CD34 Cell Dose Research Articles

Initiation of Haploidentical Stem Cell Transplantation With Post-Transplant Cyclophosphamide in Children: A Low-Middle-Income Country Institutional Experience.

Haploidentical hematopoietic stem cell transplant (HSCT) is a curative treatment especially for countries where bone marrow registries are nonexistent. We present our experience with haploidentical HSCT in pediatric patients. Retrospective data collected and analyzed for patients ≤18 years, from January 2017 to December 2022. The cohort consisted of 20 patients with median age at transplant of 61.5 (IQR: 124) months. Fourteen (70%) were malignant and 6 (30%) were benign diseases. Donors were father in majority (9/20; 45%). Stem cell source was peripheral blood 8, marrow 8, and combined 4. c-specific antibodies were positive in 6 (30%). Median CD34 cell dose infused: 9.35 × 106/kg. Median engraftment time: 15 (IQR: 17) days. Acute and chronic graft-versus-host disease (GVHD) occurred in 12/20 (60%) and 5/20 (25%), respectively. Complications included infection/sepsis (14/20; 70%), cytomegalovirus reactivation (14/20; 70%), sinusoidal obstruction syndrome (1/20; 5%), primary graft failure (PGF) (6/20; 30%), and secondary graft failure (4/20; 20%). PGF was more common in benign conditions (p = 0.003) and less prevalent in cases with aGVHD (p = 0.007). aGVHD was more common in malignant conditions (p = 0.007). Overall survival (OS), relapse-free survival (RFS), and treatment-related mortality (TRM) were 40%, 50%, and 35%, respectively. Median time of survival and relapse were 8 (IQR: 15) and 9 (IQR: 13) months, respectively. OS was comparable to that of other low-middle-income countries. GVHD was a major challenge, along with sepsis and CMV infection. Half of the leukemias relapsed. Graft failure was a major concern in nonmalignant diseases.

Clinical and Immunological Factors Associated with Poor Graft Function after Allogeneic Hematopoietic Stem Cell Transplantation in Myelofibrosis Patients

Allogeneic hematopoietic stem cell transplantation (HSCT) is widely recognized as the sole curative treatment for myelofibrosis (MF). However, patients with MF often experience graft function impairment despite successful engraftment and absence of relapse signs. Although it has been reported that poor graft function can have a negative impact on the outcomes of patients with MF after HSCT, the specific factors that can influence poor graft function are not yet clearly understood. In this background, we analyzed various clinical and immunological factors that may contribute to poor graft function after transplantation. The study included 93 patients who underwent HSCT for the treatment of MF at Seoul St. Mary's Hospital between the years 2000 and 2022. By cumulative incidence analysis of poor graft function (death, relapse, graft failure, and loss of chimerism as competing risks), we evaluated which pre-HSCT factors has significant impact on poor graft function after HSCT. The definition of poor graft function and graft failure in this study followed the criteria set by the European Society for Blood and Marrow Transplantation (EBMT). We measured the longitudinal diameter of spleen up to 2 months prior to HSCT, and classified the patients into pre-HSCT splenomegaly (≥ 14cm) or not. Next, we investigated the association of immune-related gene expression signature in bone marrow immune-microenvironment with the occurrence of poor graft function, by performing targeted gene expression profiling and gene set enrichment analysis using a custom NanoString panel composed of 579 immune-related genes in pre- and post-HSCT BM samples from patients with poor graft function and good graft function (total 24 samples). A median age of 93 patients was 57 years, and 55.9% were male. Secondary MF was observed in 30.1% of the cases. Fifty-three (57.0%) received graft from a matched sibling donor graft and 40 (43.0%) from a matched unrelated donor. Sixty-three (67.7%) patients were classified to the pre-HSCT splenomegaly group. In terms of ABO match, 45 (48.4%) patients were matched, 10 (10.8%) had bi-directional mismatch, 17 (18.3%) had major mismatch, and 19 (20.4%) had minor mismatch. The median infused CD34 (+) cell dose was 6.4 x 10^6/kg (Interquartile range 5.3 x 10^6/kg-8.3 x 10^6/kg). In our patients, cumulative incidence of poor graft function after 5 years from HSCT was 32.0% (95% CI: 23.4-42.7). Infused CD34 (+) cell dose, the presence of splenomegaly before HSCT were revealed to have an impact on the occurrence of poor graft function after HSCT. The other significant factor associated with poor graft function was ABO mismatch, in particular, with a substantial difference between matched patients and patients with bi-directional ABO mismatch. (Figure A). In NanoString panel analysis, although the expression of immune-related genes mostly upregulated after HSCT, genes related to processes such as complement system, inflammasomes, phagocytosis and degradation, and MHC class II antigen presentation pathways were significantly downregulated in PGF. Whereas, oxidative stress, inflammasomes, and autophagy pathways were downregulated in GGF (Figure B). In this study, we could observe that a significant proportion of MF patients undergoing HSCT experienced poor graft function. Factors that significantly associated with the occurrence of poor graft function included the CD34 (+) cell dose at the time of HSCT, the presence of splenomegaly before HSCT, and ABO mismatch. Interestingly, distinct gene expression signatures present in IME between pre- and post-SCT in both PGF and GGF. Further research is warranted to investigate the impact of poor graft function caused by these factors on outcomes such as transfusion requirements and quality of life.

Regimen Intensity and Age Affect Transplant-Related Outcomes after Matched Related Donor Hematopoietic Cell Transplantation for Sickle Cell Disease: A STAR Registry Study

