HLA-haploidentical Transplantation Research Articles

HLA-Haploidentical Hematopoietic Cell Transplantation of Ex Vivo Tcrαβ-Depleted Grafts with CD45RA-Depleted Memory T Cell Add-Back in Adults and Children with Hematological Malignancies: 4-Year Follow-up of Multicenter Study in Singapore

Background: Haploidentical hematopoietic cell transplantation (HCT) provides an alternative option for patients without HLA-matched donors. Graft-versus-host disease (GVHD), engraftment failure, and infectious complications are main causes of non-relapse mortality (NRM). We hypothesized that selective depletion of TCRαβ+ and CD45RA+ naïve T cells will permit hematopoietic engraftment while effectively reducing GVHD and providing donor immune reconstitution through adoptive transfer of donor's mature NK cells, γδ T cells and CD45RO+ memory T cells.Methods: Mobilized PBSC products were divided into two fractions in 9:1 ratio and depleted using CliniMACS device after labelling with TCRαβ and CD45RA reagents (Miltenyi Biotec, Bergish-Gladbach, Germany) respectively. All except 6 patients received the standard conditioning regimen of fludarabine 160mg/m 2 divided daily over 4 days, thiotepa 10mg/kg divided twice daily for 1 day, and melphalan 70 - 140mg/m 2 for 1 day, in combination with either total lymphoid irradiation 6Gy (n=53) or 7.5Gy (n=12) over 3 equal fractions, or total body irradiation of 2Gy (n=17), or thymoglobulin (n=2). Short term GVHD prophylaxis was given for 30 days to 1 patient using MMF, 73 using tacrolimus, and 2 using sirolimus.Results: Between January 2017 and July 2021, we transplanted 85 patients, including 78 adults (median age, 48 years; range 20 - 70) and 7 children (median age, 13 years, range 7 - 17), with high risk AML (n=44), ALL (n=19), MDS (n=9), plasma cell neoplasm (n=4), mast cell leukemia (n=1), acute undifferentiated leukemia (n=1), CMMoL (n=2), CML (n=1) and lymphoma (n=2). Patients were infused with TCRαβ and CD45RA depleted grafts containing median of 6.19 x 10 6 (range 3.54 - 20.78) CD34+ cells/kg, 0.00 x 10 4 (range 0 - 0.97) CD45RA+CD3+ cells/kg, and 1.10 x 10 6 (range 0.15 - 11.67) CD45RO+CD3+ cells/kg. TCRαβ depleted graft fraction contained a median of 0.42 x 10 4 (range 0 - 11.30) TCRαβ+ cells/kg, and 7.61 x 10 6 (range 0.62 - 31.84) TCRγδ+ cells/kg. Only 1 patient experienced primary graft failure with no secondary graft failures. All others had engraftment of ANC > 500 cells/µL at median of 12 days (range 8 - 22) and PLT > 20,000 cells/µL at median of 11 days (range 7 - 17). 6 patients with high donor-specific HLA antibodies (DSA) titres engrafted successfully after desensitisation with plasma exchange, rituximab, and immunoglobulin.29 patients (34%) developed acute GVHD of grade II - IV (Gd II, n=20; Gd III, n=5; Gd IV, n=4), with a cumulative incidence (CI) of grade II-IV and grade III-IV of 31% (95% CI 21-42%) and 11% (95% CI 5-19%) respectively, at 100 days. Chronic GVHD was seen in only 4 patients at a 2-year CI of 6% (95% CI 2-13%).1-year CI of non-relapse mortality (NRM) and relapse were 22.7% (95% CI 13.9 - 32.9%) and 15.7% (95% CI 8.3 - 25.3%) respectively. 4 of the 17 NRM were attributed to aGVHD. Viral reactivation included CMV (n=32), HHV-6 (n=22), EBV (n=15), and adenovirus (n=8). 15 patients (17.6%) died of infection within 180 days, including 6 patients with fatal bacteraemia (bacteria, n=4; candidemia, n=2) and 1 patient from disseminated adenovirus infection. At a median follow up of 448 days (range 16- 1648) in surviving patients, 2-year overall (OS), event-free (EFS), and GVHD-free/relapse-free (GRFS) survival were 64.2 %, 54.0 %, and 49.0%, respectively (Figure 1).In multivariate analysis, only HCT-comorbidity index (HCT-CI) showed significant impact on OS (HR 3.38; 95% CI 1.42 - 8.02; p=0.0059), EFS (HR 2.62; 95% CI 1.18 - 5.76; p=0.0017), and NRM (HR 4.92; 95% CI 1.79 - 13.58; p=0.0021). Disease risk index (DRI) showed a trend in higher risk of relapse (HR 2.83; 95% CI 0.96 - 8.33; p=0.059). 2-year OS, EFS, and GRFS for the subset of 58 patients (adults, n=52; children, n=6) with HCT-CI score of 0 were 76.6 %, 63.4%, and 57.5 %, respectively (Figure 2).Conclusions: Our preliminary results suggest that RIC haplo-HCT with TCRαβ and CD45RA+ depleted grafts allow successful allograft in high-risk patients lacking suitable matched donors, including patients with high levels of DSA. Acute GVHD was generally abortive, leading to low incidence of chronic GVHD. Best outcomes are seen in patients with favourable HCT-CI. Further efforts are needed to reduce the risk of infection-related death in patients with high risk HCT-CI, and relapse in patients with high risk DRI, through optimization of anti-microbial prophylaxis or prophylactic infusion of memory-cell DLI. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

De-Escalation of Ptcy Dosing in Matched Allogenic Transplants: A Single Institution Retrospective Study

