Signaling mechanisms underlying self-renewal of leukemic stem cells (LSCs) are poorly understood, and identifying pathways specifically active in LSCs could provide opportunities for therapeutic ...intervention. T-cell immunoglobin mucin-3 (TIM-3) is expressed on the surface of LSCs in many types of human acute myeloid leukemia (AML), but not on hematopoietic stem cells (HSCs). Here, we show that TIM-3 and its ligand, galectin-9 (Gal-9), constitute an autocrine loop critical for LSC self-renewal and development of human AML. Serum Gal-9 levels were significantly elevated in AML patients and in mice xenografted with primary human AML samples, and neutralization of Gal-9 inhibited xenogeneic reconstitution of human AML. Gal-9-mediated stimulation of TIM-3 co-activated NF-κB and β-catenin signaling, pathways known to promote LSC self-renewal. These changes were further associated with leukemic transformation of a variety of pre-leukemic disorders and together highlight that targeting the TIM-3/Gal-9 autocrine loop could be a useful strategy for treating myeloid leukemias.
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•TIM-3+ AML LSCs secrete its ligand galectin-9 in an autocrine manner•TIM-3/galectin-9 autocrine signaling co-activates NF-κB and β-catenin in LSCs•This signaling is commonly used by LSCs in most myeloid malignancies
Signaling mechanisms specifically active in leukemic stem cells (LSCs) provide therapeutic opportunities. Akashi and colleagues identify a TIM-3/Gal-9 autocrine stimulatory loop that regulates self-renewal of human LSCs, through co-activation of NF-κB and β-catenin signaling, and promotes leukemic progression in a range of myeloid malignancies.
Adult T-cell leukemia-lymphoma (ATL) is usually resistant to conventional chemotherapies, and there are few other treatment options. Because CC chemokine receptor 4 (CCR4) is expressed on tumor cells ...from most patients with ATL, KW-0761, a humanized anti-CCR4 monoclonal antibody, which markedly enhances antibody-dependent cellular cytotoxicity, was evaluated in the treatment of patients with relapsed ATL.
A multicenter phase II study of KW-0761 for patients with relapsed, aggressive CCR4-positive ATL was conducted to evaluate efficacy, pharmacokinetic profile, and safety. The primary end point was overall response rate, and secondary end points included progression-free and overall survival from the first dose of KW-0761. Patients received intravenous infusions of KW-0761 once per week for 8 weeks at a dose of 1.0 mg/kg.
Of 28 patients enrolled onto the study, 27 received at least one infusion of KW-0761. Objective responses were noted in 13 of 26 evaluable patients, including eight complete responses, with an overall response rate of 50% (95% CI, 30% to 70%). Median progression-free and overall survival were 5.2 and 13.7 months, respectively. The mean half-life period after the eighth infusion was 422 ± 147 hours (± standard deviation). The most common adverse events were infusion reactions (89%) and skin rashes (63%), which were manageable and reversible in all cases.
KW-0761 demonstrated clinically meaningful antitumor activity in patients with relapsed ATL, with an acceptable toxicity profile. Further investigation of KW-0761 for treatment of ATL and other T-cell neoplasms is warranted.
Acute myeloid leukemia (AML) originates from self-renewing leukemic stem cells (LSCs), an ultimate therapeutic target in AML. Eradication of LSCs should be a critical and efficient therapeutic ...approach for the cure of AML. T-cell immunoglobulin mucin-3 (TIM-3) is expressed in most types of AML LSCs, but not in normal hematopoietic stem cells (HSCs); therefore, TIM-3 would be one of the promising therapeutic targets to specifically kill AML LSCs, sparing normal HSCs. In xenograft models reconstituted with human AML LSCs or human normal HSCs, an anti-human TIM-3 mouse antibody with cytotoxic activities exerts a potent anti-leukemic effect by targeting AML LSCs but does not affect normal human hematopoiesis in vivo. Here, we would like to introduce the recent studies on TIM-3 in normal and malignant hematopoiesis.