Background: Serotherapies such as anti-thymocyte globulin (ATG) and alemtuzumab (AL) are added to conditioning chemotherapy for matched related donor (MRD) hematopoietic cell transplantation (HCT) for sickle cell disease (SCD) to facilitate engraftment and prevent graft-vs-host disease (GVHD). Most reports show ATG added to myeloablative (MA) conditioning; however, the use of AL has increased with investigation of different intensity regimens. The aim of this study was to compare HCT-related outcomes across common conditioning approaches to determine superiority. Methods: Retrospective data on baseline patient and HCT characteristics, and HCT outcomes were collected on 352 SCD patients >1 yr post-HCT at 14 Sickle cell Transplant Advocacy and Research (STAR) Alliance centers. Patients with a non-MRD (n=117) or without serotherapy (n=26) were excluded, leaving 209. MA included busulfan (BU) cumulative dose (CD) >8mg/kg or TBI ≥800 cGy; other regimens were termed non-MA (nMA). Summary statistics were presented as median (IQR) for continuous variables and count (%) for categorical variables. Comparisons were made using two-sample hypothesis tests, with p-value of < 0.05 as significant. Time-to-event analyses followed out to 3 years (censored after) and considered 4 outcomes. The first 3 were estimated via the Kaplan-Meier method: (1) overall survival (OS); (2) rejection-free survival (RFS); with death and rejection as events; (3) severe GVHD-free, RFS (GRFS), with death, RFS and severe GVHD as events; and (4) GVHD was estimated by Fine-Gray competing risk analyses, considering death as a competing event and censoring for rejection. Results: 209 patients received MRD HCT with MA+AL (66, 32%), nMA+AL (49, 23%), MA+horse (hATG) (71, 34%), or MA+rabbit (rATG) (23, 11%). Median recipient and donor age at HCT were 8.4yr (IQR: 5.1, 13.0) and 9.3 (5.1, 15.0) and similar across cohorts. MA+AL had a less severe clinical phenotype and nMA+AL had decreased pulmonary function; other baseline characteristics were similar (data not included). Conditioning for MA+AL included bu/cyclophosphamide (cy) (64%) or bu/fludarabine (flu) (36%), for MA+hATG bu/cy (68%) or bu/cy/flu (32%), for MA+rATG bu/cy (83%) or bu/flu (17%), and for nMA+AL melphalan/flu (92%) plus thiotepa (TT) (8%). GVHD prophylaxis was primarily calcineurin inhibitor and methotrexate or mycophenolate mofetil (91.4%). In MA, serotherapy was proximal timed with AL starting day -5 or -6 at a median (IQR) CD of 1.05mg/kg (0.8, 1.5), hATG starting day -3 at 90mg/kg (90), or rATG starting day -5 at 10mg/kg (9.6, 10.1); in nMA, AL was distal timed starting day -22 at a CD of 1.98mg/kg (1.0, 2.8). Stem cells were bone marrow in all, and GCSF primed in 15.4% of MA+AL and 4% of nMA+AL. Total nucleated and CD3 cell doses were similar across cohorts. nMA+AL had shorter median follow up at 2y (1, 4) vs 3y (2, 6) overall. nMA+AL had earliest time to neutrophil engraftment, required less platelet infusions, and had a shorter hospital stay at median 13d (12, 15), 8 infusions (4,13), and 21d (18, 26), respectively. Readmissions were highest for MA+AL at 77% (vs 64% overall). Graft rejection occurred only in nMA+AL (4, 8.2%) and MA+rATG (2, 8.7%). Table 3-yr CI of grade III/IV aGVHD was highest in nMA at 12% (CI: 0.05, 0.23) vs 0-7%, p=0.130 and for any cGVHD was significantly higher in nMA+AL at 33% (0.19, 0.46) vs 9-19%, p=0.001. 3-year OS was excellent at 94.4% (91.3, 97.7) and comparable per cohort. 3-year RFS was lowest though not significantly in nMA+AL at 87% (0.78, 0.97) vs 91-97%, p=0.260. 3-year GRFS was significantly lower in nMA+AL at 69% (0.57, 0.83) vs 83-94%, p=0.001. When age controlled GRFS in nMA+AL ≥13y was significantly lower at 59% (0.40, 0.88) vs 74-100%, p=0.007. Figure Conclusions: Despite small cohort sizes and retrospective nature, this study allowed for direct comparison of common approaches to MRD HCT for SCD. Outcomes were collectively excellent. nMA had earlier engraftment, less transfusion needs, and shorter hospital stay, although significantly more cGVHD and lower 3-yr GRFS influenced by older age. Current clinical trials in nMA+AL include TT and abatacept to mitigate this difference. We previously reported an association between MA and cardiac dysfunction (Stenger et al. Transplant Cell Ther 2023). Potential benefit of nMA must be balanced against risk of rejection and GVHD, thus providers should carefully consider such when selecting conditioning.

Allogeneic Bone Marrow Transplantation from HLA-Identical or Haploidentical Donors for Children and Adolescents with Sickle Cell Disease: A Feasible Curative Option

The only curative option widely available for sickle cell disease (SCD) is bone marrow transplantation (BMT). Since few patients have a healthy matched sibling donor (MSD), haploidentical (haplo) donors have expanded the donor pool to approximately 90% of the patients. The addition of thiotepa to the Johns Hopkins conditioning therapy backbone dor haplo BMT showed durable engraftment and excellent overall survival. However, graft rejection has remained an important obstacle. Our challenge in these patients has been to augment the conditioning therapy to provide adequate engraftment, while maintaining a low transplant-related mortality. Methods: Retrospective data of all 26 patients with SCD followed by our group after MSD (n=7) and haplo (n=19) BMT performed in four different institutions. With a MSD, conditioning was rATG 4.5mg/kg, Busulfan (Bu, AUC 4,500), Fludarabine (Flu, 120mg/m²) or rATG, Bu, Cyclophosphamide (Cy, 200mg/kg) and with haplo donors, rATG 4.5mg/kg, Thiotepa 10mg/kg, Flu 150mg/m², Cy 29 mg/kg and TBI 2Gy. Patients were prepared to BMT with intense hypertransfusion/bleeding or erythrocytapheresis to keep HbS<30 and Hb~10g/dL, reticulocytes <10% for 2-3 months prior to BMT, with intensive chelation to keep ferritin <1,000ng/mL. The presence of donor specific antibodies would exclude the patient from undergoing BMT. Due to two consecutive secondary graft failures (no detectable donor cells despite initial engraftment) and two falling mixed chimerism among the first 13 patients undergoing haplo, the doses of the conditioning therapy were increased to Cy 50 mg/kg and TBI 4Gy in a single fraction, as previously used in our patients with aplastic anemia undergoing BMT. Six consecutive patients received this augmented conditioning therapy. All patients had serial chimerism measured by STR. The graft-versus-host disease (GVHD) prophylaxis included Cyclosporine - Methotrexate in MSD and post-transplant Cy/mesna, mycophenolate mofetil and sirolimus in haplo. Results: Between September 2016 and April 2023, 26 patients underwent BMT, with a median age of 11 years (4-20), half of them females, 7 with a MSD and 19 an haplo (4 siblings, 6 fathers, and 9 mothers); 77% of the donors had sickle cell trait. The graft was bone marrow in all but one patient with Sb thal and Hodgkin's lymphoma. The median follow-up was 15.5 months. All patients engrafted. BMT with MSD had excellent outcomes and stable chimerism. Among the first 13 patients undergoing haplo, secondary graft failure occurred very suddenly in two patients (CD34 cell doses of 2 and 8x10 6 CD34/kg), both male teenagers; two additional patients had a significant drop in chimerism up to 30% donor cells but responded to serial donor leukocyte infusions 1-5 x10 6 CD3/kg (2 and 6) and developed very mild skin GVHD. The other patients maintained > 89-100% donor cells. Thereafter, with the augmented conditioning regimen, all six consecutive patients have stable 100% donor chimerism. Acute II-III GVHD was observed in 34% and chronic GVHD in 15% of the patients. Viral reactivations (CMV, HHV6, BKV, HHV7 and EBV) were observed in all patients. Overall survival is 100% and rejection-free survival is 83% at 1 year (Figures 1, 2). Conclusions: Allogeneic BMT with an HLA-identical or haploidentical family donor was feasible to treat SCD with an excellent overall survival. With a larger cohort and longer follow-up, the long-term effects of this strategy will be thoroughly studied.