IntroductionThe role of post-transplant cyclophosphamide (PTCy) in preventing acute GVHD (aGVHD) and chronic GVHD (cGVHD) has been well established in the haploidentical setting (Al-Homsi AS et al., Post-transplant high-dose cyclophosphamide for the prevention of graft-versus-host disease. Biol Blood Marrow Transplant. 2015;21(4):604-611). More recently, several studies are also supporting its use in matched related and unrelated donors (Williams L et al., Post-transplantation Cyclophosphamide: From HLA-Haploidentical to Matched-Related and Matched-Unrelated Donor Blood and Marrow Transplantation. Front Immunol. 2020;11(April):1-7). But as new emerging data are starting to show some toxicities from that regimen, a reevaluation of the optimal PTCy dose is highly valuable (Duléry R et al., Early Cardiac Toxicity Associated with Post-Transplant Cyclophosphamide in Allogeneic Stem Cell Transplantation. JACC CardioOncology. 2021;3(2):250-259; Goldsmith et al., Posttransplant cyclophosphamide is associated with increased cytomegalovirus infection: a CIBMTR analysis. Blood. 2021;137(23):3291-3305).PTCy dose de-escalation in preventing GvHD was also evaluated in a phase I/II study (NCT03983850) with initial results indicating that de-escalation of PTCy (DL2, 25 mg/kg/day given in Days 3−4) may provide a feasible and effective approach in preventing severe aGvHD(McAdams MJ et al., Phase I Study De-Intensifying Exposure of Post-Transplantation Cyclophosphamide (PTCy) after HLA-Haploidentical Hematopoietic Cell Transplantation (HCT) for Hematologic Malignancies. Transplant Cell Ther Off Publ Am Soc Transplant Cell Ther. 2021;27(3): S9-S11). However, this was in the setting of haplo-identical transplants. Currently there are no studies that investigate the safety and efficacy of a lower dose of PTCy in matched allogenic transplants.MethodsWe retrospectively selected 37 consecutive patients who underwent transplant at our center from January 2017 to April 2021. Patients who received a mismatched or haploidentical transplants were excluded. 26 matched sibling or matched unrelated donor transplants were further analyzed. These were divided into 3 cohorts according to GVHD prophylaxis: cohort 1 (No-PTCy) received standard calcineurin inhibitor-methotrexate based GVHD prophylaxis (n=16), cohort 2 (PTCy-50) received PTCy at 50 mg/kg (D+3 and D+4) in combination other immunosuppressive drugs (ISD) (n=6), and cohort 3 (PTCy-25) received PTCy at 25 mg/kg (D+3 and D+4) in combination with other ISD (n=4). The reduced PTCy dosing was based on physician discretion due to various reasons (2 cardiac risk, 1 heavy pre-treatment, 1 unknown).ResultsBaseline characteristics are summarized in table 1. Median follow up for all survivors was 523 days (range, 97-1463) while it was shorter for PTCy cohorts at 152 days (97-534). There were zero grade 3 aGVHD in PTCy groups compared to 12.5% (2/16) in No-PTCy cohort (p=0.30). cGVHD was significantly lower in PTCy-50 and PTCy-25 as compared to No-PTCy (0/6, 0/4, 5/16 respectively, p=0.04). The 100-day treatment-related mortality (TRM) was significantly lower in PTCy-25 as compared to PTCy-50 and No-PTCy (0/4, 2/6, 2/16 respectively, p<0.001). There was no viral reactivation (EBV/CMV) in PTCy-25 as compared to 1/6 in PTCy-50 and 5/16 in No-PTCy (p=0.54). The length of hospital stay (LOS) for transplant and the median days for neutrophil recovery (NR) were shorter in PTCy-25 as compared to PTCy-50 and No-PTCy (25.5 days, 31 days and 28.5 days respectively for LOS, p=0.60; 15.5 days, 22 days and 17.5 days for NR, p=0.87). Although the overall survival (OS) seems to favor PTCy-25 (Figure 1), it is limited by short follow up.ConclusionDe-escalating the dose of PTCy to 25mg/kg x 2 in GVHD prophylaxis regimens appears to be efficacious and safe in patients receiving matched allogenic transplant. Further prospective studies including a larger patient sample and longer follow-up is warranted to investigate lower PTCy dosing in matched transplants over the current standard dosing. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Letermovir Is Effective for Prevention of Cytomegalovirus Reactivation in HLA-Haploidentical Peripheral Blood Stem Cell Transplantation with Post-Transplant Cyclophosphamide

[Introduction] Cytomegalovirus (CMV) infection is a common viral infection in recipients of allogeneic hematopoietic stem cell transplantation (allo-SCT). Early CMV reactivation after allo-SCT is associated with worse non-relapse mortality (NRM) and overall survival (OS). Recently, T-cell replete HLA-haploidentical SCT using post-transplant cyclophosphamide (PTCy-haplo SCT) has been developed and spread rapidly worldwide. Rationale of this strategy is assumed to be selective and cytotoxic depletion of alloreactive T cells which are responsible for graft-versus-host disease (GVHD), while preserving non-alloreactive T cells which can contribute to fight infections. However, recent studies showed that PTCy-haplo SCT was associated with the increased incidence of CMV infection. Letermovir (LET), a novel anti-CMV agent, which inhibits the CMV DNA terminase complex, was approved for the prevention of CMV reactivation in allo-SCT recipients in 2018 in some countries including Japan based on the result of a phase 3 trial. Our facility performs LET prophylaxis in allo-SCT recipient if either donor or recipient is seropositive CMV. Although LET is effective for the prevention of CMV reactivation in allo-SCT recipients, the clinical effectiveness of LET prophylaxis in PTCy-haplo SCT is not well elucidated. Based on these things, we retrospectively evaluated the efficacy of LET prophylaxis in PTCy-haplo SCT.[Methods] We retrospectively analyzed consecutive 99 recipients who received PTCy-haplo SCT at Hokkaido University Hospital from March 2013 to March 2021. We compared the cumulative incidence of CMV reactivation between the LET prophylaxis group (LET group, 33 patients) and LET non-prophylaxis group (non-LET group, 66 patients). LET was initiated on the day 0 at a dosage of 480mg daily. All patients were monitored for CMV reactivation by using the anti-CMV pp65 monoclonal antibody HRP-C7 assay at least once a week from the time of engraftment. CMV reactivation was defined as the detection of CMV antigen positive cells per 50000 white blood cells, whereas CMV disease was defined by organ dysfunction attributable to CMV.[Results] As baseline patient's characteristics were summarized in Table1, there were no difference between LET and non-LET group in terms of age, sex, underlying disease, disease risk at transplantation, prior transplantation, conditioning intensity, and CMV serostatus. All patients received peripheral blood stem cell transplantation. GVHD prophylaxis consisted of Cy (40-50 mg/kg on day 3 and 4), tacrolimus (from day 5), and mycophenolate mofetil (from day 5). The cumulative incidence of CMV reactivation at 150 days after transplantation in LET group was significantly lower than that in non-LET group (30.3% versus 69.7%; P <.001, Figure1A). Importantly, CMV disease were occurred in three patients without LET prophylaxis (gastritis, enteritis, and retinitis), but not in the patients with LET prophylaxis. The cumulative incidence of NRM at 1 year was similar between the patients with and without LET prophylaxis (17.6% versus 9.2%; P=0.366, Figure1B), as was OS at 1 year (71.5% versus 69.4%; P=0.801, Figure1C). Neutrophil engraftment was achieved in 32 patients (97%) at a median of 15 days in LET group and 64 patients (97%) at a median of 14.5 days in non-LET group (P=0.243). Furthermore, platelet engraftment was achieved in 26 patients (79%) at a median of 34 days in LET group and 57 patients (86%) at a median of 31 days in non-LET group (P=0.282). These findings suggest that LET does not affect engraftment. Interestingly, the length of hospitalization in the LET group was significantly shorter than that in non-LET group (the median, 59.5 days versus 71 days; P=0.0488), suggesting that LET suppresses CMV reactivation leading to early discharge.[Conclusion] To our best knowledge, this is the largest retrospective study about the efficacy of LET in PTCy-Haplo SCT. LET is effective for prevention of CMV reactivation in PTCy-haplo SCT. Further studies focused on the long term effect of LET prophylaxis in PTCy-haplo SCT, such as the incidence of relapse and chronic GVHD, is warranted. [Display omitted] DisclosuresNakagawa: AbbVie GK: Research Funding; Takeda Pharmaceutical Company: Research Funding. Teshima: Gentium/Jazz Pharmaceuticals: Consultancy; Merck Sharp & Dohme: Membership on an entity's Board of Directors or advisory committees; Pfizer Inc.: Honoraria; Nippon Shinyaku Co., Ltd.: Research Funding; CHUGAI PHARMACEUTICAL CO., LTD.: Research Funding; Fuji pharma CO.,Ltd: Research Funding; Takeda Pharmaceutical Company: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis International AG: Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; TEIJIN PHARMA Limited: Research Funding; Astellas Pharma Inc.: Research Funding; Bristol Myers Squibb: Honoraria; Janssen Pharmaceutical K.K.: Other; Kyowa Kirin Co.,Ltd.: Honoraria, Research Funding; Sanofi S.A.: Research Funding.

