The outcomes of 293 patients with leukemia undergoing HLA-identical sibling (n ‫؍‬ 158) or related HLA-mismatched (n ‫؍‬ 135) hematopoietic cell transplantation (HCT) performed during the same time period were compared. Patients received BUCY2 in HLA-identical sibling HCT or BUCY2 ؉ ATG in mismatched HCT as conditioning regimens, followed by unmanipulated marrow and/or peripheral blood (PB) transplantation. All patients achieved full engraftment. The cumulative incidences of grades II to IV acute graft-versus-host disease (aGVHD) in the matched and mismatched cohorts were 32% (CI, 25%-39%) versus 40% (CI, 32%-48%, P ‫؍‬ .13), respectively, with the relative risk (RR) ‫؍‬ 0.64 (95% CI, 0.43-0.94), P ‫؍‬ .02. The incidence of chronic GVHD did not differ significantly between the cohorts (P ‫؍‬ .97). Two-year incidences of treatment-related mortality and relapse for matched versus mismatched were 14% (range, 9%-20%) versus 22% (range, 15%-29%) with P ‫؍‬ .10 and 13% (range, 8%-19%) versus 18% (range, 10%-27%) with P ‫؍‬ .40, respectively. Two-year adjusted leukemia-free survival (LFS) and overall survival were 71% (range, 63%-78%) versus 64% (range, 54%-73%) with P ‫؍‬ .27 and 72% (range, 64%-79%) versus 71% (range, 62%-77%) with P ‫؍‬ .72, respectively. Multivariate analyses showed that only advanced disease stage and a diagnosis of acute leukemia had increased risk of relapse, treatment failure, and overall mortality. In summary, HCT performed with related HLA-mismatched donors is a feasible approach with acceptable outcomes. (Blood. 2006;107:3065-3073)

Refractory or relapsed B lymphoblastic leukemia (B-ALL) patients have a dismal outcome with current therapy. We treated 42 primary refractory/hematological relapsed (R/R) and 9 refractory minimal residual disease by flow cytometry (FCM-MRD) B-ALL patients with optimized second generation CD19-directed CAR-T cells. The CAR-T-cell infusion dosages were initially ranged from 0.05 to 14 × 10/kg and were eventually settled at 1 × 10/kg for the most recent 20 cases. 36/40 (90%) evaluated R/R patients achieved complete remission (CR) or CR with incomplete count recovery (CRi), and 9/9 (100%) FCM-MRD patients achieved MRD. All of the most recent 20 patients achieved CR/CRi. Most cases only experienced mild to moderate CRS. 8/51 cases had seizures that were relieved by early intervention. Twenty three of twenty seven CR/CRi patients bridged to allogeneic hematopoietic stem cell transplantation (allo-HCT) remained in MRD with a median follow-up time of 206 (45-427) days, whereas 9 of 18 CR/CRi patients without allo-HCT relapsed. Our results indicate that a low CAR-T-cell dosage of 1 × 10/kg, is effective and safe for treating refractory or relapsed B-ALL, and subsequent allo-HCT could further reduce the relapse rate.

Despite worldwide promising clinical outcome of CD19 CART therapy, relapse after this therapy is associated with poor prognosis and has become an urgent problem to be solved. We conducted a CD22 CAR T-cell therapy in 34 relapsed or refractory (r/r) BALL pediatric and adult patients who failed from previous CD19 CAR T-cell therapy. Complete remission (CR) or CR with incomplete count recovery (CRi) was achieved in 24 of 30 patients (80%) that could be evaluated on day 30 after infusion, which accounted for 70.5% of all 34 enrolled patients. Most patients only experienced mild cytokine-release syndrome and neurotoxicity. Seven CR patients received no further treatment, and 3 of them remained in remission at 6, 6.6, and 14 months after infusion. Eleven CR patients were promptly bridged to transplantation, and 8 of them remained in remission at 4.6 to 13.3 months after transplantation, resulted in 1-year leukemia-free survival rate of 71.6% (95% CI, 44.2-99.0). CD22 antigen loss or mutation was not observed to be associated with relapsed patients. Our study demonstrated that our CD22 CAR T-cells was highly effective in inducing remission in r/r BALL patients, and also provided a precious window for subsequent transplantation to achieve durable remission.