Comparison of Biosimilar Filgrastim (Nivestym) Versus Originator Filgrastim (Neupogen) for Peripheral Blood Stem Cell Mobilization for Allogeneic Hematopoietic Stem Cell Transplantation

Background: Allogeneic hematopoietic stem cell transplantation (HSCT) is an optimal and potentially curative therapy for patients with hematologic malignancies. Granulocyte colony-stimulating factor (G-CSF) is used for the mobilization of peripheral blood stem cells (PBSCs) in allogeneic donors, and an optimal CD34 cell dose plays a critical role in successful transplantation. Nivestym, a biosimilar G-CSF to the originator Filgrastim (Neupogen), is now used by multiple institutions as it has become more available; however, there is a lack of data in this regard among healthy donors for allogeneic HSCT mobilization. In this study, we aim to compare the efficacy of Nivestym compared to Neupogen for allogeneic donor PBSC mobilization. Methods: For this retrospective single-center study, we included all (n=541) adult allogeneic HSCT donors at the University of Kansas Medical Center receiving Nivestym (January 2013-July 2020) or Neupogen (July 2020-June 2023) for donor PBSC mobilization. We conducted a bivariate analysis utilizing the ANOVA test. Statistical analyses were performed using SPSS version 28. Statistical significance was determined at p<0.05. Results: Our study included 541 allogeneic HSCT donors who received Neupogen (n=345, 64%) or Nivestym (n=196, 36%) for PBSC mobilization. The median age was 47 (range 17-76) years. The median donor weight was 86 (95% CI 87-91) kilograms. Donors receiving Neupogen had similar pre-GCSF WBC count (median 45 vs 47 K/uL, p=0.739), pre-GCSF CD34 percentages (median 17% vs 17%, p=0.527), and pre-GCSF circulating CD34 count (median 74 vs 74 million cells/kg, p=0.842) compared to donors receiving Nivestym. Neupogen recipients had similar median PBSC product total neutrophil count (TNC, 6.8 vs 6.5 K/uL, p=0.347), product CD34 percentage (75% vs 79%, p=0.068), absolute CD34 count (503 vs 533 million cells, p=0.636), and final CD34 dose (6.1 vs 6.3 million cells/kg, p=0.365) compared to Nivestym recipients. Seven percent (n=28) of donors needed two days of PBSC collection to achieve the target PBSC dose, with a statistically similar proportion noted in Neupogen (n=25, 7.3%) and Nivestym (n=13, 6.6%) cohorts. In a subgroup analysis stratified by age, donors aged 35 or older (n=154) had similar responses in all mentioned variables (p>0.05); however, for donors under the age of 35 years, the CD34 dose was higher in donors receiving Neupogen compared to Nivestym (median 6.9 vs 6.3 million cells/kg, p=0.044). Most of the PBSC collections (98%) were completed in one day, except for five donors in both Neupogen (5%) and Nivestym (8.5%) cohorts. Conclusions: Biosimilar G-CSF (Nivestym) demonstrated similar efficacy for peripheral blood stem cell mobilization compared to the originator G-CSF (Neupogen) among allogeneic HSCT donors. In donors aged 35 years or younger, a slightly lower PBSC product CD34 count was noted with Nivestym compared to Neupogen.

Immune Graft Composition Is Important for Deepening Response and Outcome after Autologous Stem Cell Transplantation in Patients with Multiple Myeloma Who Do Not Receive Maintenance Therapy

Maintenance therapy with Lenalidomide or proteasome inhibitors after autologous stem cell transplantation (ASCT) in multiple myeloma (MM) is an important component of first line treatment, resulting in deepening response (DR), converting PR to VGPR/CR or VGPR to CR in most patients and, in significantly longer PFS and OS. Of note, randomised clinical trials and real-world data confirm that DR also occurs in about 30% of patients receiving placebo or no maintenance at all. We analysed 90 patients with MM treated with first line ASCT in Hammersmith Hospital between 2017 - 2020, who did not receive maintenance therapy. We observed DR in 20 patients (22%) in the first two years. Patients achieving a DR had significantly higher PFS at 36 months post ASCT (89.4% v 41.1%, p=0.001 - Figure 1A). Baseline and ASCT characteristics, including high-risk cytogenetics, ISS, induction therapy and conditioning were comparable in DR and non-DR patients, however the use of the CXCR4 antagonist Plerixafor plus G-CSF vs G-CSF alone in the mobilisation regimen was associated with a higher probability for DR in the first 24 months post ASCT (58.3% v 23.2%, p=0.011 - Figure 1B). We suggest that improvement in depth of response after ASCT without pharmacological intervention indicates an immune anti-MM effect, underpinned by the immune composition of autologous grafts. We used 14-colour flow cytometry to analyse the immune cell frequencies in graft in 59 of the above patients, including 17 patients mobilised with Plerixafor plus G-CSF and 42 with G-CSF alone. The cell dose of each cell population was calculated from the relative frequency of CD34 cells in the graft and the CD34 cell dose infused in ASCT. In line with previous reports, the use of Plerixafor results in higher frequency and cell dose (in x10^6 cells/kg) of T cells in the graft (70.6% v 61.3%, p=0.015 and 306.2 v 161.4, p=0.007), driven mostly by a higher frequency (67.8% v 48.7%, p= 0.001) and dose (224 v 78.2, p=0.001) of central memory (CM) CD4 T cells. On the contrary, frequency and cell dose of effector memory (EM) CD4 T cells in Plerixafor plus G-CSF mobilised grafts were lower (6.7% v 21.5%, p=0.006 and 15.5 v 34.7, p=0.063). Apart from mobilisation regimen, univariate analysis showed a higher probability of achieving DR in grafts with high frequency of CD4 CM T cells (p= 0.012), NK cells (p=0.018 , Figure 1C), CD8 CM cells (p=0.06), higher dose of CD8 memory stem cells (p=0.033), lower frequency and dose of CD4 EM (p= 0.017 and p=0.007) and a lower dose of CD4 terminal effectors (TE) (p=0.039). In multivariate analysis, only a high NK cell frequency (p=0.011) and low CD4 TE cell dose (p=0.01), driven by their PD1 expression, predicted a higher probability for DR. Tregs frequency and cell dose were not affected from mobilisation regimen. However, Tregs dose was the stronger predictor of PFS at 36 months (75% with dose <5.06 x10^6/kg v 34.5% with dose >5.06 x10^6/kg, p= 0.001). Similarly, lower cell doses of CD4 EM (p=0.012) and frequency of CD4 TE (p=0.034) predicted a higher probability of PFS, but only Tregs cell dose retained significance in multivariate analysis (Figure 1D, p=0.001). In conclusion, spontaneous DR occurs in the first 2 years post ASCT in the absence of maintenance therapy and is associated with better PFS. CD4 memory subsets and NK cell graft composition appears significant for a potential immunological effect in DR. Additionally, a lower cell dose of immunosuppressive Tregs appears more important for sustaining long-term remission post ASCT.

