Combination of reduced post-transplant cyclophosphamide and early tacrolimus initiation increases the incidence of chronic graft-versus-host disease in human leukocyte antigen-haploidentical peripheral blood stem-cell transplantation.

We evaluated the clinical impacts of the concurrent modification of post-transplant cyclophosphamide (PTCy) dose and tacrolimus (Tac)-initiation timing in 61 patients with human leukocyte antigen-haploidentical transplantation. Reduced-dose PTCy (80 mg/kg) was associated with a higher incidence of moderate-to-severe chronic graft-versus-host disease (GVHD) than standard-dose PTCy (100 mg/kg) (35.0% vs. 26.6%, p = 0.053). Notably, early-initiation Tac (day -1) increased moderate-to-severe chronic GVHD than standard-initiation Tac (day 5) in the reduced-dose PTCy group (p = 0.032), whereas Tac-initiation timing did not impact chronic GVHD in the standard-dose PTCy group. These data indicate that the combination of reduced-dose PTCy and early-initiation Tac can amplify chronic GVHD.

[Relapsed primary central nervous system lymphoma treated with CD19 chimeric antigen receptor T-cell therapy and allogeneic hematopoietic stem cell transplantation].

Relapsed and/or refractory (R/R) primary central nervous system lymphoma (PCNSL) has a poor prognosis. A 57-year-old man diagnosed with PCNSL achieved a complete response by high-dose methotrexate-based chemotherapy followed by autologous hematopoietic stem cell transplantation (ASCT). The disease was not cured, so he was treated with the anti-CD19 chimeric antigen receptor (CAR) T-cell therapy tisagenlecleucel after the third relapse. However, the disease relapsed again 28 days after CAR T-cell therapy. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) was attempted as curative therapy after bridging with second ASCT and tirabrutinib monotherapy. Although a temporary response was achieved, the disease relapsed 98 days after allo-HSCT. While receiving tirabrutinib for relapse after allo-HSCT, the patient developed acute respiratory failure due to transplant-related toxicity and post-transplant thrombotic microangiopathy. He died 175 days after allo-HSCT. Although various treatments for PCNSL have been investigated in recent years, the treatment strategy for R/R PCNSL has not been established. Further studies are warranted to improve the outcomes of patients with R/R PCNSL.

Simulation-based Bone Marrow Aspiration and Trephine Biopsy Education for Medical Students: A Non-randomized Controlled Trial.

Introduction Despite the critical role of bone marrow aspiration and a trephine biopsy (BMAT) in the diagnosis and management of hematological diseases, research on effective teaching methods is limited. Medical students traditionally learn to perform BMAT through observation and replication, which poses a risk to patient safety. Therefore, we developed a novel BMAT simulator for undergraduate medical students using a simulation-based education program. Methods This program, designed for fourth- and fifth-year medical students at Okayama University Medical School, included pre-study materials and one hour of simulation training. Internists practicing hematology served as the controls. Before and after the simulation training, the students completed questionnaires regarding self-confidence, self-evaluation, interest, and knowledge. The procedures were evaluated objectively using a checklist at the end of the program. Results There were significant improvements in self-evaluation, self-confidence, interest, and knowledge acquisition after the simulation program (p≤0.001). The checklist revealed that the mean overall proficiency level of the students was 76.9%, which was significantly higher than that of internists (63.5%) (p≤0.01). Conclusion Our simulation-based education program using the novel BMAT simulator improved medical students' BMAT knowledge and skills.

Recurrent Cerebral Hemorrhaging with Platelet Dysfunction Accompanied by Anti-glycoprotein VI Autoantibodies in a Patient with TAFRO Syndrome.

Thrombocytopenia, anasarca, fever, renal dysfunction, and organomegaly (TAFRO) syndrome is an inflammatory disorder with an unclear pathogenesis. We herein report a case of TAFRO syndrome in remission in a patient who experienced recurrent intracranial bleeding despite a normal platelet count and coagulation system. A further investigation suggested the presence of anti-glycoprotein VI (GPVI) autoantibodies in the plasma, which induced platelet dysfunction and bleeding tendency. No new bleeding or relapse of TAFRO syndrome occurred after immunosuppressive therapy was initiated. These findings may help elucidate the autoimmune pathogenesis of TAFRO syndrome.

