Dual T-cell depletion with individually tailored anti-thymocyte globulin and attenuated dose of post-transplant cyclophosphamide in haploidentical peripheral stem cell transplantation.

This study aimed to assess the efficacy of dual T-cell suppression using individually tailored doses of antithymocyte globulin (ATG) and attenuated dose of post-transplant cyclophosphamide (PTCy) in haploidentical hematopoietic stem cell transplantation (haplo-HSCT). We conducted a retrospective analysis of 78 adults with acute leukemia or myelodysplastic syndrome who underwent haplo-HSCT using intravenous busulfan and fludarabine conditioning. Thirty-two patients received attenuated ATG/PTCy, while 46 patients received ATG (7.5 mg/kg) as GVHD prophylaxis. The 100-day cumulative incidence of grade III-IV (9.7% vs. 32.4%, P = 0.018) acute GVHD, as well as 2-year moderate-severe chronic GVHD (13.9% vs. 43.9%, P = 0.018) in the ATG/PTCy group were significantly lower than those in the ATG group. The 2-year overall survival was comparable between the two groups. However, 2-year GVHD-free, relapse-free survival in the ATG/PTCy group was significantly higher compared to that in the ATG group (38.9% vs. 21.7%, P = 0.021). Moreover, during post-engraftment period, the ATG/PTCy group exhibited lower incidences of life-threatening bacterial (12.5% vs. 37%, P = 0.033) and viral infection (0% vs. 17.4%, P = 0.035) than the ATG group. In conclusion, the combination of individually tailored ATG and low-dose PTCy appears to be a promising strategy in haplo-HSCT.

Memory T-cell enriched haploidentical transplantation with NK cell addback results in promising long-term outcomes: a phase II trial.

BACKGROUND: Relapse remains a challenge after transplantation in pediatric patients with hematological malignancies. Myeloablative regimens used for disease control are associated with acute and long-term adverse effects. We used a CD45RA-depleted haploidentical graft for adoptive transfer of memory T cells combined with NK-cell addback and hypothesized that maximizing the graft-versus-leukemia (GVL) effect might allow for reduction in intensity of conditioning regimen. METHODS: In this phase II clinical trial (NCT01807611), 72 patients with hematological malignancies (complete remission (CR)1: 25, ≥ CR2: 28, refractory disease: 19) received haploidentical CD34 + enriched and CD45RA-depleted hematopoietic progenitor cell grafts followed by NK-cell infusion. Conditioning included fludarabine, thiotepa, melphalan, cyclophosphamide, total lymphoid irradiation, and graft-versus-host disease (GVHD) prophylaxis consisted of a short-course sirolimus or mycophenolate mofetil without serotherapy. RESULTS: The 3-year overall survival (OS) and event-free-survival (EFS) for patients in CR1 were 92% (95% CI:72-98) and 88% (95% CI: 67-96); ≥ CR2 were 81% (95% CI: 61-92) and 68% (95% CI: 47-82) and refractory disease were 32% (95% CI: 11-54) and 20% (95% CI: 6-40). The 3-year EFS for all patients in morphological CR was 77% (95% CI: 64-87) with no difference amongst recipients with or without minimal residual disease (P = 0.2992). Immune reconstitution was rapid, with mean CD3 and CD4 T-cell counts of 410/µL and 140/µL at day + 30. Cumulative incidence of acute GVHD and chronic GVHD was 36% and 26% but most patients with acute GVHD recovered rapidly with therapy. Lower rates of grade III-IV acute GVHD were observed with NK-cell alloreactive donors (P = 0.004), and higher rates of moderate/severe chronic GVHD occurred with maternal donors (P = 0.035). CONCLUSION: The combination of a CD45RA-depleted graft and NK-cell addback led to robust immune reconstitution maximizing the GVL effect and allowed for use of a submyeloablative, TBI-free conditioning regimen that was associated with excellent EFS resulting in promising long-term outcomes in this high-risk population. The trial is registered at ClinicalTrials.gov (NCT01807611).

The function of the complement system remains fully intact throughout the course of allogeneic stem cell transplantation.

