Autologous Recovery Research Articles

Incidence, Risk Factors, Characteristics, and Outcome of Chronic Graft Versus Host Disease in Children Undergoing Haploidentical Peripheral Blood Stem Cell Transplant With Post-transplant Cyclophosphamide.

Chronic graft versus host disease (cGVHD) is a major cause of morbidity postallogeneic peripheral blood stem cell transplant (PBSCT). There is paucity of literature describing incidence, risk factors, characteristics, and outcome of cGVHD in children undergoing haploidentical PBSCT with post-transplant cyclophosphamide (PTCy). Here, we describe our experience from our center regarding the same. All children who underwent haploidentical PBSCT with PTCy between January 2016 and December 2021 at our center and survived beyond day+100 post-transplant were included in this retrospective study. Conditioning regimens used were: Thiotepa-Fludarabine-Cyclophosphamide with 2Gy single fraction total body irradiation, Thiotepa-Busulfan-Fludarabine, Fludarabine-total body irradiation and Fludarabine-Melphalan. Peripheral blood was used as stem cell source in all patients. GVHD prophylaxis was PTCy 50mg/kg on day +3 and +4, Mycophenolate mofetil and Calcineurin inhibitors. Clinical and laboratory data was electronically retrieved and analyzed based on National Institute of Health Consensus Criteria-2014 at regular intervals. Impact of various patient, donor, and transplant-related factors on development of cGVHD were analyzed. Incidence of relapse, event free survival (EFS) and overall survival (OS) were calculated and compared between cGVHD and no cGVHD groups. Patients with rejection were excluded from risk factor analysis for cGVHD but were considered for survival analysis. Fifty-one children included in this study. Median age of transplant of our cohort was 7.5 years with male:female=1.6:1. Eight patients had rejection with autologous recovery. History of acute GVHD (aGVHD) was present in 15/51 (Grade III to IV in 7/51). cGVHD developed in 19/51 patients (mild-9/51, moderate-6/51, and severe-4/51). Skin was the most common organ involved (100%) followed by gastrointestinal tract (47.4%), liver (36.8%), eyes (21%), lungs (21%), mouth (15.7%), and joints (5.2%). Advanced donor age (>30y) and previous aGVHD were found to be significantly associated with increased risk of developing cGVHD. At last follow-up, complete response and partial response of cGVHD was seen in 6/19 and 4/19 patients, respectively. Overall mortality was 15/51 (cause of mortality was relapse of cancer 8/15, cGVHD-3/15, other 4/15). EFS and OS of full cohort was 55% and 70.6%, respectively. Compared with patients without cGVHD, patients with cGVHD demonstrated a lower relapse (18.2% vs. 40%, P =0.2333), higher EFS (68.4% vs. 53.1%, P =0.283), and higher OS (73.7% vs. 68.8%, P =0.708). Incidence of cGVHD was high in children undergoing haploidentical PBSCT with PTCy. Other than PBSC graft source; donor age and previous aGVHD were the risks factors for development of cGVHD. Patients with cGVHD had lower incidence of relapse translating into better survival but this difference was not statistically significant.

Clinical remission with autologous recovery after allogeneic hematopoietic cell transplantation for juvenile myelomonocytic leukemia

Clinical remission with autologous recovery after allogeneic hematopoietic cell transplantation for juvenile myelomonocytic leukemia

FROM ALLOGENIC TRANSPLANTATION TO PRECISION IMMUNE THERAPY

Allogeneic stem cell transplantation (ASCT) represents a model for immune cellular therapy leading to Immune Precision Medicine. The pioneers Georges Mathé in Paris and E. Donall Thomas (Nobel Prize in 1990) in Cooperstown, New York, pioneered ASCCT in the clinical field. In 1958, the first 4 survivors were seen in patients after accidental exposure to lethal or near lethal dose of TBI, in Paris. However, they were subsequently shown to have autologous recovery. Understanding of ABMT immune support begun in 1954 with 1980 Nobel Prize Jean Dausset. The first ABMTs were performed in severe combined immunodeficiencies with the first success observed in 1968 (syngeneic donor), followed in 1973 by unrelated donor ABMT in London. This was also the time of the initiation of registries. Development time in hematological malignancies The first success of ABMT in acute leukemia was observed in 1976 in Seattle with a related donor and in 1976 with an unrelated donor. Thereafter, the evolution will take place within the framework of the risk-benefit balance with reduction of the intensity of the conditioning regimen, the graft versus leukemia (GVL)/graft versus host disease (GVH) balance and the donor extension with umbilical cord blood and more recently the haplo-identical allogeneic ASTC. Autologous SCT was introduced at the beginning of the 80s to amplify reduction in tumor mass, particularly in lymphoid malignancies. Stem cell transplantation as an immune therapy platform Whatever the autologous or allogeneic context, the hematopoietic SCT is an exceptional platform for combining, modulating immunotherapy. In an allogeneic context, by modifying lymphocyte subpopulations, such as the supply of cytotoxic T-cells, the modulation of Tregs, the addition or activation of NK cells have an impact on GVH/GVL balance. The enhancement of anti-tumor cytotoxicity can be brought about using monoclonal antibodies (moAb), the addition of cancer vaccines. In an autologous context, there are some windows of opportunity, in the aplasia period due to the accessibility to stressed cancer cells, and cytokine burst approximately at D15, to add cell-drugs such as NK, γδ T-cells or anti-cancer moAbs, or to associate chimeric antigen receptor (CAR) immune cells such as CAR-NK, as well as immune checkpoint inhibitors depending on the risks. This paves the way for a real dynamic personalized medicine and should cause the methodology for developing these therapeutic strategies to be rethought. Obtaining an optimization of the clinical efficiency which must be preceded by a reflection of biological efficiency can be helped by mathematical models or AI. We have thus developed a mathematical model for the optimization of the use of anti-IL-6. There is a modeling of use of cytotoxic cells. In cellular therapy, the concept of cell-drugs orients towards non-MHC dependent allogenic cells such as NK and γδ T-cells, as well as obtaining them in large batches to reduce production costs. We are entering a new medical era, with new notions such as dynamic, globalized vision, the use of new tools resulting from the digital revolution, new targeted therapies, immunotherapy, the combination of strategies for better efficiency: the Immune Precision Medicine.

Therapy-related myeloid neoplasms of recipient origin after allogeneic hematopoietic stem cell transplantation for acute leukemia.

Some allogeneic stem cell transplantation (allo-SCT) recipients develop therapy-related myeloid neoplasms (t-MNs) of recipient origin with features including karyotypically abnormal hematopoiesis without cell dysplasia and myeloblast increase. However, due to their rarity their clinical course remains unclear. We report six cases of t-MN in patients with chromosomal abnormalities (CAs) after autologous recovery following allo-SCT for acute leukemia. CAs were first detected at a median interval of 422 (range 30-1941) days from allo-SCT. The fraction of CA-bearing cells of recipient origin increased with time, and cytogenetic relapse of underlying disease was not observed. Continuous emergence of identical autologous CAs was observed in one patient who did not receive total body irradiation (TBI). The other five patients received TBI, and complex karyotypes with the appearance of different types of CAs were the most dominant feature. Despite the persistence of complex abnormalities in the irradiated patients, no patient developed therapy-related acute myeloid leukemia (t-AML). TBI appears to be the major cause of t-MN of recipient origin with different types of CAs. Although t-MNs in patients receiving TBI do not initially seem to evolve to overt t-AML, they were associated with higher risk of underlying disease and greater oncogenic potential of irradiation.

