Dose Of CD34 Research Articles

The two-step approach to allogeneic hematopoietic stem cell transplantation.

Allogeneic hematopoietic stem cell transplantation (HSCT) provides the only potentially curative option for multiple hematological conditions. However, allogeneic HSCT outcomes rely on an optimal balance of effective immune recovery, minimal graft-versus-host disease (GVHD), and lasting control of disease. The quest to attain this balance has proven challenging over the past few decades. The two-step approach to HSCT was conceptualized and pioneered at Thomas Jefferson University in 2005 and remains the main platform for allografting at our institution. Following administration of the transplant conditioning regimen, patients receive a fixed dose of donor CD3+ cells (HSCT step one-DLI) as the lymphoid portion of the graft on day -6 with the aim of optimizing and controlling T cell dosing. Cyclophosphamide (CY) is administered after the DLI (days -3 and -2) to induce donor-recipient bidirectional tolerance. On day 0, a CD34-selected stem cell graft is given as the myeloid portion of the graft (step two). In this two-step approach, the stem cell graft is infused after CY tolerization, which avoids exposure of the stem cells to an alkylating agent, allowing rapid count recovery. Here, the two-step platform is described with a focus on key results from studies over the past two decades. Finally, this review details lessons learned and current strategies to optimize the graft-versus-tumor effect and limit transplant-related toxicities.

Adverse impact of delay of platelet recovery after autologous hematopoietic cell transplantation for aggressive non-Hodgkin lymphoma and multiple myeloma

Background aimsThe prognostic impact of platelet recovery after autologous hematopoietic cell transplantation (AHCT) on clinical outcomes remains to be elucidated. We aimed to clarify the impact of platelet recovery on clinical outcomes, risk factors of delayed platelet recovery and the necessary dose of CD34+ cells for prompt platelet recovery in each patient. MethodsUsing a nationwide Japanese registry database, we retrospectively analyzed clinical outcomes of 5222 patients with aggressive non-Hodgkin lymphoma (NHL) or multiple myeloma (MM). ResultsAt a landmark of 28 days after AHCT, a delay of platelet recovery was observed in 1102 patients (21.1%). Prompt platelet recovery was significantly associated with superior overall survival (hazard ratio [HR] 0.32, P < 0.001), progression-free survival (HR 0.48, P < 0.001) and decreased risks of disease progression (HR 0.66, P < 0.001) and non-relapse/non-progression mortality (HR 0.19, P < 0.001). The adverse impacts of a delay of platelet recovery seemed to be more apparent in NHL. In addition to the dose of CD34+ cells/kg, disease status, performance status and the hematopoietic cell transplant-specific comorbidity index in both diseases were associated with platelet recovery. We then stratified the patients into three risk groups according to these factors. For the purpose of achieving 70% platelet recovery by 28 days in NHL, the low-, intermediate- and high-risk groups needed more than 2.0, 3.0 and 4.0 × 106 CD34+ cells/kg, respectively. In MM, the low-risk group needed approximately 1.5 × 106 CD34+ cells/kg, whereas the intermediate- and high-risk groups required 2.0 and 2.5 × 106 CD34+ cells/kg to achieve about 80% platelet recovery by 28 days. ConclusionsA delay of platelet recovery after AHCT was associated with inferior survival outcomes.

A machine-learning model that incorporates CD45 surface expression predicts hematopoietic progenitor cell recovery after freeze–thaw

Background aimsSufficient doses of viable CD34+ (vCD34) hematopoietic progenitor cells (HPCs) are crucial for engraftment. Additional-day apheresis collections can compensate for potential loss during cryopreservation but incur high cost and additional risk. To aid predicting such losses for clinical decision support, we developed a machine-learning model using variables obtainable on the day of collection. MethodsIn total, 370 consecutive autologous HPCs, apheresis-collected since 2014 at the Children's Hospital of Philadelphia, were retrospectively reviewed. Flow cytometry was used to assess vCD34% on fresh products and thawed quality control vials. The ratio of vCD34% thawed to fresh, which we call “post-thaw index,” was used as an outcome measure, with a “poor” post-thaw index defined as <70%. HPC CD45 normalized mean fluorescence intensity (MFI) was calculated by dividing CD45 MFI of HPCs to the CD45 MFI of lymphocytes in the same sample. We trained XGBoost, k-nearest neighbor and random forest models for the prediction and calibrated the best model to minimize falsely-reassuring predictions. ResultsIn total, 63 of 370 (17%) products had a poor post-thaw index. The best model was XGBoost, with an area under the receiver operator curve of 0.83 evaluated on an independent test data set. The most important predictor for a poor post-thaw index was the HPC CD45 normalized MFI. Transplants after 2015, based on the lower of the two vCD34% values, showed faster engraftment than older transplants, which were based on fresh vCD34% only (average 10.6 vs 11.7 days, P = 0.0006). ConclusionsTransplants taking into account post-thaw vCD34% improved engraftment time in our patients; however, it came at the cost of unnecessary multi-day collections. The results from applying our predictive algorithm retrospectively to our data suggest that more than one-third of additional-day collections could have been avoided. Our investigation also identified CD45 nMFI as a novel marker for assessing HPC health post-thaw.

