Cumulative Incidence Of Transplant-related Mortality Research Articles

Haploidentical versus Cord Blood Transplantation in Pediatric AML. A Retrospective Outcome Analysis on Behalf of the Pediatric Subcommittee of GETH (Grupo Español de Trasplante Hematopoyético)

Haploidentical stem cell transplantation (Haplo-SCT) and cord blood transplantation (CBT) are both effective alternative treatments in patients suffering from acute myeloid leukemia (AML) and lacking a matched HLA donor. In the last years, many centers have abandoned CBT procedures mostly due to concern about poorer immune recovery compared with Haplo-SCT. We conducted a retrospective multicenter study comparing the outcomes using both alternative approaches in AML. A total of 122 transplants (86 Haplo-SCTs and 36 CBTs) from 12 Spanish centers were collected from 2007 to 2021. Median age at hematopoietic stem cell transplantation (HSCT) was 7 years (0.4-20). Thirty-nine patients (31.9%) showed positive minimal residual disease (MRD) at HSCT and a previous HSCT was performed in 37 patients (30.3%). The median infused cellularity was 14.4 × 106/kg CD34+ cells (6.0-22.07) for Haplo-SCT and 4.74 × 105/kg CD34+ cells (0.8-9.4) for CBT. Median time to neutrophil engraftment was 14 days (7-44) for Haplo-SCT and 17 days (8-29) for CBT (P = .03). The median time to platelet engraftment was 14 days (6-70) for Haplo-SCT and 43 days (10-151) for CBT (P < .001). Graft rejection was observed in 13 Haplo-SCTs (15%) and in 6 CBTs (16%). The cumulative incidence of acute graft versus host disease (GvHD) grades II-IV was 54% and 51% for Haplo-SCT and CBT, respectively (P = .50). The cumulative incidence of severe acute GvHD (grades III-IV) was 22% for Haplo-SCT and 25% for CBT (P = .90). There was a tendency to a higher risk of chronic GvHD in the Haplo-SCT group being the cumulative incidence of 30% for Haplo-SCT and 12% for CBT (P = .09). The cumulative incidence of relapse was 28% and 20% for Haplo-SCT and CBT, respectively (P = .60). We did not observe statistically significant differences in outcome measures between Haplo-SCT and CBT procedures: 5-year overall survival (OS) was 64% versus 57% (P = .50), 5-year disease-free survival (DFS) 58% versus 57% (P = .80), GvHD-free and relapse-free survival (GFRFS) 41% versus 54% (P = .30), and cumulative incidence of transplant-related mortality (TRM) 14% versus 15% (P = .80), respectively. In the multivariate analysis, MRD positivity and a disease status >CR1 at the time of HSCT were significantly associated with poorer outcomes (P < .05). In conclusion, our study supports that both haploidentical and cord blood transplantation show comparable outcomes in pediatric AML patients. We obtained comparable survival rates, although CBT showed a trend to lower rates of chronic GvHD and higher GFRFS, demonstrating that it should still be considered a valuable option, particularly for pediatric patients.

Safety outcomes in adult patients with AML who achieved their first complete remission with GO prior to HSCT.

e18504 Background: Gemtuzumab ozogamicin (GO) is approved in the US for the treatment of newly diagnosed and relapsed/refractory (R/R) CD33-positive acute myeloid leukemia (AML) in adults and pediatric patients of 1 month and older and 2 years and older, respectively. Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative therapy for most adult patients with AML in first complete remission (CR1). Clinical studies have linked GO with hepatotoxicity and hepatic veno-occlusive disease (VOD); the risk of these events may be further elevated in patients receiving HSCT. This study aimed to characterize the toxicity after HSCT in adult patients with AML who were treated with GO prior to HSCT. These analyses look at outcomes in patients who were in CR1 at the time of HSCT. Methods: This non-interventional post-authorization safety study used de-identified healthcare data from the Center for International Blood and Marrow Transplant Research (CIBMTR) database. Data were collected from adult patients in the US with newly diagnosed AML treated with GO prior to proceeding with HSCT. Data collection began on 01 September 2017, data cutoff was 04 July 2023. Results: We present data of 84 patients receiving HSCT for AML in CR1 from 19 centers with a median follow-up of 23.9 months (range, 3.0-49.7). Median age was 54.2 y (range, 18.7-74.5); 55% male. Total cumulative GO dose was 1-3 mg/m2 in 15 (18%), 4-6 mg/m2 in 15 (18%), 7-9 mg/m2 in 28 (33%) and ≥10 mg/m2 in 8 (12%) patients. Measurable residual disease (MRD) was undetectable in 50% (n=42) of patients after GO and 51% (n=43) of patients at the time of HSCT. Most patients (58%; n=49) received myeloablative conditioning and 57% (n=48) received HLA matched unrelated donor HSCT. Non-fatal VOD was reported in 6 (7%) patients, most cases were mild (n=5; 83%). Cumulative incidences of transplant-related mortality (TRM) were: 6 months, 7% (95% CI, 3-14); 2 years, 15% (95% CI, 7-25). The 2-year relapse rate was 26% (95% CI, 16-36%). Kaplan-Meier probabilities of leukemia-free survival (LFS) outcomes at 1 and 2 years were, 68% (95% CI, 57-78) and 59% (95% CI, 47-71), respectively. There were 22 deaths during the study, 10 (46%) from relapse of AML, no VOD-related deaths were observed. Conclusions: The use of GO prior to allogeneic HSCT appears to be safe with low rates of posttransplant VOD observed in patients with AML in CR1. TRM and survival outcomes are similar to historically reported rates. Clinical trial information: B1767034.

What is the best treatment strategy before autologous peripheral blood stem cell transplantation in POEMS syndrome?

