The RNA helicases DDX19A/B modulate selinexor sensitivity by regulating MCL1 mRNA nuclear export in leukemia cells.

Selinexor, a first-in-class exportin1 (XPO1) inhibitor, is an attractive anti-tumor agent because of its unique mechanisms of action; however, its dose-dependent toxicity and lack of biomarkers preclude its wide use in clinical applications. To identify key molecules/pathways regulating selinexor sensitivity, we performed genome-wide CRISPR/Cas9 dropout screens using two B-ALL lines. We identified, for the first time, that paralogous DDX19A and DDX19B RNA helicases modulate selinexor sensitivity by regulating MCL1 mRNA nuclear export. While single depletion of either DDX19A or DDX19B barely altered MCL1 protein levels, depletion of both significantly attenuated MCL1 mRNA nuclear export, reducing MCL1 protein levels. Importantly, combining selinexor treatment with depletion of either DDX19A or DDX19B markedly induced intrinsic apoptosis of leukemia cells, an effect rescued by MCL1 overexpression. Analysis of Depmap datasets indicated that a subset of T-ALL lines expresses minimal DDX19B mRNA levels. Moreover, we found that either selinexor treatment or DDX19A depletion effectively induced apoptosis of T-ALL lines expressing low DDX19B levels. We conclude that XPO1 and DDX19A/B coordinately regulate cellular MCL1 levels and propose that DDX19A/B could serve as biomarkers for selinexor treatment. Moreover, pharmacological targeting of DDX19 paralogs may represent a potential strategy to induce intrinsic apoptosis in leukemia cells.

Amino acid influx via LAT1 regulates iron demand and sensitivity to PPMX-T003 of aggressive natural killer cell leukemia.

Aggressive natural killer cell leukemia (ANKL) is a rare hematological malignancy with a fulminant clinical course. Our previous study revealed that ANKL cells proliferate predominantly in the liver sinusoids and strongly depend on transferrin supplementation. In addition, we demonstrated that liver-resident ANKL cells are sensitive to PPMX-T003, an anti-human transferrin receptor 1 inhibitory antibody, whereas spleen-resident ANKL cells are resistant to transferrin receptor 1 inhibition. However, the microenvironmental factors that regulate the iron dependency of ANKL cells remain unclear. In this study, we first revealed that the anti-neoplastic effect of PPMX-T003 was characterized by DNA double-strand breaks in a DNA replication-dependent manner, similar to conventional cytotoxic agents. We also found that the influx of extracellular amino acids via LAT1 stimulated sensitivity to PPMX-T003. Taken together, we discovered that the amount of extracellular amino acid influx through LAT1 was the key environmental factor determining the iron dependency of ANKL cells via adjustment of their mTOR/Myc activity, which provides a good explanation for the different sensitivity to PPMX-T003 between liver- and spleen-resident ANKL cells, as the liver sinusoid contains abundant amino acids absorbed from the gut.

A case of successful CAR-T cell therapy for early isolated CNS recurrence of DLBCL with persistent CAR-T cells.

Secondary central nervous system (CNS) lymphomas typically require CNS-penetrating drugs; however, the available agents are limited with temporary effects and poor outcomes. Chimeric antigen receptor T (CAR-T) cell therapy (lisocabtagene maraleucel; liso-cel) has been used to treat a few cases of isolated secondary CNS lymphoma. Herein, we report the case of a 66-year-old male diagnosed with diffuse large B-cell lymphoma (Ann Arbor grade IV; R-IPI, good risk; CNS IPI: Intermediate risk) who achieved complete remission (CR) after six courses of R-CHOP therapy. Three months later, he presented with ptosis and eye movement disorder. Systemic CT and bone marrow examination revealed no lymphoma. Although cranial-enhanced MRI showed normal findings, an increased number of B-cells (51/µL) with the original lymphoma phenotype (CD19+CD79a+CD5-CD10-CD20-Igλ+) was detected in cerebrospinal fluid (CSF), indicating an isolated CNS relapse. Seven high-dose methotrexate courses led to partial response. Subsequently, the patient received CAR-T cell therapy with tolerable adverse events - cytokine release syndrome treated with tocilizumab, no immune effector cell-associated neurotoxicity syndrome, and bone marrow failure treated with granulocyte-colony stimulating factor and eltrombopag. Sequential flow cytometry revealed a high peak of CAR-T cells and the presence of residual CAR-T cells in the peripheral blood, indicating immune surveillance of CNS lymphoma by CAR-T cells. This treatment led to a second CR. This case is the first to validate the efficacy and safety of CAR-T cell therapy for isolated secondary CNS lymphoma in clinical practice. Future accumulation of evidence on the efficacy and safety of CAR-T cell therapy is essential.