Immune Reconstitution Profiling Suggests Antiviral Protection after Transplantation with Omidubicel: A Phase 3 Substudy

Allogeneic hematopoietic cell transplantation (HCT) is a potentially curative treatment for hematological malignancies and non-malignant disorders. Rapid immune reconstitution (IR) following allogeneic HCT has been shown to be associated with improved clinical outcomes and lower infection rates. A global phase 3 trial (NCT02730299) of omidubicel, an advanced cell therapy manufactured from an appropriately human leukocyte antigen-matched single umbilical cord blood (UCB) unit, showed faster hematopoietic recovery, reduced rates of infection, and shorter hospitalizations in patients randomized to omidubicel compared with those randomized to standard UCB. This optional, prospective substudy of the phase 3 trial characterized the IR kinetics following HCT with omidubicel compared with UCB in a systematic and detailed manner. In this substudy, 37 patients from 14 global sites were included (omidubicel: n=17, UCB: n=20). Peripheral blood samples were collected over 10 predefined time points from 7 to 365 days post-HCT. Flow cytometry immunophenotyping, T cell receptor excision circle quantification, and T cell receptor sequencing were employed to evaluate the longitudinal IR kinetics post-transplant and their association with clinical outcomes. Patient characteristics in the two comparator cohorts were overall statistically similar, except for age and total body irradiation (TBI) based conditioning regimens. The median age (range) for patients who received omidubicel or UCB was 30 (13-62) years and 43 (19-55) years, respectively. The percentages of patients receiving TBI based conditioning regimens were 47% and 70% for omidubicel and UCB recipients, respectively. Graft characteristics differed in their cellular composition. Omidubicel recipients received a 33-fold higher median dose of CD34+ stem cells, while receiving one third of the median CD3+ lymphocyte dose infused to UCB transplanted patients. Compared with UCB, omidubicel recipients exhibited faster IR of all measured lymphoid and myelomonocytic subpopulations, predominantly in the first 14 days post-transplant. This effect involved circulating natural killer (NK) cells, helper T cells, monocytes, and dendritic cells, with superior long-term B cell recovery from Day 28. One-week post-HCT, omidubicel recipients exhibited 4.1 and 7.7 -fold increases in the median helper T and NK cell counts respectively, compared to their UCB transplanted counterparts. By three weeks post-HCT, omidubicel transplanted patients were 3-fold more likely to achieve clinically relevant helper T and NK cell counts of 100 cells/ µL or above. Similar to UCB, omidubicel yielded a balanced cellular subpopulation composition and diverse T cell receptor repertoire in the short to long term. Omidubicel's CD34+ cell content correlated with faster IR by Day 7 post-HCT, which in turn coincided with earlier hematopoietic recovery. Lastly, early NK and helper T cell reconstitution correlated with a decreased rate of post-HCT viral infections, suggesting a plausible explanation for this phenomenon among omidubicel recipients in the phase 3 study. Our findings suggest that omidubicel efficiently promotes IR across multiple immune cells, including CD4+ T cells, B cells, NK cells, and dendritic cell subtypes as early as 7 days post-transplant, potentially endowing recipients of omidubicel with early protective immunity.

CD34 Stem Cell Boost in Pediatric Allogeneic Stem Cell Transplant Recipients: A Case Series and Review of Literature

Patients with poor graft function (PGF) or declining donor chimerism (DC) post allogeneic hematopoietic cell transplantation (HCT) may benefit from a CD34-selected stem cell boost (SCB). We retrospectively studied outcomes of fourteen pediatric patients (PGF: 12 and declining DC: 2), with a median age of 12.8 (range 0.08–20.6) years at HCT, who received a SCB. Primary and secondary endpoints included resolution of PGF or improvement in DC (≥ 15% increase), overall survival (OS) and transplant-related mortality (TRM), respectively. The median CD34 dose infused was 7.47 × 106/kg (range 3.51 × 106–3.39 × 107/kg). Among patients with PGF who survived ≥ 3 months post-SCB (n = 8), we observed a non-significant decrease in the cumulative median number of red cell transfusions, platelet transfusions, and GCSF but not intravenous immunoglobulin doses in the 3 months before and after SCB. Overall response rate (ORR) was 50%, with 29% complete and 21% partial responses. ORR was better in recipients who received lymphodepletion (LD) pre-SCB versus none (75% versus 40%; p = 0.56). The incidence of acute and chronic graft-versus-host-disease was 7% and 14%, respectively. The 1-year OS was 50% (95% CI 23–72%) and TRM was 29% (95% CI 8–58%). SCB was effective in half of our cohort with possible benefit of LD pre-SCB.

Prognostic Factors for the Long-Term Survival after Hematopoietic Stem Cell Transplantation in Patients with Hodgkin Lymphoma.

This study investigated the possible prognostic factors for the long-term survival (Cure Rate) of Hodgkin Lymphoma patients who underwent HSCT. This retrospective cohort study analyzed 116 Patients diagnosed with Hodgkin Lymphoma who received autologous hematopoietic stem cell transplantation (Auto-HSCT) between the years 2007 and 2014 and followed up until 2017. The information regarding patients' survival had been collected using phone calls, and their pre-transplant information was available in the archived documents. Prognostic effects were investigated using long-term survival models. Patients with obesity had five times higher odds of long-term survival (cure) than the others (P=0.06). Also, the recurrence experience after HSCT negatively impacted the curing potential by 78% (P=0.05). Also, with 32 years as the change point, patients younger than 32 had 76% fewer odds of surviving long-term (P=0.03), and Poor transfused stem cell dose of CD34+ (<0.16 × 106 cells/ml) reduced the odds of long-term survival by 92% (P=0.01). According to the statistical models used in this study, obesity can increase the curing potential of Hodgkin lymphoma after transplantation. Meanwhile, aging, poor transfused CD34+ cells, and recurrence after HSCT were associated with lower survival following HSCT.