Autologous peripheral blood stem cell transplantation (aPBSCT) provides optimal outcomes in POEMS syndrome but the definition of the best treatment before aPBSCT remains to be defined because of the rarity of the disease and the heterogeneity of published case series. We collected clinical and laboratory data of patients with POEMS syndrome undergoing aPBSCT from 1998 to 2020 in ten Italian centers. The primary endpoint of the study was to evaluate the impact of prior therapies and mobilization regimen on outcome. We divided the patients into three groups: patients who did not receive any treatment before transplant (15 patients, group A: front-line), patients pre-treated with other agents (14 patients, group B) and patients treated with cyclophosphamide as their mobilizing regimen (16 patients, group C). The three groups did not show differences in terms of demographic and clinical characteristics. All 45 patients underwent aPBSCT after a high-dose melphalan conditioning regimen, with a median follow-up of 77 months (range, 37-169 months). The responses were not statistically different between the three groups (P=0.38). Progression-free and overall survival rates at 6 years were: 70% (95% confidence interval: 55-85%) and 91% (95% confidence interval: 82-99) 65%, respectively, and did not differ between the three groups. The cumulative incidence of transplant-related mortality and relapse was 4% and 36%, respectively. In conclusion, in a relatively large number of patients with POEMS syndrome, undergoing an autologous transplant, pre-treatment and disease status at transplant did not appear to have an impact on major transplant outcomes.

Prognostic value of low muscle mass at the 12th thoracic vertebral level in multiple myeloma treated with transplantation: CAREMM-2101 study.

Autologous hematopoietic stem cell transplantation (ASCT) has been introduced as a standard treatment for newly diagnosed multiple myeloma (NDMM) following novel agent-based induction chemotherapy. This study investigated whether pre-ASCT low muscle mass evaluated using the paraspinal muscle index (PMI) at the 12th thoracic vertebra (T12) level is a reliable prognostic marker in NDMM after chemotherapy. A multi-center registry database was retrospectively analyzed. Between 2009 and 2020, 190 patients with chest computed tomography images underwent frontline ASCT following induction therapy. The PMI was defined as the value of the paraspinal muscle area at the T12 level divided by the square of the patient's height. The cut-off value indicating a low muscle mass was sex-specific, using the lowest quintiles. Of the 190 patients, 38 (20%) were in the low muscle mass group. The low muscle mass group had a lower 4-year overall survival (OS) rate than the non-low muscle mass group (68.5% vs. 81.2%; P = 0.074). The median progression-free survival (PFS) in the low muscle mass group was significantly shorter compared with the non-low muscle mass group (23.3 months vs. 29.2 months; P = 0.029). The cumulative incidence of transplant-related mortality (TRM) was significantly higher in the low muscle mass group than in the non-low muscle mass group (4-year probability of TRM incidence, 10.6% vs. 0.7%; P < 0.001). In contrast, no significant difference in the cumulative incidence of disease progression was found between the two groups. Multivariate analysis revealed that low muscle mass was associated with significant negative outcomes for OS [(hazard ratio (HR): 2.14; P = 0.047], PFS (HR: 1.78; P = 0.012), and TRM (HR: 12.05; P = 0.025). Paraspinal muscle mass may have a prognostic role in NDMM patients who undergo ASCT. Patients with low paraspinal muscle mass have lower survival outcomes compared to non-low muscle mass group.

Comparison of outcomes for patients with acute myeloid leukemia undergoing haploidentical stem cell transplantation in first and second complete remission.

There was no consensus on whether prognostic advantages existed when transplant conducted at first complete remission (CR1) stage than at second complete remission (CR2) stage for patients with AML who received haploidentical hematological stem cell transplantation (haplo-HSCT). In 768 consecutive AML patients who received haplo-HSCT from January 2014 to December 2017, a 1:2 ratio matched-pair analysis was performed, 69 patients who in CR2 group and 138 CR1 patients were enrolled. Hematopoietic recovery, graft versus host disease (GVHD), relapse, transplant related mortality (TRM), disease-free survival (DFS) and overall survival (OS) were compared in two groups, and further evaluated in low-, intermediate-, and high-risk subgroups. The cumulative incidences of 30-day myeloid recovery and 90-day platelet recovery were comparable in CR1 and CR2 groups. The cumulative incidences of grade II-IV and grade III-IV aGVHD were not significantly different. The cumulative incidences of relapse at 3-year and 5-year in these two groups were 12.4% versus 11.6% (P = 0.880) and 12.4% versus 17.5% (P = 0.322). The cumulative incidences of TRM at 3-year and 5-year were both 10.9% versus 23.2% (P = 0.019). The probability of DFS at 3-year and 5-year were 76.7% versus 65.2% (P = 0.029) and 76.7% versus 59.3% (P = 0.009). The probability of OS at 3-year and 5-year were 81.8% versus 68.1% (P = 0.026) and 76.7% versus 59.3% (P = 0.026). In the intermediate-risk group, TRM was lower in CR1 group, DFS and OS of CR1 group were superior to CR2 group. In conclusion, haplo-HSCT at CR1 stage was of better prognosis for intermediate-risk AML patients than at CR2 stage.

Total Marrow Irradiation for Second Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Advanced Acute Leukemia