Activated CD4+ T Cell Proportion in the Peripheral Blood Correlates with the Duration of Cytokine Release Syndrome and Predicts Clinical Outcome after Chimeric Antigen Receptor T Cell Therapy.

Objective Chimeric antigen receptor (CAR) T cell therapy is an emerging and effective therapy for relapsed or refractory diffuse large B cell lymphoma (R/R DLBCL). The characteristic toxicities of CAR T cell therapy include cytokine release syndrome (CRS) and prolonged cytopenia. We investigated the factors associated with these complications after CAR T cell therapy by analyzing lymphocyte subsets following CAR T cell infusion. Methods We retrospectively analyzed peripheral blood samples on days 7, 14, and 28 after tisagenlecleucel (tisa-cel) infusion by flow cytometry at our institution between June 2020 and September 2022. Patients Thirty-five patients with R/R DLBCL who received tisa-cel therapy were included. Results A flow cytometry-based analysis of blood samples from these patients revealed that the proportion of CD4+CD25+CD127+ T cells (hereafter referred to as "activated CD4+ T cells" ) among the total CD4+ T cells on day 7 after tisa-cel infusion correlated with the duration of CRS (r=0.79, p<0.01). In addition, a prognostic analysis of the overall survival (OS) using time-dependent receiver operating characteristic curves indicated a significantly more favorable OS and progression-free survival of patients with a proportion of activated CD4+ T cells among the total CD4+ T cells <0.73 (p=0.01, and p<0.01, respectively). Conclusion These results suggest that the proportion of activated CD4+ T cells on day 7 after tisa-cel infusion correlates with the CRS duration and predicts clinical outcomes after CAR T cell therapy. Further studies with a larger number of patients are required to validate these observations.

A phase 1/2 study of NS-87/CPX-351 (cytarabine and daunorubicin liposome) in Japanese patients with high-risk acute myeloid leukemia.

OBJECTIVES: NS-87/CPX-351 is a dual-drug liposomal encapsulation of cytarabine and daunorubicin. NS-87/CPX-351 exerts antileukemic action by maintaining a synergistic molar ratio of cytarabine to daunorubicin of 5:1 within the liposome while in circulation. Patients with high-risk acute myeloid leukemia (AML), which includes therapy-related AML and AML with myelodysplasia-related changes (AML-MRC), have poorer outcomes than those with other AML. METHODOLOGY: This open-label phase 1/2 (P1/2) study was conducted in 47 Japanese patients aged 60-75 years with newly diagnosed high-risk AML to evaluate the pharmacokinetics, safety, and efficacy of NS-87/CPX-351. RESULTS: In the 6 patients enrolled in the P1 portion, no dose-limiting toxicities (DLTs) were reported, and 100 units/m2 during the induction cycle was found to be acceptable. Cytarabine and daunorubicin had a long half-life in the terminal phase (32.8 and 28.7 h, respectively). In the 35 patients enrolled in the P2 portion, composite complete remission (CRc; defined as complete remission [CR] or CR with incomplete hematologic recovery [CRi]) was achieved in 60.0% (90% CI: 44.7-74.0) of the patients. Adverse events due to NS-87/CPX-351 were well tolerated. OUTCOMES: NS-87/CPX-351 can be considered as a frontline treatment option for Japanese patients with high-risk AML.

Collection efficiency and safety of large-volume leukapheresis for the manufacturing of tisagenlecleucel.