Second stem cell transplantation for treatment of relapsed/refractory multiple myeloma after first autologous stem cell transplant: A 15-year retrospective institutional analysis.

Multiple myeloma remains an incurable disease, with the majority of patients relapsing after autologous stem cell transplant (ASCT). After relapse, second transplant remains one of the therapeutic options, along with novel agents. We reviewed the data of our patients who underwent ASCT for myeloma (N = 202) over the last two decades (2004-2019). Of these, 12 patients underwent a second transplant. Out of 12 patients, nine underwent second autologous stem cell transplant, whereas three received an allogeneic stem cell transplantation (Allo-SCT). Median progression-free survival (PFS) after the first ASCT was 32 months (5-84 months). Median interval between both the transplants was 35 months (4-159 months). Median age of our cohort which underwent second transplant was 56 years. Overall response rate (ORR) post-second transplant on day +100 was 83.3%, without any transplant-related mortality (TRM). With the use of preemptive plerixafor, none of our patients required a second day for stem cell harvest. Median CD34 dose of stem cells infused was 4.11 × 106/kg. Similar to the first ASCT, the median time to neutrophil and platelet engraftment was 11 and 12 days, respectively. At a median follow-up of 41 months, estimated 3-year PFS and overall survival (OS) was 37% ± 15% and 63% ± 15%, respectively. ">Among all relapsed myeloma patients who were transplant eligible, 11% underwent a second transplant. Second transplant is well tolerated with similar time to engraftment after first ASCT. Hence, we believe that second transplant is a feasible, cost-effective option in a resource-limited setting, which should be more widely utilized.

A Single Center Analysis of Hematopoietic Recovery in Patients Undergoing Allogeneic BMT with Suboptimal CD34+ Doses

Background: Allogeneic stem cell transplant (allo-SCT) is the only curative treatment for many hematologic malignancies. Stem cells can be collected from bone marrow, peripheral blood, or cord blood. Peripheral blood is the most common utilized source due to its convenience and the ability to collect high numbers of stem cells, but studies suggest that bone marrow offers certain advantages over peripheral blood, especially lower rates of graft-vs-host disease (Holtick et. al. Cochrane 2014), leading to higher survival in patients with nonmalignant disorders . The ideal cell dose for SCT is 2 x 106 cells/kg CD34 cells. However, in cases of bone marrow graft, if a suboptimal cell dose is collected, it is often not feasible to repeat extraction. This is especially difficult for minority ethnic groups who already face systemic barriers to care. Our goal for this study was to assess the correlation of CD34 dose to hematopoietic recovery in a minority-rich population of fresh marrow allogeneic stem cell recipients. Prior studies have also suggested that the cell dosing for transplant should be calculated by ideal body weight (IBW) rather than the standard actual body weight (ABW) (Cilley et. al. Bone Marrow Transplantation 2004). We assessed the correlation of recovery for ABW vs IBW as well. Methods: From 2012-2022, eighteen patients were identified in the Montefiore health system who received a bone marrow graft for allo-SCT with suboptimal CD34 doses. Alongside CD34 dose, an additional predictor evaluated was total nucleated cell (TNC) dose. ABW-based and IBW-based doses were calculated for both CD34 and TNC doses. Several outcomes were tracked for the eighteen patients, including "Days to WBC 1000 cells/μL", "Days to ANC 500 cells/μL ", and "Days to Plt≥20,000 cells/μL." The relationship between cell doses (ABW and IBW-based) and outcomes were evaluated independently through calculation of Spearman's correlation. Analysis and modeling were performed in RStudio 4.1.2. Results: AML and NHL patients made up the largest proportion of the sample (7/18 and 5/18) (Table 1). The median ABW-based CD34 dose (0.530 x 106 CD34 cells/kg) was nearly four times smaller than the standard of 2 x 106 cells/kg CD34 cells. Fifteen of 18 patients achieved reconstitution goals. Of the three patients who did not, one had persistent disease at the time of transplant and developed multiorgan failure dying within 17 days prior to hematopoietic recovery. Another died at day 58 without any platelet recovery. A third maintained platelets above 20,000 cells/μL throughout transplant. Assessing ABW-based CD34 dosing and IBW-based CD34 dosing as independent predictors, none of the outcomes, were significantly correlated (P > 0.05) (Figure 2). However, the Spearman's correlation coefficients were consistently of larger magnitude for IBW-based CD34 dosing than for ABW-based CD34 dosing for all three outcomes. Assessing ABW-based TNC dosing and IBW-based TNC dosing as independent predictors yielded no significant correlation. Conclusion: Studies suggest that there are benefits to bone marrow grafts over that of peripheral stem cell grafts. However, bone marrow harvesting is a process that is not easily repeated in cases where doses are inadequate, especially if the recipient has already undergone conditioning. We reviewed 18 cases of allo-SCTs performed at a single center with suboptimal CD34+ doses. In most cases, hematopoietic reconstitution was achieved. In our cohort of patients with suboptimal CD34+ doses in allo-BM SCTs, we noted no significant correlation between the dosages and outcomes for hematopoietic reconstitution. These results suggest there may be utility in taking a more liberal approach to standards for bone marrow graft doses, but this requires further study, and a much larger sample size. Additionally, we looked at CD34 dosing based on ABW versus IBW and noted consistent increases in magnitude for the Spearman Correlation's. Given the small sample evaluated, it is worth looking at this further with larger samples to see if dosing for bone marrow harvest by IBW may be more correlated with hematopoietic reconstitution in allogeneic SCT than dosing by ABW. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Comparable Survival Following Allogeneic Haematopoietic Stem Cell Transplant Utilising HLA-Matched Versus Alternative Donors: A Single-Centre Retrospective, Consecutive Cohort Analysis