Comparison of Various Stem Cell Mobilization Regimens for Multiple Myeloma - a 15-Year Retrospective Institutional Analysis from India

Introduction For multiple myeloma (MM), Cyclophosphamide (Cy) based chemo-mobilization offers advantage in term of higher stem cell yield and can overcome adverse impact of prior lenalidomide therapy on stem cell harvest. However, considering need for hospital stay and risk of febrile neutropenia, steady state mobilization with G-CSF and pre-emptive plerixafor (PEF) is becoming increasingly popular. Until few years back, cost of PEF was prohibitive thereby limiting its use and prompting a search for alternative cheaper drugs. Mouse models have shown that Proteasome Inhibitors aid in hematopoietic stem-cell (HSC) mobilization by down-regulating very-late antigen-4 (VLA-4) on bone marrow stromal cells which interacts with vascular cell adhesion molecule (VCAM-1) on HSC. We previously reported that bortezomib (Bort) in combination with Cy-G-CSF showed a trend towards higher CD34 yield and reduced need for apheresis sessions, without additional toxicity. There is limited data comparing mobilization regimens, especially from low-middle income countries where HSC collection may not be done after 4-6 cycles of first-line therapy. We hereby report our 15-year experience of various mobilization regimens for MM. Methods All patients with MM who underwent HSC mobilization from September 2007 - December 2022 were included in this analysis. Various mobilization regimens [Group 1 - G-CSF + Bort (August 2018 - December 2022); Group 2 - G-CSF + plerixafor (August 2018 - December 2022); Group 3 - Bort-Cy-GCSF (April 2016 - July 2018); Group 4 - Cy + G-CSF (September 2007 - March 2016)] were used as per respective time-periods (Table 1). Our aim was to collect CD34 cell dose of 5million/kg to suffice for 2 transplants. G-CSF (5 mcg/kg subcutaneously BD) was given on days 1-5 (Groups 1 and 2). Bort (1.3mg/m 2 iv / sc) (Group 1) or PEF (Group 2) were given on day 4 twelve hours prior to planned apheresis on day 5. Apheresis was done on day 5, and additionally on day 6, if first harvest was inadequate for 2 transplants. In group 3, Bort (1.3mg/m 2 iv) was given on days-1,4,8,11, with Cy (1gm/m 2 iv) on days 8 and 9, followed by G-CSF from day 11 onwards. Cy (1gm/m 2 iv) was given on day 1 and 2 (Group 4), followed by G-CSF from day 4 onwards. Stem cell harvest was done in groups 3 and 4 once peripheral blood CD34 (PB CD34) was >20/µL. In groups 3 and 4, if PB CD34 was <20/µL for 2 subsequent days, PEF was used according to physician's discretion, if available. Similarly in Group 1, if PB CD34 was between 10-20/µl on day 4, PEF was used according to physician's discretion. PEF was used in any group after the first harvest if the cell dose was deemed inadequate, at physician's discretion. Primary objective was to determine proportion of patients with CD34 + dose ≥5x10 6/kg in first apheresis in various groups. Secondary objectives were to determine total median CD34 + dose (x10 6/kg) collected, median CD34 + (x10 6/kg) in first apheresis, and frequency of mobilization failure. Mobilization failure was defined as total collected CD34 + dose of <2x10 6/kg or abandoned harvest attempt anticipating a poor collection.Analysis was done as per planned regimen (intention to treat analysis). Results Total 205 patients were analyzed. Median age was 48 years (27-65 years) and 143 (70%) were males (Table 1). Median day of first collection in groups 3 and 4 was day10 from the first dose of cyclophosphamide. Percentage of patients who collected ≥5x10 6 CD34 + cells/kg in first apheresis were 26%, 53%, 69% and 63%, respectively in Groups 1-4 (p=0.0001) (Table 1). CD34+ cell-dose in first apheresis and total dose collected are shown in Table 1. In comparison to groups 1 and 2, both chemo-mobilization groups (group 3 and 4) had a significantly higher total cell dose (Figure 1). In comparison to group 1, both Cy chemo-mobilization groups had a significantly higher cell dose in first harvest, but there was no significant difference between group 2 and group 4 (p=0.23) (Figure 1). PEF was required additionally in 47%, 22%, and 7% of patients in groups 1, 3 and 4 respectively (P<0.00001). Amongst transplanted patients, there was no difference in neutrophil or platelet engraftment and the frequency of engraftment syndrome in various groups. Conclusion Cy-based chemo-mobilization regimens have advantage of higher total stem cell yield, while they are equivalent to G-CSF + Plerixafor for harvest in single apheresis. Addition of Bortezomib to Cyclophosphamide may help to increase stem cell yield.

Outcomes of Allogeneic HSCT in Elderly Patients (70 years old and above) -a Canadian Experience