Introduction: Hematopoietic stem cell transplantation (HSCT) is associated with immune complications and endothelial dysfunction due to intricate donor-recipient interactions, conditioning regimens, and inflammatory responses. Methods: This study investigated the role of the complement system during HSCT and its interaction with the cytokine network. Seventeen acute myeloid leukemia patients undergoing HSCT were monitored, including blood sampling from the start of the conditioning regimen until four weeks post-transplant. Clinical follow-up was 200 days. Results: Total complement functional activity was measured by WIELISA and the degree of complement activation by ELISA measurement of sC5b-9. Cytokine release was measured using a 27-multiplex immuno-assay. At all time-points during HSCT complement functional activity remained comparable to healthy controls. Complement activation was continuously stable except for two patients demonstrating increased activation, consistent with severe endotheliopathy and infections. In vitro experiments with post-HSCT whole blood challenged with Escherichia coli, revealed a hyperinflammatory cytokine response with increased TNF, IL-1ß, IL-6 and IL-8 formation. Complement C3 inhibition markedly reduced the cytokine response induced by Staphylococcus aureus, Aspergillus fumigatus, and cholesterol crystals. Discussion: In conclusion, HSCT patients generally retained a fully functional complement system, whereas activation occurred in patients with severe complications. The complement-cytokine interaction indicates the potential for new complement-targeting therapeutic strategies in HSCT.

Future directions in haploidentical hematopoietic stem cell transplantation.

Outcomes of haploidentical hematopoietic stem cell transplantation (haplo-SCT) have improved over time. Graft failure and graft-versus-host disease (GVHD), which were important complications in major human leukocyte antigen (HLA)-disparity stem cell transplantation, have significantly decreased. These improvements have led to an exponential increase in the use of haploidentical donors for transplantation, as well as in the number of publications evaluating haplo-SCT outcomes. Many studies focused on factors important in donor selection, novel conditioning regimens or GVHD prophylaxis, the impact of donor-specific anti-HLA antibodies (DSA), as well as strategies to prevent disease relapse post-transplant. DSA represents an important limitation and multimodality desensitization protocols, including plasma exchange, rituximab, intravenous immunoglobulin and donor buffy coat infusion, can contribute to the successful engraftment in patients with high DSA levels and is currently the standard therapy for highly allosensitized individuals. With regards to donor selection, younger donors are preferred due to lower risk of complications and better transplant outcomes. Moreover, recent studies also showed that younger haploidentical donors may be a better choice than older-matched unrelated donors. Improvement of disease relapse remains a top priority, and several studies have demonstrated that higher natural killer (NK) cell numbers early post-transplant are associated with improved outcomes. Prospective studies have started to assess the role of NK cell administration in decreasing post-transplant relapse. These studies suggest that the incorporation of other cell products post-transplant, including the administration of chimeric antigen receptor T-cells, should be explored in the future.

Successful Treatment of Refractory or Relapsed Hepatoblastoma With Autologous Hematopoietic Stem Cell Transplantation in Children.

BACKGROUND: The standard-risk hepatoblastoma has a good prognosis in children; however, refractory or relapsed (R/R) hepatoblastoma has a poor prognosis and high mortality rate. This study aimed to demonstrate the efficacy of high-dose chemotherapy and autologous hematopoietic stem cell transplantation (HSCT) rescue in pediatric patients with R/R hepatoblastoma. METHODS: We retrospectively analyzed 6 pediatric patients with R/R hepatoblastoma who underwent autologous HSCT. The MEC conditioning regimen was used for all patients, comprising melphalan 140 mg/m 2 /day intravenously (IV) on day 7 and 70 mg/m 2 on day 6, etoposide 200 mg/m 2 IV on days 5 to 8, and carboplatin 400 mg/m 2 IV on days 5 to 8. One patient received a TopoThioCarbo regimen, comprising topotecan 2 mg/m 2 /day IV on days 4 to 8, thiotepa 300 mg/m 2 /day IV on days 6 to 8, and carboplatin 500 mg/m 2 /day IV on days 3 to 5, as the conditioning regimen for the first transplantation. This was followed by salvage chemotherapy for relapse, and the second transplantation was performed using MEC as the conditioning regimen. RESULTS: We report the retrospective results of 6 patients with a median age of 1.8 (range 0.4 to 10.2) years who had R/R hepatoblastoma and underwent autologous HSCT. The median follow-up period was 58 (range 28 to 113) months after diagnosis. The median stage at diagnosis was 2.0 (range 2 to 4). Two patients had lung metastases during diagnosis. The median initial alpha-fetoprotein level was 292,888 (range 28,831 to 2,406,942) ng/mL, and the median number of chemotherapy lines before autologous HSCT was 3.5 (range 2 to 7). The disease status before HSCT was complete remission (CR) for all patients. The engraftment rate was 100%. No treatment-related mortality was reported. The 3-year event-free survival and overall survival rates were 83.3% and 100%, respectively. One patient relapsed after the second HSCT and achieved CR after salvage chemotherapy. CONCLUSION: This study suggests autologous HSCT as an effective treatment in pediatric patients with R/R hepatoblastoma. Nevertheless, future large-scale prospective studies are warranted.