Unrelated Cord Blood Transplantation in Children, Adolescents, and Young Adults with Acute Leukemia or Myelodysplastic Syndrome: A Retrospective Comparative Study from the French Society for Bone Marrow Transplantation and Cellular Therapy Between Real-World Data and Previously Reported Results of a Randomized Clinical Trial

We previously reported results of a French randomized clinical trial (RCT) comparing the risk of transplantation failure (including transplant-related mortality [TRM], engraftment failure, and autologous recovery) in single and double unrelated cord blood (UCB) transplantation in children and young adults with hematologic malignancies. We concluded that single-UCB transplantation with an adequate cell dose is the standard of care, leading to a 70% two-year overall survival (OS). It remains unclear, however, whether RCT participants have better outcomes than comparable patients not treated in the setting of a clinical trial. We compared the characteristics and outcomes of RCT participants (n=137) to a Francophone population-based registry of patients (real-world [RW] group) fulfilling the eligibility criteria used in our RCT and transplanted with 1 or 2 UCB units after a myeloablative conditioning (MAC) regimen between March 2015 (end of inclusion in the RCT) and February 2019 (n=141). The primary endpoint was the 2-year cumulative incidence (CI) of transplantation strategy failure as defined in our RCT. The 2 groups were comparable in terms of age, disease distribution, hematologic status at transplantation, follow-up, and HLA compatibility. Patients in the RW group were more likely to be transplanted with a single-unit UCB (87.9% versus 49.6%, P< .001) and to receive a radiation-free regimen (39.0% versus 60.6%, P< .001). The 2-year CI of transplantation strategy failure, TRM, and the 2-year probability of OS were similar between the 2 groups, although the relapse risk was higher in the RW group (31.2% ± 7.7% versus 20.4% ± 6.8%, P= .01), resulting in a significantly lower disease-free survival (DFS) (59.2% ± 8.4% versus 69.3% ± 8.0%, P= .047). This difference remained statistically significant only in the group of patients with acute lymphoid leukemia (ALL) who did not receive the conditioning regimen recommended by the RCT (fludarabine 75 mg/m2, total body irradiation 12 Gy, cyclophosphamide 120 mg/kg). The results of our RCT appear to be reproducible in real-world conditions, provided that the same cord blood selection criteria and conditioning regimen are used.

Haploidentical bone marrow transplantation in patients with relapsed or refractory severe aplastic anaemia in the USA (BMT CTN 1502): a multicentre, single-arm, phase 2 trial

Relapsed severe aplastic anaemia is a marrow failure disorder with high morbidity and mortality. It is often treated with bone marrow transplantation at relapse post-immunosuppressive therapy, but under-represented minorities often cannot find a suitably matched donor. This study aimed to understand the 1-year overall survival in patients with relapsed or refractory severe aplastic anaemia after haploidentical bone marrow transplantation. We report the outcomes of BMT CTN 1502, a single-arm, phase 2 clinical trial done at academic bone marrow transplantation centres in the USA. Included patients were children and adults (75 years or younger) with severe aplastic anaemia that was refractory (fulfilment of severe aplastic anaemia disease criteria at least 3 months after initial immunosuppressive therapy) or relapsed (initial improvement of cytopenias after first-line immunosuppressive therapy but then a later return to fulfilment of severe aplastic anaemia disease criteria), adequate performance status (Eastern Cooperative Oncology Group score 0 or 1, Karnofsky or Lansky score ≥60%), and the presence of an eligible related haploidentical donor. The regimen used reduced-intensity conditioning (rabbit anti-thymocyte globulin 4·5 mg/kg in total, cyclophosphamide 14·5 mg/kg daily for 2 days, fludarabine 30 mg/m2 daily for 5 days, total body irradiation 200 cGy in a single fraction), related HLA-haploidentical donors, and post-transplantation cyclophosphamide-based graft-versus-host disease (GVHD) prophylaxis. Additionally, for GVHD prophylaxis, mycophenolate mofetil was given orally at a dose of 15 mg/kg three times a day up to 1 g three times a day (maximum dose 3000 mg per day) from day 5 to day 35, and tacrolimus was given orally or intravenously from day 5 to day 180 as per institutional standards to maintain a serum concentration of 10-15 ng/mL. The primary endpoint was overall survival 1 year after bone marrow transplantation. All patients treated per protocol were analysed. This study is complete and is registered with ClinicalTrials.gov, NCT02918292. Between May 1, 2017, and Aug 30, 2020, 32 patients with relapsed or refractory severe aplastic anaemia were enrolled from 14 centres, and 31 underwent bone marrow transplantation. The median age was 24·9 years (IQR 10·4-51·3), and median follow-up was 24·3 months (IQR 12·1-29·2). Of the 31 patients who received a transplant, 19 (61%) were male and 12 (39%) female. 13 (42%) patients were site-reported as non-White, and 19 (61%) were from under-represented racial and ethnic groups; there were four (13%) patients who were Asian, seven (23%) Black, one (3%) Hawaiian/Pacific Islander, and one (3%) more than one race, with seven (23%) patients reporting Hispanic ethnicity. 24 (77%) of 31 patients were alive with engraftment at 1 year, and one (3%) patient alive with autologous recovery. The 1-year overall survival was 81% (95% CI 62-91). The most common grade 3-5 adverse events (seen in seven or more patients) included seven (23%) patients with abnormal liver tests, 15 (48%) patients with cardiovascular changes (including sinus tachycardia, heart failure, pericarditis), ten (32%) patients with gastrointestinal issues, seven (23%) patients with nutritional disorders, and eight (26%) patients with respiratory disorders. Six (19%) deaths, due to disease and unsuccessful bone marrow transplantation, were reported after transplantation. Haploidentical bone marrow transplantation using this approach results in excellent overall survival with minimal GVHD in patients who have not responded to immunosuppressive therapy, and can expand access to bone marrow transplantation across all populations. In clinical practice, this could now be considered a standard approach for salvage treatment of severe aplastic anaemia. Attention to obtaining high cell doses (>2·5 × 108 nucleated marrow cells per kg of recipient ideal bodyweight) from bone marrow harvests is crucial to the success of this approach. US National Heart, Lung, and Blood Institute and US National Cancer Institute.