Phase I/II Study of Reduced Dosing of Post-Transplantation Cyclophosphamide (PTCy) after HLA-Haploidentical Bone Marrow Transplantation

Background: Post-transplantation cyclophosphamide (PTCy) is widely used for graft-versus-host-disease (GVHD) prophylaxis after hematopoietic cell transplantation (HCT). However, the standard PTCy dose (50 mg/kg/day) and timing (given on days +3 and +4) were largely extrapolated from murine skin allografting models, and these have never been rigorously tested to determine if they are optimal. We have shown in murine HCT models that an intermediate PTCy dose of 25 mg/kg/day on days +3/+4 is superior at preventing severe GVHD compared with 50 mg/kg/day on days +3/+4 (Wachsmuth et al., JCI. 2019). Furthermore, PTCy 25 mg/kg/day given on day +4 alone is equivalent to 25 mg/kg/day given on days +3/+4 at preventing severe GVHD (Wachsmuth et al. BBMT. 2019). Thus, the standard clinical dosing may be higher than necessary and potentially come at the cost of increased toxicity, delayed engraftment, and impaired immune reconstitution.Methods: This is a single institutional prospective phase I/II study (NCT03983850) to de-escalate PTCy exposure for adult patients with hematologic malignancies. All patients received myeloablative conditioning with IV daily busulfan/fludarabine, HLA-haploidentical bone marrow, and GVHD prophylaxis with PTCy (dose and timing based on Dose Level (DL)), mycophenolate mofetil (days +5 to +35), and sirolimus (days +5 to +80).The first 5 patients received PTCy 50 mg/kg/day on days +3/+4 (standard dosing, Dose Level 1) for comparative data. This was followed by a 3+3 dose de-escalation design testing 25 mg/kg/day on days +3/+4 (experimental, Dose Level 2) and 25 mg/kg on day +4 only (experimental, Dose Level 3), followed by a phase II expansion cohort at the better experimental dose level. The primary endpoint and dose limiting toxicity for the dose de-escalation was grade III-IV acute GVHD.Results: Phase I enrolled 19 patients, and the phase II expansion has enrolled 13 of 14 patients, 9 of whom have sufficient follow-up (60 days) to be considered evaluable for the primary endpoint; median follow-up of survivors evaluable for the primary endpoint is 288 (range 60-676) days. Patient and disease characteristics and outcomes for these patients are summarized in Table 1.No grade III-IV acute GVHD was seen at either experimental DL, and there have been no cases of grade II-IV acute GVHD at DL2 (Figure 1). Based on more reliable early engraftment (see below) but less intense and shorter duration of engraftment fevers, DL2 was taken to phase II.Engraftment was faster at the experimental DLs but was most consistent with DL2. Median neutrophil engraftment was at day 14 at DL2 compared with day 19 at the standard dosing (p=0.0004) (Figure 2A). Median platelet engraftment was at day 23 at DL2 compared with day 33 at the standard dosing (p=0.026) (Figure 2B). Correspondingly, transfusional requirements were lessened with DL2 (Figure 2C-D). Engraftment syndrome, manifesting as fever, rash, and mild transaminitis, occurred in 1 patient at DL2 and 2 patients at DL3, but resolved rapidly without intervention in all cases. Primary graft failure was seen in 1 patient at DL2, and relapse prior to engraftment was seen in 1 patient at DL3.Mucositis was less severe and shorter in duration for both experimental DLs when compared with standard PTCy dosing (Figure 2E). CMV reactivation requiring pre-emptive therapy was less frequently seen after lower PTCy dosing (Figure 3A). Symptomatic BK virus-associated cystitis in at-risk patients was shorter in duration for patients receiving lower PTCy; median duration was 74 days for the standard DL versus 26 days at DL2 and 7 days at DL3 (Figure 3B). At DL2, there have been 3 cases to date of chronic GVHD requiring systemic immunosuppression among the 13 engrafting patients with at least 100 days of follow-up.Conclusions: De-escalating PTCy exposure is feasible and effective in maintaining protection against severe acute GVHD while promoting more rapid engraftment and less early post-transplant toxicity. Two-day dosing of 25 mg/kg/day PTCy appears to allow for more consistent early engraftment and protection against protracted engraftment fevers compared with day +4 only. Longer follow-up and comparative studies are needed to understand if de-escalated PTCy is superior to the standard dosing schedule. [Display omitted] DisclosuresNo relevant conflicts of interest to declare. OffLabel Disclosure:The use of cyclophosphamide as graft-versus-host disease prophylaxis

Post-Transplant Cyclophosphamide after HLA Identical Compared to Haploidentical Donor Transplant in Acute Myeloid Leukemia: A Study on Behalf of Geth-TC

Introduction: High-dose post transplant cyclophosphamide (PTCY) effectively prevents graft-versus-host disease (GVHD) after unmanipulated HLA-haploidentical hematopoietic stem cell transplant (HSCT) and offer low rates of GVHD in the setting of HLA identical transplant. The objective of our study was to compare the outcomes of haplo vs HLA identical HSCT in patients undergoing HSCT for acute myeloid leukemia (AML) using PTCY.Patients and methods: We conducted a retrospective study of 229 patients undergoing a first HSCT for AML using PTCY, 130 from an haploidentical donor between 2013 and 2018 (median follow up 62.5 months) and 99 from a matched sibling (MSD) (n=38) or unrelated donor (MUD) (n=61) (median follow up 27 months) between 2013 and 2019, in 20 centers in Spain. Last update of the cohort was performed in March 2021.Results: Baseline characteristics are summarized in Table 1. There were more patients with active disease at transplant (5% MSD/MUD vs. 20% haplo, p=0.001), high/very high DRI (32% vs. 67%, p=0.000) and prior autologous HSCT (2% vs. 11%, p=0.010) in the haplo group. Mobilized peripheral blood stem cells was the most frequent stem cell source in both groups. Most patients received myeloablative conditioning (55% vs. 64%, p=0.170). All Patients in the haplo group received PTCY days +3+4 followed by a calcineurin inhibitor (CNI) and MMF from +5. In the MSD/MUD group, 37% received both CNI+MMF, 33% only CNI and 30% PTCY with sirolimus+MMF (this group included only MUD donors). None of the patients received ATG. Cumulative incidence of neutrophil recovery at day 28 was 97% in both groups, with a median of 16 and 17 days respectively (p=0.948). Both 2-year overall survival (OS) (72% vs. 62%, p=0.07) and event-free survival (EFS) (70% vs. 54%, p=0.055) were higher in the MSD/MUD group, but the difference was not statistically significant (Figure 1). Multivariate analysis only identified age and pre-transplant status as independent risk factors for OS, and pre-transplant status for EFS. No differences were found in the cumulative incidence of relapse at 2 years (19% vs. 25%, p=0.13) and non-relapse mortality (14% vs. 19%, p=0.145). Cumulative incidence of grade II-IV acute GVHD was lower in MSD/MUD (14% vs. 47%, p=0.000, Figure 2), while III-IV aGVHD was similar (4% vs. 9%, p=0.14). Cumulative incidence of chronic GVHD and moderate-severe cGVHD at 2 years was similar for both groups (42% vs. 33% (p=0.051); 22% vs. 19% (p=0.28)). No differences were found in GRFS (48% vs. 46% (p=0.506)). Most frequent cause of death in the early post-transplant period was non-GVHD related infection in both groups.Conclusions: in our experience, PTCY as GVHD prophylaxis in both MSD/MUD and Haplo transplant in AML using mostly PBSC effectively prevents GVHD and offers similar NRM, relapse and survival rates. Poor control of the disease before transplant was the only factor affecting OS and EFS in this setting. Prospective studies are needed to confirm our results. [Display omitted] DisclosuresBailen: Pfizer, Kite-Gilead, Gilead: Honoraria. Guerreiro: Novartis, Gilead: Consultancy, Honoraria. Oarbeascoa: Gilead: Honoraria, Speakers Bureau. Kwon: Novartis, Celgene, Gilead, Pfizer: Consultancy, Honoraria.