Haploidentical HSCT in the Treatment of Pediatric Hematological Disorders.

Allogeneic hematopoietic stem cell transplantation has become a treatment option for otherwise non-curative conditions, both malignant and benign, affecting children and adults. Nevertheless, the latest research has been focusing extensively on transplantation from related and unrelated haploidentical donors, suitable for patients requiring emergent hematopoietic stem cell transplantation (HSCT) in the absence of an HLA-matched donor. Haploidentical HSCT (haplo-HSCT) can be an effective treatment for non-malignant pediatric disorders, such as primary immunodeficiencies or hemoglobinopathies, by enabling a much quicker selection of the appropriate donor for virtually all patients, low incidence of graft-versus-host disease (GVHD), and transplant-related mortality (TRM). Moreover, the outcomes of haplo-HSCT among children with hematological malignancies have improved radically. The most demanding tasks for clinicians are minimizing T-cell-mediated alloreactivity as well as early GVHD prevention. As a result, several T-cell depletion approaches, such as ex vivo T-cell depletion (TCD), and T-cell replete approaches, such as a combination of anti-thymocyte globulin (ATG), post-transplantation cyclophosphamide (PTCy), cyclosporine/tacrolimus, mycophenolate mofetil, or methotrexate, have been taken up. As more research is needed to establish the most beneficial form of therapy, haplo-HSCT is currently considered an alternative donor strategy for pediatric and adult patients with complications like viral and bacterial infections, invasive fungal disease, and GVHD.

Immune reconstitution and survival, following hematopoietic stem cell transplantation in Omani patients with inborn errors of immunity.

BACKGROUND: Hematopoietic stem cell transplantation (HSCT) is a curative treatment for certain inborn errors of immunity. METHODS: A 17-year retrospective cohort study was conducted on 40 immunodeficient patients who underwent HSCT. RESULTS: The median age at transplant was 11.0 months (4.6-61.0). Donors were primarily matched sibling donors (60%). 90% and 85% of patients received conditioning and graft-versus-host disease (GVHD) prophylaxis, respectively. The mean donor chimerism at the last follow-up was 88.6% ± 17.9% (40-100). Median serum immunoglobulin (Ig) G level, CD4+ T-cell count, and CD19+ B-cell count were 11.7 g/L (9.2-13.6), 0.9 × 109/L 0.6-1.2), and 0.5 × 109/L (0.2-0.7), respectively. 29 patients (72.5%) received intravenous immunoglobulins (IVIG) therapy, with a median duration of 10.0 months (4.0-14.0). The median post-transplant follow-up was 6.5 years (IQR:1.4-11.5). The 10-year overall probability of survival is 84.3%. CONCLUSION: Monitoring IRC is important in ensuring adequate disease-free survival.

Case report: Donor-derived CLL-1 chimeric antigen receptor T-cell therapy for relapsed/refractory acute myeloid leukemia bridging to allogeneic hematopoietic stem cell transplantation after remission.

Background: Explore the efficacy and safety of donor-derived CLL-1 chimeric antigen receptor T-cell therapy (CAR-T) for relapsed/refractory acute myeloid leukemia (R/R AML) bridging to allogeneic hematopoietic stem cell transplantation (allo-HSCT) after remission. Case presentation: An adult R/R AML patient received an infusion of donor-derived CLL-1 CAR-T cells, and the conditioning regimen bridging to allo-HSCT was started immediately after remission on day 11 after CAR-T therapy upon transplantation. Then, routine post-HSCT monitoring of blood counts, bone marrow (BM) morphology, flow cytometry, graft-versus-host disease (GVHD) manifestations, and chimerism status were performed. Result: After CAR-T therapy, cytokine release syndrome was grade 1. On day 11 after CAR-T therapy, the BM morphology reached complete remission (CR), and the conditioning regimen bridging to allo-HSCT started. Leukocyte engraftment, complete donor chimerism, and platelet engraftment were observed on days +18, +23, and +26 post-allo-HSCT, respectively. The BM morphology showed CR and flow cytometry turned negative on day +23. The patient is currently at 4 months post-allo-HSCT with BM morphology CR, negative flow cytometry, complete donor chimerism, and no extramedullary relapse/GVHD. Conclusion: Donor-derived CLL-1 CAR-T is an effective and safe therapy for R/R AML, and immediate bridging to allo-HSCT after remission may better improve the long-term prognosis of R/R AML.

