Flow cytometric analysis of CD34+ CD38- cells; cell frequency and immunophenotype based on CD45RA expression pattern.

INTRODUCTION: The CD34+ CD38- population in bone marrow includes hematopoietic stem/progenitor cells. Recently, in acute myeloid leukemia, the focus has shifted to flow cytometry analysis targeting CD34+ CD38- leukemic cells due to their effectiveness in minimal/measurable residual disease detection and prognosis prediction. Nevertheless, the immunophenotype and cell frequency of these cells in the bone marrow, in the absence of leukemic cells, remains unknown. We aimed to evaluate detailed characteristics of CD34+ CD38- cells in both normal and leukemic cells by flow cytometry. METHODS: We compared the cell frequency and immunophenotype of the CD34+ CD38- fraction in the following groups: patients with idiopathic thrombocytopenic purpura and malignant lymphoma as controls (n = 17), post-treatment patients without abnormal blasts (n = 35), and patients with myeloid malignancies (n = 86). The comparison was based on the presence or absence of CD45RA expression, a marker commonly used to prospectively isolate lymphoid-primed cell populations within the CD34+ CD38- fraction. RESULTS: The CD34+ CD38- CD45RA+ cell population exhibited a significant expansion in bone marrow without leukemic cells 1 month after cord blood transplantation and in various type of myeloid malignancies, compared to the control group (p < 0.01). Continuous CD45RA expression and notable expansion of the CD34+ CD38- CD45RA- population were exclusively observed in myelodysplastic syndrome-related diseases. The CD34+ CD38- CD45RA+ population displayed frequent expression of various markers in both leukemic and non-leukemic cells, in contrast to the CD34+ CD38- CD45RA- population. CONCLUSIONS: The CD34+ CD38- fraction should be carefully evaluated considering the nature of normal hematopoietic precursor cells, their cell frequency and immunophenotype, including CD45RA expression pattern, for improving the accuracy of myeloid malignancy diagnosis.

Successful Treatment of Warm Autoimmune Hemolytic Anemia with a Positive Donath-Landsteiner Test Using Rituximab.

Paroxysmal cold hemoglobinuria (PCH) is a rare disease in adults, and its concurrent presentation with warm-type autoimmune hemolytic anemia (AIHA) has not yet been reported. We encountered a 19-year-old woman with AIHA and a positive Donath-Landsteiner test result identified by a hemolytic attack during blood transfusion. She also showed positive results for the direct Coombs and Donath-Landsteiner antibody tests. After treatment with prednisolone followed by rituximab, the AIHA improved, and the Donath-Landsteiner antibody test result turned negative. Clinicians should be aware that patients may present with concurrent warm-type AIHA and PCH and consider rituximab for its treatment.

Mild Acute Graft-Versus-Host Disease Improves Outcomes After HLA-Haploidentical-Related Donor Transplantation Using Posttransplant Cyclophosphamide and Cord Blood Transplantation.

Haploidentical-related donor transplantation using posttransplant cyclophosphamide (PTCy-haplo) and cord blood transplantation (CBT) are valid alternatives for patients with hematological malignancies when HLA-matched donor transplantation (MDT) is unavailable. However, the effects of graft-versus-host disease (GVHD) on outcomes after these transplants have not been fully elucidated. Therefore, we evaluated the effects of acute and chronic GVHD on transplant outcomes after PTCy-haplo transplants and compared them with CBT and MDT. We included a total of 914 adult patients with hematological malignancies in the Kyoto Stem Cell Transplantation Group registry who received PTCy-haplo (N = 120), CBT (N = 402), and MDT (N = 392), and achieved neutrophil engraftment. A multivariate analysis revealed that grade I-II acute GVHD improved of overall survival (OS) after PTCy-haplo [hazard ratio (HR) = 0.39, P = 0.018] and CBT (HR = 0.48, P < 0.001), but not after MDT (HR = 0.80, P = 0.267) compared with patients without acute GVHD. Grade I-II acute GVHD had a trend toward reducing the risk of nonrelapse mortality (NRM) after PTCy-haplo (HR = 0.13, P = 0.060) and this positive effect was significant after CBT (HR = 0.39, P = 0.003). A negative impact of grade III-IV acute GVHD on NRM was observed after CBT and MDT, but not after PTCy-haplo. Limited chronic GVHD had a positive impact on OS after CBT and MDT, but not after PTCy-haplo. In conclusion, mild acute GVHD improved outcomes after PTCy-haplo and CBT, and limited chronic GVHD improved outcomes after CBT and MDT. These data indicated that the effects of GVHD on transplant outcomes depended on transplant platforms.