Acute GvHD after HLA-Haploidentical Hematopoietic Cell Transplantation with Regulatory and Conventional T Cell Immunotherapy Does Not Adversely Affect Transplantation Outcomes

IntroductionAdoptive immunotherapy with CD4+CD25+FOXP3+ regulatory T cells (Tregs) and conventional T cells (Tcons) has been employed after allogeneic hematopoietic stem cell transplantation (HSCT) to prevent Graft-versus-Host Disease (GvHD) while mantaining Graft-versus-Leukemia effect in the absence of any further immune suppressive GvHD prophylaxis (Di Ianni, Blood 2011; Martelli, Blood 2014). A recent study of age-adapted haploidentical HSCT with Treg/Tcon adoptive immunotherapy (Treg/Tcon haplo-HSCT) resulted in an unprecedented 75% chronic GvHD (cGvHD)/leukemia-free survival (CRFS) in acute myeloid leukemia patients. Acute GvHD (aGvHD) occured in 33% of patients and was the most frequent complication of the procedure (Pierini, Blood Advances 2021). Here, we analyzed clinical and histological characteristics of aGvHD and evaluated its impact on outcomes in patients who received Treg/Tcon haplo-HSCT.MethodsWe retrieved data of patients who underwent Treg/Tcon haplo-HSCT at Perugia University Hospital and who were evaluable for aGvHD from January 2015 until June 2021 (clinicaltrials.gov: NCT03977103). Histological features and lymphoid infiltration by immunohistochemistry were analyzed in gut samples of patients who received diagnostic colonscopy and biopsy for gastrointestinal symptoms.ResultsA total of 105 patients engrafted after Treg/Tcon haplo-HSCT. Mean age at transplant was 48 years (range 18-70). Acute leukemia was the most frequent diagnosis (78/105 myeloid, 23/105 lymphoblastic), 4 patients had myelodisplastic syndrome and 2 multiple myeloma. Twenty-seven (26%) patients had active disease at the time of HSCT. Fourteen (13%) patients received Treg/Tcon haplo-HSCT as a second HSCT procedure. Thirty-one (29%) patients developed grade II-IV aGvHD. Four patients had grade II aGvHD, 23 grade III, and 4 grade IV. Almost all patients (90%) presented gut involvement, while skin was involved in 64% of them and liver in 35%. To explain why gut symptoms such as diarrhea and abdominal pain were more frequently present than symptoms of skin or liver involvement, we evaluated 40 histological samples from 34 patients who received colonoscopy for suspected aGvHD. Twenty-two of them (65%) received a clinical diagnosis of aGvHD and pharmacological immune suppression was promptly started. Clinical diagnosis did not always match histological findings: biopsies were suggestive of aGvHD in 20/22 patients who required treatment, but also in 8/12 patients who did not. We found no difference in median CD3+ cell infiltration among patients who did not need immune suppressive treatments and patients with aGvHD (460 cells/mmq vs 446 cells/mmq). However, FOXP3+ Tregs preferentially infiltrated gut mucosa of patients who resolved clinical symptoms with no need of immune suppressive treatments (120 cells/mmq vs 59 cells/mmq, p = 0.008; FOXP3/CD3 ratio: 0.27 vs 0.18, p = 0.004). This observation suggested Treg defective homing to gut mucosa of aGvHD patients. Indeed, we found infused Tregs expressed lower levels of gut homing receptor α4β7 in comparison with Tcons (p< .001).Despite severe presentation at diagnosis, aGvHD resolved in the majority of patients (71%), and immune suppressive therapy could be completely withdrawn after a relatively short-course (median: 98 days, range 48-404). Sixteen/31 patients (52%) were steroid refractory and required further treatments after first-line (e.g. Ruxolitinib). Only two of them developed moderate/severe cGvHD and one is alive and off-therapy.Indeed, aGvHD diagnosis did not result in higher incidence of non-relapse mortality (cumulative incidence of 29% in aGvHD patients vs 27% in controls; p=non significant, ns, Fig.1A), relapse (13% vs 20%; p=ns, Fig.1B), or cGvHD (6.5% vs 3%; p=ns, Fig.1C). In fact, CRFS of aGvHD patients was similar to CRFS of patients that did not develop aGvHD (Fig. 1D, p=ns, median follow up of live patients: 1246 days).ConclusionsTreg/Tcon haplo-HSCT is followed by low rates of relapse and cGvHD and results in good CRFS in high risk leukemia patients. aGvHD after Treg/Tcon haplo-HSCT preferentially involves the gut where Treg homing is defective. Strategies that enhance Treg homing in the gut (e.g. low-dose IL-2) may help reduce aGvHD after Treg/Tcon haplo-HSCT. In conclusion, despite aGvHD occurred in 29% of patients, it was responsive to treatments and it did not result in disease relapse or cGvHD. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Signatures of GVHD and relapse after posttransplant cyclophosphamide revealed by immune profiling and machine learning

AbstractThe key immunologic signatures associated with clinical outcomes after posttransplant cyclophosphamide (PTCy)-based HLA-haploidentical (haplo) and HLA-matched bone marrow transplantation (BMT) are largely unknown. To address this gap in knowledge, we used machine learning to decipher clinically relevant signatures from immunophenotypic, proteomic, and clinical data and then examined transcriptome changes in the lymphocyte subsets that predicted major posttransplant outcomes. Kinetics of immune subset reconstitution after day 28 were similar for 70 patients undergoing haplo and 75 patients undergoing HLA-matched BMT. Machine learning based on 35 candidate factors (10 clinical, 18 cellular, and 7 proteomic) revealed that combined elevations in effector CD4+ conventional T cells (Tconv) and CXCL9 at day 28 predicted acute graft-versus-host disease (aGVHD). Furthermore, higher NK cell counts predicted improved overall survival (OS) due to a reduction in both nonrelapse mortality and relapse. Transcriptional and flow-cytometric analyses of recovering lymphocytes in patients with aGVHD identified preserved hallmarks of functional CD4+ regulatory T cells (Tregs) while highlighting a Tconv-driven inflammatory and metabolic axis distinct from that seen with conventional GVHD prophylaxis. Patients developing early relapse displayed a loss of inflammatory gene signatures in NK cells and a transcriptional exhaustion phenotype in CD8+ T cells. Using a multimodality approach, we highlight the utility of systems biology in BMT biomarker discovery and offer a novel understanding of how PTCy influences alloimmune responses. Our work charts future directions for novel therapeutic interventions after these increasingly used GVHD prophylaxis platforms. Specimens collected on NCT0079656226 and NCT0080927627 https://clinicaltrials.gov/.