Allogeneic haematopoietic cell transplantation for chronic myeloid leukaemia in Switzerland in the face of rapid development of effective drugs.

AIM: Until the year 2000, allogeneic haematopoietic cell transplantation (HCT) was the standard treatment for young and fit chronic myeloid leukaemia (CML) patients. CML was the main indication for allogeneic HCT. The introduction of tyrosine kinase inhibitors changed the treatment of CML patients dramatically. Allogeneic HCT was rapidly replaced by tyrosine kinase inhibitors as first-line treatment for CML, and the indication shifted to the treatment of non-responders, patients intolerant to tyrosine kinase inhibitors and patients whose CML is transforming to the accelerated phase and blast crisis. This paper describes changes in the use of transplantation technology for CML patients in the face of rapid drug development. METHODS: All patients receiving a transplant for CML between 1997 and 2021 in Switzerland were included in the study. For the purpose of this analysis, time periods were analysed in quinquennia, 1997-2001 (Q1), 2002-2006 (Q2), 2007-2011 (Q3), 2012-2016 (Q4) and 2017-2021 (Q5), as the observation period spanned 25 years. RESULTS: Overall, 239 patients received a transplant. These included 96 in Q1, 56 in Q2, 25 in Q3, 34 in Q4 and 28 in Q5. Patient characteristics changed over time: recent patients were older and had a longer interval from diagnosis to transplantation because of tyrosine kinase inhibitor treatment. However, the proportions of patients receiving transplants during an early versus advanced disease stage differed little. Transplant technology changed, as well. Patients received intensive conditioning regimens less often due to higher age and more commonly had peripheral blood as opposed to bone marrow transplants. However, the type of stem cell donor selected did not differ. In a univariable analysis, there were no significant differences in survival, progression-free survival, non-relapse mortality, relapse incidence or incidences of acute and chronic graft-versus-host disease among the five quinquennia. In a multivariable analysis, older age, donors other than HLA-identical siblings and more advanced disease stage, but not the quinquennium, were associated with higher risk of death. CONCLUSION: Since the introduction of tyrosine kinase inhibitors haematopoietic cell transplantation has been used less frequently to treat CML. Patients in recent cohorts received transplants at an older age and later in the disease course; despite these higher risks, the outcome of allogeneic HCT has not worsened over time but has not improved, either. As the outcome is worse in advanced phases, it is important to conduct transplants before disease progression. Therefore, patients with advanced disease should be monitored closely and receive transplants in time.

Allogeneic Stem Cell Transplantation in Refractory Acute Myeloid Leukaemia.

Refractory acute myeloid leukaemia is very difficult to treat and represents an unmet clinical need. In recent years, new drugs and combinations of drugs have been tested in this category, with encouraging results. However, all treated patients relapsed and died from the disease. The only curative option is allogeneic transplantation through a graft from a healthy donor immune system. Using myeloablative conditioning regimens, the median overall survival regimens is 19%. Several so-called sequential induction chemotherapies followed by allogeneic transplantation conditioned by reduced intensity regimens have been developed, improving the overall survival to 25-57%. In the allogeneic transplantation field, continuous improvements in practices, particularly regarding graft versus host disease prevention, infection prevention, and treatment, have allowed us to observe improvements in survival rates. This is true mainly for patients in complete remission before transplantation and less so for refractory patients. However, full myeloablative regimens are toxic and carry a high risk of treatment-related mortality. In this review, we describe the results obtained with the different modalities used in more recent retrospective and prospective studies. Based on these findings, we speculate how allogeneic stem cell transplantation could be modified to maximise its therapeutic effect on refractory acute myeloid leukaemia.

A retrospective study of an irradiation-based conditioning regimen and chidamide maintenance therapy in T-ALL/LBL.