Second allogeneic hematopoietic stem cell transplantation (HSCT) is a treatment option for patients with acute leukemia who relapse after a first HSCT. Although myeloablative conditioning (MAC) regimens before the first HSCT are considered superior to reduced- intensity conditioning (RIC) in terms of disease control in acute leukemia patients, the optimal conditioning regimen for the second allogeneic HSCT remains controversial. The most important prognostic factors are the remission disease phase at the time of the second HSCT and an interval >12 months from the first HSCT to the second HSCT. Total marrow irradiation (TMI) is an advanced high-precision radiation treatment that delivers therapeutic doses over extensively selected targets while substantially reducing radiation to vital organs compared to conventional total body irradiation (TBI). Here we report the results of a retrospective analysis of second allogeneic HSCT treated with TMI as an MAC regimen with the intent of limiting toxicity. We investigated the efficacy of high dose per fraction TMI in combination with thiotepa, fludarabine, and melphalan in 13 consecutive patients with acute leukemia who had relapsed after a first allogeneic HSCT treated between March 2018 and November 2021. Donor type was haploidentical in 10 patients, unrelated in 2 patients, and HLA-identical sibling in 1 patient. The conditioning regimen consisted of 8 Gy TMI in 5 patients on days -8 and -7 and 12 Gy TMI in 8 patients on days -9 to -7, plus thiotepa 5 mg/kg on day -6, fludarabine 50 mg/day on days -5 to -3, and melphalan 140 mg/day on day -2. The TMI was delivered at the dosage og 4 GY for 2 consecutive days (total = 8 GY) or for 3 consecutive days (total = 12 GY). The median patient age was 45 years (range, 19 to 70 years); 7 patients were in remission, and 6 had active disease at the time of their second allogeneic HSCT. The median time to a neutrophil count of >.5×109/L was 16 days (range, 13 to 22 days), and the median time to a platelet count of >20×109/L was 20 days (range, 14 to 34 days). All patients showed complete donor chimerism on day +30 post-transplantation. The cumulative incidence of grade I-II acute graft-versus-host disease (GVHD) was 43%, and that of chronic GVHD was 30%. The median duration of follow-up was 1121 days (range, 200 to 1540 days). Day +30 and +100 transplantation-related mortality (TRM) was 0. The overall cumulative incidence of TRM, relapse rate, and disease free-survival were 27%, 7%, and 67%, respectively. This retrospective study demonstrates the safety and efficacy of a hypofractionated TMI conditioning regimen in patients with acute leukemia undergoing second HSCT with encouraging outcomes in terms of engraftment, early toxicity, GVHD, and relapse.

Impact of Allele-Level HLA-Matching on Outcomes after Double Unrelated Cord Blood Transplantation in Adults with Malignant Diseases

Introduction: In single unrelated cord blood transplantation (sCBT), an increasing number of HLA-mismatches (MM) has been associated with inferior overall survival (OS) attributed to higher transplant-related mortality (TRM). These findings have prompted current guidelines to endorse high resolution HLA typing in the selection of CB (cord blood) units, including double CBT (dCBT). However, a comprehensive appraisal of the effect of allele-level HLA matching following dCBT was likely hindered by the relatively small sample sizes in previous studies. Herein we aimed to analyze the impact of allele-level HLA-matching on outcomes of a large cohort of dCBT recipients to improve CB unit selection and further explore the unique dCBT biology. Methods: We included patients ≥18 years-old receiving a dCBT between 2006-2019 with the availability of HLA typing minimally at HLA-A, -B, -C at the antigen-level and HLA-DRB1 at the allele-level for the recipient and both CB units. A validated high-resolution imputation tool, HaploStats, was used to adjudicate allele-level match status for a subset of cord and recipient pairs (n = 173) having only antigen-level typing at HLA-A, -B or -C. A sensitivity analysis for OS was performed excluding imputed cases, and results were unchanged. HLA matching was classified according to the CB unit with the greatest degree of HLA mismatch with the patient, meaning that only the most mismatched unit was considered and that the interunit matching was not considered. Continuous covariates were dichotomized to find an optimal cutoff value by using the Contal-O'Quigley method, except for cryopreserved CD34 and total nucleated cell (TNC) count, whose cutoffs were based on previous findings reported by our group. Pairwise comparisons of the numbers of allele MM showed that receiving units with ≥4 MM had the highest negative impact on OS. Cox and Fine-Gray regression models were built for the different outcomes using the backward elimination method (p<.05 to stay). Results: 963 patients met the eligibility criteria, of which 392 received at least one CB unit with 0-3 allele MM while 571 with ≥4 allele MM. Of those receiving at least one unit with ≥4 allele MM, 18% had a maximum HLA disparity of 5/6 at lower HLA-typing resolution, 69% of 4/6 and 13% of ≤3/6. Median age at dCBT was 49 years old. Acute leukemia and myelodysplastic syndrome (MDS) accounted for 70% of the cases. There was a larger proportion of patients receiving CB units with fewer allele MM after 2012. Other patient-, disease- and CB unit-related characteristics are summarized in Table 1. The day-42 cumulative incidence of neutrophil recovery was 83% (95%CI 81-85). The number of allele MM had no significant impact on neutrophil recovery (≥ 4 MM vs 0-3 MM, multivariate HR 0.94 [0.80-1.11], P=.46). The cumulative incidence of TRM at 4 years was 36% (95% CI 32-40) for patients receiving CB units with ≥4 MM vs. 23% (95% CI 19-28) for those with 0-3 MM (multivariate HR 1.58 [95%CI 1.18-2.11], P=.002] - Fig. 1A). Infectious complications were the most frequent cause of TRM in the group receiving dCBT with ≥ 4 allele MM (40%). Relapse, grade II-IV/III-IV acute and chronic GVHD were not significantly different between the two groups. Patients receiving CB units with 0-3 allele MM had a 4-year survival of 54% (95%CI 49-59) compared to 43% (95%CI 39-47) for those receiving units with ≥4 allele MM (multivariate HR 1.40 [1.11-1.78], P=.005 - Fig. 1B). The inferior OS associated with higher allele HLA disparity was only partially mitigated by increasing the TNC count in multivariate analysis (0-3 MM + TNC ≤ 3.9x10ˆ7/kg vs.0-3 MM + TNC > 3.9x10ˆ7/kg, HR 1.50 [0.97-2.32], P=.07; ≥4 MM + TNC > 4.9x10ˆ7/kg vs. 0-3 MM + TNC > 3.9x10ˆ7/kg, HR 1.42 [1.06-1.89], P=.02; ≥4 MM + TNC ≤ 4.9x10ˆ7/kg vs. 0-3 MM + TNC > 3.9x10ˆ7/kg, HR 1.66 [1.24-2.22], P=<.001 - Fig. 1C). Discussion: Our results confirm that allele-level HLA typing is a significant factor for OS following dCBT. The inferior OS associated with the increasing number of allele-level MM was driven by higher TRM. Selection of CB units with 0-3 allele-level MM is recommended. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