Effect of Donor NKG2D Polymorphism on Relapse after Haploidentical Transplantation with Post-Transplantation Cyclophosphamide

NKG2D-mediated cytotoxicity is regulated by the single nucleotide polymorphism rs1049174, and its antitumor effect has been observed in various clinical settings. There are no previously published data on the influence of donor rs1049174 polymorphism on HLA-haploidentical allogeneic hematopoietic cell transplantation using post-transplantation cyclophosphamide (PTCy-haplo). We aimed to investigate the effect of donor NKG2D gene polymorphism on PTCy-haplo recipients. We retrospectively reviewed 91 consecutive PTCy-haplo recipients at our institution, and genotyped rs1049174 of the NKG2D gene in both donors and patients. In the patients who received PTCy without antithymocyte globulin (ATG) as graft-versus-host disease prophylaxis, the 2-year cumulative incidence of relapse/progression (RI) of PTCy-haplo from rs1049174 CC donors was lower than that from rs1049174 CG/GG donors (25.0% versus 52.4%; P=.041), and rs1049174 CC donors were associated with a decreased risk of relapse/progression (adjusted hazard ratio, 0.2; 95% confidence interval, 0.0 to 0.6; P=.007). Furthermore, a beneficial effect of rs1049174 CC donor on OS and RI was observed in non-acute myelogenous leukemia patients. This study demonstrates that receipt of PTCy-haplo from rs1049174 CC donors was associated with a decreased risk of relapse/progression in the patients who underwent PTCy-haplo without ATG. Future large-scale validation studies are needed to test the significance of donor NKG2D polymorphism in the development of a new donor selection algorithm for PTCy-haplo.

Identifying Risk Factors for Acute and Chronic Graft-Versus-Host Disease in T-Replete HLA-Haploidentical Hematopoietic Cell Transplantation with Post-Transplant Cyclophosphamide

Introduction: Acute(aGVHD) and chronic graft-versus-host disease (cGVHD) cause significant morbidity and mortality in patients post hematopoietic cell transplantation (HCT). The use of T-replete HLA-haploidentical transplantation (HIDT) with post-transplant cyclophosphamide has become a common donor source for patients lacking a suitably matched donor. In spite of the increase in HIDT, there is paucity of data describing aGVHD and cGVHD outcomes and potential risk factors for developing graft-versus-host disease after HIDT.Methods: The outcomes and the characteristics of 203 patients undergoing first allogeneic transplantation using HIDT with post-transplant cyclophosphamide between 2005 and 2016 were retrospectively assessed to identify the incidence and risk factors for aGVHD and cGVHD. Variables included in the analysis included patient related (age, sex, race, karnofsky, HCT-CI), disease related (diagnosis, disease type, disease risk index DRI, CIBMTR risk status) and transplant related (graft source as marrow vs peripheral blood, donor age, donor/recipient relationship, donor/recipient gender match, donor/recipient CMV match, conditioning intensity, high dose TBI in conditioning intensity, CD34 cell dose, CD3 cell dose and year of transplant). Univariate analysis with Gray's test and log-rank was carried for cumulative incidence and survival respectively. The proportional hazard cox model was used with backward elimination to select significant covariates. Multivariate analyses for developing GVHD, overall survival (OS), disease free survival (DFS), and relapse were conducted.Results: The median age was 51 years (range 19, 75) with a median follow up for survivors of 37 months. Seventy patients (34%) received bone marrow as graft source and 43% had Myeloablative conditioning. All patients received GVHD prophylaxis consisting of post-transplant cyclophosphamide on Days +3 and +4, MMF till day +35 and tacrolimus till day +180. The cumulative incidence for aGVHD grade II-IV and grade III-IV were 45% and 12% respectively. The common organs involved in aGVHD were skin (76% of cases, 39% stage 3 /4), gut (58% of cases, stage 3 /4 11%) and liver (7% of cases, stage 3 /4 of 1%). Subsequent aGVHD flare developed in 6 patients (5 with gut GVHD and 1 skin GVHD). The cumulative incidences of all grade cGVHD and moderate-severe cGVHD were 32% and 24% respectively (table 1). Conditioning intensity was the only risk factor associated with developing grade 2-4 aGVHD (p=0.04). Patients that received myeloablative regimens as compared to those who received a reduced intensity or non-myeloablative regimen had statistically higher rates of grade 2-4 aGVHD (hazard ratio [HR] of 1.52 (95% CI, 1.01-2.29, p=0.04). Risk factors for cGVHD showed that race and hematopoietic cell transplantation-comorbidity index (HCT-CI) had a statistically significant bearing on the likelihood of developing all-grade cGVHD (p=0.004 and 0.01 respectively). Graft source (marrow vs Peripheral blood) was a significant risk factor for developing moderate-severe cGVHD (p=0.03). Multivariate analysis on OS, DFS and relapse showed that Patients aged 55 or older (HR of 1.91, 95% CI 1.22-2.99, p =.005) and High/very high DRI risk (HR 2.06, CI 1.05-4.00, p=0.03) had worse overall survival rates. Older age, not developing chronic GVHD and receiving a transplant between 2005 and 2010 were all associated with a worse DFS (P<0.01 for all). High/very high DRI, male gender and not developing cGVHD were all significant factors for a higher relapse rate.Conclusions: This single center analysis of GVHD incidence and risk factors after HIDT using post-transplant cyclophosphamide showed that conditioning intensity, graft source and HCT-CI to be factors affecting incidence of GVHD. Higher disease risk and older patient age were associated with worse overall survival. [Display omitted] DisclosuresSolh:Amgen: Speakers Bureau; ADC Therapeutics: Research Funding; Celgene: Speakers Bureau.

Low-Toxicity/High-Efficacy HLA Haploidentical Transplantation for Elderly/Unfit Patients with Acute Leukemia