No abstract

The prognosis of relapsed acute lymphoblastic leukemia (ALL) after allogeneic transplantation is dismal when treated with conventional approaches. While single‐target CD19 or CD22 chimeric antigen receptor (CAR) T‐cell therapy has achieved high complete remission (CR) rates in refractory/relapsed B‐ALL, it could not maintain a durable remission in most patients. To prolong relapse‐free survival, we sequentially combined CD19 and CD22 CAR‐T cells to treat post‐transplant relapsed B‐ALL patients with both CD19/CD22 antigen expression on lymphoblasts. Patient‐derived donor cells were collected to produce CAR‐T cells that were transfected by lentiviral vectors encoding second generation CARs composed of CD3ζ and 4–1BB. The second T‐cell infusion was scheduled at least 1 month, and usually within 6 months after the first CAR‐T treatment. Twenty‐seven adult and pediatric patients, including 11 (41%) with extramedullary diseases (EMD), received the first CD19 CAR‐T and 23 (85%) achieved CR. Subsequently, 21 out of 27 patients received the second CD22 CAR‐T and were followed‐up for a median of 19.7 (range, 5.6–27.3) months; 14 cases remained in CR, seven relapsed and two of them died from disease progression; Kaplan–Meier survival analysis showed overall survival and event‐free survival rates of 88.5% and 67.5%, respectively, at both 12 months and 18 months. CAR‐T associated graft‐versus‐host disease (GVHD) occurred in 23% of patients, with 8% new‐onset acute GVHD and 15% persistent or worsened pre‐existing cGVHD before CAR‐T. This combination strategy of sequential CD19 and CD22 CAR‐T therapy significantly improved the long‐term survival in B‐ALL patients who relapsed after transplantation.

Accurate analyses of the delayed effects of acute radiation exposure (DEARE) in survivors of the hematopoietic acute radiation syndrome (H-ARS) are hampered by low numbers of mice for examination due to high lethality from the acute syndrome, increased morbidity and mortality in survivors, high cost of husbandry for long-term studies, biological variability, and inconsistencies of models from different laboratories complicating meta-analyses. To address this, a compilation of 38 similar H-ARS studies conducted over a seven-year period in the authors' laboratory, comprising more than 1,500 irradiated young adult C57BL/6 mice and almost 600 day-30 survivors, was assessed for hematopoietic DEARE at various times up to 30 months of age. Significant loss of long-term repopulating potential of phenotypically-defined primitive hematopoietic stem cells (HSC) was documented in H-ARS survivors, as well as significant decreases in all hematopoietic lineages in peripheral blood, prominent myeloid skew, significantly decreased bone marrow cellularity and numbers of lineage-negative Sca-1+ cKit+ CD150+ cells (KSLCD150+; the phenotype known to be enriched for HSC), and increased cycling of KSLCD150+ cells. Studies interrogating the phenotype of bone marrow cells capable of initiation of suspension cultures and engraftment in competitive transplantation assays documented the phenotype of HSC in H-ARS survivors to be the same as that in non-irradiated age-matched controls. This compilation study adds rigor and validity to our initial findings of persistent hematopoietic dysfunction in H-ARS survivors that arises at the level of the HSC and which affects all classes of hematopoietic cells for the life of the survivor.

Summary Although chimeric antigen receptor T cells (CAR‐T) targeted at CD19 or CD22 have achieved high complete remission (CR) in refractory/relapsed B‐cell acute lymphoblastic leukaemia (B‐ALL), it is uncertain if allogeneic haematopoietic stem cell transplantation (allo‐HSCT) should be performed after CAR‐T therapy to accomplish a sustainable remission. Fifty‐two cases with relapsed/refractory B‐ALL who underwent allo‐HSCT after CR by CD19 or CD22 CAR‐T were enrolled. The median time from CAR‐T infusion to allo‐HSCT was 50 (34–98) days. Myeloablative reduced‐intensity conditioning (RIC) with total body irradiation/fludarabine‐based or busulfan/fludarabine‐based regimens was used. Incidences of grade II–IV acute graft‐versus‐host disease (aGVHD) and severe aGVHD were 23·1% and 5·8% respectively. Of 48 evaluable cases, 16 developed chronic GVHD (cGVHD) and in three of them the pattern was extensive. With a median follow‐up of 334 (41–479) days, one‐year overall survival and event‐free survival (EFS) were 87·7% and 73·0%. One‐year relapse rate and transplant‐related mortality (TRM) were 24·7% and 2·2% respectively. With quick bridge to allo‐HSCT after CAR‐T therapy, high EFS for refractory/relapsed B‐ALL has been achieved in this relatively large cohort. Our myeloablative RIC regimens have resulted in low incidences of aGVHD, cGVHD, viral reactivation and very low TRM even majority of transplants from haploidentical donors. Long‐term follow‐up is warranted.