OBJECTIVES: T-cell acute lymphoblastic leukemia/lymphoblastic lymphoma (T-ALL/LBL) are highly malignant and aggressive hematologic tumors for which there is no standard first-line treatment. Chidamide, a novel histone deacetylase inhibitor, shows great promise. We assessed the efficacy and safety of an irradiation-containing conditioning regimen for allogeneic hematopoietic stem cell transplantation (allo-HSCT) and post-transplantation chidamide maintenance in patients with T-ALL/LBL. METHODS: We retrospectively analyzed the clinical data of six patients with T-ALL/LBL who underwent allo-HSCT with a radiotherapy-containing pretreatment regimen and post-transplant chidamide maintenance therapy. The endpoints were relapse, graft-versus-host disease (GVHD), transplant-related mortality (TRM), progression-free survival (PFS), overall survival (OS), and adverse events (AEs). RESULTS: All of the patients had uneventful post-transplant hematopoietic reconstitution, and all achieved complete molecular remission within 30 days. All six patients survived, and two relapsed with a median relapse time of 828.5 (170-1335) days. The 1-year OS rate was 100%, the 2-year PFS rate was 66.7%, and the TRM rate was 0%. After transplantation, two patients developed grade I-II acute GVHD (2/6); grade III-IV acute and chronic GVHD were not observed. The most common AEs following chidamide administration were hematological AEs, which occurred to varying degrees in all patients; liver function abnormalities occurred in two patients (grade 2), and symptoms of malaise occurred in one patient (grade 1). CONCLUSION: Chidamide maintenance therapy after T-ALL/LBL transplantation is safe, but the efficacy needs to be further investigated.

[Efficacy of allogeneic hematopoietic stem cell transplantation based on a total body irradiation conditioning treatment regimen for adult acute lymphocytic leukemia].

Objective: To analyze the efficacy of allo-HSCT with total body irradiation (TBI) and chemotherapy alone in the treatment of adult ALL and to explore the factors affecting prognosis. Methods: The clinical data of 95 adult patients with ALL who underwent allo-HSCT from January 2015 to August 2022 were included. According to the conditioning regimen, the patients were divided into two groups: the TBI plus cyclophosphamide (TBI/Cy) group (n=53) and the busulfan plus cyclophosphamide (Bu/Cy) group (n=42). Hematopoietic reconstitution after transplantation, GVHD, transplantation-related complications, relapse rate (RR), non-relapse mortality (NRM), OS, and LFS were compared, and the factors related to prognosis were analyzed. Results: The median time of neutrophil engraftment was 14 (10-25) days in the TBI/Cy group and 14 (10-24) days in the Bu/Cy group (P=0.106). The median time of megakaryocyte engraftment was 17 (10-42) days in the TBI/Cy group and 19 (11-42) days in the Bu/Cy group (P=0.488). The incidence of grade Ⅱ-Ⅳ acute GVHD (aGVHD) in the TBI/Cy and Bu/Cy groups was 41.5% and 35.7%, respectively (P=0.565). The incidence of grade Ⅲ-Ⅳ aGVHD in these two groups was 24.5% and 4.8%, respectively (P=0.009). The incidence of severe chronic GVHD in the two groups was 16.7% and 13.5%, respectively (P=0.689). The incidence of cytomegalovirus infection, Epstein-Barr virus infection, severe infection, and hemorrhagic cystitis in the two groups was 41.5% and 35.7% (P=0.565), 34.0% and 35.7% (P=0.859), 43.4% and 33.3% (P=0.318), and 20.8% and 50.0% (P=0.003), respectively. The median follow-up time was 37.1 months and 53.3 months in the TBI/Cy and Bu/Cy groups, respectively. The 2-year cumulative RR was 17.0% in the TBI/Cy group and 42.9% in the Bu/Cy group (P=0.017). The 2-year cumulative NRM was 24.5% and 7.1%, respectively (P=0.120). The 2-year LFS was 58.5% and 50.0%, respectively (P=0.466). The 2-year OS rate was 69.8% and 64.3%, respectively (P=0.697). In the multivariate analysis, the conditioning regimen containing TBI was a protective factor for relapse after transplantation (HR=0.304, 95% CI 0.135-0.688, P=0.004), whereas the effect on NRM was not significant (HR=1.393, 95% CI 0.355-5.462, P=0.634). Infection was an independent risk factor for OS after allo-HSCT in adult patients with ALL. Conclusion: allo-HSCT based on TBI conditioning regimen had lower relapse rate and lower incidence of hemorrhagic cystitis for adult ALL, compared with chemotherapy regimen. While the incidence o grade Ⅲ/Ⅳ aGVHD was hgher in TBI conditioning regimen than that in chemotherapy regimen.