Nonmyeloablative HLA-Identical Sibling Donor Transplantation for Children and Young Adults with Sickle Cell Disease: Interim Results of the SUN Multicenter Phase II Trial

Background: HLA-identical sibling hematopoietic stem cell transplant (HSCT) using myeloablative chemotherapy conditioning is a proven cure for sickle cell disease (SCD), but is associated with serious short and long-term toxicities. Additionally graft versus host disease (GVHD) can complicate care post-HSCT and contribute to mortality. Given these concerns many pediatric hematologists and families are reluctant to pursue HSCT for SCD. Nonmyeloablative HSCT resulting in stable mixed chimerism has been demonstrated to abrogate the SCD phenotype in adults. Data on outcomes of this approach to decrease toxicities and achieve cure in children remains scarce.Objective: To evaluate event-free survival (EFS), toxicity, health-related quality of life (HRQL), and transfusion burden among pediatric patients with SCD using a chemotherapy-free nonmyeloablative regimen.Methods/design: Children and young adults with SCD were prospectively enrolled in the Sickle transplant Using a Nonmyeloablative approach (SUN) multicenter clinical trial (NCT03587272). Six Sickle Cell Transplant Advocacy and Research Alliance (STAR) sites in the United States and Canada enrolled patients. The conditioning regimen consisted of alemtuzumab IV (0.03mg/kg on Day -7, 0.1mg/kg on Day -6, 0.3mg/kg on Days -5 to -3), low-dose total body irradiation with gonadal shielding (300 cGY on day -2), peripheral blood stem cells from an HLA-identical sibling, and sirolimus for at least one year. Baseline HRQL was compared with scores at day +30 and day +100 post-HSCT using the PedsQL and PROMIS measures. EFS was defined by any of the following events: death, graft failure (myeloid donor chimerism <10%), or GVHD.Results: All 30 of the patients planned for the primary endpoint of EFS have been enrolled. As of 7/20/2021, 24 patients are greater than 100 days post-HSCT with a median follow-up of 365 days (range 189-1105). The median age of this group at time of transplant was 13.5 years (range 2-22). All patients had neutrophil recovery (ANC >500/ul x 3 days) at a median of 21.5 days (range 0-29). Eleven patients (46%) did not require any platelet transfusions. Median transplant hospitalization was 16.5 days (range 14-43). Seven patients (29%) were again hospitalized (median 4 days, range 1-26). Three patients had secondary graft rejection at Day +71, +91, and +92 with no major complications and autologous recovery resulting in an EFS of 87.5% (Figure 1). Three additional patients have stable low donor chimerism (myeloid chimerism 11%, 38%, and 47%). The remaining 18 patients (75%) are disease-free and have robust donor engraftment (72-100% myeloid chimerism). Nine of these patients are >1 year post-HSCT and off sirolimus. Overall survival is 100% with no acute or chronic GVHD. Figure 2 shows total PedsQL scores during the peri-transplant time period. The median change in day +30 scores compared to baseline was 0 (IQR -7, +10), p=0.66. The median change in day +100 scores compared to baseline was +5 (IQR 0, +10), p=0.02.Conclusions: Outcomes of pediatric nonmyeloablative HLA-identical sibling HSCT for SCD appear similar to the larger adult experience with a GVHD-free, rejection-free survival of >80%. Importantly, patients have no worsening of their quality of life in the first month post-HSCT and already an improvement at day +100, suggesting that the short-term toxicities experienced by patients transplanted with this regimen are minimal. The majority of patients achieve disease resolution with no GVHD, but graft failure incidence appears higher than with myeloablative HSCT. Given the low intensity of this approach, a reasonable strategy may be to reserve myeloablation for a second transplant in the minority of patients who experience graft failure. [Display omitted] DisclosuresRangarajan: Medexus (Treosulfan): Consultancy, Honoraria. Guilcher: BlueBirdBio: Research Funding; Project Sickle Cure Study: Other: Principal Investigator, Research Funding. OffLabel Disclosure:alemtuzumab and sirolimus were used off-label as part of the studied transplant regimen

Umbilical Cord Blood Transplantation after Graft Failure from a Previous Hematopoietic Stem Cell Transplantation

Graft failure (GF) is a life-threatening complication after allogeneic hematopoietic stem cell transplantation (HCT). The incidence of GF after HCT using human leukocyte antigen (HLA) matched donors is lower than 5%; however, a higher incidence is observed when considering HLA mismatched donors or alternative donor sources and the use of reduced intensity conditioning (RIC) regimens.In the absence of autologous recovery, a second HCT is necessary to attempt preventing death due to prolonged pancytopenia. Previous studies describing outcomes of second HCT performed after a GF with different types of donor sources report a wide range of overall survival (OS) and transplant related mortality (TRM), however studies including a large number of patients receiving a second transplant with umbilical cord blood (UCB) are scarce.In this retrospective study, using registry data from Eurocord and the European Society for Blood and Marrow Transplantation (EBMT), we report the outcomes of 247 umbilical cord blood transplants (UCBT) performed after GF following a previous HCT. Data were analyzed separately for patients with malignant (n=141) and non-malignant diseases (n=106). UCB was the most frequent stem cell source that resulted in GF (65.0% and 68.9%, for malignant and non-malignant diseases, respectively), and most of the reported GF occurred within 100 days after HCT (92.3% and 85.9%). The most frequent diagnosis in malignant diseases was acute leukemia (64.5%), mainly acute myeloid leukemia (AML). In non-malignant diseases, the diagnoses most often reported were inborn error of metabolism (IEM) (37.7%), followed by bone marrow failure syndrome (BMF) (34.0%) and primary immune deficiency (PID) (21.7%). In malignant and non-malignant diseases, we observed a similar cumulative incidence of neutrophil engraftment of 59.1% (95% CI 51.4- 67.9%) and 60.4% (95% CI 51.7- 70.6%), in a median time of 23 and 24 days, and a 3-year OS of 28.9% (95% CI 21.8- 37.3%) and 49.1% (95% CI 39.5- 58.8%). TRM at 100 days and at 3 years for malignant diseases was 39.9% (95%CI 32.5 - 49.1%), and 57.5% (95%CI 49.4 - 66.8%). In multivariate analyses, none of the characteristics were statistically significantly associated with engraftment or overall survival.Although survival for patients requiring a second transplant is not optimal, UCB remains a valid life-saving option for some patients with GF as it is an immediately available source of stem cells in severely ill patients. The most appropriate stem cell source for salvage transplants remains controversial, as it depends on multiple factors including center choice, donor availability, underlying disease and existing comorbidities. DisclosuresPeffault De Latour: Pfizer: Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding; Amgen: Consultancy, Other, Research Funding; Jazz Pharmaceuticals: Honoraria; Alexion, AstraZeneca Rare Disease: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding.