Effects of combined test dose and therapeutic drug monitoring strategy in exposure-directed busulfan.

Although exposure-directed busulfan (BU) dosing can improve allogeneic hematopoietic stem cell transplantation outcomes, there is still large variability in BU exposure with test dose alone due to changes in BU clearance caused by drug interactions. We conducted a single-arm phase II trial using the combined test dose and therapeutic drug monitoring strategy (PK-guided group) and compared the outcomes with an external historical cohort receiving a fixed-dose (fixed-dose group). The first eight and second eight doses were adjusted based on the area under the blood concentration-time curve (AUC) of the test and first doses, respectively, targeting a total AUC of 82.1 mg·h/L. All patients received either BU and cyclophosphamide conditioning (BU/CY) or fludarabine (FLU)-containing conditioning. The BU clearance at the first dose decreased more in patients receiving FLU than in those receiving BU/CY; however, BU clearance also declined over time in patients who received BU/CY. The simulated total AUC (sAUC) with test dose only was significantly higher in patients who received FLU than in those who received BU/CY, but sAUC with the combined strategy was comparable. The 100-day progression-free survival was 85.5% (95% confidence interval [CI]: 71.9-92.8%), and was not inferior to that in the fixed-dose group. For the FLU-containing regimens, the PK-guided group showed decreased relapse (0.0% vs. 26.9%, p = 0.03), and favorable overall survival (75.1% vs. 57.0%, p = 0.07) at 1 year. The combined strategy effectively controlled the BU exposure close to the target levels, potentially improving efficacy, especially in patients receiving the FLU-containing regimen. Clinical evaluation of efficacy of dose-modified intravenous busulfan in allogeneic hematopoietic stem cell transplantation for hematological malignancy (#UMIN000014077, June 15th, 2014).

Postazacitidine clone size predicts long-term outcome of patients with myelodysplastic syndromes and related myeloid neoplasms.

Azacitidine is a mainstay of therapy for myelodysplastic syndrome (MDS)-related diseases. The purpose of our study is to elucidate the effect of gene mutations on hematological response and overall survival (OS), particularly focusing on their posttreatment clone size. We enrolled a total of 449 patients with MDS or related myeloid neoplasms. They were analyzed for gene mutations in pretreatment (n = 449) and posttreatment (n = 289) bone marrow samples using targeted-capture sequencing to assess the impact of gene mutations and their posttreatment clone size on treatment outcomes. In Cox proportional hazard modeling, multihit TP53 mutation (hazard ratio [HR], 2.03; 95% confidence interval [CI], 1.42-2.91; P < .001), EZH2 mutation (HR, 1.71; 95% CI, 1.14-2.54; P = .009), and DDX41 mutation (HR, 0.33; 95% CI, 0.17-0.62; P < .001), together with age, high-risk karyotypes, low platelets, and high blast counts, independently predicted OS. Posttreatment clone size accounting for all drivers significantly correlated with International Working Group (IWG) response (P < .001, using trend test), except for that of DDX41-mutated clones, which did not predict IWG response. Combined, IWG response and posttreatment clone size further improved the prediction of the original model and even that of a recently proposed molecular prediction model, the molecular International Prognostic Scoring System (IPSS-M; c-index, 0.653 vs 0.688; P < .001, using likelihood ratio test). In conclusion, evaluation of posttreatment clone size, together with the pretreatment mutational profile as well as the IWG response play a role in better prognostication of azacitidine-treated patients with myelodysplasia.

Epitope Mismatch at HLA-DRB1 Associates with Reduced Relapse Risk in Cord Blood Transplantation for Standard-Risk Hematologic Malignancy.