P779: OPTIMIZING TREATMENT OUTCOMES FOR CHILDREN WITH HIGHER-RISK MYELODYSPLASTIC SYNDROME UNDERGOING ALLOGENEIC HEMATOPOIETIC STEM CELL TRANSPLANTATION

Background: Myelodysplastic syndrome (MDS) are rare clonal hematopoietic disorders in children. Risk stratification system for adults is unfit for children. Refractory anemia with excess blasts(RAEB), acute myeloid leukemia with myelodysplasia-related changes(AML-MRC), monosomy 7 and complex karyotype always indicate poor prognosis. Hypomethylating agent (HMA) improved survivals of high-risk MDS in adults, and decitabine as part of conditioning regimen for allogenetic hematopoietic stem cell transplantation(allo-HSCT) was associated with favorable outcomes. However, these findings have not been tested in pediatric cohorts broadly. Aims: To evalute the efficacy and safety of hypomethylating agents as a part of pre-transplant treatments and contidioning regimens in children with higher-risk MDS. Methods: Patients from 1 to 14 years of age who were diagnosed with higher-risk MDS and underwent allo-HSCT consecutively between February 2019 and August 2020 in Pediatric Blood Diseases Center were enrolled. All identified patients were retrospectively reviewed with a collection of clinical data, laboratory test results, and outcome. Results: We reviewed 18 pediatric patients with higher-risk MDS, including 7 with RAEB, 8 with AML-MRC, and 3 with refractory cytopenia of childhood with monosomy 7. Regardless of initial diagnosis, monosomy 7 is the most common cytogenetic aberration (8/18, 44.4%). Next-generation sequencing (NGS) was performed on 15 specimens and the most frequent detection of mutation gene was SETBP1, followed by ETV6. Before transplantation, ten patients received monotherapies or combined chemotherapies with HMA, two patients received AML-like chemotherapies, and nine of those achieved bone marrow complete remission. The stem cell sources came from matched sibling donor (n=1), haploidentical donor (n=11), and unrelated cord blood (n=6), respectively. Low-dose decitabine-containing myeloablative conditioning regimens were administered in all cases. About 50% of patients (n=9) experienced Grade II- IV acute graft versus host diseases post-transplant. The cumulative incidence of transplantation-related mortality (TRM) was 11.1%. During a median follow-up of 10.5 (range, 2–36) months after transplantation, 15 of 18 patients were alive. At time of last follow-up, all survivors had resolution of hematologic disorder without relapse. Summary/Conclusion: In summary, administration of hypomethylating agents to allogeneic SCT resulted in excellent outcomes in children with higher-risk MDS.

Allogeneic hematopoietic stem cell transplantation in infants is associated with significant morbidity and mortality

Infants are subjected to hematopoietic stem cell transplantation (HSCT) due to malignant and non-malignant diseases. However, specific data concerning the outcome and transplantation-related complications in infants, as a separate age group, are limited. Our aim was to evaluate the impact of infancy on the outcome, toxicity, and complications after HSCT. We retrospectively analyzed data of 55 infants that underwent HSCT in our unit from May 1997 until February 2020, emphasizing on the probability of overall survival (OS) and the cumulative incidence (CI) of transplantation-related mortality (TRM) and complications. We report a probability of OS of 61%, a CI of TRM at day 100 and 365 post transplantation of 22% and 30%, respectively, and additionally a CI of graft failure, acute graft-versus-host disease (GvHD), and infectious complications, 18%, 44%, and 39%, respectively. No statistically significant association was detected between the above mentioned parameters and diagnosis, the use of myeloablative or non-myeloablative/reduced toxicity conditioning regimens or the type of donor. We conclude that HSCT in infancy is associated with significant mortality and morbidity. This is possibly attributed to endogenous, age-related factors. More specifically, infants may be at a higher risk of toxicities due to the immaturity of developing vital organs and the deficiency of the newly adopted immune system that predisposes them to infectious complications. The development of GvHD further augments the danger of infections, in a potential vice-versa relationship. Moreover, there are few data on pharmacokinetics of chemotherapy agents, making safe and efficacious drug administration hard.

HLA-haploidentical peripheral blood stem cell transplantation following reduced-intensity conditioning with very low-dose antithymocyte globulin for relapsed/refractory acute leukemia in pediatric patients: a single-institution retrospective analysis.

The prognosis of relapsed/refractory (R/R) pediatric acute leukemia is extremely poor. We retrospectively reviewed 20 consecutive pediatric patients with R/R acute leukemia who underwent a first HLA-haploidentical peripheral blood stem cell transplantation following reduced-intensity conditioning (haplo-RIC-PBSCT) with very low-dose antithymocyte globulin (ATG) between 2012 and 2019. Of these 20 patients, 7 patients had acute lymphoblastic leukemia, and 13 had acute myeloid leukemia. At the time of haplo-RIC-PBSCT, 15 patients had active disease. The median follow-up duration for survivors was 56months (range 22-108months). Graft-versus-host disease (GVHD) prophylaxis consisted of tacrolimus, short-term methotrexate, methylprednisolone, and ATG 1.25mg/kg on day-2. The 2-year cumulative incidence of transplant-related mortality and relapse were 5.0% [95% confidence interval (CI) 0.7-30.5%)] and 57.8% (95% CI 37.4-79.6%), respectively. Among the 20 patients, 16 (80.0%) developed grade III-IV acute GVHD, and 2 developed severe chronic GVHD. The 2-year event-free survival and overall survival rates were 40.0% (95% CI 19.3-60.0%) and 50.0% (95% CI 27.1-69.2%), respectively. Although the sample size is small, the survival outcomes of the present study are encouraging.

A fludarabine and melphalan reduced-intensity conditioning regimen for HSCT in fifteen chronic granulomatous disease patients and a literature review.