Introduction: Allogeneic haematopoietic stem cell transplant (alloHCT) is a potentially curative therapy for many serious haematological disorders. The advent of alternative donor alloHCT, such as umbilical cord blood unit (CBU) and haploidentical (HAPLO), greatly widened the donor pool for recipients without HLA (human leukocyte antigen)-matched donor (MD), providing near universal donor availability. Although survival outcome of MD and alternate donor is considered to be similar, there is ongoing debate about preference of CBU and HAPLO (Wagner et al Blood Adv 2021; Wieduwilt et al Blood Adv 2022). Increased relapse after HAPLO versus increased non-relapse mortality with CBU makes selection of alternative donors difficult, with minimal supporting evidence. Hence, we compared single-centre outcomes of MD versus alternative donor alloHCT. Method: We performed a retrospective, consecutive cohort review of all patients who underwent alloHCT between 1st Jan 2010 and 30th Jun 2021 at our centre. Donors matched with recipients at HLA-A, HLA-B, HLA-C and HLA-DRB1, HLA-DQB1 loci (10/10) were considered MD, HAPLO (5/10) and CBU matched (5 - 6/8). Graft versus Host Disease (GVHD) prophylaxis for MD and CBU was calcineurin inhibitor, whereas HAPLO utilised post-HCT cyclophosphamide. Unrelated MD recipients also received rabbit anti-thymoglobulin (rATG) for in vivo T cell depletion. Neutrophil engraftment was defined as first of three consecutive days of absolute neutrophil count (ANC) > 0.5x109/L. Platelet (PLT) engraftment was defined as first of three consecutive days of PLT count > 20x109/L, unsupported for ≥7 days. Overall survival (OS) was assessed by Kaplan Meier (KM) method. Cumulative incidence (CI) of GVHD and relapse (REL) were estimated as competing events. Univariate and multivariate analysis (U/MVA) was conducted via Cox regression model. Statistical significance was defined as P<0.05. Results: Four-hundred and sixteen alloHCT were performed at our centre: 354 (85.10%) MD (41% related and 59% unrelated), 44 (10.58%) CBU and 18 (4.33%) HAPLO. Median follow up was 65.12 months. CBU recipients were significantly younger than other MD or HAPLO (median age 52 vs 45 vs 61 years, respectively: P=0.0001). Primary indication for transplant of total cohort was myeloid malignancy (64%) with majority in complete remission (68%) at transplant - there was no significant difference between donor groups. MD alloHCT utilised myeloablative conditioning significantly more than CBU and HAPLO (57% vs 23% vs 11%, respectively: P<0.0001). Median CD34 dose infused was 5.02 (4.28 - 5.98), 0.29 (0.24 - 0.36) and 4.98 (4.37 - 5.00) x106/kg for MD, CBU and HAPLO, respectively (P=<0.0001). There was no difference in ANC recovery (median D+19 vs 19 vs 25 for MD, CBU and HAPLO, respectively: P=0.2) between donor groups. PLT recovery was significantly faster for MD than CBU and HAPLO (median D+23 vs 41 vs 38, respectively: P=0.0139). Cumulative incidence of Grade II - IV acute GVHD (aGVHD) by D+100 was significantly higher in CBU than MD (48.46% vs 23.06%: P<0.001) and HAPLO (48.46% vs 34.81%: P=0.001). There was no difference of aGVHD CI between MD and HAPLO (P=0.2). Cumulative incidence of relapse was significantly higher following HAPLO versus CBU (3yr CI 52% vs 23%: P=0.025). However, there was no difference in REL between MD and CBU (32% vs. 23%; P=0.1) or MD and HAPLO (32% vs. 52%; P=0.3). Median and 3-year OS in our total cohort was 40.1 months and 51.8% (95% CI 0.570), respectively. We did not observe OS difference according to donor groups. Three-year OS was 51%, 63% and 45% for MD, CBU and HAPLO, respectively (P=0.4). UVA did not identify OS difference between donor groups. However, UVA revealed significant difference in other variables that were reassessed by MVA, per Table 1. Interestingly, MVA demonstrated significantly lower OS in fresh versus cryopreserved (cryo) alloHCT (HR fresh vs cryo 0.33, 0.15 - 0.72, P=0.005). Conclusion: Overall, we observed higher rates of aGVHD with CBU, versus higher rates of REL for HAPLO. However, the overall survival was comparable. Our results demonstrate that with careful patient selection and optimal management, alternative donor alloHCT have comparable outcomes to MD. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Frequency and Clinical Significance of Mixed T-Cell Chimerism Following Myeloablative Busulfan and Cyclophosphamide Conditioning in HLA -Matched Donor Transplants for Myeloid Malignancies: An Analysis of 179 Patients Transplanted at a Single Center

