Impact of Consolidative Unrelated Cord Blood Transplantation on Clinical Outcomes of Patients With Relapsed/Refractory Acute B Lymphoblastic Leukemia Entering Remission Following CD19 Chimeric Antigen Receptor T Cells

Background

While chimeric antigen receptor (CAR)-T cell therapy is becoming widely used in hematological malignancies with remarkable remission rate, their high recurrence remains an obstacle to overcome. The role of consolidative transplantation following CAR-T cell-mediated remission remains controversial. We conducted a retrospective study to explore whether bridging to unrelated cord blood transplantation (UCBT) could improve the prognosis of patients entering remission after CAR-T therapy with different characteristics through subgroup analyses.

Methods

We reviewed 53 patients with relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL) successfully infused with CD19 CAR-T cells and achieved complete remission (CR). In this study, 25 patients received consolidative UCBT (UCBT group) and 28 patients did not accept any intervention until relapse (non-UCBT group). Subgroup analysis on prognosis was then performed according to gender, age, number of previous relapses, tumor burden, presence of poor prognostic markers, and structure of CAR.

Results

Compared with the non-UCBT group, patients who underwent consolidative UCBT had better median event-free survival (EFS; 12.3 months vs. 6.2 months; P = 0.035) and relapse-free survival (RFS; 22.3 months vs. 7.2 months; P = 0.046), while no significant difference was found in overall survival (OS; 30.8 months vs. 15.3 months; P = 0.118). Subsequent multivariate analysis revealed that bridging to UCBT was a protective factor for RFS (P = 0.048) but had no significant effect on EFS (P = 0.205) or OS (P = 0.541). In the subgroup analysis, UCBT has an added benefit in patients with specific characteristics. Patients who experienced ≥2 relapses or with sustained non-remission (NR) showed better RFS (P = 0.025) after UCBT. Better EFS was seen in patients with poor prognostic markers (P = 0.027). In the subgroup with pre-infusion minimal residual disease (MRD) ≥5% or with extramedullary disease (EMD), UCBT significantly prolonged EFS (P = 0.009), RFS (P = 0.017), and OS (P = 0.026). Patients with occurrence of acute graft-versus-host disease (aGVHD) appeared to have a longer duration of remission (P = 0.007).

Conclusion

Consolidative UCBT can, to some extent, improve clinical outcomes of patients with R/R B-ALL entering remission following CD19 CAR-T therapy, especially in patients with more recurrences before treatment, patients with poor prognostic markers, and patients with a higher tumor burden. The occurrence of aGVHD after UCBT was associated with better RFS.

Low donor chimerism may be sufficient to prevent demyelination in adrenoleukodystrophy

Adrenoleukodystrophy (ALD) is a peroxisomal disorder characterized by white matter degeneration caused by adenosine triphosphate-binding cassette subfamily D member 1 (ABCD1) gene mutations, which lead to an accumulation of very-long-chain fatty acids (VLCFA). Hematopoietic stem cell transplantation (HSCT) is the most effective treatment; however, the ratio of donor-to-recipient cells required to prevent the progression of demyelination is unclear. The proband was diagnosed with the childhood cerebral form of ALD at 5 years of age based on the clinical phenotype, elevated plasma VLCFA levels, and pathogenic ABCD1 mutation c.293C>T (p.Ser98Leu). Soon after the diagnosis, he became bedridden. At 1 year of age, his younger brother was found to carry the same ABCD1 mutation; despite being asymptomatic, at 1 year and 9 months, head magnetic resonance imaging (MRI) showed high-signal-intensity lesions in the cerebral white matter. The patient underwent unrelated cord blood transplantation (UCBT) with a reduced conditioning regimen, which resulted in mixed chimerism. For 7 years after UCBT, the donor chimerism remained low (<10%) in peripheral blood and cerebrospinal fluid. However, even though a second HSCT was not performed, his neurological symptoms and brain MRI findings did not deteriorate. Our case suggests that even a small number of donor cells may prevent demyelination in ALD. This is an important case when considering the timing of a second HSCT.