Introduction: Allogeneic hematopoietic cell transplant (alloHCT) in elderly patients is a challenge, as with increasing age, there is higher incidence of co-morbidities and pre-frail status. In our recent study on alloHCT in patients 60 years (y) or older, those who were 70y or more had worse outcome and high 2-y non-relapse mortality (NRM) of 53% (Al-Shaibani E et al. Ann Hematol, 2023, 102: 917-926). We therefore implemented a number of changes to improve outcomes in elderly patients undergoing alloHCT. In this study, we analyze transplant outcomes in patients ≥ 70 y, and compare the earlier cohort with the more recent cohort. Methods: This is a retrospective analysis of all consecutive patients 70y or older, who had an alloHCT from Jan 2015 to Dec 2022. We compared those who underwent an alloHCT from 2015-2019 (Cohort A, n=44) with those who had a transplant from 2020-2022 (Cohort B, n=40). The median age of the patients was 71y (range 70-76). The underlying diagnosis was mainly a myeloid malignancy (AML, MDS, MPN, CMML, n=82; lymphoid (ALL, TPLL, n=2). There were 54 males. Stages of disease at transplant were in CR1 (n=51), CR2 (n=4) or stable disease (n=15, MDS, MPN or CMML pts). All patients received RIC regimens for conditioning including Flu4/Bu2/TBI200 (n=73), Flu4/Treo30 (n=7) and Flu/Treo42 (n=3). The GVHD prophylaxis regimens used included ATG2/PTCy/CSA (n=32), ATG4.5/PTCy/CSA (n=35), ATG4.5/CSA/MTX (n=7), ATG2/CSA/MTX (n=3). The donors were either matched related (n=10), matched unrelated (including minor mismatch) (n=57) or haploidentical (n=16). Graft source was peripheral blood in all except one who received bone marrow. (Details in Table). The overall survival (OS), event free survival (EFS), NRM, cumulative incidence of relapse (CIR), incidence of acute and chronic GVHD, length of transplant hospitalization and the number of hospital re-admissions in first 6 months were assessed. The Kaplan Meier curves were plotted for OS and EFS for the overall sample, as well as stratified by the two eras (cohort A and B) and the differences assessed using log-rank tests. Cumulative incidence curves for NRM and CIR were generated, and differences assessed using Gray's K-sample. Results: For all patients transplanted in 2015-2022, the 1-year OS was 53%, the 1-year EFS was 45% and the 1-year NRM was 35%. The median number of days of transplant hospitalization for the whole population was 33.5 days (range 16 - 116). The incidence of grade I-II aGVHD was 32%, and grade III-IV aGVHD was 9.5%; mild to moderate cGVHD was 14% and severe cGVHD was 2%. The 1-year CIR was approximately 18%. Comparing the two cohorts A and B, the 1y OS was 45% vs 62% (p=0.10) respectively; the 1-year EFS was 37% vs 58% (p=0.07) respectively and the 1-year NRM was 45% vs 23% (p=0.04) respectively (Figures attached). The incidence of GVHD and CIR were similar in both cohorts, despite reducing the ATG dose in cohort B. Conclusions: Our study shows that there were statistically significant improvements in NRM and a trend towards improvement in the OS and EFS in the patients transplanted during 2020-2022 compared to patients undergoing alloHCT from 2015-2019. This improvement may be due to one or more changes implemented in recent years, although it is not possible to identify a single factor. These changes were (a) introduction of Frailty testing in all patients (Salas MQ et al. BMT. 2021; 56:60-69). (b) capping the CD34 cell dose in grafts (c) introduction of Treosulfan for selected indications (MDS/CMML) (Pasic I et al. Leuk Res 2023, 128: 107131). (d) Letermovir for CMV prophylaxis (e) reducing ATG dose for GVHD prophylaxis and (f) focus on diet, nutrition, exercise. While alloHCT should be offered to medically eligible elderly patients, there is a special need to minimize the risks that are part of age related vulnerabilities.

Impact of SARS-CoV-2 infection on graft composition and early transplant outcomes following allogeneic hematopoietic stem cell transplantation

Objective: To assess the feasibility of using donors with novel coronavirus disease 2019 (COVID-19) for allogeneic hematopoietic stem cell transplantation (allo-HSCT) when there are no other available donors and allo-HSCT cannot be delayed or discontinued. Methods: Seventy-one patients with malignant hematological diseases undergoing allo-HSCT between December 8, 2022, and January 10, 2023, were included. Of these, 16 received grafts from donors with mild COVID-19 (D-COVID(+) group) and 55 received grafts from donors without COVID-19 (D-COVID(-) group). The graft compositions were compared between the two groups. Engraftment, acute graft-versus-host disease (aGVHD), overall survival (OS), and relapse were also evaluated. Results: There were no serious side effects or adverse events in the D-COVID(+) group. The mononuclear cell dose and CD34(+) cell dose were comparable between the two groups, and no additional apheresis was required. There were no significant differences in the lymphocyte, monocyte, and T-cell subset doses between the two groups. The median natural killer cell dose in the D-COVID(+) group was significantly higher than that in the D-COVID(-) group (0.69×10(8)/kg vs. 0.53×10(8)/kg, P=0.031). The median follow-up time was 72 (33-104) days. All patients achieved primary engraftment. The 60-day platelet engraftment rates in the D-COVID(+) and D-COVID(-) groups were 100% and (96.4±0.2) %, respectively (P=0.568). There were no significant differences in neutrophil (P=0.309) and platelet (P=0.544) engraftment times. The cumulative incidence of grade 2-4 aGVHD was (37.5±1.6) % vs. (16.4±0.3) % (P=0.062), and of grade 3-4 aGVHD was 25.0% ±1.3% vs. 9.1% ±0.2% (P=0.095) in the D-COVID(+) and D-COVID(-) groups, respectively. The probabilities of 60-day OS were 100% and 98.1% ±1.8% (P=0.522) in the D-COVID(+) and D-COVID(-) groups, respectively. There was no relapse of primary disease during the study period. Conclusion: When allo-HSCT cannot be delayed or discontinued and no other donor is available, a donor with mild COVID-19 should be considered if tolerable. Larger sample sizes and longer follow-up periods are required to validate these results.

Impact of Allograft T-Cell (CD3) Dose on Outcomes When CD34 Cell Dose Is Capped: Analysis of 811 Consecutive Allogeneic PBSC Transplants from a Single Center