Chronic granulomatous disease (CGD) is a life-threatening immunodeficiency condition. To date, hematopoietic stem cell transplantation (HSCT) is the only curative modality. We prospectively studied the outcomes of fifteen CGD patients undergoing HSCT with fludarabine and melphalan plus anti-thymocyte globulin (ATG). Most of the donors were fully matched siblings (n = 12). Cyclosporine A and methylprednisolone were used for graft-versus-host disease (GVHD) prophylaxis. CGD diagnosis had been suspected upon clinical symptoms and was confirmed in all patients by an abnormal neutrophil functional assay. The three-year overall survival (OS) and event-free survival (EFS) rates were 73.3% and 46.7%, respectively. With the median follow-up time of 33.12months, the mean OS and EFS were 42.6 and 26.8months; respectively. Eleven patients (73.33%) achieved full donor chimerism. Two stable mixed chimerisms with no sign of the underlying disease (13.33%) and two secondary graft failure (13.33%) occurred as well. The cumulative incidence of transplant-related mortality was 23.1% and it was two times more in adults compared with children. Three years GVHD-FS (free survival) was 57.8% in all patients and it was 70% and 42.9% in children and adults, respectively. Our results indicate that fludarabine, melphalan, and ATG have relatively favorable outcomes in CGD patients. Also, we suggest that HSCT should be performed as soon as a suitably matched donor is found.

The day 100 score predicts moderate to severe cGVHD, transplant mortality, and survival after hematopoietic cell transplantation

AbstractThe aim of this study was to develop a predictive score for moderate-severe chronic graft-versus-host disease (cGVHD) on day +100 after allogeneic stem cell transplantation (HSCT). We studied 1292 patients allografted between 1990 and 2016, alive on day +100 after transplant, without cGVHD, and with full biochemistry laboratory values available. Patients were randomly assigned to a training and a validation cohort (ratio 1:1). In the training cohort, a multivariate analysis identified 4 independent predictors of moderate-severe cGVHD: gamma-glutamyl transferase ≥75 UI/l, creatinine ≥1 mg/dl, cholinesterase ≤4576 UI/l, and albumin ≤4 g/dl. A score of 1 was assigned to each variable, producing a low (0 to 1), intermediate (2 to 3), and high (4) score. The cumulative incidence of moderate-severe cGVHD was 12%, 20%, and 52% (P < .0001) in the training cohort, and 13%, 24%, and 33% (P = .002) in the validation cohort, respectively. The 5-year cumulative incidence of transplant-related mortality (TRM) was 5%, 14%, 27% (P < .0001) and 5%, 16%, 31% (P < .0001), respectively. The 5-year survival was 64%, 57%, 54% (P = .009) and 70%, 59%, 42% (P = .0008) in the 2 cohorts, respectively. In conclusion, Day100 score predicts cGVHD, TRM, and survival and, if validated in a separate group of patients, could be considered for trials of preemptive therapy.

Optimized Conformal Total Body Irradiation Among Recipients of TCRαβ/CD19-Depleted Grafts in Pediatric Patients With Hematologic Malignancies: Single-Center Experience

Total body irradiation (TBI) in combination with chemotherapy is widely used as a conditioning regimen in pediatric and adult hematopoietic stem cell transplantation (HSCT). The combination of TBI with chemotherapy has demonstrated superior survival outcomes in patients with acute lymphoblastic and myeloid leukemia when compared with conditioning regimens based only on chemotherapy. The clinical application of intensity-modulated radiation therapy (IMRT)-based methods (volumetric modulated arc therapy (VMAT) and TomoTherapy) seems to be promising and has been actively used worldwide. The optimized conformal total body irradiation (OC-TBI) method described in this study provides selected dose reduction for organs at risk with respect to the most significant toxicity (lungs, kidneys, lenses). This study included 220 pediatric patients who received OC-TBI with subsequent chemotherapy and allogenic HSCT with TCRαβ/CD19 depletion. A group of 151 patients received OC-TBI using TomoTherapy, and 40 patients received OC-TBI using the Elekta Synergy™ linac with an Agility-MLC (Elekta, Crawley, UK) using volumetric modulated arc therapy (VMAT). Twenty-nine patients received OC-TBI with supplemental simultaneous boost to bone marrow—(SIB to BM) up to 15 Gy: 28 patients (pts)—TomoTherapy; one patient—VMAT. The follow-up duration ranged from 0.3 to 6.4 years (median follow-up, 2.8 years). Overall survival (OS) for all the patients was 63% (95% CI: 56–70), and event-free survival (EFS) was 58% (95% CI: 51–65). The cumulative incidence of transplant-related mortality (TRM) was 10.7% (95% CI: 2.2–16) for all patients. The incidence of early TRM (<100 days) was 5.0% (95% CI: 1.5–8.9), and that of late TRM (>100 days) was 5.7 (95% CI: 1.7–10.2). The main causes of death for all the patients were relapse and infection. The concept of OC-TBI using IMRT VMAT and helical treatment delivery on a TomoTherapy treatment unit provides maximum control of the dose distribution in extended targets with simultaneous dose reduction for organs at risk. This method demonstrated a low incidence of severe side effects after radiation therapy and predictable treatment effectiveness. Our initial experience demonstrates that OC-TBI appears to be a promising technique for the treatment of pediatric patients.