Effects and long-term follow-up of using umbilical cord blood-derived mesenchymal stromal cells in pediatric patients with severe BK virus-associated late-onset hemorrhagic cystitis after unrelated cord blood transplantation

This is a retrospective study to evaluate the efficacy and safety of umbilical cord blood-derived mesenchymal stromal cells (MSCs) for the treatment of pediatric patients with severe BK virus-associated late-onset hemorrhagic cystitis (BKV-HC) after unrelated cord blood transplantation (UCBT). Thirteen pediatric patients with severe BKV-HC from December 2013 to December 2015 were treated with MSCs. The number of MSCs transfused in each session was 1 × 10⁶ /kg once a week until the symptoms improved. The median follow-up time was 1432 (89-2080) days. The median frequency of MSC infusion was 2 (1-3), with eight cured cases and five effective cases; the total efficacy rate was 100%. The copy number of urine BKV DNA was 4.43 (0.36-56.9) ×10⁸ /mL before MSC infusion and 2.67 (0-56.3) ×10⁸ /mL after MSC infusion; the difference was not significant (P = .219). There were no significant differences in the overall survival, disease-free survival, and the incidence of relapse and acute and chronic graft-versus-host disease between the MSC infusion group and non-MSC infusion group. There was also no significant difference in the cytomegalovirus, Epstein-Barr virus (EBV), and fungal and bacterial infection rates between the two groups. Although umbilical cord blood-derived MSCs do not reduce the number of BKV DNA copies in the urine, the cells have a high efficacy rate and minimal side effects in treating severe BKV-HC after UCBT among pediatric patients. MSCs do not affect the rates of relapse, long-term infection, or survival of patients with leukemia.

Clinical outcomes of unrelated cord blood transplantation in children with malignant and non-malignant diseases: Multicenter experience in China

This multicenter retrospective study included 184 children with malignant and non-malignant diseases who underwent UCBT between January 1998 and August 2012. The malignant disease group included 101 children with ALL, AML, CML, JMML, and MDS, and the non-malignant disease group included 83 children with PID, β-thalassemia, IMD BMF, and HLH. The median duration to neutrophil and platelet engraftment was 16 and 35 days in the malignant disease group vs 15 and 38 days in the non-malignant disease group. The cumulative incidence of grade II-IV aGVHD and cGVHD was 25.6% and 13.5% in the malignant disease group vs 19.7% and 11.1% in the non-malignant disease group, respectively. The median duration and cumulative incidence of neutrophil and platelet engraftment, and the cumulative incidence of grade II-IV aGVHD and cGVHD were similar between the two groups. Of the 184 pediatric patients, 114 patients survived during a median follow-up period of 14 months (range 4-138). The 5-year OS and DFS were not statistically different between the two groups (56.3% and 46.1% in malignant disease group vs 68.5% and 52.8% in non-malignant disease group). The above results indicate that UCB is a viable source for HSCT for children with malignant or non-malignant diseases, especially in urgent cases.

A case of Chediak-Higashi syndrome presented with accelerated phase could be treated effectively by unrelated cord blood transplantation

CHS is a rare immunodeficiency syndrome with defects in the functions of cytotoxic cells and neutrophils. Approximately 85% of patients with CHS undergo an AP within the first decade, which is similar to FHLH. Chemotherapy could induce transient remission, but only allogeneic HCT could correct the underlying genetic defect and prevent relapse. We reported a case of CHS diagnosed at 19 months, who had an elder brother who had previously succumbed to the same disease. The little girl presented with severe AP manifestations including recurrent high fever, enlarged superficial lymph nodes, and extraordinary hepatosplenomegaly occupying the whole abdominal and pelvic cavity. Comprehensive therapies including HLH 2004 protocol, supportive care, and antibiotics, especially antituberculous agents, were given to her to induce remission. After remission, the patient received fully HLA-matched UCBT. The transplantation course was uneventful, except for fluctuation of donor chimerism. The patient has been alive for 36 months without infection and neurologic manifestations and is under further follow-up. Our result provides another case that UCBT can be effective for treating patients with CHS and remission before HCT is important for good prognosis.