BACKGROUND: In patients with relapsed or refractory B cell acute lymphoblastic leukemia or B cell non-Hodgkin lymphoma (r/r B-ALL/B-NHL) with low CD3+ cells in the peripheral blood (PB), sufficient CD3+ cell yield in a single day may not be obtained with normal-volume leukapheresis (NVL). Large-volume leukapheresis (LVL) refers to the processing of more than three times the total blood volume (TBV) in a single session for PB apheresis; however, the efficiency and safety of LVL for manufacturing of tisagenlecleucel (tisa-cel) remain unclear. This study aimed to investigate the tolerability of LVL. STUDY DESIGN AND METHODS: We retrospectively collected data on LVL (≥3-fold TBV) and NVL (<3-fold TBV) performed for patients with r/r B-ALL/B-NHL in our institution during November 2019 and September 2023. All procedures were performed using a continuous mononuclear cell collection (cMNC) protocol with the Spectra Optia. RESULTS: Although pre-apheresis CD3+ cells in the PB were significantly lower in LVL procedures (900 vs. 348/µL, p < .01), all patients could obtain sufficient CD3+ cell yield in a single day with a comparably successful rate of final products (including out-of-specification) between the two groups (97.2% vs. 100.0%, p = 1.00). The incidence and severity of citrate toxicity (no patients with grade ≥ 3) during procedures was not significantly different between the two groups (22.2% vs. 26.1%, p = .43) and no patient discontinued leukapheresis due to any complications. CONCLUSION: LVL procedures using Spectra Optia cMNC protocol was well tolerated and did not affect the manufacturing of tisa-cel.

Chimeric antigen receptor T-cell therapy after COVID-19 in refractory high-grade B-cell lymphoma.

Although chimeric antigen receptor T-cell (CAR-T) therapies have dramatically improved the outcomes of relapsed/refractory B-cell malignancies, recipients suffer from severe humoral immunodeficiencies. Furthermore, patients with coronavirus disease 2019 (COVID-19) have a poor prognosis, as noted in several case reports of recipients who had COVID-19 before the infusion. We report the case of a 70-year-old woman who developed COVID-19 immediately before CAR-T therapy for high-grade B-cell lymphoma. She received Tixagevimab-Cilgavimab chemotherapy and radiation therapy but never achieved remission. She was transferred to our hospital for CAR-T therapy, but developed COVID-19. Her symptoms were mild and she was treated with long-term molnupiravir. On day 28 post-infection, lymphodepleting chemotherapy was restarted after a negative polymerase chain reaction (PCR) test was confirmed. The patient did not experience recurrence of COVID-19 symptoms or severe cytokine release syndrome. Based on the analysis and comparison of the previous reports with this case, we believe that CAR-T therapy should be postponed until a negative PCR test is confirmed. In addition, Tixagevimab-Cilgavimab and long term direct-acting antiviral agent treatment can be effective prophylaxis for severe COVID-19 and shortening the duration of infection.

Antitumor activity of α-pinene in T-cell tumors.

T-cell acute leukemia and lymphoma have a poor prognosis. Although new therapeutic agents have been developed, their therapeutic effects are suboptimal. α-Pinene, a monoterpene compound, has an antitumor effect on solid tumors; however, few comprehensive investigations have been conducted on its impact on hematologic malignancies. This report provides a comprehensive analysis of the potential benefits of using α-pinene as an antitumor agent for the treatment of T-cell tumors. We found that α-pinene inhibited the proliferation of hematologic malignancies, especially in T-cell tumor cell lines EL-4 and Molt-4, induced mitochondrial dysfunction and reactive oxygen species accumulation, and inhibited NF-κB p65 translocation into the nucleus, leading to robust apoptosis in EL-4 cells. Collectively, these findings suggest that α-pinene has potential as a therapeutic agent for T-cell malignancies, and further investigation is warranted.

CDK4/6 signaling attenuates the effect of epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors in EGFR-mutant non-small cell lung cancer.