Umbilical Cord Blood Transplantation after Graft Failure from a Previous Hematopoietic Stem Cell Transplantation

Graft failure (GF) is a life-threatening complication after allogeneic hematopoietic stem cell transplantation (HCT). In the absence of autologous recovery, a second HCT is necessary to attempt to prevent death due to prolonged pancytopenia. Previous studies describing outcomes of second HCT performed after GF with different types of donor sources report wide ranges of overall survival (OS) and transplantation-related mortality (TRM); however, studies including a large number of patients undergoing a second HCT with umbilical cord blood (UCB) as the graft source are scarce. This retrospective registry-based study examined data extracted from Eurocord and the European Society for Blood and Marrow Transplantation (EBMT) databases to evaluate outcomes of 247 UCBTs performed in EBMT transplant centers after GF following a previous HCT. Data were analyzed separately for patients with malignant diseases (n=141) and those with nonmalignant diseases (n=106). The most frequent HCT that resulted in GF was also UCBT (65.0% for patients with malignant diseases and 68.9% for those with nonmalignant diseases), and most GFs occurred within 100 days after transplantation (92.3% and 85.9%, respectively). The median follow-up was 47 months for surviving patients with malignant diseases and 38 months for those with nonmalignant diseases. We observed a similar cumulative incidence of neutrophil engraftment of 59.1% (95% confidence interval [CI], 51.4% to 67.9%) and 60.4% (95% CI, 51.7%-70.6%), respectively, at a median time of 23 days and 24 days, correspondingly. The 3-year OS was 28.9% (95% CI, 21.8% to 37.3%) in the malignant disease group and 49.1% (95% CI, 39.5%-58.8%) in the nonmalignant disease group. In patients with malignancies, TRM was 39.9% (95% CI, 32.5% to 49.1%) at 100 days and 57.5% (95% CI, 49.4%-66.8%) at 3 years. In multivariate analyses, none of the characteristics studied was statistically significantly associated with engraftment or OS. Although survival is not optimal in patients requiring a second HCT, UCBT remains a valid life-saving option for patients with GF.

Excellent Outcome of Alternative Donor HSCT in Fanconi Anemia Using Chemotherapy Only Regimen: Single Korean Institution Experience

Title) Excellent outcome of alternative donor HSCT in Fanconi anemia using chemotherapy only conditioning regimen: single Korean institution experience.Introduction) Fanconi anemia (FA) is a rare autosomal (or X linked) recessive disorder characterized by bone marrow failure, secondary malignancies, and skeletal anomalies. Hematopoietic stem cell transplantation (HSCT) remains the standard treatment of hematologic disease. Although HSCT from a matched sibling donor (MSD) is the optimal mode of transplant, many patients lack such a donor necessitating alternative donor HSCT (AD-HSCT). Radiation treatment during the conditioning regimen results in a high incidence of post-HSCT complications in FA patients, while serotherapy with alemtuzumab has been reported to increase infectious toxicities. Here, we report on the excellent outcome of 15 FA patients who received AD-HSCT with a fludarabine-based conditioning regimen with in vivo T cell depletion using rabbit anti-thymocyte globulin (ATG).Methods and Results) We reviewed the medical records of FA patients diagnosed by chromosomal breakage test and who received AD-HSCT between September 2007 and December 2016. Median age at transplant was 10.8 years (4.2~18.6) and 7 were male (46.7%). Eleven of 14 patients who received genetic study for FA were found to have mutations (6 with FANC-A mutations (40%), and 5 with FANC-G mutations (33.3%)). Hematologic reasons for HSCT were severe aplastic anemia in 13 (93.3%) and myelodysplastic syndrome in 2 patients (13.3%). One patient received HSCT from a mismatched related donor, while the remaining patients received unrelated HSCT. Seven transplants were human leukocyte antigen (HLA) fully matched (13.3%). Cell sources were as follows: peripheral blood stem cells 9 (60%), cord blood 4 (26.7%), bone marrow 2 (13.3%). Conditioning regimen consisted of fludarabine 30mg/BSA/day x5days (D-8,-7,-6,-5,-4), cyclophosphamide 5mg/kg/day x4days (D-5,-4,-3,-2), rabbit ATG 2.5mg/kg/day x3days (D-3,-2,-1). Graft-versus-host disease prophylaxis consisted of cyclosporine and mini-dose methotrexate. Medians of infused cell doses were as follows: TNC 16.51 x108/kg (5.17~42.4), CD34+ 15.49x106/kg(3.49~33.7).Twelve patients (80%) showed initial engraftment and full donor chimerism according to short tandem repeat polymerase chain reaction (STR-PCR) analysis. Of the 3 patients who showed primary graft failure, one showed autologous recovery, while the remaining 2 received additional HSCs from the same donor and a haploidentical family donor respectively, leading to engraftment. Acute GVHD grade II or above was diagnosed in 8 patients (53.5%) and resolved with steroid therapy. Chronic GVHD developed in two patients, one mild and one of moderate severity. The patient with moderate oral chronic GVHD was diagnosed with squamous cell carcinoma of the tongue 5years after HSCT. She received surgical resection and remains disease-free for 40 months. After transplantation, 5 patients (33.3%) experienced infectious complications including viral reactivation, bacteremia and fungemia but all recovered without complications. At a median follow-up of 59.6 months (6.3~107.9) all 15 FA patients are alive and remain free of hematologic disease.Conclusion) FA patients who received AD-HSCT with fludarabine-based conditioning with in vivo T cell depletion using rabbit ATG showed excellent outcome with a lower rate of infectious toxicities than has been reported with conditioning incorporating alemtuzumab. The incidence of primary graft failure should be monitored in a larger cohort of patients. DisclosuresNo relevant conflicts of interest to declare.

Post-Allogeneic Stem Cell Transplant Surveillance of CD34+ Sorted Peripheral Blood to Quantify Emergent DNMT3A, IDH and NPM1 clones and Correlation with Clinical Outcome