Cytokine release syndrome (CRS) is the most prominent and potentially life-threatening toxicity caused by chimeric antigen receptor (CAR) T cell therapy, therefore, effectively controlling severe CRS is critical to ensure patient safety. Tocilizumab, an interleukin-6 receptor antagonist, has been widely used to treat CRS, whereas it is not clear if corticosteroids could be as another optimal choice for managing CRS. We applied corticosteroids instead of tocilizumab as the first-line agent to control CRS in patients with relapsed/refractory B-cell acute lymphoblastic leukemia during CAR-T therapy. The impacts of steroids on treatment efficiency and kinetics of CAR-T cells were assessed by comparing two groups of patients who did (42 cases) or did not (26 cases) receive steroids. Patients followed up less than one month (went to other hospitals for transplantation or died within one month) were excluded. Treatment effects were evaluated on day 30 after T-cell infusion and then monthly in follow-up patients. Minimal residual disease (MRD) was detected by multiparameter flow cytometry (FCM) and quantitative PCR for fusion genes. The dynamic monitoring of CAR-T cells was performed through flow cytometric quantitation of FITC+CD3+ T cells. B-cell aplasia (BCA) was assayed by FCM. Dexamethasone or methylprednisolone or both (alternately) were administrated. Dexamethasone was used in most cases especially for patients with neurologic symptoms; methylprednisolone was preferred for patients with pulmonary or liver dysfunction, and patients accepting high dose steroids. Steroids started with low dose and could be increased if symptoms were not resolved, for severe CRS, steroids would be escalated up to dexamethasone 20mg/m2/d or more higher up to methylprednisolone 10mg/kg/d. Once CRS was improved, steroids were rapidly reduced and stopped. A total of 68 patients (28 adults and 40 children younger than 18 years) were included, 22 (32.4%) presented with extramedullary diseases (EMD), bone marrow blasts in patients without EMD varied between 5%-96.5%, 31 (45.6%) patients had an allogeneic transplantation, 54 (79.4%) cases received CD19-specific and 14 (20.6%) received CD22-specific CAR-T therapy. Forty-two (61.8%) cases, including all (10) of grade III CRS, 68.2% (30/44) of grade II CRS and 2 patients with no CRS but with GVHD (1 case) or neurotoxicity (1 case), were administered steroids, among them, 23/42 (54.8%) received high dose steroids (>10mg/m2/d dexamethasone or equivalent), the duration of steroid use was 1-16 days (78.6% <= 7 days); whereas 26 (38.2%) patients were not given any steroids but the supportive care. We found that there was no difference either in complete remission (CR) rate (95.2% vs 92.3%, p=.344) or in MRD negative CR rate (80.0% vs 79.2%, p=.249) between steroid and non-steroid group, verified that corticosteroids even high dose steroids did not influence the treatment response. Furthermore, we investigated the dynamics of CAR-T cells. Firstly, the expansion of CAR-T cells in peripheral blood (PB) was evaluated, the average CAR-T cell counts in steroid group were significantly higher than those in non-steroid group on D11 (p=.0302), D15 (p=.0053), D20 (p=.0045) and D30 (p=.0028), except for D7 when CAR-T cells began to expand (p=.9815), this demonstrated that steroids did not suppress the proliferation of CAR-T cells in PB. Secondly, the percentages of patients with detectable CAR-T cells in bone marrow (BM) and cerebrospinal fluid (CSF) were compared between steroid and non-steroid group, there were no differences both in BM (85.2% vs 78.6%, p=.923) and in CSF (68.6% vs 57.9%, p=.433), which implied steroids did not influence the trafficking of T-cells to BM and CSF. Thirdly, we monitored B-cell aplasia (BCA) in part of patients followed-up more than 2 months without further treatments, the percentages of patients with BCA in steroid group had no significant differences compared to non-steroid group at 2-month (p=.086) and 3-month (p=.146). Later, although limited cases left, in the steroid group, 100% of patients (4-month, 7/7; 5-month, 7/7; 6-month, 5/5) still maintained BCA and CR, indicating that corticosteroids did not impact the duration of functional CAR-T cells. In conclusion, corticosteroids do not compromise the treatment efficacy and kinetics of CAR-T cells, could be as a feasible and effective approach to manage CAR-T associated CRS. Disclosures No relevant conflicts of interest to declare.