Background: Epidermal growth factor receptor (EGFR) mutations, such as exon 19 deletion and exon 21 L858R, are driver oncogenes of non-small cell lung cancer (NSCLC), with EGFR tyrosine kinase inhibitors (TKIs) being effective against EGFR-mutant NSCLC. However, the efficacy of EGFR-TKIs is transient and eventually leads to acquired resistance. Herein, we focused on the significance of cell cycle factors as a mechanism to attenuate the effect of EGFR-TKIs in EGFR-mutant NSCLC before the emergence of acquired resistance. Methods: Using several EGFR-mutant cell lines, we investigated the significance of cell cycle factors to attenuate the effect of EGFR-TKIs in EGFR-mutant NSCLC. Results: In several EGFR-mutant cell lines, certain cancer cells continued to proliferate without EGFR signaling, and the cell cycle regulator retinoblastoma protein (RB) was not completely dephosphorylated. Further inhibition of phosphorylated RB with cyclin-dependent kinase (CDK) 4/6 inhibitors, combined with the EGFR-TKI osimertinib, enhanced G0/G1 cell cycle accumulation and growth inhibition of the EGFR-mutant NSCLC in both in vitro and in vivo models. Furthermore, residual RB phosphorylation without EGFR signaling was maintained by extracellular signal-regulated kinase (ERK) signaling, and the ERK inhibition pathway showed further RB dephosphorylation. Conclusions: Our study demonstrated that the CDK4/6-RB signal axis, maintained by the MAPK pathway, attenuates the efficacy of EGFR-TKIs in EGFR-mutant NSCLC, and targeting CDK4/6 enhances this efficacy. Thus, combining CDK4/6 inhibitors and EGFR-TKI could be a novel treatment strategy for TKI-naïve EGFR-mutant NSCLC.

Evaluating the efficiency and safety of large-volume leukapheresis using the Spectra Optia continuous mononuclear cell collection protocol for peripheral blood stem cell collection from healthy donors: A retrospective study.

BACKGROUND: Large-volume leukapheresis (LVL) refers to processing of more than three volumes of blood in a single session for peripheral blood stem cell collection. Recently, continuous mononuclear cell collection (cMNC) protocol has been developed using the Spectra Optia system, which is a widely used apheresis device. LVL using the novel protocol has been investigated in patients. However, the efficiency and safety of LVL in healthy donors using this protocol has not been characterized. Therefore, this study aimed to evaluate the efficiency and tolerability of CD34+ collection of LVL with the cMNC protocol in healthy donors. STUDY DESIGN AND METHODS: We retrospectively collected data on LVL (>3 total blood volume) and normal-volume leukapheresis (NVL) performed in healthy donors between October 2019 and December 2021. All procedures were performed using the cMNC protocol. RESULTS: Although pre-apheresis CD34+ cell count was lesser in LVL (23.5 vs. 58.0/µL, p < .001), CD34+ collection efficiency was comparable between LVL and NVL (61.2% vs. 61.4%, p = .966). Platelet loss was significantly higher in LVL compared to NVL (38.0% vs. 29.4%, p < .001), with no correlation between attrition of platelet and processing blood volume. Moreover, the incidence of citrate toxicity during procedures was comparable between the two groups (31.6% vs. 21.4%, p = .322). All LVL procedures could be completed without any adverse events. CONCLUSION: Allogeneic LVL procedure using Spectra Optia cMNC protocol was well tolerated by the donors and resulted in efficient collection of CD34+ cells, which was comparable to that of NVL.

Distribution and clinical impact of molecular subtypes with dark zone signature of DLBCL in a Japanese real-world study.

The distribution and clinical impact of cell-of-origin (COO) subtypes of diffuse large B-cell lymphoma (DLBCL) outside Western countries remain unknown. Recent literature also suggests that there is an additional COO subtype associated with the germinal center dark zone (DZ) that warrants wider validation to generalize clinical relevance. Here, we assembled a cohort of Japanese patients with untreated DLBCL and determined the refined COO subtypes, which include the DZ signature (DZsig), using the NanoString DLBCL90 assay. To compare the distribution and clinical characteristics of the molecular subtypes, we used a data set from the cohort of British Columbia Cancer (BCC) (n = 804). Through the 1050 patient samples on which DLBCL90 assay was successfully performed in our cohort, 35%, 45%, and 6% of patients were identified to have germinal center B-cell-like (GCB) DLBCL, activated B-cell-like (ABC) DLBCL, and DZsig-positive (DZsigpos) DLBCL, respectively, with the highest prevalence of ABC-DLBCL, differing significantly from the BCC result (P < .001). GCB-DLBCL, ABC-DLBCL, and DZsigpos-DLBCL were associated with 2-year overall survival rates of 88%, 75%, and 66%, respectively (P < .0001), with patients with DZsigpos-DLBCL having the poorest prognosis. In contrast, GCB-DLBCL without DZsig showed excellent outcomes after rituximab-containing immunochemotherapy. DZsigpos-DLBCL was associated with the significant enrichment of tumors with CD10 expression, concurrent MYC/BCL2 expression, and depletion of microenvironmental components (all, P < .05). These results provide evidence of the distinct distribution of clinically relevant molecular subtypes in Japanese DLBCL and that refined COO, as measured by the DLBCL90 assay, is a robust prognostic biomarker that is consistent across geographical areas.

