent diarrhea attributed to engraftment syndrome (cf: Spitzer TR. Bone Marrow Transplant 2001;27:893-8) commencing at a median of 10 (range, 8-13) days after aHSCT and not associated with CDE mobilization or detection of FRE. Nineteen other patients, 8 of whom tested positive for FRE, did not receive corticosteroids for management of regimen-related toxicities (an additional 7 pts received preplanned corticosteroids starting at day +8). No center effect is yet evident. Conclusions: FRE are detected in a high proportion of pts undergoing aHSCT in the treatment of MM. However, FQL prophylaxis is not associated with FRE BSI in this ongoing study. FRE colonization is not predictive of delayed engraftment or prolonged hospitalization, and does not appear predictive of non-infectious diarrhea.

Peripheral Blood Grafts Vs Bone Marrow Grafts in Young Acute Myeloid Leukemia Patients with HLA-Matched Sibling Donors Undergoing Myeloablative Conditioning

In allogeneic hematopoietic cell transplantation (allo-HSCT), graft source has been changed from bone marrow grafts (Bone marrow stem cell, BMSC) to peripheral blood grafts (Peripheral blood stem cell, PBSC) mobilized by granulocyte colony-stimulating factor. PBSC transplantation is known to have numerous advantages over BMSC, including faster engraftment, improved survival outcomes, and for the donor, the elimination of invasive marrow harvesting procedure under general anesthesia. However, previous studies regarding graft source included various hematologic malignancies and lacked consistency in conditioning intensity and disease status at allo-HSCT. Still, there are limited data on the comparison of graft sources specifically in patients with acute myeloid leukemia (AML) undergoing myeloablative conditioning. In this background, we conducted an analysis to investigate the impact of graft source on transplant outcomes in AML patients who underwent HLA A, B, C, DR-matched sibling donor (MSD) HSCT with myeloablative conditioning. This study was a retrospective, single-center study for patients with AML who received first allo-HSCT from 2002 to 2022. We included the patients aged < 60 at the time of allo-HSCT, in a state of complete remission (CR) or CR with incomplete hematologic recovery, from a MSD, and underwent myeloablative conditioning. We classified the patients into three groups: the BMSC graft group (BMSC group), the PBSC graft group without antithymocyte globulin (ATG) (PBSC/ATG- group), and the PBSC graft group with ATG (PBSC/ATG+ group). Patients who received both PBSC and BMSC grafts were excluded from the analysis. We examined the differences in overall survival (OS), relapse-free survival (RFS) among these three groups. A total of 480 patients were included in this analysis, with 234 patients in the BMSC group, 66 patients in the PBSC/ATG+ group, and 180 patients in the PBSC/ATG- group. BMSC transplantation was mostly performed before 2010, whereas PBSC transplantation started in 2007, and allo-HSCT with ATG administration were conducted after 2014. In the PBSC/ATG+ group, the median ATG dose was 2.5 mg/kg (Interquartile range, IQR: 1.6-2.5). The BMSC group tended to be younger at the time of HSCT (median 38 years [31-46]) compared to the other groups (median age of PBSC/ATG+ group: 44 years [37-51], PBSC/ATG- group: 46 years [39-51], p<0.01). Of total patients in the three groups, there was only 1 case of neutrophil engraftment failure (in the PBSC/ATG- group) and 5 cases of platelet engraftment failure (3 in the BMSC group and the other 2 in the PBSC/ATG- group). BMSC patients demonstrated superior OS compared to PBSC patients, with the most pronounced difference was observed over PBSC/ATG- group (Figure A). Similar trends were presented in relapse-free survival (RFS) as well. After adjusting for other covariates through multivariate Cox modeling, the difference caused by the graft source remained significant, particularly in terms of RFS (Figure B). The hazard ratios for RFS of PBSC comparing to BMSC were as follows; PBSC/ATG+: 1.64 [1.04-2.58], PBSC/ATG-: 1.95 [1.45-2.63]. In conclusion, Despite the clear differences in allo-HSCT era between groups, even BMSC patients underwent allo-HSCT at an earlier time, patients receiving BMSC grafts showed superior survival compared to those receiving PBSC grafts in young AML patients undergoing MSD myeloablative allo-HSCT. Parallel evaluation of the transplant outcomes between BMSC and PBSC would be crucial for assessing the advantages and disadvantages of PBSC and BMSC grafts in this setting.