Allogeneic hematopoietic stem cell transplantation (allo-HSCT) has improved survival for patients with hematological malignancy, especially for those highly at risk of relapse. However, disease ...relapse after allo-HSCT remains the most common cause of treatment failure and death, even with conventional chemotherapy and donor lymphocyte infusion. Disease relapse in allo-HSCT can be reduced via pre-emptive treatment based on measurable residual disease and maintenance therapy for patients at high risk of relapse as promising treatment strategies. Recently, the development of novel agents and cellular therapies with high antitumor activity and less toxicity, which can be used in the post-transplant setting, has increased their clinical applications in the therapeutic approach. This review examines the current landscape and future strategies for maintenance therapy, mainly for AML and ALL after allo-HSCT.
Acute myeloid leukemia (AML) originates from self-renewing leukemic stem cells (LSCs), an ultimate therapeutic target for AML. Here we identified T cell immunoglobulin mucin-3 (TIM-3) as a surface ...molecule expressed on LSCs in most types of AML except for acute promyelocytic leukemia, but not on normal hematopoietic stem cells (HSCs). TIM-3
+ but not TIM-3
− AML cells reconstituted human AML in immunodeficient mice, suggesting that the TIM-3
+ population contains most, if not all, of functional LSCs. We established an anti-human TIM-3 mouse IgG2a antibody having complement-dependent and antibody-dependent cellular cytotoxic activities. This antibody did not harm reconstitution of normal human HSCs, but blocked engraftment of AML after xenotransplantation. Furthermore, when it is administered into mice grafted with human AML, this treatment dramatically diminished their leukemic burden and eliminated LSCs capable of reconstituting human AML in secondary recipients. These data suggest that TIM-3 is one of the promising targets to eradicate AML LSCs.
► TIM-3 is highly expressed in stem cells in AML of most FAB types except for M3 ► TIM-3 is not expressed in normal hematopoietic stem cells ► TIM-3 killing antibody treatment could eradicate human AML in a xenograft model ► Targeting TIM-3 could be a practical approach for human AML treatment
Abstract
Castleman disease (CD) is a rare lymphoproliferative disorder. Among subtypes of CD, idiopathic multicentric CD-not otherwise specified (iMCD-NOS) has a poor prognosis and its pathogenesis ...is largely unknown. Here we present a xenotransplantation model of iMCD-NOS pathogenesis. Immunodeficient mice, transplanted with lymph node (LN) cells from iMCD-NOS patients, develop iMCD-like lethal inflammation, while mice transplanted with LN cells from non-iMCD patients without inflammation serve as negative control. Grafts depleted of human CD3
+
T cells fail to induce inflammation in vivo. Upon engraftment, peripheral helper T (Tph) cells expand and levels of human CXCL13 substantially increase in the sera of mice. A neutralizing antibody against human CXCL13 blocks development of inflammation and improves survival in the recipient mice. Our study thus indicates that Tph cells, producing CXCL13 play a critical role in the pathogenesis of iMCD-NOS, and establishes iMCD-NOS as an immunoregulatory disorder.
We report here that in chronic lymphocytic leukemia (CLL), the propensity to generate clonal B cells has been acquired already at the hematopoietic stem cell (HSC) stage. HSCs purified from patients ...with CLL displayed lymphoid-lineage gene priming and produced a high number of polyclonal B cell progenitors. Strikingly, their maturation into B cells was restricted always to mono- or oligo-clones with CLL-like phenotype in xenogeneic recipients. These B cell clones were independent of the original CLL clones because they had their own immunoglobulin VDJ genes. Furthermore, they used preferentially VH genes frequently used in human CLL, presumably reflecting the role of B cell receptor signaling in clonal selection. These data suggest that HSCs can be involved in leukemogenesis even in mature lymphoid tumors.