Negative Prognostic Impact of High-Dose or Long-Term Corticosteroid Use in Patients with Relapsed or Refractory B-Cell Lymphoma Who Received Tisagenlecleucel.

The prognostic impact of corticosteroid therapy in patients receiving tisagenlecleucel (tisa-cel) treatment who are more likely to develop cytokine release syndrome (CRS) remains unclear. This study aimed to evaluate the clinical impact and lymphocyte kinetics of corticosteroid administration for CRS in 45 patients with relapsed and/or refractory B-cell lymphoma treated with tisa-cel. This was a retrospective evaluation of all consecutive patients diagnosed with relapsed and/or refractory diffuse large B-cell lymphoma, follicular lymphoma with histologic transformation to large B-cell lymphoma, or follicular lymphoma who received commercial-based tisa-cel treatment. The best overall response rate, complete response rate, median progression-free survival (PFS), and median overall survival (OS) were 72.7%, 45.5%, 6.6 months, and 15.3 months, respectively. CRS (predominantly grade 1/2) occurred in 40 patients (88.9%), and immune effector cell-associated neurotoxicity syndrome (ICANS) of all grades occurred in 3 patients (6.7%). No grade ≥3 ICANS occurred. Patients with high-dose (≥524 mg, methylprednisolone equivalent; n = 12) or long-term (≥8 days; n = 9) corticosteroid use had inferior PFS and OS to patients with low-dose or no corticosteroid use (both P < .05). The prognostic impact remained even in 23 patients with stable disease (SD) or progressive disease (PD) before tisa-cel infusion (P = .015). but not in patients with better disease status (P = .71). The timing of corticosteroid initiation did not have a prognostic impact. Multivariate analysis identified high-dose corticosteroid use and long-term corticosteroid use as independent prognostic factors for PFS and OS, respectively, after adjusting for elevated lactate dehydrogenase level before lymphodepletion chemotherapy and disease status (SD or PD). Lymphocyte kinetics analysis demonstrated that after methylprednisolone administration, the proportions of regulatory T cells (Tregs), CD4+ central memory T (TCM) cells, and natural killer (NK) cells were decreased, whereas the proportion of CD4+ effector memory T (TEM) cells was increased. Patients with a higher proportion of Tregs at day 7 had a lower incidence of CRS, but this did not affect prognosis, indicating that early elevation of Tregs may serve as a biomarker for CRS development. Furthermore, patients with higher numbers of CD4+ TCM cells and NK cells at various time points had significantly better PFS and OS, whereas the number of CD4+ TEM cells did not impact prognostic outcomes. This study suggests that high-dose or long-term corticosteroid use attenuates the efficacy of tisa-cel, especially in patients with SD or PD. Additionally, patients with high levels of CD4+ TCM cells and NK cells after tisa-cel infusion had longer PFS and OS.

Efficient granulocyte collection method using high concentrations of medium molecular weight hydroxyethyl starch.

BACKGROUND: Granulocyte transfusion therapy is a rational therapeutic option for patients with prolonged, severe neutropenia. Although high molecular weight hydroxyethyl starch (hHES) facilitates the separation of red blood cells during granulocyte collection, renal dysfunction has been noted as a potential side effect. HES130/0.4 (Voluven®) is a medium molecular weight HES (mHES) with superior safety profiles compared to hHES. Although HES130/0.4 is reportedly effective in the collection of granulocytes, we lack studies comparing the efficiency of granulocyte collection using HES130/0.4 and hHES. STUDY DESIGN AND METHODS: We retrospectively collected the data from 60 consecutive apheresis procedures performed on 40 healthy donors at the Okayama University Hospital between July 2013 and December 2021. All procedures were performed using the Spectra Optia system. Based on the HES130/0.4 concentration in the separation chamber, granulocyte collection methods using HES130/0.4 were classified into m0.46, m0.44, m0.37, and m0.8 groups. We used HES130/0.4 and hHES groups to compare the various sample collection methods. RESULTS: The median granulocyte collection efficiency (CE) was approximately 24.0% and 28.1% in the m0.8 and hHES groups, respectively, which were significantly higher than those in the m0.46, m0.44, and m0.37 groups. One month following granulocyte collection with HES130/0.4, no significant changes were observed in serum creatinine levels compared to those before the donation. CONCLUSION: Therefore, we propose a granulocyte collection approach employing HES130/0.4, which is comparable to the use of hHES in terms of the granulocyte CE. A high concentration of HES130/0.4 in the separation chamber was considered crucial for granulocyte collection.