Cord blood transplantation (CBT) is an attractive therapeutic option for patients with hematologic malignancies. CBT tolerates HLA mismatches between donors and recipients, but the HLA mismatches that generate graft-versus-tumor (GVT) effects remain unknown. Given that HLA molecules contain epitopes comprising polymorphic amino acids that determine their immunogenicity, we investigated associations between epitope-level HLA mismatches and relapse following single-unit CBT. A total of 492 patients with hematologic malignancies who underwent single-unit, T cell-replete CBT were included in this multicenter retrospective study. HLA epitope mismatches (EMs) were quantified using HLA matchmaker software from donor and recipient HLA-A, -B, -C, and -DRB1 allele data. Patients were dichotomized by median EM value and divided into 2 groups: patients who underwent transplantation in complete/partial remission (standard stage: 62.4%) and others (advanced stage: 37.6%). The median number of EMs in the graft-versus-host direction (GVH-EM) was 3 (range, 0 to 16) at HLA class I and 1 (range, 0 to 7) at HLA-DRB1. Higher HLA class I GVH-EM was associated with increased nonrelapse mortality (NRM) in the advanced stage group (adjusted hazard ratio [HR], 2.12; P = .021), with no significant advantage for relapse in either stage. In contrast, higher HLA-DRB1 GVH-EM was associated with better disease-free survival in the standard stage group (adjusted HR, .63; P = .020), which was attributed to lower relapse risk (adjusted HR, .46; P = .014). These associations also were observed even within HLA-DRB1 allele-mismatched transplantations in the standard stage group, indicating that EM might have an impact on relapse risk independent of allele mismatch. High HLA-DRB1 GVH-EM did not increase NRM in either stage. High HLA-DRB1 GVH-EM may lead to potent GVT effects and a favorable prognosis following CBT, especially in patients who underwent transplantation at the standard stage. This approach may facilitate appropriate unit selection and improve the overall prognosis of patients with hematologic malignancies who undergo CBT.

Coexistence of HLA and KIR ligand mismatches as a risk factor for viral infection early after cord blood transplantation.

Viral infection is one of the lethal adverse events after cord blood transplantation (CBT). Human leukocyte antigen (HLA) and killer immunoglobulin-like receptor (KIR) ligand divergences can increase the risk of viral infection due to conflicting interactions between virus-infected cells and immune cells. However, the relationship between these disparities and the frequency of viral infection after CBT remains to be evaluated. Herein, we have conducted a retrospective multicenter study to assess the effect of HLA and KIR ligand mismatches on viral infections after CBT. The study included 429 patients, among which 126 viral infections occurred before day 100. Viral infection was significantly associated with poorer overall survival (OS; hazard ratio [HR] 1.74, p < 0.01). Patients harboring ≥3 mismatches in the HLA allele and inhibitory KIR ligand mismatches (HLA & KIR mismatches) had a significantly greater prevalence of viral infection (HR 1.66, p = 0.04). Thus, patients with HLA & KIR mismatches had poorer outcomes in terms of non-relapse mortality (HR 1.61, p = 0.05). Our study demonstrates the unfavorable impacts of HLA & KIR mismatches on viral infections and non-relapse mortality after CBT. Evaluating the viral infection risk and performance of an appropriate and early intervention in high-risk patients and optimizing the graft selection algorithm could improve the outcome of CBTs.

Bortezomib-cyclophosphamide-dexamethasone induction/consolidation and bortezomib maintenance for transplant-eligible newly diagnosed multiple myeloma: phase 2 multicenter trial.

OBJECTIVES: We conducted a phase II trial to prospectively evaluate the efficacy and safety of bortezomib-cyclophosphamide-dexamethasone (VCD) induction, autologous stem cell transplantation (ASCT), VCD consolidation, and bortezomib maintenance in transplant-eligible newly diagnosed multiple myeloma (NDMM) patients in Japan (UMIN000010542). METHODS: From 2013 to 2016, 42 patients with a median age of 58 (range 42-65) years with NDMM were enrolled in 15 centers. The primary endpoint was the complete response (CR) /stringent CR (sCR) rate after transplantation, and overall/progression-free survival rates were also evaluated. RESULTS: Following induction therapy, the overall response rate was obtained in 71% of patients, including a CR/sCR of 10% and a very good partial response (VGPR) of 26%. Twenty-six of the 42 patients completed ASCT following the protocol and CR/sCR and VGPR rate 100 days after ASCT was 26% and 17%, respectively. During consolidation therapy, 3 of the 24 patients achieved deeper responses. Eight of the 18 patients completed 2-year bortezomib maintenance without disease progression and grade 3/4 toxicities. Five patients were VGPR or partial response after ASCT but maintained response with 2-year bortezomib maintenance. Two-year overall and progression-free survival rates were 92.5% (95% confidence interval [CI]: 78.5%-97.5%) and 62.6% (95% CI: 45.8%-75.5%), respectively. Grade 3/4 toxicities (≥ 10%) included neutropenia (19%) and anemia (17%) in induction, and thrombocytopenia (29%) in consolidation. CONCLUSION: VCD induction/consolidation and bortezomib maintenance with ASCT for NDMM resulted in a high CR/sCR rate and provided good overall/progression-free survival in Japan.