Allogeneic hematopoietic transplantation is the most powerful therapy for patients with acute leukemia at high risk of relapse. For HLA haploidentical transplantation, we recently applied a protocol consisting of a high-intensity TBI-based conditioning regimen and a peripheral blood CD34+ hematopoietic stem cell graft combined with the adoptive transfer of naturally occurring regulatory T cells (Tregs) and conventional T cells (Tcons). No post-transplant pharmacologic immune suppressive GvHD prophylaxis was given. Such a protocol was associated with remarkably low GvHD and relapse rates (Martelli MF et al., Blood. 124:638-644, 2014; reviewed in Mancusi A et al., Blood 128:2616-2623, 2016).However, patients who are unfit (because of multiple chemotherapy cycles, previous transplants, infections, or co-morbidities) or elderly are not expected to withstand high-intensity conditioning regimens. For these patients, we developed a reduced-toxicity version based on total marrow and total lymphoid irradiation (TMI/TLI) (Rosenthal J et al., Blood. 2011;117:309-315). TMI/TLI (13.5 Gy and 11.5 Gy respectively) were administered by means of Helical Tomotherapy HI-ART (in 9 fractions delivered two times a day in 4 and a half days). Target volumes were defined as the skeletal bone and major lymph node chains and spleen. In patients with ALL the brain was added as target volume. TMI/TLI was followed by chemotherapy with Thiotepa (2,5mg/kg/day for 2 days), Fludarabine (30 mg/m2/day for 5 days) and Cyclophosphamide (15 mg/kg/day for 2 days). As per our high-intensity protocol, the hematopoietic stem cell graft was foregone by an infusion of 2x10e6/Kg freshly isolated CD4/CD25/FOXP3-positive Tregs and a subsequent infusion of 1x10e6 Tcons. No post-transplant pharmacologic immune suppressive GvHD prophylaxis was given. To date 19 patients with high-risk acute leukemia in remission were enrolled (16 AML, 3 ALL). Median age was 57 years (range: 22-68). All patients engrafted. Four patients developed aGvHD grade ≥ 2. Transplant-related mortality was 21% (2 patients died of infections, 1 of VOD and 1 of aGvHD). Remarkably, no relapse or cGvHD were observed. With a median follow up of 12 months (range: 1-24), 15 of the 19 patients are alive. Thus, leukemia/cGvHD-free survival is 79%. Of course, these data need to be confirmed in a larger cohort of patients and with longer follow up.In conclusion, the present transplantation protocol was designed to make HLA haploidentical transplantation feasible and effective for unfit or elderly patients with high-risk leukemia. It combines a reduced-toxicity conditioning regimen with safe cellular immunotherapy of leukemia. To date, the clinical results are excellent and extremely encouraging. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Donor T Cells Genetically Modified with a Novel Suicide Gene (inducible Caspase 9, iC9) Expand and Persist over Time after Post-Allograft Infusion in Patients Given αβ T-Cell and B-Cell Depleted HLA-Haploidentical Allogeneic Stem Cell Transplantation (αβ haplo-HSCT) Contributing to Accelerate Immune Recovery

Background: αβ haplo-HSCT is an effective option for children with non-malignant disorders (Bertaina et al., Blood 2014) or acute leukemia (Locatelli et al. Blood 2017) and in need of an urgent allograft. In patients given this type of HSCT, recovery of adaptive immunity is, however, suboptimal. With the aim of accelerating reconstitution of adaptive immunity, we evaluated an innovative approach based on post-transplant infusion of titrated numbers of donor αβ T cells, transduced with the suicide gene iC9 (BPX-501 cells). Since the transduced gene contains sequences for the CD19 marker, BPX-501 cells are CD3+/CD19+ and, thus, can be easily tracked in peripheral blood. We report data on immune recovery of children transplanted at Bambino Gesù Children's Hospital, Rome, and enrolled in a multicenter prospective phase I-II trial on BPX-501 cells (sponsored by Bellicum Pharmaceuticals®, ClinicalTrials.gov identifier: NCT02065869).Patients and study design: Included in this analysis were 108 children. Median age at transplant was 5.6 years (range, 0.3-18) and the male/female ratio was 61/47. Patients were subdivided according to the original disorder in 5 groups: group A (53 children with acute leukemia), group B (22 with primary immune-deficiency, PIDs), group C (14 with erythroid disorders), group D (7 with Fanconi anemia) and group E (12 with other diseases). No patient was given any post-transplant graft-versus-host disease (GvHD) prophylaxis. Nine children were enrolled in the phase I portion of the trial consisting of 3 cohorts, receiving escalating doses of BPX-501 cells of 2.5x105, 5x105, and 1x106 cells/kg, respectively. The remaining 99 patients included in the phase II portion received 1x106 BPX-501 cells/kg. Per protocol, BPX-501 cells were to be infused within the first month after αβ haplo-HSCT. We evaluated the absolute number of circulating CD3+, CD3+/CD4+, CD3+/CD8+, CD19+, and NK cells at 1, 2, 3, 6, 9, 12 and 24 months after αβ haplo-HSCT. We also analyzed the number of BPX-501 cells, αβ T cells and γδ T cells at the same time points. The impact of patient gender, age (0-2, 2-6, 6-12 and >12 years), original disease, use of total body irradiation (TBI) during conditioning regimen, occurrence of cytomegalovirus (CMV) reactivation, of acute GvHD and of leukemia relapse (only in group A patients), on recovery of different lymphocyte subsets was investigated, as well. Data were expressed as mean value+SEM (standard error of mean). Six patients given Rimiducid, the agent activating iC9, were censored at time of drug infusion.Results: After infusion, BPX-501 cells expanded progressively reaching a peak at 9 months after the allograft, when their mean value was 144+36/μL. In the 16 patients with 2-year follow-up, the mean number of BPX-501 cells was still 62+23/μL. Details on expansion/persistence of BPX-501 cells, as well as on recovery of CD3+, CD4+ and CD8+ T cells, are shown in Figure 1A and 1B, respectively. A mean number of CD3+ cells greater than 1.000/μL was reached at 6 months after transplantation. Figure 1C depicts the progressive recovery of B cells. NK and γδ T cells promptly recovered after the allograft; the number of αβ T cells overcomes that of γδ T cells at 2 months after transplant. CMV reactivation promoted a statistically better expansion of BPX-501 cells (see also Figure 1D). This effect was paralleled by an improved recovery of both CD3+ and αβ T cells in patients who experienced CMV reactivation. A statistically higher number of both CD3+ and αβ T cells was observed at 6 and 12 months after αβ haplo-HSCT in patients who did not receive TBI. Neither acute GvHD nor leukemia recurrence occurrence statistically affected the number of BPX-501 cells. Children with an age comprised between 0-2 years or with PIDs had a better recovery of both CD3+ and αβ T cells at 6, 9 and 12 months after the allograft.Conclusions: Our results indicate that BPX-501 cells infused after αβ haplo-HSCT expand in vivo and persist over time, contributing to fasten adaptive immunity recovery. Their peak of expansion is reached at 9 months after the allograft, but they are consistently detected also at 2 years after infusion. CMV reactivation is the main driver of BPX-501 cell expansion, this finding suggesting that BPX-501 cells cooperate to the viral clearance. Overall, the whole pattern of immune recovery of these 108 children is improved as compared with that of patients given αβ haplo-HSCT without BPX-501 cell infusion. [Display omitted] DisclosuresO'Neill:Bellicum Pharmaceuticals: Other: contractor. Spencer:Bellicum Pharmaceuticals: Employment, Equity Ownership, Other: stockholders . Foster:Bellicum Pharmaceuticals: Employment, Other: stockholders .