Procalcitonin elevation in febrile recipients during pre-transplant conditioning with anti-thymocyte globulin.

Infection is a major contributor to non-relapse mortality in allogeneic hematopoietic stem cell transplantation (allo-HSCT). Detecting infectious diseases in febrile patients during pretransplant conditioning is crucial for subsequent transplant success. Procalcitonin (PCT) is an auxiliary diagnostic marker of severe bacterial infections and has been proposed as a useful predictor of infection in patients undergoing allo-HSCT. Pre-transplant use of anti-thymocyte globulin (ATG) can cause side effects, such as fever and hypotension, which must be distinguished from infectious diseases. Although ATG administration may increase PCT levels, data on PCT levels in febrile patients after ATG administration are limited. Furthermore, no studies have compared PCT levels during allo-HSCT conditioning using ATG or non-ATG regimens. To investigate whether ATG increases PCT levels during febrile episodes in pre-transplant conditioning and whether PCT could be used to discriminate infections during this period, we analyzed 17 ATG and 59 non-ATG patients with fever and who underwent PCT level measurements during pre-transplant conditioning. Our findings revealed that ATG administration was the only significant factor that increased PCT positivity during fever (p = 0.01). In contrast, infectious diseases did not affect PCT positivity in the ATG group (p = 0.24). Furthermore, bloodstream infection was a significant risk factor for PCT positivity in patients who received non-ATG regimens (p < 0.01). Incorporating PCT levels into the diagnostic workup for infectious diseases requires careful consideration, particularly for patients receiving ATG regimens.

Interstitial Pneumonia Associated with Nodal T-follicular Helper Cell Lymphoma: A Case Report.

Nodal T-follicular helper cell lymphoma (nTFHL), a hematologic neoplasm originating from T-follicular helper (TFH) cells, occasionally presents with pulmonary radiographic abnormalities, without neoplastic cellular infiltration. However, the precise mechanisms underlying non-neoplastic pulmonary opacities in patients with nTFHL remain unclear. Previous reports have shown that TFH cell abnormalities are associated with collagen disease and interstitial pneumonia with autoimmune features (IPAF). We herein report a patient with nTFHL accompanied by interstitial pneumonia diagnosed via lung and lymph node biopsies. These findings suggest the need to rule out nTFHL before diagnosing IPAF.

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.

Real-world clinical characteristics of post-essential thrombocythemia and post-polycythemia vera myelofibrosis.

There are few prospective studies on patients with post-essential thrombocythemia myelofibrosis (PET-MF) and post-polycythemia vera myelofibrosis (PPV-MF). Therefore, we conducted a nationwide longitudinal prospective survey to clarify the clinical characteristics of these diseases. A total of 197 PET-MF and 117 PPV-MF patients diagnosed between 2012 and 2021 were analyzed. The median age at diagnosis was 70.0 years for both diseases. The time from diagnosis of ET or PV to that of MF was 9.6 and 10.4 years, respectively, with no significant difference. Patients with PPV-MF had higher hemoglobin levels and white blood cell counts than those with PET-MF, whereas those with PET-MF had higher platelet counts than those with PPV-MF. Although splenomegaly was more frequent in patients with PPV-MF at diagnosis, there was no difference in the frequency of constitutional symptoms. Ruxolitinib was the most common treatment administered to 74.6% and 83.8% of patients with PET-MF and PPV-MF, respectively. Patients with PET-MF and PPV-MF had similar prognoses, with 3-year overall survival (OS) of 0.742 in PET-MF and 0.768 in PPV-MF patients. In both diseases, leukemic transformation was the leading cause of death, followed by infection. The 3-year OS for patients with PET/PPV-MF and primary MF diagnosed during the same period was 0.754 and 0.626, respectively, with no significant difference. This survey provides real-world clinical features and prognostic data on secondary myelofibrosis in the ruxolitinib era.

Safety and efficacy of tisagenlecleucel in patients with relapsed or refractory B-cell lymphoma: the first real-world evidence in Japan.