Continuously improving outcome over time after second allogeneic stem cell transplantation in relapsed acute myeloid leukemia: an EBMT registry analysis of 1540 patients.

Second allogeneic stem cell transplantation (alloSCT2) is among the most effective treatments for acute myeloid leukemia (AML) relapse after first alloSCT (alloSCT1). Long-term EBMT registry data were used to provide large scale, up-to-date outcome results and to identify factors for improved outcome. Among 1540 recipients of alloSCT2, increasing age, better disease control and performance status before alloSCT2, more use of alternative donors and higher conditioning intensity represented important trends over time. Between the first (2000-2004) and last (2015-2019) period, two-year overall and leukemia-free survival (OS/LFS) increased considerably (OS: 22.5-35%, LFS: 14.5-24.5%). Cumulative relapse incidence (RI) decreased from 64% to 50.7%, whereas graft-versus-host disease and non-relapse mortality (NRM) remained unchanged. In multivariable analysis, later period of alloSCT2 was associated with improved OS/LFS (HR = 0.47/0.53) and reduced RI (HR = 0.44). Beyond, remission duration, disease stage and patient performance score were factors for OS, LFS, RI, and NRM. Myeloablative conditioning for alloSCT2 decreased RI without increasing NRM, leading to improved OS/LFS. Haploidentical or unrelated donors and older age were associated with higher NRM and inferior OS. In summary, outcome after alloSCT2 has continuously improved over the last two decades despite increasing patient age. The identified factors provide clues for the optimized implementation of alloSCT2.

Treosulfan is a safe and effective alternative to busulfan for conditioning in adult allogeneic HSCT patients: Data from a single center.

INTRODUCTION: Type of conditioning regimen impacts the outcome of patients who undergo allogeneic HSCT since graft versus host disease (GVHD), infections, regimen related toxicities (RRT) are important causes of post-transplant mortality. Despite the RRT profile of busulfan, it is frequently used worldwide. Treosulfan has advantages in terms of dose of administration, lower incidence of sinusoidal obstruction syndrome and lower neurotoxicity. We retrospectively investigated outcomes of patients who underwent allogeneic HSCT with treosulfan or busulfan based conditioning regimens in our institution. METHODS: Treosulfan was administered to 94 patients while 85 patients received busulfan. Our outcomes were RRT, chronic and acute GVHD, relapse related mortality (RRM), non-relapse mortality, and fungal infection. The clinical follow up data, regarding the primary and secondary endpoints of our study, of the patients who received treosulfan or busulfan based conditioning regimens were statistically analyzed. RESULTS: The median follow-up was 14 months for the treosulfan group while it was 11 months for the busulfan group (p = 0.16). RRT was 11.7% and 7.1% for treosulfan and busulfan respectively. The incidence of extensive chronic GVHD was less frequent in the treosulfan group compared to the busulfan group (15.7% vs. 32.1%) (p < 0.001). The incidence of acute GVHD (Grade 3 or higher) was 32.2% in the treosulfan group while it was 31.6% in the busulfan group. The RRM was 17% in the treosulfan group while it was 34% in the busulfan group. The non-relapse mortality was 35.5% and 29.4% in the treosulfan group and in the busulfan group respectively (p = 0.962). CONCLUSION: Treosulfan, with a lower RRM, lower chronic GVHD incidence and with a similar RRT profile appears to be a safe alternative to busulfan.

The use of haploidentical stem cell transplant as an alternative donor source in patients with decreased access to matched unrelated donors.