The Combination of Pegfilgrastim and Filgrastim Improves the Outcomes of Mobilization and Engraftment after Transplantation of Autologous Hematopoietic Stem Cells for the Treatment of Lymphoma

BACKGROUND : Hematopoietic stem cell transplantation (HSCT) is broadly utilized for the treatment of lymphoma. Autologous peripheral blood stem cell (PBSC) transplantation (ASCT) requires mobilization of hematopoietic stem cell/ hematopoietic progenitor cell (HSC/HPC) in peripheral blood (PB) to collect HSCs. The high mobilization failure rate with the mobilization strategy of combining chemotherapy and filgrastim (rhG-CSF, recombinant human granulocyte colony-stimulating factor) in ASCT is one of the unresolved issues. Whether the combination of polyethylene glycol filgrastim [pegfilgrastim (PEG-FIL), PEG-rhG-CSF] and filgrastim (FIL) improves the mobilization success rate and the timing of combination therapy has not been studied. METHODS: To test the hypothesis that the combination of pegfilgrastim and filgrastim schedule has superiority, we retrospectively investigated a cohort of 107 lymphoma patients who received auto-HSCT and collection in the First Hospital of Jilin University from Jan 1st 2015 to Dec 1st 2022. These patients were categorized into PEG+FIL group and FIL group. The group of PEG+FIL received pegfilgrastim (9 mg) on the third day of the chemotherapy, followed by filgrastim (10 μg/kg/day) based on the counts of peripheral blood stem cells (PBSC). The group of FIL received filgrastim 10 μg /kg/day depending on the number PBSCs. Demographic information, laboratory results, and treatment plans were collected for these two groups of patients. RESULTS：We compared their mobilization efficacy (mononuclear cell [MNC] and CD34 + cell counts) and transplantation efficacy (days to leukocyte and platelet recovery post-transplantation). Successful ASCT mobilization was achieved in 93 patients (86.9%), with the PEG+FIL group exhibiting a higher success rate compared to the FIL group (89.2% [58/65] vs. 83.3% [35/42], p = 0.032). The PEG+FIL group also demonstrated significantly higher CD34+ cell counts [MNC: 8.9 (6.9, 11.2) vs. 7.8 (6.2, 9.8) × 10 8 cells/kg, p = 0.024; CD34 + cell count: 7.5 (5.6, 13.0) vs. 4.9 (3.2, 9.2) × 10 6 cells/kg, p = 0.008] and a lower incidence of neutropenic fever compared to the FIL group (11.8% vs. 24.3%, p = 0.038). The PEG+FIL group also demonstrated a shorter mean leukocyte recovery time in autologous stem cell transplantation than the FIL group (10.02 ± 0.73 vs. 10.9 ± 1.1 days, p < 0.001). To delve deeper into the safety considerations of both groups, we evaluated the advantages of each regimen and the methodologies for selecting time windows. A bone marrow aspiration and biopsy were performed on all patients before stem cell collection. Among 18 patients who had a hematopoietic area less than 30% and a fat area greater than 40%, 10 were in the PEG+FIL group and 8 in the FIL group. For patients who required only one collection, the durability was 80% in the PEG+FIL group compared to 0% in the FIL group (p < 0.01), indicating a superior recommendation for patients with a bone marrow hematopoietic area of less than 30%. In the PEG+FIL group, monitoring was carried out for PB CD34 + percentage and WBC count following pegfilgrastim administration, with subsequent computation of CD34 + cells in PB. Filgrastim administration was found to be optimal 5-6 days post-pegfilgrastim administration. CONCLUSIONS: In conclusion, relative to conventional filgrastim mobilization, the conjunctive use of pegfilgrastim and filgrastim demonstrates superior efficacy, non-inferior safety during ASCT. The schedule enhanced the the outcomes of mobilization in the patients of less hematopoietic area. KEY WORDS: Pegylated recombinant human granulocyte-stimulating factor (pegfilgrastim, PEG-rhG-CSF), recombinant human granulocyte-colony stimulating factor (filgrastim, rhG-CSF), lymphoma, hematopoietic stem cell transplantation (HSCT) autologous hematopoietic stem cell mobilization.