Myeloablative busulfan and cyclophosphamide (BuCy2) is one of the most used preparative regimens for allogeneic hematopoietic cell transplantation for myeloid malignancies from HLA-identical (MRD) and 8 of 8 HLA-A, B, C and DRB1 allele matched unrelated (MUD) donors. However, mixed T-cell chimerism may be relatively common during the early post-engraftment phase using this regimen. The significance of early incomplete donor T-cell chimerism following BuCy2 allotransplants with respect to post-transplant outcomes is unclear. Methods: We analyzed 179 consecutive patients who underwent allotransplants for myeloid malignancies using myeloablative BuCY2 conditioning at our center. Cyclophosphamide was administered at 60mg/m2/d x 2 and busulfan was administered over four days with pharmacokinetically targeted exposure (usually 4.9 mgxhr/L) based on test dosing. Tacrolimus/methotrexate was used for GVHD prophylaxis. Uniform institutional supportive care protocols were employed for all patients. Lineage specific chimerism on T-cell (CD3) and myeloid (CD33) peripheral blood (PB) cells separated using immunomagnetic beads was performed monthly through d 100 following transplant. Patients with < 50% donor CD3 chimerism on d30 were scheduled to receive low dose DLI if available (starting at 5-10 x 10e5 CD3 cells /kg) while maintaining therapeutic tacrolimus levels. No intervention was performed if d30 donor CD3 chimerism was > 50%. Outcomes were analyzed using data extracted from our institutional database where information had been prospectively entered. GVHD diagnosis and grading were determined by a single dedicated practitioner. Results: Patient characteristics were: median age 50 (18-66), male 51%; diagnosis AML (65%), CML (23%) MDS/MPS (12%); MRD (52%) MUD (48%); graft source- PBSC 81%, BM18%, both 1%; DRI - low 12%, intermediate 57%, high 25%, very high 6%; donor CMV pos 51%, neg 49%; year of transplant- 2004-2012 (35%), 2013-2016 (32%) 2017-2021(33%). Median follow-up for surviving patients was 84 months (6-213). Kaplan-Meier (K-M) estimates for survival and relapse-free survival at 5 years for all patients were 66% (95%CI 58-73%) and 59% (51-66%). Median (range) donor chimerism on d 30 for CD3 cells was 80% (6-100%) and for CD33 cells was 100% (84-100%). Median CD3 chimerism on d 60, d 100 and d 180 were 86%(7-100%), 91% (8-100%) and 95% (12-100%) respectively. Twenty-four patients (13%) had CD3 <50% on d30 of which 9 received DLI. On multiple regression modeling (Table1) the following factors were associated with higher d 30 CD3 chimerism - diagnosis (AML vs other) (difference 0.104, p=0.001), DRI (high/v.high vs low/intermediate)(diff 0.070, p=0.03) and graft CD3 dose (>15.5x 10e7/kg vs < 15.5) (diff 0.105, p<0.001) For patients who had > 80% vs <80% donor CD3 chimerism on d 30, 5-year K-M estimates of survival and RFS were 56% vs 76% (p=0.003) and 54% vs 64% (p=0.16). Five-year cumulative incidences of NRM and relapse were 20% vs 8% (p=0.010) and 26% vs 28% (p=0.85). Cumulative incidences of grade 2-4 and grade 3-4 acute GVHD at 6 months were 49% vs 27% (p=0.002) and 20% vs 4% (p=0.001) respectively. Cumulative incidences of moderate to severe and severe chronic GVHD at 3 years were 81% vs 64% (p=0.017) and 53% vs 34% (p=0.008). On a Cox proportional-hazards model adjusting for significant patient, disease and transplant covariates, d 30 CD3 chimerism > 80% was associated with a significantly higher risk of NRM (HR 3.42, p=0.007), aGVHD gd 2-4(HR1.79, p=0.013), aGVHD gd 3-4 (HR 2.66, p=0.008) and severe cGVHD (HR 1.84, p=0.011). However, d 30 CD3 chimerism was not significantly associated with relapse, survival and relapse-free survival (Fig 1). Conclusions: These data suggest that while pharmacokinetically-targeted BuCy2 as administered is almost always myeloablative (CD33 chimerism 100%), early mixed T-cell chimerism is relatively common (CD3 chimerism < 80% in 50% of patients). d30 CD3 chimerism ≥80% is not associated with lower relapse rates or better survival outcomes, but is associated with higher rates of acute and chronic GVHD. No intervention to improve CD3 chimerism appears necessary for patients with d 30 CD3 chimerism between 50 and 80%. Patients with ≥ 80% CD3 chimerism at d 30 may benefit from more aggressive measures to prevent acute and chronic GVHD Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

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.

215.9: Achievement of Persistent Mixed Chimerism in Recipients of Matched and Mismatched Living Donor Kidney Transplants in a Tolerance Induction Protocol

Purpose: The induction of tolerance to kidney transplants after development of specific unresponsiveness of recipient immune cells to donor alloantigens allows elimination of maintenance immunosuppressive (IS) drugs while preventing graft loss due to rejection. We have previously reported successful induction of mixed chimerism and tolerance in recipients of fully HLA-matched living donor kidney and hematopoietic cell (HCT) transplants. This work continues in HLA-mismatched transplants, wherein achieving persistent mixed chimerism is more challenging. Methods: Living donors underwent hematopoietic stem cell mobilization and leukopheresis 6 weeks before kidney donation. The recipient conditioning regimen for the HCT consisted of 10 doses of total lymphoid irradiation (TLI) and 5 doses of anti-thymocyte globulin (ATG) following kidney transplant, with HCT on day 11. The HCT consisted of CD34+ hematopoietic progenitor cells and CD3+ cells. Twenty-nine patients received fully HLA-matched living donor transplants. Twenty-five patients received HLA-mismatched (1-haplotype matched) living donor transplants with an escalating dose of CD3+ cells to enhance HCT engraftment. Six patients recently received HLA-mismatched living donor transplants with substitution of a dose of total body irradiation (TBI) for the final dose of TLI. Results: Of the 29 fully HLA-matched living donor transplants, complete IS drug withdrawal was achieved in 24, all of whom had at least 6 months of persistent mixed chimerism. Of the 24, 17 are alive, well and have been off IS drugs from 4 to 14 years without evidence of rejection. Two off IS drugs died due to cardiovascular events at 2 and 3 years. Two returned to IS drugs after loss of chimerism at 1 year followed by acute rejection at 4 years off IS drugs, and 3 after relapse of kidney disease at 1, 5 and 6 years off IS drugs. In the 25 1-haplotype matched living donor transplants, mixed whole blood chimerism persisted in 10 (mean 20% chimerism) at the end of the 1st year posttransplant while immunosuppression was reduced to tacrolimus monotherapy. Chimerism was lost during the 2nd year in the 5 who were withdrawn from monotherapy; they returned to IS drug(s). Mixed chimerism without rejection has persisted in 3 maintained on IS monotherapy, for up to 5 years. The recent addition of a dose of TBI markedly increased levels and stability of mixed chimerism during the 1st year posttransplant. Conclusions: The loss of chimerism during withdrawal of IS drug monotherapy in the HLA-mismatched transplants may have been due to the low level of whole blood chimerism, a contrast to the HLA-matched. A very low single dose of TBI added to the TLI/ATG conditioning regimen increased early chimerism. The stability of high levels of mixed chimerism after complete IS drug withdrawal during the 2nd year posttransplant is the subject of continuing investigation.