Introduction - Rising NPM1 mutant minimal residual disease (MRD) is strongly associated with relapse post-chemotherapy for Acute Myeloid Leukaemia (AML). Utility of other mutations affecting DNMT3A, IDH1 and IDH2 for MRD tracking has been hampered by persistence of clonal hematopoiesis after chemotherapy. In the post-allogeneic stem cell transplant (alloHSCT) context however, we show that host-derived clonal hematopoiesis is erased by donor hematopoiesis. We therefore sought to examine kinetics of re-emergence of host-derived mutations in CD34+, CD33+ CD3+ fractionated peripheral blood (PB) and correlation with loss of donor chimerism (DC) and clinical outcome.Aim - To utilize ddPCR monitoring to track mutant DNMT3A, IDH1, IDH2 and NPM1 clones in CD34+/CD33+ and CD3+ sorted peripheral blood fractions following alloHSCT for AML.Methods - Patients undergoing alloHSCT between January 2014 and December 2016 with known mutations in the hotspot regions of DNMT3A, IDH1, IDH2 and NPM1 as detected by Sequenom Mass Array were included in the analysis cohort. An unfractionated pre-transplant peripheral blood sample was utilized for mutation determination, with serial fractionated PB samples analyzed and stored as part of routine DC assessment. DC was assessed by selection of disparate donor-recipient short tandem repeats (STR) sequences. CD3+, CD33+ CD34+ cell fractions sorted using MAC beads. Cell fractions with sufficient input DNA were analyzed by ddPCR utilizing FAM and HEX probes to quantify mutant and wildtype DNMT3A R882H and R882C, IDH1 R132C and R132H, IDH2 R140Q and NPM1 insA. Mutant and wild-type copy number was determined utilizing Poisson statistics and fractional abundance (FA) determined. Statistical analysis was performed in R version 3.3.2 and GraphPad Prism version 7.0b.Results - 23 patients were analyzed with 9 with DNMT3A (8 R882H, 1 R882C), 2 IDH1 (1 R132C, 1 R132H), 6 IDH2 (all R140Q) and 14 NPM1 insA mutations. Demographic information is summarized in table 1. Based on known mutational profile of the cohort, FA of pre-transplant DNMT3A and IDH mutations ranged between 0.06% - 45.8%, while only 1 of 7 pre-transplant NPM1 samples was positive (0.0512%). FA rose earlier in CD34 fraction, then in CD33 or CD3 fractions. In 9 out of 10 paired pre-transplant and post-transplant samples, there was a significant reduction in FA (median 97% reduction), despite a variety of conditioning intensities. Many positive post-transplant blood specimens represented pre-leukemic mutations, with mutant positivity in both CD34+ and CD3+ fractions. In 6/6 cases with either a persistently high or rising peripheral blood mutant FA, clinical relapse occurred (Figure 1A). All 5 subjects with a progressive rise in mutant burden had detectable disease prior to clinical disease relapse by a median of 30 days (range 25 - 51 days). Low-level (<1%) fluctuating positivity was seen in most post-transplant cases (figure 1B). A single case demonstrated autologous recovery post-transplant with their IDH2 clone followed by relapse. Falling CD34+ chimerism to ≤80% was detected in 9 patients during surveillance. Of these, an emergent mutant clone was detected in all but one who was confirmed negative for NPM1 insA on RT-qPCR on marrow. In contrast to the pre-transplant setting, rising levels of rising levels of pre-leukemic IDH and DNMT3A from a negative baseline post donor engraftment was a strong predictor of impending relapse (figure 1A). 5 cases with emerging clones identified during MRD surveillance molecularly responded to immune manipulation, such as withdrawal of immunosuppression or donor lymphocyte infusion, resulting in restoration of donor chimerism and falling FA (figure 1C).Conclusion - Monitoring of DNMT3A, IDH1, IDH2 and NPM1 mutations in peripheral blood sorted fractions post alloHSCT was feasible and a valuable adjunct to chimerism monitoring. CD34+ sorted peripheral blood samples were most sensitive for early detection of molecular relapse. Serial PB monitoring of recurrent AML mutations, including pre-leukemic clones, may have utility after SCT for AML. Prospective studies of mutational tracking and therapeutic intervention are suggested. [Display omitted] DisclosuresFleming:Abbvie: Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astellas: Membership on an entity's Board of Directors or advisory committees; BMS: Speakers Bureau; MSD: Speakers Bureau. Spencer:Amgen: Consultancy, Honoraria, Research Funding; Janssen: Honoraria, Research Funding. Wei:AbbVie, Celgene, Servier: Research Funding; AbbVie, Celgene, Novartis, Amgen, Servier: Membership on an entity's Board of Directors or advisory committees; AbbVie, Celgene, Novartis, Amgen, Servier: Honoraria.

Autologous Stem Cells as Backup for Patients Undergoing Allogeneic Related Transplant for Thalassemia Major.

Abstract 4539Autologous backup of harvested stem cells from patients with Beta thalassemia major, undergoing allogeneic HLA matched sibling transplantation, in order to rescue the patient in the event of graft failure, has been practiced in some transplant centers in the world. From February 2007 we instituted a program of harvesting and cryopreserving autologous bone marrow for all patients undergoing transplant for thalassemia at our center and this abstract is a report on 62 patients for whom this was done over the past 26 months till June 2009. Since most of the patients were below 10 years a bone marrow harvest was performed under general anesthesia. The harvest was depleted of red cells by gravity sedimentation using hydroxyethyl starch, plasma depleted and cryopreserved using 10% dimethyl sulfoxide and stored at -18-degC in the vapor phase of a liquid nitrogen storage system. The mean volume of the product before freezing was 180 ml. The median CD34 cell dose was 8.35 × 106 cells/kg (range 0.6 to 24.6 × 106 cells/kg).During this 26 month period there was one early rejection, after initial engraftment, without autologous recovery with the patient being critically ill and febrile. Autologous stem cells were re-infused on day + 90 when the ANC was 0. However there was progressive deterioration in respiratory function and the patient died on day+92 with disseminated pulmonary aspergillosis. It is extremely difficult to decide when to re-infuse autologous stem cells in a patient who is sick post transplant and may not engraft. There was only one other rejection in this cohort of 62 patients but this patient had spontaneous recovery of autologous hematopoiesis and did not require intervention.The total cost of harvesting autologous stem cells under anesthesia and Cryopreservation, at this center is approximately $ 1600 and this represents 10% of the total cost of an allogeneic stem cell transplant. In this cohort of 62 patients, cryopreserved stem cells were used in only one patient without preventing mortality. The increased cost, manpower and time required for this procedure needs further evaluation and also the criteria on which autologous stem cells are to be re-infused needs to be established. Disclosures:No relevant conflicts of interest to declare.

Correction: Roato et al. A Novel Method to Optimize Autologous Adipose Tissue Recovery with Extracellular Matrix Preservation. Processes 2020, 8, 88

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Partially mismatched pediatric transplants with allogeneic CD34^+ blood cells from a related donor