High-dose Chemotherapy with Stem Cell Rescue Provided Durable Remission for Classical Hodgkin Lymphoma-type Post-transplant Lymphoproliferative Disorder after Unrelated Cord Blood Transplantation: A Case Report and Review of the Literature

An adult woman developed polymorphic post-transplant lymphoproliferative disorder (PTLD) 58 months after unrelated cord blood transplantation. She was treated successfully with chemotherapy and radiation therapy but presented with lymphadenopathy and splenomegaly 74 months after transplantation. A lymph node biopsy confirmed the diagnosis of nodular sclerosis type Hodgkin lymphoma (classical Hodgkin lymphoma [CHL]-type PTLD). After salvage therapy and hematopoietic stem cell harvesting, she was subsequently treated with consolidative high-dose chemotherapy with melphalan followed by stem cell rescue, which resulted in durable remission. High-dose chemotherapy using stem cell rescue has potential as a therapeutic option for subsequent CHL-type PTLD.

Decitabine prior to salvaged unrelated cord blood transplantation for refractory or relapsed childhood acute leukemia

No clinical studies have investigated the role of decitabine as a part of the myeloablative conditioning regimen prior to UCBT for refractory or relapsed childhood AL in patients in NR status. The aim of this study was to identify the potential benefits of decitabine as a prior therapy before salvaged unrelated UCBT for refractory or relapsed childhood AL. Eight consecutive patients with childhood refractory/relapsed AL were enrolled in our study between 2013 and 2014. All patients were in NR status before the time of transplant and had features associated with poor outcomes, such as CNSL, MDS-AML, high WBC count at diagnosis, and hypodiploid status (FLT3+/ITD+). Additionally, all patients had one of the following disease statuses: PIF, multiple relapse, or early relapse. All transplants were performed with decitabine as part of the myeloablative conditioning regimen, which was decitabine+Flu/Bu/CY±BCNU or decitabine+Ara-c/BU/CY2±BCNU. A total of seven patients (7 of 8) achieved neutrophil engraftment and platelet engraftment, and one patient experienced primary graft failure. All eight patients (100%) developed PES at a median of 7 days. Three patients developed stage II-IV acute GVHD at a median of 18 days. Additionally, three patients developed chronic GVHD, but it was not extensive in any of those three patients. The median follow-up time after CBT was 19.9 months (range, 9.2-30.7 months). The estimated probability of OS was 75%. Two patients (2 of 8) experienced a testis relapse, and two patients (2 of 8) died. Our experience suggests that the additional application of decitabine as part of the myeloablative conditioning regimen prior to UCBT for refractory or relapsed childhood AL among patients who are not in remission is safe and might be an effective treatment option.

Effect of Decitabine Combined with Unrelated Cord Blood Transplantation in an Adult Patient with -7/EVI1+ Acute Myeloid Leukemia: a Case Report and Literature Review

Patients with relapsed or refractory acute myeloid leukemia (rAML) have a poor prognosis if they do not undergo hematopoietic stem cell transplantation (HSCT). We describe a case herein of acute myeloid leukemia (AML) with monosomy 7 and EVI1(+)(-7/EVI1(+)) in a patient who failed to achieve a complete remission (CR) after two cycles of standard induction chemotherapy. He subsequently received decitabine (DAC) as "bridge therapy" and directly underwent unrelated cord blood transplantation (UCBT) due to the absence of an available sibling donor. Although DAC treatment did not induce CR, it did produce hematologic improvement and control disease progression with acceptable side effects, thus effectively bridging the time of donor search. Following UCBT, the marrow showed complete hematologic and cytogenetic remission. At present, 18 months after the transplantation, the patient's general condition is still good.

Peripheral blood cells chimerism after unrelated cord blood transplantation in children: kinetics, predictive factors and impact on post-transplant outcome

This study aimed to describe kinetics of complete donor chimerism occurrence (cDC, >99·9% donor) after unrelated cord blood transplantation (UCBT), to identify its predictive factors and its impact on post-transplant outcome. Ninety-four children who received single UCBT after a myeloablative conditioning regimen had blood chimerism evaluation at predefined post-transplant dates, using a real-time polymerase chain reaction method with 0·1% sensitivity. Cumulative incidence of cDC at 1 year post-transplantation was 61·8%. Three predictive factors were identified in multivariate analysis: history of malignant disease (P = 0·03), older age (above 2·16 years, the first quartile of age, P = 0·0055) and higher level of cord/recipient human leucocyte antigen mismatch (4/6 vs. 5-6/6, P < 0·001) increased the probability of post-transplant cDC. Although graft cell dose had a strong impact on haematological recovery, it did not apparently influence cDC occurrence. Early cDC (i.e. more than 99·9% donor chimerism on days 15-30 post-transplant) appeared useful to predict engraftment (P = 0·003) as well as acute and chronic graft-versus-host disease (GvHD). Severe acute or chronic GvHD never occurred in patients with DC ≤99·9%, suggesting than even minimal residual host haematopoiesis is associated with a very low risk of GvHD after UCBT.