Automated closed volume reduction process for apheresis stem cell grafts: From development to clinical implementation.

Collection of HPC by apheresis (HPC-A) can sometimes result in higher collection volumes, increasing the dimethyl sulfoxide (DMSO) volume infused into patients and the space requirements in liquid nitrogen freezers. Volume reduction prior to the addition of cryoprotectant is an efficient means to reduce the DMSO load infused into patients and to optimize freezer storage space. To implement a closed semi-automated volume reduction process, a method was developed to produce leukocyte-rich mock apheresis products using buffy coats derived from whole blood collections. The mock HPC products were then used to measure the efficiency and reliability of the semi-automated process over a range of volumes and cell concentrations. The resulting data was used to support the implementation of the process with concurrent monitoring. A closed, semi-automated volume reduction process resulted in recoveries of over 93% and 91% of white blood cells and CD34+ cells with no significant loss of product viability or potency. Mean doses of CD34+ and CFU infused per kilogram recipient body weight were 4.0 ± 1.1 × 106 /kg and 4.2 ± 1.7 × 105 /kg, resulting in no delays in median time to neutrophil and platelet engraftment, significant increase in adverse reaction or nonconformances. The effectiveness outcomes of the first Canadian experience in the implementation of a closed semi-automated volume reduction system in the processing of HPC-A products for autologous transplant have met the predetermined acceptance criteria, supporting its use in a stem cell manufacturing laboratory compliant with good manufacturing practice regulations.

The effect of cryopreserved and noncryopreserved stem cells on the outcome of autologous stem-cell transplantation in multiple myeloma patients

Background The CD34+ stem cells are either noncryopreserved (non-CP) or cryopreserved (CP) in autologous stem-cell transplantation (ASCT). Some retrospective studies have shown that engraftment failure and engraftment rate are similar in CP cells and infusion reactions are lower in CP cells due to the absence of dimethyl sulfoxide. Objective In this study, we presented our clinical experience comparing the outcomes and safety of ASCT with CP and non-CP stem cells. Patients and methods A total of 163 patients were enrolled between January 2019 and June 2021. Duration of neutrophil/platelet engraftment, rates of infusion-related reactions, febrile neutropenia, and duration of hospitalization were compared between the CP and non-CP groups. Results Fifty five (33.7%) received CP cells, 108 (66.3%) received non-CP cells. The median dose of CD34+ cells was similar in both groups (P=0.755). The median duration of neutrophil and platelet engraftment was not statistically significantly different in CP and non-CP groups (P=0.896 and 0.183, respectively). No statistical difference was observed in the median duration of hospitalization between the two groups [CP: 16 (13–26) vs. non-CP: 15 (11–31) days, P=0.124]. The febrile neutropenia rate was higher in the CP group, but there was no statistical difference between the two groups (CP: 56.4% vs. non-CP, 48.1%, P=0.301). The rates of infusion-related reaction such as nausea, vomiting, and rash were higher in the CP group (21.8 vs. 12%), with no statistically significant difference (P=0.159). Conclusion Non-CP cells have similar outcomes to CP cells and lower toxicity than CP cells, which are safe and effective in ASCT.

P1365: DONOR LYMPHOCYTE INFUSION IN ALLOGENEIC HEMATOPOIETIC STEM CELL TRANSPLANTATION: RESULTS FROM A RETROSPECTIVE STUDY