VS38 staining contributes to a novel gating strategy in flow cytometry for small B cell lymphoma, especially in lymphoplasmacytic lymphoma/Waldenström macroglobulinemia.

BACKGROUND: Multi-parametric flow cytometry (MFC) is a helpful tool for detecting neoplastic cells in malignant lymphoma; however, lymphoma cells can be difficult to detect when characteristic immunophenotypic abnormalities are not evident. We evaluated the stainability of VS38, which is used for multiple myeloma, in normal and abnormal B cells using MFC to develop a new strategy for detecting lymphoma cells. METHODS: We compared the median fluorescence intensity of VS38 staining in lymphocytes from patients without hematopoietic neoplasms and in B cells from 26 patients with B cell lymphoma (BCL). To evaluate the performance of VS38 gating, we compared VS38-positive B cells with the percentages of BCL cells, and with the mutation ratios of MYD88 L265P measured by droplet digital PCR in patients with lymphoplasmacytic lymphoma (LPL)/Waldenström macroglobulinemia (WM). RESULTS: CD27-positive memory B cells were stained with VS38, whereas normal lymphocytes were faintly stained. Lymphoma cells were stained with VS38 in 11 of 12 patients with LPL/WM, 3 of 3 with chronic lymphocytic leukemia, 3 of 5 with mantle cell lymphoma, 2 of 4 with follicular lymphoma, and 1 of 1 with splenic marginal zone lymphoma. The percentages of VS38-positive B cells in VS38-positive BCL were equivalent to those of lymphoma cells and the mutation ratios of MYD88 L265P in LPL/WM. CONCLUSIONS: VS38 identified neoplastic cells in plasma cell disorders and BCL. This might improve the accuracy of BCL diagnosis, especially in patients with LPL/WM.

Establishment of a predictive model for GVHD-free, relapse-free survival after allogeneic HSCT using ensemble learning.

Graft-versus-host disease-free, relapse-free survival (GRFS) is a useful composite end point that measures survival without relapse or significant morbidity after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We aimed to develop a novel analytical method that appropriately handles right-censored data and competing risks to understand the risk for GRFS and each component of GRFS. This study was a retrospective data-mining study on a cohort of 2207 adult patients who underwent their first allo-HSCT within the Kyoto Stem Cell Transplantation Group, a multi-institutional joint research group of 17 transplantation centers in Japan. The primary end point was GRFS. A stacked ensemble of Cox Proportional Hazard (Cox-PH) regression and 7 machine-learning algorithms was applied to develop a prediction model. The median age for the patients was 48 years. For GRFS, the stacked ensemble model achieved better predictive accuracy evaluated by C-index than other state-of-the-art competing risk models (ensemble model: 0.670; Cox-PH: 0.668; Random Survival Forest: 0.660; Dynamic DeepHit: 0.646). The probability of GRFS after 2 years was 30.54% for the high-risk group and 40.69% for the low-risk group (hazard ratio compared with the low-risk group: 2.127; 95% CI, 1.19-3.80). We developed a novel predictive model for survival analysis that showed superior risk stratification to existing methods using a stacked ensemble of multiple machine-learning algorithms.

Single Cord Blood Transplantation Versus HLA-Haploidentical-related Donor Transplantation Using Posttransplant Cyclophosphamide in Patients With Hematological Malignancies.

BACKGROUND: Unrelated cord blood (UCB) and haploidentical related donor transplantation using posttransplant cyclophosphamide (PTCy-haplo) have become alternative options to treat patients with hematological malignancies without a HLA-matched donor. METHODS: We conducted a retrospective study using registry data from the Kyoto Stem Cell Transplantation Group for patients with hematological malignancies who received their first allogeneic hematopoietic cell transplantation using a single UCB unit (n = 460) or PTCy-haplo (N = 57) between 2013 and 2019. RESULTS: We found that overall survival in the UCB group was comparable to that in the PTCy-haplo group (hazard ratio, 1.00; 95% confidence interval, 0.66-1.52), although neutrophil and platelet engraftment were significantly delayed. Nonrelapse mortality risk and the incidence of graft-versus-host disease in the UCB group were also comparable to those in the PTCy-haplo group. Although the relapse risk was similar between the UCB group and the PTCy-haplo group regardless of the disease risk, acute myeloid leukemia patients benefit from UCB transplant with a significantly lower relapse rate (hazard ratio, 0.38; 95% confidence interval, 0.18-0.76). CONCLUSIONS: UCB transplant gives outcomes comparable to PTCy-haplo transplant, and both UCB and PTCy-haplo units are suitable as alternative donor sources for patients without an HLA-matched sibling or unrelated donor.