G-CSF mobilized PBSC allografts contain higher T-cell doses than bone marrow grafts and have been associated with a significantly higher risk of chronic GVHD. Higher CD34+ cell content in PBSC grafts has also been shown to predict higher rates of chronic GVHD and associated mortality 1,2 To mitigate this risk our center adopted a policy of capping CD34+ cell dose at 5 x 10e6/kg recipient weight for unmanipulated PBSC grafts. For this study, we assessed the effect of T-cell (CD3) dose administered under this capped CD34 strategy, on GVHD and other transplant outcomes. Consecutive first PBSC allografts for hematologic malignancy performed using the CD34 cap strategy between 2010 and 2022 (n=811) were included in this analysis. GVHD prophylaxis was tacrolimus/methotrexate for MRD and MUD and post-transplant cyclophosphamide based for Haplo. Patients receiving anti-T cell serotherapy or ex-vivo T-depletion were excluded. GVHD was uniformly assessed and graded by a dedicated practitioner for all cases. Patient characteristics were: median age 55 (18-80); 57% male; race -white 74%, black 21%, Asian 5%; diagnosis AML 38%, ALL 18%, MDS 18%, NHL 10%; donor type haplo 42%, MRD 32%, MUD 26%, %; high/v. high 25%, low/intermediate 73%; HCT-CI (0-2) 43%, (>3)57%, regimen - myeloablative 48%, RIC 31%, NMA 21%). Median follow-up for survivors was 64 (16-151) months. Median CD34 and CD3 doses infused were 5.0 x 10e6/kg (min 1.59) and 17.3 x 10e7/kg (range 1.2-83.3) respectively. Median CD3 dose infused were higher with female donors (20.5 vs 15.5 x 10e7/kg, p<0.001) and older donors (18.6 vs 15.9 x 10e7 for donors aged >38 vs <38, p<0.001). The effect of Infused CD3 dose was assessed in terciles (ranges 1.2-13.5, 13.6-22, 22.1-83.3 x 10e7/kg). Median peripheral blood donor CD3 chimerism was 100% for all CD3 dose terciles at d 30, through 180 post-transplant. On univariate analysis - estimated 3-year survival, DFS, NRM, relapse and acute GVHD incidence were not significantly different between the low, middle and high CD3 terciles. In contrast, the cumulative incidence (CI) of moderate-to-severe chronic GVHD at 3 years was significantly higher in the highest vs lowest tercile (36.8% vs 28.6%, p=0.042) (Fig 1), while severe chronic GVHD (14.5% vs 13%) was not significantly different. On stratified Cox multivariable analysis comparing the highest to the lowest CD3 dose terciles - survival, DFS, NRM, relapse and acute GVHD were not significantly different. Moderate-to-severe chronic GVHD was significantly higher in the highest versus lowest tercile (HR 1.53, p=0.005). In order to address specific effects of CD3 dose for particular donor groups, we analyzed incidence of chronic GVHD by CD3 dose terciles separately for the three donor types (MRD n=258, MUD n=210 and Haplo n=343). Whereas the CI of moderate-to-severe chronic GVHD was not significantly different for lowest versus highest CD3 tercile in MRD and Haplo transplant recipients, it was significantly higher for MUD recipients (50% vs 26%, p=0.008, GRFS 29% vs 9%, p=0.005). On multivariable analysis, risk of moderate-to-severe chronic GVHD was significantly higher for the highest versus lowest CD3 dose terciles (HR 2.62, p=0.002) and for the middle vs lowest terciles (HR1.77, p=0.043) in MUD patients (Fig 1). In contrast, CD3 dose had no significant impact on chronic GVHD for MRD and Haplo recipients. This large retrospective analysis of PBSC allografts using a CD34 cap (<5 x 10e6/kg) shows that this approach produced infused CD3 doses ranging between 1.2 and 83.3 x 10e6 /kg. The median and upper limit of infused CD3 dose was lower than previously reported by studies with no CD34 cap 2,3. CD3 dose had a significant impact on the rate of moderate-to-severe chronic GVHD in MUD recipients. A prospective comparison of capped versus uncapped CD34 dosing may help determine the value of this strategy in mitigating GVHD risk of PBSC grafts. These data suggest the need for more aggressive GVHD prophylaxis in patients infused with higher CD3 doses in MUD patients. 1. Mohty M, Bilger K, Jourdan E, et al. Leukemia. 2003;17(5):869-875. 2. Zaucha JM, Gooley T, Bensinger WI, et al. Blood. 2001;98(12):3221-3227. 3. Saad A, Lamb L, Wang T, et al. Biol Blood Marrow Transplant. 2019;25(9):1875-1883.

Abatacept-Prophylaxis Based Haploidentical Transplantation May Allow Sustained Engraftment and Offset Gvhd in Non-Malignant Disorders

Introduction: Non-malignant disorders (NMD) derive no benefit from graft-versus-host disease (GVHD) after allogeneic hematopoietic transplantation (HCT). Transplantation designed to optimize engraftment and immune reconstitution while minimizing GVHD and organ toxicities is desirable. Post-transplant cyclophosphamide (PTCy) decreases severe chronic GVHD risk in radiation-containing regimens for NMD when combined with serotherapy (anti-thymocyte globulin) (PMID: 22955919; PMID: 30500440). Abatacept effectively offsets GVHD following unrelated donor (URD) HCT (PMID: 33449816; PMID: 32813873). Based on these reports, NCT03128996 was developed for haploidentical transplantation in NMD after radiation-free reduced intensity conditioning (RIC) combining PTCy + Abatacept for GVHD prophylaxis. Serotherapy does not contribute to GVHD prophylaxis in this RIC approach. Outcomes focused on safety and GVHD- free donor engraftment in children with NMD and no better donor options. Method: Conditioning included alemtuzumab (day -22 to -19), fludarabine (day -8 to -4), melphalan (day -3) and thiotepa (day -4) as previously published (hydroxyurea prior to RIC was used in proliferative marrow disorders) (PMID: 32813873). Stem cell source was bone marrow (BM) or CD34-selected peripheral blood cells with a fixed CD3 cell dose of 1x10^6/kg recipient weight. GVHD prophylaxis included tacrolimus (day -1, with wean beginning 6-9 months post-HCT), PTCy on days +3 and +4, mycophenolate mofetil until day +28, and monthly abatacept doses until 13 months post-HCT. Survival, safety, donor chimerism, GVHD incidence, and incidence of post HCT infection were primary outcome measures. Results: Eleven patients 6 to 24 years old (median 9 years) underwent HCT for adrenoleukodystrophy ( 2), sickle cell disease (SCD) ( 6), aplastic anemia ( 1), second transplant for severe combined immunodeficiency ( 1) and STAT 5B gain-of-function mutation ( 1). Eight were trial participants and 3 treated according to trial guidelines. All patients tolerated abatacept infusions and engrafted with neutrophil recovery (>500/cu mm) at a median of 17 days (range 15-24 days). As of 7/31/2023, median follow up is 411 days (range 83-1979 days). The mean myeloid and T-cell chimerisms at D100 (n=10) and 1 year (n=6) were 97.8%+/- 5.3 and 96.3% +/- 6.4 and 98.6% +/- 3.3 and 95% +/-8.7, respectively. One patient with SCD has low myeloid engraftment (24%) at 7 months post-HCT (lymphoid 91%); a stem cell boost is planned after immune suppression with fludarabine/Cytoxan/ATG (PMID: 35798858). Viral reactivation was noted in 4 patients, none developed CMV disease or EBV post-transplant lymphoproliferation. One patient developed grade 1 acute GVHD. Of 6 evaluable patients, one developed localized chronic skin GVHD. This patient remains on systemic immune suppression beyond 13 months (ruxolitinib). The overall and GVHD-free survival at 1-year post HCT in evaluable patients (N=6) is 100 % and 83%, respectively. Conclusion: Promising preliminary results in this cohort support continuation of the trial with longer term follow-up. The effective suppression of GVHD without serious infectious complications in the first year post-HCT is encouraging. Virus reactivation was however noted early post-HCT and requires monitoring and prophylaxis. Incorporating abatacept into GVHD prophylaxis was successful in achieving desired outcomes; the phase 1 portion of the study is completed and the phase 2 trial and follow-up are ongoing.