INTRODUCTION: The likelihood of finding HLA-matched unrelated donors for rare HLA types and non-white European ancestry continues to be a challenge with less than a 70% chance of finding a full match. Mismatched transplants continue to have high rates of transplant-related mortality. With the near-universal ability to find a haploidentical donor in families, haploidentical transplants have become of more critical importance in ethnic minority groups and patients with rare HLA types. METHODS: Data was collected through clinical trials, review articles, and case reports published in the National Library of Medicine. RESULTS: The use of improved lymphodepleting conditioning regimens, graft versus host disease (GVHD) prophylaxis using regimens such as post-transplant cyclophosphamide, mycophenolate, and tacrolimus have improved engraftment to nearly 100 percent and reduced transplant-related mortality to less than 20 percent. Attention to donor-specific antibodies (DSAs) with interventions using bortezomib, rituximab, and plasmapheresis has decreased graft failure rates. CONCLUSION: With improved prevention of GVHD with interventions such as post-transplant cyclophosphamide and management of DSAs, haploidentical transplants continue to improve transplant-related mortality (TRM) compared to patients who received matched-related donor transplants. While TRM continues to improve, ongoing research with haploidentical transplants will focus on improving graft and donor immunosuppression and identifying the best regimens to improve TRM without compromising relapse-free survival.

Breaking barriers: supporting hematopoietic stem cell transplant program through collaborative radiation therapy service from a physically distant center.

BACKGROUND: Total body irradiation (TBI) for hematopoietic stem cell transplant (HSCT) has certain distinct advantages, such as uniform dose distribution and lack of drug resistance, but it is not widely available in resource-constrained settings. To overcome the limitations of in-house radiotherapy services in hematology centers, we evaluated the feasibility of conducting HSCT programs in coordination with two physically distant centers using a reduced-intensity TBI protocol. METHODS: Thirty-two patients with a median age of 20.5 years were included in the study. Fifteen patients were diagnosed with aplastic anemia, 10 patients with acute myeloid leukemia (AML), 3 patients with acute lymphocytic leukemia (ALL), and 4 patients with other hematological conditions. Conditioning regimens used were fludarabine plus cyclophosphamide in 29 cases, fludarabine-cytarabine ATG in 2 cases, and busulfan plus fludarabine in 1 case. The TBI dose was 3 Gy in 28 cases and 2 Gy in 4 cases. Patients were followed monthly after TBI, and the major toxicities were recorded. RESULTS: The median follow-up was 22 months. The most common acute complication was acute graft-versus-host disease (GVHD), which occurred in 15.6% of patients. The major late complications were chronic GVHD (9.3%), Cytomegalovirus (CMV) infection (34.3%), and CMV-induced secondary graft failure (6.2%). Seventy-five percent of patients were alive, 21.9% were dead, and 1 patient was lost to follow-up. CONCLUSIONS: HSCT based on TBI is feasible even if the center lacks a radiotherapy facility by coordinating with a remote radiotherapy facility. without compromising the patient's outcome.

Outcomes from hematopoietic stem cell transplantation following treosulfan-based conditioning: A clinical and pharmacokinetic analysis.

BACKGROUND: The aims of this study are to report our experience with treosulfan-based conditioning regimens for patients with non-malignant hematologic conditions, correlating clinical outcomes at different time points post-transplant with treosulfan exposure (AUC). METHODS: This study was a single-center observational study investigating overall survival (OS), disease-free survival (DFS), and event-free survival (EFS) end-points post-transplant. The consequences of treosulfan AUC with respect to toxicity, correction of underlying disease, and long-term chimerism were also explored using pharmacokinetic analysis. RESULTS: Forty-six patients received 49 transplants with treosulfan and fludarabine-based conditioning between 2005 and 2023. Twenty-four patients also received thiotepa. Donor chimerism was assessed on either whole blood or sorted cell lines at different time points post-transplant. Thirty-nine patients received treosulfan pharmacokinetic assessment to evaluate cumulative AUC, with five infants receiving real-time assessment to facilitate daily dose adjustment. OS, DFS, and EFS were 87%, 81%, and 69%, respectively. Median follow-up was 32.1 months (range 0.82-160 months) following transplant. Lower EFS was associated with patient age (<1 year; p = .057) and lower cumulative treosulfan dose (<42 g/m2; p = .003). Stable donor chimerism in B-cell, NK-cell, and granulocyte lineages at 1-year post-transplant were more prevalent in patients receiving thiotepa conditioning. Two infants required daily dose adjustment to treosulfan to avoid high AUC. CONCLUSIONS: Excellent clinical outcomes and stable chimerism were observed in this patient series. The addition of thiotepa conferred no significant toxicity and trended toward sustained ongoing donor engraftment. Correlating treosulfan AUC with long-term patient outcomes is required.