Safety of Intravenous Autologous Bone Marrow-Derived Mesenchymal Cell Transplantation in 5 Patients With Reduced Left Ventricular Ejection Fraction.

Background: Although intracardiac injection or intracoronary delivery of mesenchymal stem cells (MSCs) has been reported, there have been few studies on the intravenous injection of MSCs, particularly in Japan. Methods and Results: Five patients with left ventricular ejection fraction (LVEF) ≤45% received 1.0×108 MSCs intravenously. The procedure did not induce significant changes in vital signs. One patient had an elevated body temperature after 1 day, but recovered spontaneously. Laboratory tests remained normal for 1 month after cell delivery. Computed tomography was performed after 1-2 years, and there was no evidence of malignancy. Conclusions: In this pilot study of patients with reduced LVEF, intravenous MSC delivery had no adverse effects.

Secondary failure of platelet recovery in patients treated with high-dose thiotepa and busulfan followed by autologous stem cell transplantation.

Autologous stem cell transplantation (ASCT) with high-dose thiotepa and busulfan is a treatment option for patients with central nervous system (CNS) lymphoma. We report here the occurrence of secondary failure of platelet recovery (SFPR) in three out of 24 patients who received high-dose thiotepa and busulfan followed by ASCT. Although there was no obvious abnormality in the primary platelet engraftment as well as the recovery of other blood cells, they developed SFPR with a median time to onset of day 38, and the platelets gradually recovered over several months with steroid therapy. During the same period, there was no development of SFPR among 50 patients who received ASCT with a conditioning regimen of MEAM (ranimustine, etoposide, cytarabine, and melphalan) or high-dose melphalan. However, one of the two patients who received a conditioning regimen of busulfan and melphalan developed SFPR, suggesting that the use of a busulfan-based conditioning regimen may be one of the risk factors for SFPR. It is important to be aware of this possible adverse effect of ASCT with high-dose thiotepa and busulfan to ensure timely diagnosis and prevention of subsequent serious complications.

Impact of Donor Source on Allogeneic Hematopoietic Stem Cell Transplantation for Mature T Cell and Natural Killer Cell Neoplasms in the Kyoto Stem Cell Transplantation Group.

Although allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the key strategy to cure patients with mature T and natural killer (NK) cell lymphomas/leukemia, especially those with relapsed/refractory diseases, there is no consensus strategy for donor selection. We retrospectively analyzed the outcomes of allo-HSCT in 111 patients in 15 Japanese institutions as a multi-institutional joint research project. Thirty-nine patients received bone marrow or peripheral blood stem cell transplantation from related donors (rBMT/rPBSCT), 37 received BMT/PBSCT from unrelated donors (uBMT/uPBSCT), and 35 received cord blood transplantation (CBT). Overall survival (OS) and progression-free survival (PFS) at 4 years were 42% and 34%, respectively. The cumulative incidences of relapse and nonrelapse mortality were 43% and 25%. In multivariate analysis, CBT showed comparable OS with rBMT/rPBSCT (rBMT/rPBSCT versus CBT: hazard ratio [HR], 1.63; P = .264) and better OS compared with uBMT/uPBSCT (HR, 2.99; P = .010), with a trend toward a lower relapse rate (rBMT/rPBSCT versus CBT: HR, 2.60; P = .010; uBMT/uPBSCT versus CBT: HR, 2.05; P = .082). This superiority of CBT was more definite in on-disease patients (OS: rBMT/rPBSCT versus CBT: HR, 5.52; P = .021; uBMT/uPBSCT versus CBT: HR, 6.80; P = .007). Better disease control was also strongly associated with better OS and PFS with lower relapse rate. In conclusion, allo-HSCT is beneficial for the survival of patients with mature T and NK cell lymphomas/leukemia if performed in a timely fashion. Since CBT showed favorable survival with a lower relapse risk, it could be a preferred alternative, especially in on-disease patients.