Cytokine release syndrome in haploidentical stem cell transplant may impact T-cell recovery and relapse

AbstractCytokine release syndrome (CRS) following haploidentical hematopoietic cell transplantation (HCT) resembles CRS after chimeric antigen receptor-T therapy. We conducted this single-center retrospective study to evaluate the association of posthaploidentical HCT CRS with clinical outcomes and immune reconstitution. One hundred sixty-nine patients who underwent haploidentical HCT between 2011 and 2020 were identified. Of these, 98 patients (58%) developed CRS after HCT. CRS was diagnosed based on the presence of fever within the first 5 days after HCT without evidence of infection or infusion reaction and was graded according to established criteria. The development of posthaploidentical HCT CRS was associated with a lower incidence of disease relapse (P = .024) but with an increased risk of chronic graft-versus-host disease GVHD (P = .01). The association of CRS with a lower incidence of relapse was not confounded by graft source or disease diagnosis. Neither CD34 nor total nucleated cell dose was associated with CRS independently of graft type. In patients developing CRS, CD4+ Treg (P < .0005), CD4+ Tcon (P < .005), and CD8+ T cells (P < .005) increased 1 month after HCT compared with those who did not develop CRS, but not at later time points. The increase in CD4+ regulatory T cells 1 month after HCT was most notable among patients with CRS who received a bone marrow graft (P < .005). The development of posthaploidentical HCT CRS is associated with a reduced incidence of disease relapse and a transient effect on post-HCT immune reconstitution of T cells and their subsets. Therefore, the validation of these observations in a multicenter cohort is required.

CT-026 Prevalence and Impact of Donor Specific Anti-HLA Antibodies in the Setting of Myeloablative Haploidentical Transplant for Malignant Hematological Diseases: Single-Center Experience

To study the outcomes, prevalence, and impact of DSA and anti-HLA of myeloablative haploidentical transplant for malignant hematological diseases. We conducted retrospective analysis of our blood and marrow transplant database. We identified 107 patients who received myeloablative haploidentical hematopoietic cell transplantation between January 2013 and December 2020. Sixty-two recipients were male (58%) and 45 were female (48%). The median recipient age was 22 (range: 1-56). Most pairs had matched ABO blood groups (76 pairs [71%]). The graft source was bone marrow in 83 patients (78%). The median infused CD34 cell dose was 4.02×106/kg (range: 1.3-13.1). Sixty-one recipients (57%) had positive anti-HLA; of these, 17 had DSA (15% of the total number of patients, 28% of patients with anti-HLA antibodies). The median cumulative mean fluorescence intensity was 2,062 (IQR: 1,038-6,500). Overall survival, cumulative incidence of relapse, acute graft-versus-host disease, and chronic graft-versus-host disease were comparable between patients with anti-HLA antibodies and those without and between patients with DSA and those without. Recipient and donor gender and recipient/donor gender mismatch showed statistical association with the incidence of anti-HLA antibodies but not DSA. Of the 17 patients with DSA, five underwent desensitization. C1q assay was done pre and post desensitization. Three patients developed GF (2.8%): one was primary (0.9%) due to low CD34 dose, and two had secondary GF (1.9%). None of these cases occurred in patients with anti-HLA antibodies or DSA. The median time from transplant to GF was 2.23 months (range: 0.8-2.89). The median time to absolute neutrophil count and platelet engraftment was 16 days. Our study shows that desensitization may not be required in the setting of myeloablative transplant for malignant hematological disorders. This warrants further investigations in prospective trials.

CT-098 Impact of T-Cell Dose on Outcome of T Cell–Replete HLA-Mismatched Allogeneic Peripheral Blood Stem Cell Transplantation

The outcome of allogeneic hematopoietic cell transplantation (HCST) relies on both disease-related factors and transplant-related factors including the conditioning regimen and immunotherapy exploiting the graft-versus-tumor (GVT) effect. CD3+ T cells are the main player in the GVT process, but an increased dose of these cells results in an increased risk of acute graft-versus-host disease (GVHD). We aimed to study whether the T-cell dose of allogeneic peripheral blood stem cell (PBSC) products influences transplantation outcomes in our patient population. This is a retrospective chart review study including patients over 18 years of age, diagnosed with AML, ALL, or MDS, who underwent PBSC mismatched allogeneic transplant, including haploidentical, one-antigen mismatched related, or 2-alleles mismatched related transplants at the King Hussein Cancer Center's bone marrow transplant program between January 2010 and December 2020. We calculated the median CD3 cell dose and divided all patients into 2 groups (Low and High dose groups) and then measured the cumulative incidence of acute GVHD, chronic GVHD, and 1- and 2-year overall survival (OS). Thirty-five patients were stratified according to the median CD3+ cell dose into the Low CD3 group, which included 18 (51%) patients with a mean dose of 13.7×107/kg (range: 2.8-19.7), and the High CD3 group, which included 17 (49%) patients with a mean dose of 29.7×107/kg (range: 19.8-93.1) (P-value: 0.000). The cumulative incidence of acute GVHD was 60% (n=12) in the Low CD3 group and 40% (n=8) in the High CD3 group (P-value: 0.24). The cumulative incidence of chronic GVHD was 64% (n=9) in the Low CD3 group and 35% (n=5) in the High CD3 group (P-value: 0.26). The overall survival for the cohort (n=35) at 12 months was 60.9% and reached 49.6% at 24 months. The 12-month OS for the Low and High CD3 groups was 66.7% and 52.9%, respectively. The 24-month OS for the Low and High CD3 groups was 66.7% and 33.1%, respectively (P-value: 0.084). Although the study showed a trend toward better OS in the Low CD3+ dose group, the difference was not statistically significant.

Costs of matched-sibling, unrelated, and haploidentical hematopoietic cell transplantation and risk factors for greater financial burden - a Brazilian FACT-accredited single-center analysis.

The complexity and costs of hematopoietic cell transplantation (HCT) have increased over the last decades with the popularization of unrelated donor (URD) transplantation and the introduction of haploidentical transplantation with posttransplant cyclophosphamide. Few studies have addressed this issue. The objective of this study was to analyze HCT costs in a single FACT-accredited private non-profit hospital. We included 79 patients who underwent HCT between 2018 and 2020. We have included all costs from admission day until D + 180. We used a lognormal regression. Median age was 53 y/o and most donors were unrelated (51%). Costs were higher with haploidentical donor (42%, p = 0.017, compared with URD), higher HCT-CI (15% for each point, p = 0.0056), and in patients with liver or gastrointestinal GVHD (45%, p = 0.033), and lower in patients who received CD34 > 2.5 × 10E6/kg (42%, p = 0.0038). We built a score based on the following risk factors: HCT-CI > 3, CD34 ≤ 2.5 × 10E6/kg, haploidentical donor, and donor age > 30 y/o. Patients with 2 + risk factors (N = 53) had a median cost of USD 226,156.00, compared with USD 93,048.00 in patients with zero or 1 point (N = 26, p < 0.0001). In summary, we have shown that HCT costs are higher with lower doses of CD34 cells, haploidentical HCT (provided that the costs of stem cell procurement and ATG are not included), and in patients with higher HCT-CI. Prospective and refined cost analyses comparing haploidentical and URD transplants, as well as effective strategies for patients with higher HCT-CI scores, are warranted. We found no difference in costs between URD and MSD transplantation.