Chimeric Antigen Receptor T Cell Therapy followed by Unrelated Cord Blood Transplantation for the Treatment of Relapsed/Refractory B Cell Acute Lymphoblastic Leukemia in Children and Young Adults: Superior Survival but Relatively High Post-Transplantation Relapse

Several studies have indicated that chimeric antigen receptor (CAR) T cell therapy followed by allogeneic hematopoietic stem cell transplantation is beneficial for treating patients with relapsed or refractory (R/R) B cell acute lymphoblastic leukemia (B-ALL). Whether consolidative unrelated cord blood transplantation (UCBT) is suitable in R/R B-ALL after CAR-T therapy remain uncertain. We aimed to assess the efficacy and safety of CAR-T therapy before UCBT in children and young adults with R/R B-ALL. We retrospectively analyzed 43 patients aged <18 years with R/R B-ALL who underwent single-unit UCBT at the First Affiliated Hospital of the University of Science and Technology of China between February 2012 and November 2020. Among them, 21 patients achieved complete remission (CR) following CAR-T therapy before UCBT (the CAR-T group), and the remaining 22 patients remained in nonremission (NR) without prior CAR-T therapy before UCBT (the NR group). The clinical outcomes in the 2 groups were analyzed. The median time from CAR-T therapy to UCBT was 62 days (range, 42 to 185 days). There were no significant between-group differences in the incidences of grade II-IV acute graft-versus-host disease (GVHD), grade III-IV acute GVHD, and 2-year extensive chronic GVHD. Compared with the NR group, the CAR-T group had a lower 2-year cumulative incidence of transplantation-related mortality and higher probabilities of 2-year overall survival, leukemia-free survival, and GVHD-free relapse-free survival (P=.037, .005, .028, and .017, respectively). However, the 2-year cumulative incidence of relapse (CIR) was comparably high in the 2 groups (26.7% in the CAR-T group and 38.3% in the NR group; P=.41). In the CAR-T group, patients who were minimal residual disease (MRD)-positive before UCBT had a higher CIR compared with those who were MRD-negative before UCBT (66.7% versus 19.2%; P=.006). CAR-T therapy followed by UCBT produces superior survival in R/R B-ALL, but treated patients still have a high post-transplantation relapse rate.

CAR-T Therapy Followed By Unrelated Cord Blood Transplantation for the Treatment of Children and Young Adults Relapsed/Refractory B-Cell ALL: Superior Survival but Relatively High Post-Transplant Relapse

Relapsed/refractory (R/R) acute lymphoblastic leukemia (ALL) has poor long-term survival even after chimeric antigen receptor (CAR)-T cell therapy or allogeneic hematopoietic stem cell transplantation (allo-HSCT). Several studies supported that CAR-T therapy followed by allo-HSCT is benefit for improving long-term leukemia free survival (LFS). Since probably a stronger graft versus leukemia (GVL) effect of unrelated cord blood transplantation (UCBT), it is uncertain whether consolidative UCBT is suitable for R/R B-ALL after CAR-T therapy. Here, we conducted a retrospective comparative study for R/R B-ALL patients receiving UCBT in our transplantation center. Totally 43 cases with R/R B-ALL who underwent UCBT were assigned to CAR-T group (patients achieved CR or CRi by CAR-T cell therapy before bridging to UCBT, n = 21) or non-remission (NR) group (n = 22). The median time from CAR-T infusion to UCBT was 62 (range, 42-185) days. All patients achieved neutrophil engraftment by day 42 in CAR-T group. The 180-day cumulative incidence of platelet engraftment was higher in CAR-T group than in NR group (90.5% vs 65.7%, P = 0.16). Incidence of grade II-IV and III-IV acute graft-versus-host disease (GVHD) were 28.6% and 23.8% in CAR-T group, which were both tendency lower than in NR group (45.5% and 31.8%, P = 0.32 and P = 0.63, respectively). No patient suffered from extensive chronic GVHD in CAR-T group, which was lower than in NR group (9.1%, P = 0.23). Lower 2-year cumulative incidence of transplant-related mortality (TRM), and higher probabilities of 2-year overall survival, leukemia free survival (LFS), graft-versus-host disease (GVHD)-free relapse-free survival (GRFS) were found in CAR-T group (4.8% vs 28.2%; 75.0% vs 37.7%; 49.8% vs 23.0%; 42.4% vs 14.8%; P = 0.037, 0.005, 0.028 and 0.017; respectively). However, 2-year cumulative incidence of relapse was comparably high between CAR-T and NR group (26.7% vs 38.3%; P = 0.41). CAR-T therapy followed by UCBT has a superior survival for R/R B-ALL, but remains relatively high post-transplant relapse rate. Prevention of relapse after UCBT is warranted in this patient cohort. DisclosuresNo relevant conflicts of interest to declare.

Post-Transplant High Dose Cyclophosphamide and Bortezomib As Graft-Versus-Host Disease Prophylaxis Following Allogeneic Hematopoietic Stem Cell Transplantation