This was a phase I, multi-center study of 13 pediatric patients (median age, 11 years) to evaluate toxicity, hematopoietic recovery, and graft-versus-host disease (GVHD) after allogeneic transplantation of enriched blood CD34(+) cells obtained from genotypically haploidentical but partially HLA-mismatched related donors (8 parents and 5 siblings). With regard to rejection, donor HLA disparity was 1 (5), 2 (6), or 3 loci (2). With regard to GVHD, recipient HLA disparity was 0 (1), 1 (3), 2 (8), or 3 (1). The patients suffered from acute myelogenous leukemia (6), chronic myelogenous leukemia (4), acute lymphoblastic leukemia (2), or hemolytic anemia plus immunodeficiency disorder (1). To reduce the risk of graft failure through the infusion of a large amount of stem cells, peripheral blood cells (PBC) were mobilized by recombinant granulocyte colony-stimulating factor (G-CSF; lenograstim, 10 microgram/kg/d for 5 days) and collected by 2 to 5 aphereses. To both enhance engraftment and reduce GVHD, CD34(+) cells were enriched using immunomagnetic procedures with the Baxter ISOLEX 300 system (Baxter Healthcare Corp, Irvine, CA) and cryopreserved. After variable cytoreductive regimens, a median of 7.7 (range, 2.2 to 14) x 10(6)/kg of CD34(+) cells and 1.03 (0.05 to 2.09) x 10(5)/kg CD3(+) cells were infused. Using Center-specific posttransplant supportive care and immunosuppressive GVHD prophylaxis, two patients experienced early death; one from veno-occlusive disease at day 17 and one from sepsis at day 18. Nine of 11 patients showed signs of engraftment; however, subsequent rejection was seen in 4 patients, 2 of whom had autologous recovery. Eight patients were evaluated in the early phase of marrow recovery. The median number of days to achieve an absolute granulocyte count of 0.5 x 10(9)/L was 14 (range, 9 to 20) and that to achieve a platelet count of 20 x 10(9)/L was 17.5 (range, 12 to 23). Donor chimerism persisted in five patients until death or current survival. All of the surviving patients with functioning-donor-type hematopoiesis were given total body irradiation. De novo acute GVHD (grades II and IV) was observed in two of the eight evaluated patients. Scheduled donor lymphocyte infusion (DLI), using the CD34(-) fraction, was administered to four patients, free of de novo acute GVHD, beginning between 28 to 43 days after transplant. Three of these patients developed acute GVHD (grades I, II, and IV). Cytomegalovirus infection was a major infectious complication but was successfully managed with gamma-globulin and gancyclovir treatment with or without additional DLI. Five patients are currently surviving, free of disease, with a follow-up ranging from 476 to 937 days. Each survivor has functioning hematopoiesis, three of donor origin and two of autologous origin. In conclusion, our results show that enriched blood CD34(+) cells from a mismatched haploidentical donor are a feasible alternative source of stem cells, but do not appear to ensure engraftment. Because none of the patients who were administered DLI survived, the therapeutic efficacy and safety of periodic DLI, as an integrated part of such transplants, needs to be clarified in further studies.

International Retrospective Study of Allogeneic Hematopoietic Cell Transplantation (HCT) for Activated Phosphoinositide 3-Kinase Delta (PI3K) Syndrome

Mutations resulting in increased PI3K signaling confer increased risk of B cell lymphoma, recurrent infections, poor viral control, and autoimmunity. Allogeneic HCT is curative, but the optimal approach to HCT for these patients is still evolving as experience grows. Herein, we present the clinical outcomes of 27 patients transplanted for activating PI3K mutations. Required approvals were obtained by contributing centers. Nineteen <i>PIK3CD</i> patients and 8 <i>PIK3R1</i> patients received 22 and 10 HCTs respectively, at median age 12 years (range 2-66) at time of first HCT. Significant pre-HCT comorbidities were common, Fig 1. Conditioning platforms varied in intensity; most included serotherapy (84%). With median survivor follow up of 26.3 months from first HCT (range 2.4-71.8), overall survival was 85% (3 infectious deaths and 1 due to organ toxicity); graft failure (GF)-free survival (GFFS) was estimated at 80% at 1 year but declined to 68% by 2 years, Fig 2. Neutrophil engraftment occurred at median 15.5 days (range 11-33) with autologous recovery in 1 patient at day +14 and another deceased prior to engraftment. Four engrafted patients are alive and well despite mixed donor chimerism (<95%). Nine (33%) patients required 24 total subsequent unplanned donor cell infusions (DCI) for mixed chimerism (n=15), poor graft function (n=2), infection (n=1), GF (n=3), malignancy relapse (n=1), or to improve immune reconstitution (n=2). Grade 2-4 acute graft versus host disease (GVHD) occurred in 27% patients, with Grade 3-4 acute GVHD and limited self-resolved chronic GVHD in 1 (4%). Organ toxicities and infectious complications are summarized in Fig 3; CMV infection requiring treatment occurred in 11 (41%) patients with disease in 3 (11%). Serotherapy use, conditioning intensity, and degree of donor human leukocyte antigen (HLA) match were not significantly associated with cumulative incidence of GF or subsequent unplanned DCI (with death as a competing risk), while mTOR inhibitor use post-HCT was associated with subsequent unplanned DCI for graft augmentation or GF (p=0.006). An mTOR inhibitor was used within the year following 12 HCTs, for primary GVHD prophylaxis (n=7) or to treat disease manifestations or GVHD; loss of chimerism and/or need for subsequent DCI occurred in 9 of these. Patients with activating PI3K mutations are at overall significant risk of GF or need for subsequent DCI. While we found no association with GF or DCI for discrete elements such as serotherapy use, donor source, or conditioning intensity, small numbers preclude conclusions regarding the optimal HCT approach, and more HCTs with longer follow up are needed to refine these preliminary findings. Post-HCT mTOR inhibitor exposure was associated with need for subsequent unplanned DCI, perhaps by providing a survival advantage to host lymphocytes, and may thus be detrimental in these patients during the early post-HCT timeframe.

Hematopoietic Stem Cell Transplantation in Children with Sickle Cell Disease: Myeloablative Versus Reduced Intensity Conditioning

<h3>Background</h3> Sickle cell disease (SCD) is prevalent in Saudi Arabia. We reviewed transplant outcome among SCD patients who underwent HLA-matched related donor HSCT at our institution using either myeloablative or reduced intensity conditioning (RIC) <h3>Methods</h3> myeloablative conditioning (MAC) regimen was intravenous (IV) busulfan (Bu) 16mg/kg, cyclophosphamide (Cy) 200mg/kg, and rabbit anti-thymocyte globulin (ATG) 10mg/kg (BuCyATG) and recently we use TBF regimen (thiotepa 8mg/kg, IV Bu 16mg/kg, and fludarabine 160mg/m²). GVHD prophylaxis included calcineurin inhibitor (CNI) and methotrexate (10mg/m²) on day 1, 3, and 6. CNI was continued for one year post transplant then tapered slowly. Based on parental preference, we used RIC regimen that included alemtuzumab, fludarabine, and melphalan (AFM) in 4 patients as reported by (King et al. AJH 2015). Three patients participated in a pilot RIC study (NCT02776202) which included pre-conditioning hydroxyurea (40mg/kg) from day -60 to day -10 and intensive iron chelation if needed followed by conditioning that included ATG 10 mg/kg, fludarabine 175mg/m², and melphalan 140 mg/m² (ATGFM) with GVHD prophylaxis consisting of mycophenolate mofetil from day -3 to +45 and sirolimus from day -1 until at least one year post transplant. Bone marrow was the source of stem cells in all patients. SCD-specific supportive care was implemented <h3>Results</h3> A total of 41 SCD patients were transplanted, 34 received MAC and 7 RIC. Indications for HSCT were recurrent pain crisis (n=25), stroke or abnormal transcranial doppler (n=13), and other (n=3). Patient and transplant characteristics are shown in Table. All patients who underwent MAC are alive and free of SCD at a median follow up of 444 days. Among patients who received RIC, 4 had late graft failure with autologous recovery. Of those, two underwent successful second HSCT using MAC and 2 patients are alive with SCD. In addition, 2 patients who received RIC (1 AFM and 1 ATGFM) are off immunosuppressant with full donor chimerism more than 2 years post-transplant and one patient (ATGFM) is still on sirolimus at 351 days post-transplant with low donor chimerism. There was no mortality in our study <h3>Conclusions</h3> MAC HSCT in SCD is well tolerated and associated with excellent outcome. There is high rate of late graft failure with the use of RIC in SCD.