Tfl deletion induces extraordinary Cxcl13 secretion and cachexia in VavP-Bcl2 transgenic mice.

STATEMENT OF SIGNIFICANCE: Loss of TFL, found in several types of lymphoma, induces excessive CXCL13 secretion through RNA dysregulation contributing to body weight loss and early death in lymphoma model mice. Follicular lymphoma (FL) is associated with overexpressed BCL-2 and other genetic aberrations, including 6q-. We identified a novel gene on 6q25, "Transformed follicular lymphoma (TFL)," from a transformed FL. TFL regulates several cytokines via mRNA degradation, which has been suggested to underlie resolving inflammation. Fluorescence in situ hybridization revealed a deletion of TFL occurred in 13.6% of various B-cell lymphoma samples. We developed VavP-bcl2 transgenic, TFL deficit mice (Bcl2-Tg/Tfl -/-) to seek how TFL affects disease progression in this lymphoma model. While Bcl2-Tg mice developed lymphadenopathy and died around 50 weeks, Bcl2-Tg/Tfl -/- mice lost body weight around 30 weeks and died about 20 weeks earlier than Bcl2-Tg mice. Furthermore, we found a unique B220-IgM+ cell population in the bone marrow of Bcl2-Tg mice. cDNA array in this population revealed that Cxcl13 mRNA in Bcl2-Tg/Tfl -/- mice expressed significantly higher than Bcl2-Tg mice. In addition, bone marrow extracellular fluid and serum showed an extremely high Cxcl13 concentration in Bcl2-Tg/Tfl -/- mice. Among bone marrow cells, the B220-IgM+ fraction was the main producer of Cxcl13 in culture. A reporter assay demonstrated TFL regulates CXCL-13 via induction of 3'UTR mRNA degradation in B lineage cells. These data suggest Tfl regulates Cxcl13 in B220-IgM+ cells in the bone marrow, and a very high concentration of serum Cxcl13 arising from these cells may contribute to early death in lymphoma-bearing mice. Since several reports have suggested the association of CXCL13 expression with lymphoma, these findings provide new insights into cytokine regulation via TFL in lymphoma.

Venetoclax plus low-dose cytarabine in patients with newly diagnosed acute myeloid leukemia ineligible for intensive chemotherapy: an expanded access study in Japan.

BACKGROUND: In a Phase 3 international clinical trial (VIALE-C), venetoclax plus low-dose cytarabine improved the response rate and overall survival versus placebo plus low-dose cytarabine in patients with newly diagnosed acute myeloid leukemia who were ineligible for intensive chemotherapy. After the enrollment period of VIALE-C ended, we conducted an expanded access study to provide preapproval access to venetoclax in combination with low-dose cytarabine in Japan. METHODS: Previously, untreated patients with acute myeloid leukemia who were ineligible for intensive chemotherapy were enrolled according to the VIALE-C criteria. Patients received venetoclax (600 mg, Days 1-28, 4-day ramp-up in Cycle 1) in 28-day cycles and low-dose cytarabine (20 mg/m2, Days 1-10). All patients took tumor lysis syndrome prophylactic agents and hydration. Safety endpoints were assessed. RESULTS: Fourteen patients were enrolled in this study. The median age was 77.5 years (range = 61-84), with 78.6% over 75 years old. The most common grade ≥ 3 treatment-emergent adverse event was neutropenia (57.1%). Febrile neutropenia was the most frequent serious adverse event (21.4%). One patient developed treatment-related acute kidney injury, leading to discontinuation of treatment. Two patients died because of cardiac failure and disease progression that were judged not related to study treatment. No patients developed tumor lysis syndrome. CONCLUSIONS: The safety outcomes were similar to those in VIALE-C without new safety signals and were well managed with standard medical care. In clinical practice, more patients with severe background disease are expected, in comparison with in VIALE-C, suggesting that it is important to carefully manage and prevent adverse events.