Introduction. Prevention of graft-versus-host disease (GvHD) following allogeneic hematopoietic cell transplantation (AHCT) remains a major challenge. The combination of methotrexate (MTX) and a calcineurin inhibitor has been the standard regimen for prophylaxis in patients receiving matched sibling donor (MSD) or matched unrelated donor (MUD) transplants for the past few decades. However, over 50% of patients undergoing AHCT still develop acute or chronic GvHD or even both, causing high rates of morbidity and mortality. Moreover, calcineurin inhibitors also have untoward toxic side effects. High dose post-transplant cyclophosphamide (PTCy), initially introduced for GvHD prevention in the setting of haploidentical transplantation, has now been studied in MSD and MUD transplants. We adopted a novel approach to prevent GvHD using a short course of PTCy and bortezomib. We hypothesized that such combination is safe and effective and omits the need for calcineurin or m-TOR inhibitors.Study Design. We report the outcomes of a prospective cohort of patients who received PTCy and bortezomib for GvHD prevention following MSD or MUD transplants. Twenty-eight patients were treated in a phase I-II trial and their clinical outcomes were previously reported (al-Homsi AS et al, BBMT 2019). Most of the remaining patients were treated on an extension trial. GvHD prevention consisted of PTCy 50 mg/kg IV on day +3 and +4, and bortezomib 1.3mg/m 2 IV 6 hours after transplant and again 72 hours after. Patients receiving MUD transplants also received rabbit ATG (thymoglobulin®) 5mg/kg total IV fractionated on day -4 to -2. All patients received peripheral blood grafts and standard supportive care as per Institutional policy. G-CSF was administered routinely until neutrophil engraftment.Results. Fifty-eight patients are included in this analysis. Median age was 60 (range 22-78) years. Fifty-three percent of patients were male. Underlying malignancies consisted of myeloid and lymphoid malignancies in 79.3% and 20.6%, respectively. Acute myeloid leukemia (50%) and myelodysplastic syndromes (24.1%) were the most common diseases. At transplant, disease risk index was low, intermediate, high and very high in 19.0%, 48.3%, 31.0% and 1.7% of patients, respectively. Median Pretransplant Assessment of Mortality Score (PAM) was 16.7 (5.4-29.4). Grafts were from MSD in 24.1% or MUD in 75.9% of patients. Recipient (R)/Donor (D) CMV status at transplant was as follows: R+/D+: 43%; R+/D-: 21%; R-/D+: 14% and R-/D-: 22%. Conditioning regimens consisted of reduced intensity fludarabine and busulfan in all but 2 patients who were conditioned with myeloablative fludarabine and busulfan. Overall, the regimen was remarkably well tolerated. Median times to neutrophil and platelet engraftment were 16 (13-28) and 26 (15-57) days respectively. No patient experienced primary graft failure. CMV and EBV reactivation rates were 46.6% and 24%. Cumulative incidences of grade II-IV and grade III-IV acute GVHD were 35% (95% CI: 22%-47%) and 15% (95% CI: 7%-25%) at day +120, respectively. Cumulative incidence of chronic GvHD was 14% at 1 year . Overall, 34% of patients required immunosuppression with systemic steroids after day +4 either for grade III-IV acute or chronic GvHD. Disease relapse rate was 26%. One-year cumulative incidence of transplant-related mortality was 14% (95% CI: 6%-25%). Median overall survival was 30.7 (95% CI: 15.7-not yet reached) months. One-year overall survival was 72% (95% CI: 57%-82%). One-year composite GvHD (acute and chronic) free and relapse free survival (GRFS) was 41.6% (95% CI: 28.9%-54%).Conclusion. PTCy and bortezomib combination for GvHD prophylaxis following MSD and MUD transplants is well tolerated and effective. It offers an alternative regimen to calcineurin and m-TOR inhibitor-containing regimens and may be preferred in certain settings including patients with limited resources, poor medication compliance, and with impaired renal function. A comparison of this cohort to a matched control group of patients receiving methotrexate and cyclosporine for GvHD prevention is ongoing. DisclosuresAbdul-Hay: Amgen: Membership on an entity's Board of Directors or advisory committees; Servier: Other: Advisory Board, Speakers Bureau; Jazz: Other: Advisory Board, Speakers Bureau; Abbvie: Consultancy; Takeda: Speakers Bureau. Al-Homsi: Celyad: Other: Advisory Board; Daichii Sanyko: Consultancy. OffLabel Disclosure:Cyclophosphamide and Bortezomib are used for GvHD prevention

Poor survival and prediction of prolonged isolated thrombocytopenia post umbilical cord blood transplantationin patients with hematological malignancies.

Prolonged isolated thrombocytopenia (PIT) is a common complication after umbilical cord blood transplantation (UCBT). However, data on PIT prediction and impacts on transplantation outcomes for UCBT patients are rare. We retrospectively analyzed 244 patients with hematological malignancies who received single-unit UCBT at the First Affiliated Hospital of USTC between August 2018 and December 2019. Among them, PIT occurred in 49 recipients, with a crude incidence of 20.1%. In the PIT patients, the 2-year cumulative incidence of transplant-related mortality (TRM) was significantly higher, and the probabilities of 2-year overall survival, leukemia-free survival and graft-versus-host disease (GVHD)-free relapse-free survival were significantly poorer (57.1% vs. 88.6%; 53.1% vs. 81.9%; 22.4% vs. 59.8%; p<0.001), without remarkable increases in the cumulative incidence of relapse or chronic GVHD. Importantly, the multivariate analysis revealed that lower high-resolution HLA compatibility (≤6/10), lower infused CD34+ cell count (≤1.78×105 /kg), grade II-IV acute GVHD preplatelet engraftment, a lower pretransplantation platelet count (≤100×109 /L), and a longer neutrophil engraftment time (≥17 days) were independent risk factors for PIT after UCBT. These results demonstrate that PIT is common after UCBT, predicting inferior survival and the need for more monitoring during the early phase.

Nonmyeloablative Allogeneic Transplantation With Post-Transplant Cyclophosphamide for Acute Myeloid Leukemia With IDH Mutations: A Single Center Experience

IntroductionMutations in the IDH1 or IDH2 genes are detected in approximately 20% of cases of acute myeloid leukemia (AML). Few studies have examined the impact of IDH mutations in AML on allogeneic bone marrow transplant (alloBMT) outcomes. Patients and MethodsIn this single center study, alloBMT outcomes for 61 patients with IDH-mutated (mIDH) AML were compared to those for 146 patients with IDH-wildtype (wtIDH) AML. ResultsPatients with mIDH AML had a 2-year overall survival (OS) of 85% (95% CI 76%-95%), 2-year relapse free survival (RFS) of 71% (95% CI 59%-85%), 1-year cumulative incidence of relapse (CIR) of 14% (95% CI 5%-23%) and a 1-year cumulative incidence of transplant related mortality (CITRM) of 3% (95% CI 0%-8%). Patients with wtIDH had a 2-year OS of 61% (95% CI 53%-70%), 2-year RFS of 58% (95% CI 50%-67%), 1-year CIR of 27% (95% CI 20%-35%), and a 1-year CITRM of 9% (95% CI 5%-14%). In a univariate analysis cox-proportional hazard model, mIDH was associated with significantly better OS (HR 0.52, 95% CI 0.29-0.96) and a trend toward better RFS (HR 0.60, 95% CI 0.35-1.01). After controlling for donor age, diagnosis, and ELN risk category, mIDH was associated with a nonsignificantly improved OS (HR 0.54, 95% CI 0.29-1.01) and RFS (HR 0.67, 95% CI 0.39-1.15). ConclusionAmong patients with mIDH AML, patients who received a peritransplant IDH inhibitor had improved OS (P = .03) compared to those who did not, but there was no detectable difference for RFS (P = .29).