Clinical course of autologous recovery with chromosomal abnormalities after allogeneic hematopoietic stem cell transplantation.

After primary graft failure following allogeneic hematopoietic stem cell transplantation, some patients experience autologous recovery of hematopoiesis without salvage transplantation. However, clinicians occasionally encounter unusual chromosomal abnormalities in recipient cells, not related to the original underlying diseases. In this study, through a survey based on data from the nationwide registry at the Japan Society for Hematopoietic Cell Transplantation, 42 patients were identified as having chromosomal abnormalities after autologous recovery. The complex chromosomal abnormalities were not consistent and randomly changed at each testing. Of the 42 patients, seven experienced disappearance of chromosome abnormalities without any treatment, and the probability was estimated as 17.4% (95% CI: 7.5-30.7%) at the 5-year observation. On the other hand, two patients developed hematologic malignancy at 1447 and 6202 days. Ten patients were alive without relapse or development of hematologic disorders, even though chromosomal abnormalities were continuously detected at a median of 3192 (103-4710) days. In conclusion, chromosomal abnormalities can persist for more than 10 years, and may eventually contribute to hematologic malignancy development in a small fraction of cases. Although oncogenic effects of the chromosomal abnormalities are still unclear, these findings may provide supporting evidence for late occurrence of secondary malignant neoplasms after cancer treatment.

Reduced-Toxicity (BuFlu) Conditioning Is Better Tolerated but Has a Higher Second Transplantation Rate Compared to Myeloablative Conditioning (BuCy) in Children with Inherited Metabolic Disorders.

Hematopoietic stem cell transplantation (HCT) is a primary treatment for various inherited metabolic disorders (IMDs). Achieving stable and sustained engraftment while minimizing transplantation-related morbidity and mortality is critical to optimizing outcomes for IMDs. Traditional regimens have used myeloablative approaches, primarily busulfan and cyclophosphamide (BuCy), which is associated with significant regimen-related toxicity. Alternatively, reduced-toxicity regimens, such as busulfan and fludarabine (BuFlu), have been proposed to offer similar efficacy with reduced toxicities. We compared transplantation-related outcomes with BuCy-based and BuFlu-based conditioning in patients with IMDs. We retrospectively analyzed the University of Minnesota's transplantation database for patients with IMDs who underwent HCT using a BuCy (with alemtuzumab) or BuFlu (with antithymocyte globulin) preparative regimen between March 2008 and September 2017. Overall survival (OS), event-free survival (EFS), and incidence of neutrophil and platelet recovery were determined using standard definitions. Complications such as graft failure, sinusoidal obstruction syndrome, hemorrhagic cystitis, and respiratory failure were compared. Graft failure includes primary and secondary aplastic graft failure with and without autologous recovery. The incidence of viral infections post-transplantation in the 2 regimens was also determined. A total of 99 patients underwent HCT for IMDs during the study period. Sixty-four patients received BuCy conditioning, and the other 35 received BuFlu. Hurler syndrome (46%) and adrenoleukodystrophy (43%) were the most common IMDs, and umbilical cord blood was the most common graft source (74%). One-year OS was similar in the 2 groups (81.2% in BuCy versus 85.5% in BuFlu; P=.8), with an EFS of 75% versus 63%, respectively. The 2 groups also had similar incidences of grade III-IV acute GVHD (9% versus 6%; P=.5) and chronic GVHD (9% versus 7%; P=.67). Neutrophil and platelet recovery were similar in the 2 groups, with a significantly shorter duration of hospital stay noted in the BuFlu cohort (median, 21 days versus 34 days; P=.002). The cumulative incidence of graft failure was significantly higher in the BuFlu group (29% versus 14%; P=.08), as was the rate of second HCT (27% versus 3%; P=.001). The incidences of adenoviral infection (14% versus 0%; P=.02) and hemorrhagic cystitis (23% versus 3%; P=.01) were higher in the BuCy group. T cell engraftment occurred significantly sooner with BuCy conditioning until 1-year post-transplantation, but donor myeloid engraftment was similar in the 2 groups. Our data indicate that reduced-toxicity conditioning is associated with lower rates of infection and other transplantation-related complications but is concerning for a higher rate of graft failure in patients with IMDs. Alternate immunosuppressive agents and novel techniques should be considered to minimize toxicities and reduce complications.

Abatacept Is Effective for Gvhd Prophylaxis after Unrelated Donor Stem Cell Transplantation (URD SCT) for Severe Sickle Cell Disease (SCD)

Background In 2016, results from the first URD SCT for SCD (the SCURT Trial) revealed a 2-year overall survival (OS) and event-free survival (EFS) of 79% (95% CI 59-90) and 69% (95% CI, 48-82) respectively following reduced intensity conditioning (RIC).1 Though the RIC approach provided successful engraftment in the majority, the transplant approach was not considered safe for widespread adoption due to high rates of graft-versus-host disease (GVHD) especially in children &amp;gt;13 years, a predominant cause of mortality. Strategies to minimize GVHD were essential if URD SCT was to be considered with curative intent in SCD. Aim/Method Multicenter trial (NCT03128996) with the primary objective of determining EFS in non-malignant disorders at one-year was amended as follows. The phase I SCD cohort included conditioning with hydroxyurea, proximal alemtuzumab, fludarabine, and melphalan in patients with 8/8 HLA-matched URD (-A, -B, - C and -DRB1).1 Thiotepa (8 mg/kg) was added in 7/8 HLA-mismatched SCT. GVHD prophylaxis included a calcineurin inhibitor and methotrexate as previously described. Abatacept (10 mg/kg) was administered on days -1, +5, +14, +28, +60, +100, +180, +270 and +365 based on efficacy described against acute GVHD with early dosing after SCT for malignant disorders.2,3 The latter 3 doses were omitted in cord transplant recipients. Result Thirteen children (7-21 years) underwent SCT (8/8 URD marrow- 7; 7/8 URD marrow or cord-6) primarily for stroke (N=6), ≥3 severe vaso-occlusive pain crises (N=4) or ≥2 acute chest syndrome episodes per year (N=3). The conditioning regimen was well tolerated. One patient had primary graft rejection after CMV infection (7%) and had autologous recovery. All other patients engrafted; neutrophils at median of 18 days (10-24), platelets at median of 28 days (16-39) and are surviving free of SCD with median follow-up of 12 months (range 4-59). Myeloid lineage donor chimerism was &amp;gt;95% and lymphoid was 39%- 100% at day+100. Two-year OS and EFS was 100% and 92.3% (95% CI, 6.57-35.7), respectively. The day+100 incidence of grade II-IV and III-IV acute GVHD incidence was 23% and 15% respectively. One-year incidence of chronic GVHD was 38%. However, only one patient (7%) developed extensive cGVHD. One patient (7%) developed posterior reversible encephalopathy syndrome and recovered. Viral replication in blood was detected in 7 of 13 patients (7 CMV, 1 EBV reactivation). No patient developed EBV PTLD or required EBV-related intervention. Conclusion In comparison to previous experience1 with RIC and URD SCT, our early observations are (1) a lower incidence of PRES (7 vs 34%) (2) low incidence of severe acute GVHD (15% vs 17% grade III -IV) despite mismatched donors, (3) low incidence of extensive chronic GVHD (7% vs 38%) and (4) no mortality despite patient age (10/13 were &amp;gt;13 years old). We attribute this gain to avoiding steroid use, and the benefit of including abatacept into the treatment regimen. The engraftment, safety, and immune reconstitution profile continue to be monitored in this ongoing trial now accruing in a Phase II cohort. As we and others work toward expanding donor options for SCD transplants, we submit that all alternate donor transplants for severe SCD are experimental and should be performed on clinical trials that track success and pitfalls. Reference: 1. Shenoy S et al. A trial of unrelated donor marrow transplantation for children with severe sickle cell disease. Blood. 2016 Nov 24; 128(21): 2561-2567. 2. Koura et al. In vivo T cell costimulation blockade with abataceptfor acute graft-versus-host disease prevention: a first-in-disease trial. Biol Blood Marrow Transplant. 2013 Nov; 19(11): 1638-49. 3. Watkins BK et al. T cell co-stimulation blockade with CTLA-4 Ig (Abatacept) for acute GVHD prevention in HLA-matched and mismatched unrelated donor transplantation: Results of a Phase 2 trial. Abstract 65. ASTCT Meetings, Houston 2019. Figure Disclosures Shah: Jazz pharmaceuticals: Speakers Bureau. OffLabel Disclosure: Abatacept, FDA approved for rheumatoid arthritis is a fusion protein that inhibits T-cell activation by binding to CD80/CD86 on antigen-presenting cells (APCs).It is used for acute graft-versus-host disease (aGVHD) prevention during unrelated-donor hematopoietic cell transplantation in this study