Background: Allogeneic hematopoietic stem cell transplantation (alloHSCT) is a therapeutic option with curative intent in hematological malignancies. Despite improvements in alloHSCT, relapse of the underlying disease is still one of the main causes of mortality. Donor lymphocyte infusion (DLI) is an immunotherapy that can be used after alloHSCT in patients with high-risk disease (prophylaxis), mixed donor chimerism or minimal residual disease (preemptive) and relapse (therapeutic). Donor derived graft versus tumor effects induce a durable remission after DLI. Aims: To characterize the use of DLI as prophylaxis, preemptive or therapeutic strategy in alloHSCT and evaluate overall survival (OS). Methods: A retrospective unicenter study was conducted to evaluate the use of DLIs in a cohort of 50 patients (91 DLIs), treated in a Bone Marrow Transplantation Unit, between January 2005 and December 2021. The chi-square test (categorical variables) and t-test or Wilcoxon-Mann-Whitney test (continuous variables) were used. OS was estimated according to Kaplan-Meier and compared by the log-rank test. Statistical analysis was made using SPSS28®. Results: Our cohort showed male predominance (n= 29, 58%) and a median age of 40 years (4-65), with 4 pediatric patients. Patients were affected by acute myeloid leukemia (n=20), acute lymphoblastic leukemia (n=12), chronic myeloproliferative leukemia (n=6), Hodgkin lymphoma (n=2), myelodysplastic/myeloproliferative syndrome (n=4), non-Hodgkin lymphoma (n=3), chronic lymphocytic leukemia (n=1), mixed phenotype leukemia, (n=1), multiple myeloma (n=1). Conditioning regimen was myeloablative in 19 (38%) patients and reduced-intensity in 31 (62%). All 50 donors were HLA-matched, and 8 (16%) were HLA-matched unrelated (MUR). DLIs use was prophylactic in 2 (4%) patients, preemptive in 7 (14%) and therapeutic in 41 (82%) patients. The median number of DLI/patient was 1 (1-8) and the median dose of total CD3+ cells infused was 1,0x107/Kg (0,1-13,48). The median time between alloHSCT and the first DLI was 17 months (1-133). Complete Response (CR) was defined by completed donor chimerism or no MRD detected. CR was maintained in 1/2 (50%) patients undergoing prophylactic DLIs. Patients who received preemptive and therapeutic DLIs achieved CR in 2/7 (29%) and 9/41 (22%) cases, respectively. Overall, 11 patients (22%) developed GVHD after DLIs. Presence of GVHD was associated with higher number of DLIs (2,45 vs 1,64) and with CR (p=0,041) No significant differences were observed in age (p=0,154), number of CD3+ infused (p=0,414), DLIs strategy (p=0,433), time between alloHSCT to first DLI (p=0,668) and CR. Death occurred in 30 (60%) patients. OS survival was defined as time from date of first DLI to date of last follow-up (FU) or date of death. With a median FU of 141 months, the OS was superior in patients who achieved CR compared to relapsed patients (34 months), Log-rank p=0.109. OS was significantly superior in preemptive and prophylaxis DLIs compared with therapeutic DLIs (Log-rank p<0,01). Overall, 8/19 (42%) patients are currently alive in CR. Summary/Conclusion: DLI has been widely applied to the therapeutic intervention, with promising results in prevention and preemptive strategy. Although with the limits of a relatively small and heterogeneous cohort, we describe our experience in the use of DLI and demonstrate that it is an effective prophylactic and preemptive treatment option in alloHSCT patients. Prospective studies on homogeneous patient cohorts are needed improve the effectiveness of DLI.

Higher Dose of CD34+ cells Promotes Early Reconstitution of Natural Killer Cells and Is Associated with Better Outcomes After Unmanipulated Hematopoietic Stem Cell Transplantation for Myeloid Malignancies

Natural killer (NK) cells are the first lymphocyte population to recover after allogenic hematopoietic stem cell transplantation (allo-HSCT) and mediate potent graft versus leukemia effect, particularly in the settings of T-cell depletion. However, the significance of NK cells after unmanipulated transplantation is less clear, and factors affecting early NK reconstitution remain elusive. We retrospectively analyze 180 patients with acute myeloid leukemia or myelodysplastic syndrome who received unmanipulated allografts. We focus on the early NK reconstitution and its association with disease relapse, overall survival, and cytomegalovirus (CMV) reactivation. We also analyze factors that affect NK recovery, such as dose of CD34+ cells in the graft and T-cell recovery after transplantation. Penalized splines and receiver operator characteristic curves demonstrate a strong association between blood NK counts at 30 days after allo-HSCT (NK30) and all-cause mortality, with the cutoff value being close to the median value that divides patients dichotomously. Subsequent analysis shows that rapid NK recovery (higher NK30 or higher NK60) is associated with reduced disease relapse and better survival. Robust NK recovery (NK30 and NK60) also correlates with lower incidence of CMV reactivation. We find that NK30 is associated with the numbers of CD34+ cells (r = 0.739, P < .001) but not mature NK cells contained in the graft. In a small subset (N = 12) of the cohort, patients in continuous complete remission (N = 6) demonstrate higher frequencies of CD34+CD7+ progenitor cells and CD56bright NK cells in the day 30 bone marrow as compared to patients with disease relapse within 1 year (N = 6). Furthermore, neither T-cell recovery after transplantation nor application of anti-thymocyte globulins (ATG) in the conditioning regimen demonstrate suppressive effect on NK recovery. Rapid NK cell recovery is associated with improved prognosis of unmanipulated transplantation for myeloid malignancies. Manipulation of NK cell recovery represents a feasible approach to improve transplant outcomes for example by optimizing CD34+ cells in the graft.

Autologous stem cell transplantation in favorable-risk acute myeloid leukemia: single-center experience and current challenges.

Autologous stem cell transplantation (ASCT) has gained growing consideration as a treatment option for favorable-risk acute myeloid leukemia (FR-AML) in first complete remission (CR1), compared with chemotherapy. We report the long-term outcomes of 117 consecutive patients with FR-AML fit for intensive chemotherapy diagnosed in our center between 1999 and 2020, who underwent ASCT. Sixty-five of the 117 were eligible for intensive post-remission treatment, and 42 of those 65 received ASCT. Median follow up was 132 months. Overall survival (OS) and disease-free survival (DFS) were 75% and 76%. Higher doses of CD34 + stem cell infusions negatively impacted DFS in multivariate analysis. Core-binding factor (CBF) leukemia was an independent prognostic factor for improved DFS. No differences based on pre-transplant measurable residual disease (MRD) were observed. In CBF leukemia, 10-year DFS is 72% for MRD-positive patients versus 100% for MRD negative patients. ASCT is effective and safe in FR-AML patients. In CBF leukemia, ASCT provides excellent results regardless of achievement of bone marrow MRD negativity. In NPM1-mutated/FLT3-wild type (mNPM1) AML, early molecular response seems to have more impact on prognosis. Prospective investigation of the role of gemtuzumab ozogamicin in this setting is ongoing.