Effect of Multiple HLA Locus Mismatches on Outcomes after Single Cord Blood Transplantation

The effect of single or multiple mismatches at each HLA locus on outcomes after cord blood transplantation (CBT) is controversial. We analyzed the effects of single or multiple HLA locus mismatches on the outcomes after single CBT using Japanese registry data from the Japan Society for Hematopoietic Cell Transplantation. Patients age ≥16 years with acute leukemia and myelodysplastic syndromes who underwent their first CBT between 2003 and 2017 (n=4074) were included. The effect of the number of HLA locus mismatches (0, 1, or 2 for the HLA-A, -B, -C, and -DRB1 loci) on outcomes was analyzed after adjusting for other significant variables. The patient cohort had a median age of 54 years. The median total nucleated and CD34 cell doses were 2.6×107/kg and .8×105/kg, respectively. The number of CBTs with single or double mismatches were 2099 and 292, respectively, for the HLA-A locus, 2699 and 341 for the HLA-B locus, 2555 and 609 for the HLA-C locus, and 2593 and 571 for the HLA-DRB1 locus. Single and double HLA-DRB1 mismatches were associated with a higher risk of grade II-IV acute graft-versus-host disease (GVHD; single: hazard ratio [HR], 1.29, P < .001; double: HR, 1.49, P < .001; P for trend <.001). Single and double mismatches at HLA-DRB1 as well as single mismatches at HLA-A and HLA-B also were associated with grade III-IV acute GVHD. Single and double HLA-B mismatches and double HLA-DRB1 mismatches were associated with a high risk of nonrelapse mortality (NRM). On the other hand, double mismatches at HLA-A or HLA-DRB1 and single mismatches at HLA-B were associated with a lower risk of relapse. HLA-DRB1 double mismatch was associated with high risk of grade II-IV and grade III-IV acute GVHD and NRM but lower risk of relapse. Not only the locus mismatch, but also the number of mismatches, should be considered in cord blood unit selection.

289 - Updated Outcomes during the Pandemic: Relationship between CD34 and CD3 Cell Doses, One-Year Graft-Versus-Relapse-Free-Survival, Graft-Versus-Host Disease, and Overall Survival in Haploidentical Hematopoietic Stem Cell Transplantation Using Post Transplant Cytoxan: A Single Center Experience

289 - Updated Outcomes during the Pandemic: Relationship between CD34 and CD3 Cell Doses, One-Year Graft-Versus-Relapse-Free-Survival, Graft-Versus-Host Disease, and Overall Survival in Haploidentical Hematopoietic Stem Cell Transplantation Using Post Transplant Cytoxan: A Single Center Experience

Commentary: Target CD34 Cell Dose for Allogeneic Hematopoietic Cell Transplantation: Can We Finally Agree?

Commentary: Target CD34 Cell Dose for Allogeneic Hematopoietic Cell Transplantation: Can We Finally Agree?

Hematopoietic Stem Cell Transplantation is a cost-effective alternative to enzyme replacement therapy in Gaucher Disease.

Allogeneic hematopoietic stem cell transplantation (HSCT) is a feasible treatment option for Gaucher disease (GD). Among 60 patients diagnosed with GD over 15 years (2004-2019), three children who underwent HSCT (January-November 2017) were analyzed. Two boys (cases 1 and 2) and one girl (case 3) received HSCT at 3, 7, and 10 years of age, respectively. Cases 1 and 3 received haplo-HSCT, while case 2 received HLA-identical related-donor transplantation. The CD 34 cell dose was 5-10×106/kg. Neutrophil and platelet engraftment were between days +14 to +21 and days +15 to +76. Post-HSCT chimerism was a 100% donor. None of the patients developed acute or significant chronic graft versus host disease (GVHD). All patients had febrile episodes with negative blood cultures. Major post-HSCT complications included EBV-viremia and recurrent lobar pneumonia in case 1, delayed engraftment and pure red cell aplasia (PRCA) in case 2, and pericardial effusion with tamponade in case 3. At a median of 49 months post-HSCT, all patients were stable with improved growth, absent organomegaly, and had completed immunization. The median cost of treatment was $23,038.96, which is 10.7%-13% of the yearly enzyme replacement therapy (ERT) cost. In a resource-limited setting like India, ERT is a financial burden and not a sustainable option. With improved treatment outcomes, haplo-HSCT is now a possible option for almost every patient, even if no HLA-identical donor is identified.

Allogeneic Hematopoietic Stem Cell Transplantation in Severe Aplastic Anemia: A Single Centre Experience in Malaysia.

Hematopoietic stem cell transplantation (HSCT) provides curative therapy in almost 90% of patients with severe aplastic anemia (SAA). Older age, long duration of disease with consequent heavy exposure to transfusion, and active infection at the time of HSCT have a negative influence on the outcomes, causing graft failure (GF) and graft versus host disease (GVHD). To describe the outcomes of all patients with SAA who received hematopoietic stem cell transplantation at a tertiary center in Malaysia. We included a 20 y cohort of patients who underwent transplantation from January 1, 1999 to December 31, 2019. Data were obtained from electronic medical records. Demographics, clinical characteristics, and treatment outcomes were analyzed using descriptive statistics. Overall survival (OS) was analyzed using Kaplan-Meier curves. All analyses were conducted using the Statistical Package for the Social Sciences (SPSS) version 25. Eighty patients were analyzed. The median age at diagnosis was 19 years, and 59% patients were male (n = 47). Malay ethnicity was the highest (52.5%), followed by Chinese (20.0%) and Native Sabah (15.0%). The median duration from diagnosis to transplantation was 13.5 weeks. A majority of patients received Cy-ATG conditioning (n = 51, 63.8%). Forty-one patients (51.2%) used peripheral blood as stem cell source, 36 patients (45.0%) used granulocyte colony stimulating factor (G-CSF) primed marrow graft and 3 patients (3.8%) used both. The mean nucleated mononuclear cell and CD34 cell doses were 4.7 ± 1.7 × 108/kg and 4.6 ± 1.9 × 106/kg, respectively. Median engraftment for WBCs and platelets was 14 and 15 days, respectively. There was no difference in WBC and platelet engraftment in patients who received peripheral blood stem cell transplantation or bone marrow transplant. At a median follow-up of 54 months, 49 patients (61.3%) achieved complete remission and 8 patients (10.0%) achieved partial remission. The estimated 5 y OS was 63% and higher among those who received HSCT within 3 months of diagnosis. Twenty-two patients (27.5%) died within 100 d of transplantation, and a majority of these died due to pre-engraftment death. Our study found that patients who received early allogeneic transplantation for SAA had better outcomes. Pre-engraftment failure was the major cause of transplant-related mortality within 100 d. Further studies are required to identify the factors responsible for delaying transplantation to improve treatment outcomes.