Sirolimus Combined with Cyclosporine (CSP) and Mycophenolate Mofetil (MMF) As Graft-Vs-Host Disease (GVHD) Prophylaxis after Nonmyeloablative (NMA) Hematopoietic Cell Transplantation (HCT) Using HLA Class I or Class II Antigen Mismatched Donors: Results from a Phase II Multi-Center Trial

The success of HCT is highly dependent on the availability of compatible donors. Depending on ethnicity, fully HLA-matched donors cannot be identified for 25-84% of patients. In an effort to extend the use of HLA-mismatched donors to patients only eligible for NMA HCT, we previously demonstrated that engraftment and long-term survival can be achieved using CSP and MMF immunosuppression after HLA class I antigen-mismatched HCT (Nakamae et al, 2010). Based on this trial, we designed a phase II multi-center trial to assess the efficacy of GVHD prophylaxis with triple immune suppression with CSP, MMF and sirolimus after HLA class I or class II antigen mismatched NMA HCT (fludarabine 90mg/m2 and 2-3 Gy TBI). Patients ineligible for high-dose conditioning with only HLA class I or class II antigen mismatched donors available were eligible for inclusion. The primary objective was to determine whether the incidence of grades 2-4 acute GVHD can be reduced to less than the historical rate of 70% with the triple-immunosuppression. The evaluation was planned to be carried out separately among HLA class I and class II mismatched patients. Secondary objectives included day 100 non-relapse mortality (NRM) and grades 3-4 acute GVHD. CSP was started on day -3 and continued to day +150 and then tapered off by day +180. Sirolimus was started on day -3 through day +180 and then tapered off by day +365. MMF was given thrice daily from days 0 to +30 then twice daily to day +100 and tapered off by day +150. A total of 76 patients were enrolled and received conditioning with fludarabine and TBI followed by infusion of unmodified G-CSF mobilized peripheral blood stem cell (PBSC) grafts. The median age was 63 (21-76) years, and median follow-up of surviving patients was 47 (4-94) months. 51 (67%) and 25 (33%) of patients had HLA class I or II mismatches, respectively. Transplant demographics are summarized in Table 1. Sustained engraftment was observed in all but 1 (1%) patient with myeloproliferative disease who had autologous recovery after transplant. Median number of days with neutrophils &amp;lt; 500 cells/ml and platelets &amp;lt;20,000 platelets/ml were 14 (0-67) and 2 (0-70), respectively. Full donor T-cell chimerism (&amp;gt;95% donor) was achieved in 48% and 63% at days +28 and 84, respectively. Outcomes are summarized in Table 2.The cumulative incidence of grade 2-4 acute GVHD at day +100 was 34% in all patients (29% and 48% after HLA class I and class II mismatched, respectively; p=0.09) (Figure 1), with only 3% of patients experiencing grade 3 acute GVHD and no patients experienced grade 4 acute GVHD. NRM at day +100, 2 years and 4 years were 4%, 15% and 17%, respectively (HLA class I vs class II: p=0.58) (Figure 2). The 2- and 4-year cumulative incidences of chronic GVHD were 54% and 57% (HLA class I vs. class II: p=0.11). Relapse incidences at 2 and 4 years were 26% and 31% with no differences between the class I and II mismatched patients (p=0.54) (Figure 2). The cumulative incidences at 2 and 4 years of progression-free survival (PFS) were 59% and 52%, and overall survival (OS) were 68% and 62% with no differences between HLA class I and II mismatches for PFS or OS (p=0.64 and 0.90, respectively) (Figure 2). Compared to historical data from our previous trial using MMF and CSP prophylaxis alone in patients with HLA class I mismatches, the addition of sirolimus to GVHD prophylaxis with CSP/MMF improved outcomes both after HLA class I or class II mismatched HCT (Nakamae et al, 2010). In a comparison of HLA class I mismatches only, day +100 grade 2-4 acute GVHD was reduced from 69% in the historical cohort to 29% in the current trial. The relapse incidences were comparable, while 2-year NRM decreased from 47%, in historical controls, to 16%, and translated into improved OS from 26% to 67% at 2 years in the current study. No difference was observed in the incidence of chronic GVHD. Furthermore, in the current trial, similar results were seen using HLA class II mismatched donors, suggesting that the triple drug immunosuppression could be used with either type of mismatch. The current trial demonstrates that triple drug immunosuppression with CSP, MMF, and sirolimus is safe and effective in reducing both acute GVHD and NRM after NMA HCT with either HLA class I or class II antigen mismatched donors. Disclosures Maloney: Juno Therapeutics: Honoraria, Patents &amp; Royalties: patients pending , Research Funding; Celgene,Kite Pharma: Honoraria, Research Funding; BioLine RX, Gilead,Genentech,Novartis: Honoraria; A2 Biotherapeutics: Honoraria, Other: Stock options . OffLabel Disclosure: In the current study cyclosporine, mycophenolate mofetil and sirolimus are used to prevent graft versus host disease after allogeneic hematopoietic cell transplantation. Fludarabine is used together with total body irradiation as at part of the conditioning prior to allogeneic hematopoietic cell transplantation.