Encouraging the outcomes of children with beta-thalassaemia major who underwent fresh cord blood transplantation from an HLA-matched sibling donor

ABSTRACT Background Allogeneic haematopoietic stem cell transplantation (allo-HSCT) is currently the only curative treatment for thalassaemia major (TM). Cord blood (CB) from a sibling has different characteristics from marrow and has potential advantages and disadvantages as a stem cell source. Methods We retrospectively analyzed 68 children with beta-thalassaemia major (β-TM) who underwent fresh cord blood transplantation (F-CBT) from an HLA-matched sibling donor (MSD) between June 2010 and July 2018 in the Department of Pediatrics, Nanfang Hospital and Haematology-Oncology, Shenzhen Children’s Hospital. Results The median infused doses of total nucleated cells (TNCs) and CD34 + cells were 8.51×107/kg and 3.16×105/kg, respectively. The median time to neutrophil and platelet engraftment were, respectively, 27 and 31 days. The cumulative probabilities of acute and chronic graft-versus-host disease (GVHD) were very low after F-CBT (7.8% and 0.0%, respectively). Of the 68 paediatric patients, 67 patients survived during a median follow-up period of 61 months. The estimated 5-year probability of overall survival (OS) and disease-free survival (DFS) were 98.5% and 87.9%, respectively. Three patients experienced graft rejection (GR) (4.5%), and we identified CD34 + cell dose as a significant risk factor for graft failure (p = 0.036) in stratify analysis. Conclusions The above results indicate that patients with β-TM have excellent outcomes after F-CBT from an HLA-MSD.

Poor graft function - causes and potential solutions

Introduction. Poor graft function is one of the most severe complications after allogeneic hematopoietic stem cell transplantation, which manifests as pancytopenia/cytopenia in the blood count, with the presence of complete or incomplete donor chimerism. There are three entities of graft weakness: 1. poor graft function: pancytopenia with complete donor chimerism, 2. graft failure: pancytopenia with incomplete, i.e., mixed donor chimerism and 3. graft rejection: progressive decline of donor chimerism. Definition. Poor graft function is diagnosed as pancytopenia (hemoglobin &lt; 70 g/L, absolute neutrophil count &lt; 0.5 x 109/L, platelets &lt; 20 x 109/L) for 3 consecutive days from D+28, excluding the presence of severe graft versus host disease and relapse, with complete donor chimerism in poor graft function, and incomplete in graft failure. Risk factors and therapeutic principles. The most common risk factors for poor graft function are a small dose of CD34+ hematopoietic stem cells in the transplant, graft versus host disease, cytomegalovirus infection, the presence of donor-specific antibodies, high serum ferritin, i.e., iron overload, as well as splenomegaly. Pathogenetic mechanisms in the development of poor graft function are still not fully elucidated. The role of the microenvironment of the patient?s bone marrow is also important, as well as disorders of the immune system Therapeutic options for overcoming this complication include using selected ?stem cell boost?, mesenchymal stem cells, and newer medical agents (N-acetyl cysteine, atorvastatin, thrombopoietin receptor agonists). Conclusion. The type of poor function of the graft is defined in relation to the percentage of donor chimerism, and is necessary for planning further treatment strategy.

BK Polyomavirus Hemorrhagic Cystitis in Hematopoietic Cell Transplant Recipients.

Introduction:BK polyomavirus-associated hemorrhagic cystitis (BKPyV-HC) is a well-recognized infective complication of hematopoietic cell transplant (HCT) with increased organ dysfunction and mortality. This study was performed to describe the local incidence, risk factors, and outcomes of BKPyV infection.Methods:This retrospective case–control study was conducted between 2007 and 2016 from a tertiary hospital in South India. We identified HCT recipients diagnosed with BKPyV-HC and compared them with recipients over the same period who did not develop BK virus infection matched for age, sex, diagnosis, and donor type. We collected data from central electronic medical records and databases maintained in the departments of hematology and virology.Results:Over the study period, 1276 transplants were performed, of which 262 patients (20.5%) developed HC and 105 (8.2%) were BKPyV-positive. Grade 3 HC was most commonly (57.1%) seen, and the median time to develop BKPyV-HC was 35 (range 0–858) days. Survival was significantly lower in the cases (42.9% vs. 61%, P < 0.05). On univariate analysis, the protective effect of nonmyeloablative conditioning (P = 0.04), residual disease at the time of transplant in malignant conditions (P = 0.001), lower CD34 dose (P = 0.006), presence of acute graft versus host disease (GVHD, P < 0.001), reactivation of cytomegalovirus infection (P < 0.001), and presence of bacterial urinary tract infection (UTI) (P < 0.001) were significant factors. Multivariate logistic regression confirmed the presence of acute GVHD (P = 0.041), bacterial UTI (P < 0.001), and residual disease (P = 0.009) at HCT as significant risk factors for BKPyV-HC.Conclusions:Our study affirms the homogeneity of BKPyV-HC disease in low- and middle-income HCT settings with prior reports and the need for therapeutic strategies to reduce its resultant mortality.