► HSCs in CLL have cell-intrinsic propensity to generate clonal CLL-like B cells ► Abnormal karyotypes are not required for appearance of such B cell clones ► The majority of single HSCs in patients with CLL display lymphoid-lineage priming ► HSCs can be involved in oncogenesis even in mature lymphoid tumors
We conducted two parallel prospective, multicenter, phase II studies to evaluate the safety and efficacy of HLA-haploidentical peripheral blood stem cell transplantation using post-transplant ...cyclophosphamide (PTCy-haploPBSCT) following myeloablative conditioning (MAC, n = 50) and reduced-intensity conditioning (RIC, n = 77). Event-free survival (EFS) at 1-year as for primary endpoint was 64% and 43% in the MAC and RIC groups, respectively. Neutrophil engraftment was achieved in 98% and 94% in the MAC and RIC groups, respectively. The incidences of grades II-IV and III-IV acute graft-versus-host disease (GVHD) were 18% and 8% in the MAC group, and 14% and 5% in the RIC group, respectively. Those of all grade and moderate to severe chronic GVHD at 2-year were 36% and 20% in the MAC group, and 27% and 20% in the RIC group, respectively. Overall survival (OS), EFS, nonrelapse mortality, and relapse rate at 2-year were 68%, 54%, 10%, and 36% in the MAC group, and 44%, 35%, 20%, and 45% in the RIC group, respectively. Notably, 83% and 86% of patients who survived without relapse stopped immunosuppressant at 2-year in the MAC and RIC groups, respectively. Our results indicate that both MAC and RIC are valid options for PTCy-haploPBSCT for adults with hematological malignancies.
Prophylactic use of letermovir (LMV) markedly reduces the incidence of early clinically significant cytomegalovirus (csCMV) infection within the first 100 days after allogeneic hematopoietic cell ...transplantation (allo-HCT), which improves transplant outcomes. However, some patients eventually develop late-csCMV infection (beyond day 100) after completing LMV prophylaxis. To assess the incidence of late-csCMV infection as well as its risk factors and impacts on transplant outcome, a total of 81 allo-HCT recipients who had not developed early csCMV infection during LMV prophylaxis were retrospectively analyzed. Among them, 23 (28.4%) patients developed late-csCMV infection (until day 180) at a median time of 131 days after transplantation and 30 days after LMV discontinuation, respectively. Late-csCMV infection was correlated with apparent delayed immune reconstitution: patients transplanted from HLA-mismatched donors (hazard ratio HR = 13.0,
p
= 0.011) or CMV-IgG-negative donors (HR = 2.39,
p
= 0.043) had a significantly higher risk. In this study, transplant outcomes did not differ between patients with and without late-csCMV infection. This suggests a need to clarify the efficacy of extended administration of LMV for preventing late-csCMV infection in a larger number of allo-HCT recipients, especially those with “high-risk” donors.
Relapsed acute leukemia after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is associated with poor prognosis. In a subset of patients, durable remissions can be achieved with a ...second allo-HSCT (allo-HSCT2). However, many patients experience relapse after allo-HSCT2 and they may be considered for a third allo-HSCT (allo-HSCT3). Nevertheless, the benefit of allo-HSCT3 remains unconfirmed. Thus, herein a retrospective analysis of 253 allo-HSCT3s in patients with relapsed/refractory acute leukemia was carried out. In total, 29 (11.5%) survived at a median follow-up of 794 days (range: 87-4 619). The 3-year leukemia-free survival and overall survival (OS) rates were 9.7% and 10.9%, respectively. Patients who maintained remission for ≥2 years after allo-HSCT2 had a significantly better 3-year OS (35.8%) than those who experienced early relapse (<1 year, 7.8%; 1-2 years, 14.0%; P = 0.004). Complete remission at allo-HSCT3, performance status score of 0-1 at allo-HSCT3, grade I acute graft-versus-host disease after allo-HSCT2, and relapse ≥2 years after allo-HSCT2 were associated with better survival in patients who received allo-HSCT3. The prognosis after allo-HSCT3 in patients with relapsed/refractory acute leukemia is generally unfavorable. However, given the lack of alternative treatment options, allo-HSCT3 may be considered in a group of patients.