Unrelated donor cord blood transplantation for non-malignant disorders in children and adolescents

This study analyzes the data reported to the Korean Cord Blood Registry between 1994 and 2008, involving children and adolescents with non-malignant diseases. Sixty-five patients were evaluated in this study: SAA (n = 24), iBMFS, (n = 16), and primary immune deficiency/inherited metabolic disorder (n = 25). The CI of neutrophil recovery was 73.3% on day 42. By day 100, the CI of acute grade II-IV graft-versus-host disease was 32.3%. At a median follow-up of 71 months, five-yr OS was 50.7%. The survival rate (37.5%) and CI of neutrophil engraftment (37.5%) were lowest in patients with iBMFS. Deaths were mainly due to infection, pulmonary complications, and hemorrhage. In a multivariate analysis, the presence of >3.91 × 10(5) /kg of infused CD34 + cells was the only factor consistently identified as significantly associated with neutrophil engraftment (p = 0.04) and OS (p = 0.03). UCBT using optimal cell doses appears to be a feasible therapy for non-malignant diseases in children and adolescents for whom there is no appropriate HLA-matched related donor. Strategies to reduce transplant-related toxicities would improve the outcomes of UCBT in non-malignant diseases.

Study for the improvement of umbilical cord blood sampling using a new trial apparatus

AIM

The aim of this study was to evaluate the usefulness of the trial umbilical cord blood sampling bag for unrelated cord blood transplantation.

MATERIAL AND METHODS

Data were obtained from 100 vaginal deliveries. In 50 cases, umbilical cord blood (UCB) was taken with the traditional Kawasumi type UCB sampling bag. In another 50 cases, UCB were taken with trial UCB sampling bag offered by NIPRO Co. We compared the sampling volume between the two groups. Furthermore, 10 cases in each group were matched by sampling volume; we examined the quality of UCB on the number and concentration of nucleated cells, mononuclear cells, CD34+ cells and colony-forming unit granulocyte macrophage and the numbers tested positive for bacteria.

RESULTS

Whereas there were no significant differences in gestational weeks at sampling, the ratio of primipara women to multipara women, maternal age, and neonatal weight between the two groups, the sampling UCB volumes with the trial sampling bag were significantly higher than those with traditional sampling bags (P < 0.05). In addition, this phenomenon was more significant in the latter part of the study period (P < 0.05). On the other hand, there were no significant differences in the quality of UCB between the two groups.

CONCLUSION

Once clinicians have become accustomed to the trial UBC sampling bag, this method might be a useful method for collecting UCB for unrelated cord blood transplantation.

Mutation of the NPM1 gene contributes to the development of donor cell-derived acute myeloid leukemia after unrelated cord blood transplantation for acute lymphoblastic leukemia

Donor cell leukemia (DCL) is a rare but severe complication after allogeneic stem cell transplantation. Its true incidence is unknown because of a lack of correct recognition and reporting, although improvements in molecular analysis of donor-host chimerism are contributing to a better diagnosis of this complication. The mechanisms of leukemogenesis are unclear, and multiple factors can contribute to the development of DCL. In recent years, cord blood has emerged as an alternative source of hematopoietic progenitor cells, and at least 12 cases of DCL have been reported after unrelated cord blood transplantation. We report a new case of DCL after unrelated cord blood transplantation in a 44-year-old woman diagnosed as having acute lymphoblastic leukemia with t(1;19) that developed acute myeloid leukemia with normal karyotype and nucleophosmin (NPM1) mutation in donor cells. To our knowledge, this is the first report of NPM1 mutation contributing to DCL development.