Post-Transplantation Cyclophosphamide and Short-Term Methotrexate for Tolerance Induction in HLA-Haploidentical Transplantation for Severe Aplastic Anemia

Background. Haploidentical related donors (HIDs) are attractive donors for patients with severe aplastic anemia (SAA) because they are readily available for nearly all the patients. Bone marrow transplant (BMT) using post-transplant cyclophosphamide (PTCy) has been shown effective to cross the immune barriers between the recipients and their HIDs. Short-term low dose of methotrexate (ST-MTX) has long been adopted either alone or combined with calcineurin inhibitors to get across the immune barrier in hematopoietic stem cell transplant (HSCT).Aim of the study. We presented the outcome of 15 patients with SAA who underwent haploidentical transplant (HIT) using T-cell-replete peripheral graft and combination of PTCy with ST-MTX.Patients and grafts. We analyzed the medical records of 15 patients with SAA between Jan 2015 and July 2017. The transplants were either upfront (8/15) or rescue treatment (7/15). The median age of the patients was 16 (range 5-39) years and 66.7% (10/15) were male. All the patients received granulocyte colony-stimulating factor (G-CSF) mobilized peripheral graft from haploidentical related donors. The median mononuclear cells (MNCs) was 12.4 × 108 cells/kg recipient ideal body weight (IBW) with the range of (7.0-22.0) × 108 cells/kg, the CD34+ cell was 7.5 × 106 cells/kg with the range of (5-23) × 106 cells/kg and the CD3+ cells was 2.7 × 108 cells/kg with the range of (1.8-5.0) × 108 cells/kg.Conditioning regimen and GvHD prophylaxis. We used a TBI-free transplantation platform named FBC+PTCy/ST-MTX. Fludarabine was administered at 40 mg/m2 IV daily for 5 days. Busulfan was delivered in a total dose of 6.4mg/kg. Cyclophosphamide was given 14.5 mg/kg daily for 2 days. PTCy was administered at 60mg/kg/day IV on days +3 and +4 post-transplant. Low doses of MTX were delivered on days +1, +2 and +5 post-transplant at 15mg/m2, 10mg/m2 and 10mg/m2. Cyclosporine was given from day +6 through day +180 with the target through level 150~180ng/ml and then was tapered until 12 months post transplant. Mycophenolate mofetil (MMF) was given from day +6 to +35 days for the first 3 patients and then was eliminated for the following patients.Results.Neither primary nor secondary graft failure (GF) was seen in this study. Neutrophil engrafted at 15 days (range, 13-18 days). Platelets engrafted at 19 days (range, 14-36 days) and recovered over 100 × 109/L at 38 days (range, 14-77 days). The time to total lymphocytes recovery over 0.5 × 109/L for 3 consecutive days was 34 days (range, 25-72 days). The accumulated engraftment of neutrophil and platelets were both 100% at +40 days. (Figure 1-A, B.)The cumulative incidence of aGvHD at 100 days was 20.0%(3/15). Two patients had grade I skin aGvHD and the other one had grade II skin aGvHD. No grade III-IV aGvHD was seen. 12 patients were evaluable for the incidence of cGvHD and none of them developed moderate or sever cGvHD with a median of 150 (102-806) days post transplant. (Figure 1-C, D.) During the follow-up, one patients had skin cGvHD and received systemic therapy with corticoid. The treatment was discontinued after 8 months post transplant. All 3 patients, who survived beyond 12 months post transplant at the end of our follow-up, were off immunosuppress.With a median follow-up of 230 days (range 41-806 days), all the patients are alive. They are transfusion independent with karnofsky performance status scale (KPS) scores 100.Conclusion.This study shows that haploidentical related transplant can be successfully applied using T-cell-repleted peripheral grafts. ST-MTX may facilitate PTCy to achieve a stable engraftment with a minimal risk of GvHD in HIT for patients with SAA. Our approach should expand the donor pool for patients with SAA. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

HLA-haploidentical vs matched unrelated donor transplants with posttransplant cyclophosphamide-based prophylaxis

Posttransplant cyclophosphamide (PTCy) graft-versus-host disease (GVHD) prophylaxis has enabled haploidentical (Haplo) transplantation to be performed with results similar to those after matched unrelated donor (MUD) transplantation with traditional prophylaxis. The relative value of transplantation with MUD vs Haplo donors when both groups receive PTCy/calcineurin inhibitor/mycophenolate GVHD prophylaxis is not known. We compared outcomes after 2036 Haplo and 284 MUD transplantations with PTCy GVHD prophylaxis for acute leukemia or myelodysplastic syndrome in adults from 2011 through 2018. Cox regression models were built to compare outcomes between donor types. Recipients of myeloablative and reduced-intensity regimens were analyzed separately. Among recipients of reduced-intensity regimens, 2-year graft failure (3% vs 11%), acute grades 2 to 4 GVHD (hazards ratio [HR], 0.70; P = .022), acute grades 3 and 4 GVHD (HR, 0.41; P = .016), and nonrelapse mortality (HR, 0.43; P = .0008) were lower after MUD than with Haplo donor transplantation. Consequently, disease-free (HR, 0.74; P = .008; 55% vs 41%) and overall (HR, 0.65; P = .001; 67% vs 54%) survival were higher with MUD than with Haplo transplants. Among recipients of myeloablative regimens, day-100 platelet recovery (95% vs 88%) was higher and grades 3 and 4 acute (HR, 0.39; P = .07) and chronic GVHD (HR, 0.66; P = .05) were lower after MUD than with Haplo donor transplantation. There were no differences in graft failure, relapse, nonrelapse mortality, and disease-free and overall survival between donor types with myeloablative conditioning regimens. These data extend and confirm the importance of donor-recipient HLA matching for allogeneic transplantation. A MUD is the preferred donor, especially for transplantations with reduced-intensity conditioning regimens.

Natural killer cell alloreactivity in HLA-haploidentical hematopoietic transplantation: a study on behalf of the CTIWP of the EBMT.

Human leukocyte antigen (HLA) class-I mismatches that trigger donor-versus-recipient natural killer (NK)-cell alloreactivity reduce the incidence of leukemia relapse and improve survival of acute myeloid leukemia patients after T-cell-depleted HLA-haplotype mismatched ("haploidentical") hematopoietic transplantation. In murine graft-versus-host disease (GvHD) models, alloreactive NK-cells also prevent GvHD. Here we report the results of a non-interventional, prospective study performed on behalf of the Cellular Therapy and Immunobiology Working Party of the European Society for Blood and Marrow Transplantation. The study was aimed at re-assessing the role of NK-cell alloreactivity in a cohort of haploidentical transplants performed in Europe between 2012 and 2015 and composed of unmanipulated, as well as T-cell-depleted transplants. One hundred thirty-eight patients with acute myeloid or lymphoid leukemias were analyzed. Eighty-six patients received ex-vivo T-cell-depleted transplants, 52 patients received unmanipulated transplants. Fifty patients were transplanted from NK alloreactive donors, 88 from non-NK alloreactive donors. NK cell alloreactivity did not impact on GvHD/relapse-free survival (GRFS) in unmanipulated transplants (HR: 1.66 (0.9-3.1), p = 0.1). In contrast, it did impact beneficially on GRFS in T-cell-depleted transplants (HR: 0.6, (0.3-1.2), p = 0.14, interaction p < 0.001). This effect was the consequence of reduced incidences of acute and chronic GvHD and non-relapse mortality.