Hematopoietic stem cell-derived Tregs are essential for maintaining favorable B cell lymphopoiesis following posttransplant cyclophosphamide.

Posttransplant cyclophosphamide (PTCy) is associated with a low incidence of chronic graft-versus-host disease (cGVHD) following hematopoietic stem cell (HSC) transplantation. Previous studies have shown the important roles of B cell immunity in cGVHD development. Here, we investigated the long-term reconstitution of B lymphopoiesis after PTCy using murine models. We first demonstrated that the immune homeostatic abnormality leading to cGVHD is characterized by an initial increase in effector T cells in the bone marrow and subsequent B and Treg cytopenia. PTCy, but not cyclosporine A or rapamycin, inhibits the initial alloreactive T cell response, which restores intra-bone marrow B lymphogenesis with a concomitant vigorous increase in Tregs. This leads to profound changes in posttransplant B cell homeostasis, including decreased B cell activating factors, increased transitional and regulatory B cells, and decreased germinal center B cells. To identify the cells responsible for PTCy-induced B cell tolerance, we selectively depleted Treg populations that were graft or HSC derived using DEREG mice. Deletion of either Treg population without PTCy resulted in critical B cytopenia. PTCy rescued B lymphopoiesis from graft-derived Treg deletion. In contrast, the negative effect of HSC-derived Treg deletion could not be overcome by PTCy, indicating that HSC-derived Tregs are essential for maintaining favorable B lymphopoiesis following PTCy. These findings define the mechanisms by which PTCy restores homeostasis of the B cell lineage and reestablishes immune tolerance.

Bone marrow microenvironment disruption and sustained inflammation with prolonged haematologic toxicity after CAR T-cell therapy.

Mechanisms of prolonged cytopenia (PC) after chimeric antigen receptor (CAR) T-cell therapy, an emerging therapy for relapsed or refractory diffuse large B-cell lymphoma, remain elusive. Haematopoiesis is tightly regulated by the bone marrow (BM) microenvironment, called the 'niche'. To investigate whether alterations in the BM niche cells are associated with PC, we analysed CD271+ stromal cells in BM biopsy specimens and the cytokine profiles of the BM and serum obtained before and on day 28 after CAR T-cell infusion. Imaging analyses of the BM biopsy specimens revealed that CD271+ niche cells were severely impaired after CAR T-cell infusion in patients with PC. Cytokine analyses after CAR T-cell infusion showed that CXC chemokine ligand 12 and stem cell factor, niche factors essential for haematopoietic recovery, were significantly decreased in the BM of patients with PC, suggesting reduced niche cell function. The levels of inflammation-related cytokines on day 28 after CAR T-cell infusion were consistently high in the BM of patients with PC. Thus, we demonstrate for the first time that BM niche disruption and sustained elevation of inflammation-related cytokines in the BM following CAR T-cell infusion are associated with subsequent PC.

A mysterious triangle of blood, bones, and nerves.

The relationship between bone tissue and bone marrow, which is responsible for hematopoiesis, is inseparable. Osteoblasts and osteocytes, which produce and consist of bone tissue, regulate the function of hematopoietic stem cells (HSC), the ancestors of all hematopoietic cells in the bone marrow. The peripheral nervous system finely regulates bone remodeling in bone tissue and modulates HSC function within the bone marrow, either directly or indirectly via modification of the HSC niche function. Peripheral nerve signals also play an important role in the development and progression of malignant tumors (including hematopoietic tumors) and normal tissues, and peripheral nerve control is emerging as a potential new therapeutic target. In this review, we summarize recent findings on the linkage among blood system, bone tissue, and peripheral nerves.