TCRαβ/CD19 depleted HSCT from an HLA-haploidentical relative to treat children with different nonmalignant disorders

AbstractSeveral nonmalignant disorders (NMDs), either inherited or acquired, can be cured by allogeneic hematopoietic stem cell transplantation (HSCT). Between January 2012 and April 2020, 70 consecutive children affected by primary immunodeficiencies, inherited/acquired bone marrow failure syndromes, red blood cell disorders, or metabolic diseases, lacking a fully matched donor or requiring urgent transplantation underwent TCRαβ/CD19-depleted haploidentical HSCT from an HLA-partially matched relative as part of a prospective study. The median age at transplant was 3.5 years (range 0.3-16.1); the median time from diagnosis to transplant was 10.5 months (2.7 for SCID patients). Primary engraftment was obtained in 51 patients, while 19 and 2 patients experienced either primary or secondary graft failure (GF), the overall incidence of this complication being 30.4%. Most GFs were observed in children with disease at risk for this complication (eg, aplastic anemia, thalassemia). All but 5 patients experiencing GF were successfully retransplanted. Six patients died of infectious complications (4 had active/recent infections at the time of HSCT), the cumulative incidence of transplant-related mortality (TRM) being 8.5%. Cumulative incidence of grade 1-2 acute GVHD was 14.4% (no patient developed grade 3-4 acute GVHD). Only one patient at risk developed mild chronic GVHD. With a median follow-up of 3.5 years, the 5-year probability of overall and disease-free survival was 91.4% and 86.8%, respectively. In conclusion, TCRαβ/CD19-depleted haploidentical HSCT from an HLA-partially matched relative is confirmed to be an effective treatment of children with NMDs. Prompt donor availability, low incidence of GVHD, and TRM make this strategy an attractive option in NMDs patients. The study is registered at ClinicalTrial.gov as NCT01810120.

Unrelated Donor Peripheral Blood Stem Cell Transplantation for Thalassaemia: A Single Institution Experience of 53 Patients

AbstractBackground: Thalassemia major (TM) is a fatal genetic disease currently only curable with allogeneic stem cell transplantation, which is limited by the lack of suitable donors. For patients lacking matched related donors, unrelated donor peripheral blood stem cell transplantation (UD-PBSCT) is increasingly being utilized. Despite this success in leukemia patients, UD-PBSCT is not widely practiced in thalassemia patients because of higher graft-versus-host disease (GVHD) risk and increased transplant-related mortality (TRM).Methods: The purpose of the study is to assess the safety and efficacy of UD-PBSCT for patients with thalassemia major. The trial was designed as a prospective, open-label, single-center clinical protocol, where 53 TM patients were enrolled between March 2013 and April 2017 and transplanted with peripheral blood stem cell (PBSC), from an HLA-matched unrelated donor. This study was approved by the Medical Ethics Committee of the First Affiliated Hospital of Guangxi Medical University and was registered at the Chinese Bone Marrow Transplant Registry (CBMTR). The primary end point was 2-year thalassemia free survival (TFS). Secondary end points included 2-year overall survival (OS), the cumulative incidence of GVHD, transplant related mortality (TRM), graft rejection (GF). The conditioning regimen were: 1) busulphan (BU) 1mg/kg given intravenously (IV) four times per day for 4 days (day -9 to day -6); 2) fludarabine (FLU) (50mg/m2/day) given IV for 3 days (day -12 to day -11); 3) cyclophosphamide (CTX) (50 mg/kg/day) given IV for 4 days (day -5 to day -4); 4) anti-thymocytes globulin (ATG, Genzyme ) (2.5 mg/kg/day) given IV for 4 days (days -4 and day -1). All patients were placed on 30 mg/kg hydroxyurea orally once daily for 2-3 months before transplantation. GVHD prophylaxis consisted of a combination of cyclosporin A, methotrexate and mycophenolate mofetil regimen.Results: Data cut off for survival follow-up was June 30, 2017. The median follow-up time was 22 months (range, 4 months -58 months). The median age of patients was 5 years (range, 2-13 years). The median numbers of MNCs and CD34 cells infused per graft were 17.6 ×108/kg (range, 10.0 to 34.6)and 9.2×106/kg (range, 3.5 to 32.9), respectively. A total of 52 (98.1%) patients achieved sustained myeloid engraftment. The median time of absolute neutrophil count engraftment was 11(range 9-15) days. The median time of platelet engraftment was 13(range, 9 to 35) days. The rate of Graft rejection was 1.9%. The cumulative incidence of acute (a)GVHD and grade II-IV aGVHD were 41.5% (95% confidence interval [CI], 29.1 to 56.2) and 32.0% (95% CI, 21.1 to 48.6) , respectively . The chronic (c)GVHD and extensive cGVHD were 6.2% (95% confidence interval [CI], 2.1 to 16.6) and 2.2% (95% CI, 0.3 to 15.1), respectively. The cumulative incidence of TRM at 2 years was 8.0% (95% CI, 3.1 to 20.4). The OS and TFS at 2 years were 92.0% (95% CI, 87.8 to 100) and 90.1% (95% CI, 85.0 to 99.6), respectively. (Figure 1)Conclusion: Our results demonstrate that MUD-PBSCT in TM yields excellent engraftment rate and TFS when the protocol consisted of busulphan, cyclophosphamide, fludarabine and antithymocyte globulin was used, and suggest that patients without an available HLA-compatible sibling but who have well-matched unrelated donors should also be considered for MUD-PBSCT. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.