279 - HLA-Haploidentical Transplantation with Regulatory and Conventional T-Cells Adoptive Immunotherapy in Pediatric Patients with High-Risk Acute Leukemia

279 - HLA-Haploidentical Transplantation with Regulatory and Conventional T-Cells Adoptive Immunotherapy in Pediatric Patients with High-Risk Acute Leukemia

11 - Phase I Study De-Intensifying Exposure of Post-Transplantation Cyclophosphamide (PTCy) after HLA-Haploidentical Hematopoietic Cell Transplantation (HCT) for Hematologic Malignancies

11 - Phase I Study De-Intensifying Exposure of Post-Transplantation Cyclophosphamide (PTCy) after HLA-Haploidentical Hematopoietic Cell Transplantation (HCT) for Hematologic Malignancies

Outcomes of Unmanipulated Haploidentical Transplantation Using Post-Transplant Cyclophosphamide (PT-Cy) in Pediatric Patients With Acute Lymphoblastic Leukemia

HLA-haploidentical transplantation (haplo-HCT) using post-transplantation-cyclophosphamide (PT-Cy) is a feasible procedure in children with malignancies. However, large studies on Haplo-HCT with PT-Cy for childhood acute lymphoblastic leukemia (ALL) are lacking. We analyzed haplo-HCT outcomes in 180 children with ALL. Median age was 9 years, and median follow-up was 2.7 years. Disease status was CR1 for 24%, CR2 for 45%, CR+3 for 12%, and active disease for 19%. All patients received PT-Cy day +3 and +4. Bone marrow (BM) was the stem cell source in 115 patients (64%). Cumulative incidence of 42-day engraftment was 88.9%. Cumulative incidence of day-100 acute graft-versus-host disease (GVHD) grade II-IV was 28%, and 2-year chronic GVHD was 21.9%. At 2 years, cumulative incidence of nonrelapse mortality (NRM) was 19.6%. Cumulative incidence was 41.9% for relapse and 25% for patients in CR1. Estimated 2-year leukemia free survival was 65%, 44%, and 18.8% for patients transplanted in CR1, CR2, CR3+ and 3% at 1 year for active disease. In multivariable analysis for patients in CR1 and CR2, disease status (CR2 [hazard ratio {HR}=2.19; P=.04]), age at HCT older than 13 (HR=2.07; P=.03) and use of peripheral blood stem cell (PBSC) (HR=1.98; P=.04) were independent factors associated with decreased overall survival. Use of PBSC was also associated with higher NRM (HR=3.13; P=.04). Haplo-HCT with PT-Cy is an option for children with ALL, namely those transplanted in CR1 and CR2. Age and disease status remain the most important factors for outcomes. BM cells as a graft source is associated with improved survival.

Impaired T- and NK-cell reconstitution after haploidentical HCT with posttransplant cyclophosphamide

AbstractAdministration of posttransplant cyclophosphamide (PTCy) has significantly expanded the number of patients undergoing HLA-haploidentical hematopoietic cell transplantation (haplo-HCT). To examine immune reconstitution in these patients, we monitored T- and natural killer (NK)-cell recovery in 60 patients receiving bone marrow or peripheral blood stem cell (PBSC) grafts after haplo-HCT with PTCy and 35 patients receiving HLA-matched donor PBSC grafts with standard graft-versus-host disease (GVHD) prophylaxis. Compared with HLA-matched recipients, early T-cell recovery was delayed in haplo-HCT patients and skewed toward effector memory T cells with markedly reduced naive T cells. We found higher regulatory T (Treg)-cell/conventional T (Tcon)-cell ratios early after HCT and increased PD-1 expression on memory T cells. Within the haplo-HCT, patients who did not develop chronic GVHD (cGVHD) had higher PD-1 expression on central and effector memory CD4+ Treg cells at 1 month after transplant. These findings suggest an immunologic milieu that promotes immune tolerance in haplo-HCT patients. NK cells were decreased early after haplo-HCT with preferential expansion of immature CD56brightCD16− NK cells compared with matched donor transplants. One month after transplant, mass cytometry revealed enrichment of immature NK-cell metaclusters with high NKG2A, low CD57, and low killer-cell immunoglobulin-like receptor expression after haplo-HCT, which partially recovered 3 months post-HCT. At 2 months, immature NK cells from both groups were functionally impaired, but interleukin-15 priming corrected these defects in vitro. Increased immature/mature NK-cell ratios were associated with cytomegalovirus reactivation and increased incidence of cGVHD after haplo-HCT. These homeostatic imbalances in T- and NK-cell reconstitution after haplo-HCT reveal opportunities for early immune-based interventions to optimize clinical outcomes.

Cytokine release syndrome after haploidentical hematopoietic stem cell transplantation with antithymocyte globulin: risk factors analysis and poor impact on outcomes for non-remisssion patients

ABSTRACT Introduction Cytokine release syndrome (CRS) is a common complication after T-replete HLA haploidentical hematopoietic cell transplantation (haplo-HCT) with PTCy. We aim to assess the incidence, severity, and impact of CRS on clinical outcomes of patients who received haplo-HCT using Beijing Protocol. Methods This was a single-enter retrospective analysis of 286 subjects who received haplo-HCT with Antithymocyte Globulin (ATG). Results We identified 147/268 (54.9%) patients who developed CRS, grade 1 CRS (32.5%) and grade ≥2 CRS (22.4%). Eight patients developed severe CRS. The incidence and severity of CRS did not show significant discrimination among patients who received different doses of ATG. By multivariable analysis, age and the disease status at transplantation were significantly associated with the occurrence of CRS (p =.000 and p = .021). In the univariate analysis for the severity of CRS, compared with CRS grade ≥2, patients with CRS grade 0-1 had higher 1-year overall survival (OS) (p = .009). The cumulative incidence of 100-day grades II-IV acute GVHD was 12.4%. The incidence did not show significant differences between patients with CRS or not. The devolvement of CRS is associated with worse OS, inferior disease-free survival, and higher nonrelapse mortality significantly. But the result appeared to be limited to patients in uncomplete remission status before transplantation. Discussion and Conclusions CRS is less frequent and milder with a protocol based on ATG. CRS can potentially affect the outcomes after haplo-HCT especially for patients in an uncomplete remission. Prospective clinical trials are needed to provide an appropriate scheme for CRS prophylaxis.

Myeloablative Haploidentical Transplant as an Alternative to Matched Sibling Transplant for Peripheral T-Cell Lymphomas

The number of HLA-haploidentical allogeneic hematopoietic stem-cell transplantation (Haplo-HSCT) is increasing. Comparative studies about Haplo-HSCT versus allo-HSCT with HLA-matched sibling donors (MSD-HSCT) have been tried in leukemias and B-cell lymphomas. Few studies were reported in Peripheral T-cell lymphomas (PTCLs). We performed a multicenter retrospective study about 52 patients with PTCLs undergoing Haplo-HSCT (n = 20) or MSD-HSCT (n = 32). All Haplo-HSCT recipients received antithymocyte globulin (ATG) based graft versus host disease (GVHD) prophylaxis. The median follow-up for all survivors was 38 months. The 100-day cumulative incidence of grade II to IV acute GVHD was similar (19% in the MSD-HSCT group versus 28% in the Haplo-HSCT group, P = 0.52). The 2-year cumulative incidence of chronic GVHD (limited and extensive) after Haplo-HSCT (30%) was also similar with that in the MSD-HSCT group (50%, P = 0.15). The 3-year relapse rates (33% vs 27%, P = 0.84) and non-relapse mortality (21% vs 22%, P = 0.78) did not differ between these two groups. There were also no differences in 3-year overall survival (OS) (48% vs 50%, P = 0.78) and progression-free survival (47% vs 51%, P = 0.95) between these two groups. On multivariate analysis, prognostic index for T-cell lymphoma (PIT) score (higher than 1: hazard ratio [HR], 4.0; P = 0.003) and disease status (stable or progression disease before HSCT: HR, 2.8; P = 0.03) were independent variables associated with worse OS. We concluded that ATG-based haplo-HSCT platform could work as an alternative to MSD-HSCT for patients with PTCLs.