Peripheral blood stem cell transplantation vs. bone marrow transplantation for aplastic anemia: a systematic review and meta-analysis

BackgroundHematopoietic stem cell transplantation (HSCT) is an effective treatment for aplastic anemia. Recently, peripheral blood stem cell transplantation (PBSCT) has gradually replaced traditional bone marrow transplantation (BMT). However, which graft source has a better therapeutic effect and prognosis for aplastic anemia (AA) remains unclear. Therefore, we conducted this systematic review and meta-analysis.MethodsWe systematically searched PubMed, EMBASE, and the Cochrane Library without language limitations for studies using PBSCT or BMT for AA. Data were analyzed using the Open Meta-Analyst.ResultsWe identified 17 of 18,749 studies, including seven comparative reports and nine single-arm reports, with a total of 3,516 patients receiving HSCT (1,328 and 2,188 patients received PBSCT and BMT, respectively). The outcomes of the comparative studies showed similar 5-year overall survival [OS; relative risk (RR) = 0.867; 95% confidence interval (CI), 0.747–1.006], similar transplant-related mortality (RR = 1.300; 95%CI, 0.790–2.138), graft failure rate (RR = 0.972; 95%CI, 0.689–1.372) between the PBSCT group and the BMT group, while the PBSCT group had a significantly higher incidence of chronic graft-versus-host disease (GVHD; RR = 1.796; 95% CI, 1.571–2.053) and a higher incidence of grade IV acute GVHD (RR = 1.560; 95% CI, 1.341–1.816) compared to the BMT group. The outcomes of single-arm reports showed similar 3-year OS and incidences of chronic GVHD, acute II–IV GVHD, III–IV GVHD, transplant-related mortality and graft failure rate between PBSCT and BMT.ConclusionBefore 2010, PBSCT was not superior to BMT in terms of 5-year OS, transplant-related mortality and graft failure rate, but it exhibited a higher risk of both chronic and acute GVHD. After 2010, PBSCT and BMT showed similar 3-year OS, GVHD risks, transplant-related mortality and graft failure rate. PB grafts are more suitable for HSCT of the AA for convenience and pain relief.Systematic review registrationwww.crd.york.ac.uk/PROSPERO/, CRD42023412467.

Stem cell collection after lenalidomide, bortezomib and dexamethasone plus elotuzumab or isatuximab in newly diagnosed multiple myeloma patients: a single centre experience from the GMMG-HD6 and -HD7 trials

BackgroundWhile quadruplet induction therapies deepen responses in newly diagnosed multiple myeloma patients, their impact on peripheral blood stem cell (PBSC) collection remains incompletely understood. This analysis aims to evaluate the effects of prolonged lenalidomide induction and isatuximab- or elotuzumab-containing quadruplet induction therapies on PBSC mobilization and collection.MethodsA total of 179 transplant-eligible patients with newly diagnosed MM treated at a single academic center were included. The patients were evaluated based on PBSC mobilization and collection parameters, including overall collection results, CD34+ cell levels in peripheral blood, leukapheresis (LP) delays, overall number of LP sessions, and the rate of rescue mobilization with plerixafor. The patients underwent four different induction regimens: Lenalidomide, bortezomib, and dexamethasone (RVd, six 21-day cycles, n = 44), isatuximab-RVd (six 21-day cycles, n = 35), RVd (four 21-day cycles, n = 51), or elotuzumab-RVd (four 21-day cycles, n = 49).ResultsThe patients' characteristics were well balanced across the different groups. Collection failures, defined as the inability to collect three sufficient PBSC transplants, were rare (n = 3, 2%), with no occurrences in the isatuximab-RVd and elotuzumab-RVd groups. Intensified induction with six 21-day cycles of RVd did not negatively impact the overall number of collected PBSCs (9.7 × 106/kg bw versus 10.5 × 106/kg bw, p = 0.331) compared to four 21-day cycles of RVd. Plerixafor usage was more common after six cycles of RVd compared to four cycles (16% versus 8%). Addition of elotuzumab to RVd did not adversely affect overall PBSC collection (10.9 × 106/kg bw versus 10.5 × 106/kg bw, p = 0.915). Patients treated with isatuximab-RVd (six cycles) had lower numbers of collected stem cells compared to those receiving RVd (six cycles) induction (8.8 × 106/kg bw versus 9.7 × 106/kg bw, p = 0.801), without experiencing significant delays in LP or increased numbers of LP sessions in a multivariable logistic regression analysis. Plerixafor usage was more common after isatuximab plus RVd compared to RVd alone (34% versus 16%).ConclusionsThis study demonstrates that stem cell collection is feasible after prolonged induction with isatuximab-RVd without collection failures and might be further explored as induction therapy.Trial registrationPatients were treated within the randomized phase III clinical trials GMMG-HD6 (NCT02495922, 24/06/2015) and GMMG-HD7 (NCT03617731, 24/07/2018). However, during stem cell mobilization and -collection, no study-specific therapeutic intervention was performed.