BACKGROUND: Tisagenlecleucel, an autologous CD19-directed T-cell immunotherapy, can induce a durable response in adult patients with relapsed/refractory (r/r) B-cell lymphoma. METHODS: To elucidate the outcome of chimeric antigen receptor (CAR) T-cell therapy in Japanese, we retrospectively analyzed the outcomes of 89 patients who received tisagenlecleucel for r/r diffuse large B-cell lymphoma (n = 71) or transformed follicular lymphoma (n = 18). RESULTS: With a median follow-up of 6.6-months, 65 (73.0%) patients achieved a clinical response. The overall survival (OS) and event-free survival (EFS) rates at 12 months were 67.0% and 46.3%, respectively. Overall, 80 patients (89.9%) had cytokine release syndrome (CRS), and 6 patients (6.7%) had a grade ≥ 3 event. ICANS occurred in 5 patients (5.6%); only 1 patient had grade 4 ICANS. Representative infectious events of any grade were cytomegalovirus viremia, bacteremia and sepsis. The most common other adverse events were ALT elevation, AST elevation, diarrhea, edema, and creatinine elevation. No treatment-related mortality was observed. A Sub-analysis showed that a high metabolic tumor volume (MTV; ≥ 80 ml) and stable disease /progressive disease before tisagenlecleucel infusion were both significantly associated with a poor EFS and OS in a multivariate analysis (P < 0.05). Notably, the combination of these 2 factors efficiently stratified the prognosis of these patients (HR 6.87 [95% CI 2.4-19.65; P < 0.05] into a high-risk group). CONCLUSION: We report the first real-world data on tisagenlecleucel for r/r B-cell lymphoma in Japan. Tisagenlecleucel is feasible and effective, even in late line treatment. In addition, our results support a new algorithm for predicting the outcomes of tisagenlecleucel.

Targeting a mitochondrial E3 ubiquitin ligase complex to overcome AML cell-intrinsic Venetoclax resistance.

To identify molecules/pathways governing Venetoclax (VEN) sensitivity, we performed genome-wide CRISPR/Cas9 screens using a mouse AML line insensitive to VEN-induced mitochondrial apoptosis. Levels of sgRNAs targeting March5, Ube2j2 or Ube2k significantly decreased upon VEN treatment, suggesting synthetic lethal interaction. Depletion of either Ube2j2 or Ube2k sensitized AML cells to VEN only in the presence of March5, suggesting coordinate function of the E2s Ube2j2 and Ube2k with the E3 ligase March5. We next performed CRISPR screens using March5 knockout cells and identified Noxa as a key March5 substrate. Mechanistically, Bax released from Bcl2 upon VEN treatment was entrapped by Mcl1 and Bcl-XL and failed to induce apoptosis in March5 intact AML cells. By contrast, in March5 knockout cells, liberated Bax did not bind to Mcl1, as Noxa likely occupied Mcl1 BH3-binding grooves and efficiently induced mitochondrial apoptosis. We reveal molecular mechanisms underlying AML cell-intrinsic VEN resistance and suggest a novel means to sensitize AML cells to VEN.

RHAMM marks proliferative subpopulation of human colorectal cancer stem cells.

The cancer stem cell (CSC) theory features typically rare self-renewing subpopulations that reconstitute the heterogeneous tumor. Identification of molecules that characterize the features of CSCs is a key imperative for further understanding tumor heterogeneity and for the development of novel therapeutic strategies. However, the use of conventional markers of CSCs is still insufficient for the isolation of bona fide CSCs. We investigated organoids that are miniature forms of tumor tissues by reconstructing cellular diversity to identify specific markers to characterize CSCs in heterogeneous tumors. Here, we report that the receptor for hyaluronan-mediated motility (RHAMM) expresses in a subpopulation of CD44+ conventional human colorectal CSC fraction. Single-cell transcriptomics of organoids highlighted RHAMM-positive proliferative cells that revealed distinct characteristics among the various cell types. Prospectively isolated RHAMM+CD44+ cells from the human colorectal cancer tissues showed highly proliferative characteristics with a self-renewal ability in comparison with the other cancer cells. Furthermore, inhibition of RHAMM strongly suppressed organoid formation in vitro and inhibited tumor growth in vivo. Our findings suggest that RHAMM is a potential therapeutic target because it is a specific marker of the proliferative subpopulation within the conventional CSC fraction.

Potential therapeutic targets discovery by transcriptome analysis of an in vitro human gastric signet ring carcinoma model.

BACKGROUND: Loss of E-cadherin expression is frequently observed in signet ring carcinoma (SRCC). People with germline mutations in CDH1, which encodes E-cadherin, develop diffuse gastric cancer at a higher rate. Loss of E-cadherin expression is thus assumed to trigger oncogenic development. METHODS: To investigate novel therapeutic targets for gastric SRCC, we engineered an E-cadherin-deficient SRCC model in vitro using a human gastric organoid (hGO) with CDH1 knockout (KO). RESULTS: CDH1 KO hGO cells demonstrated distinctive morphological changes similar to SRCC and high cell motility. RNA-sequencing revealed up-regulation of matrix metalloproteinase (MMP) genes in CDH1 KO hGO cells compared to wild type. MMP inhibitors suppressed cell motility of CDH1 KO hGO cells and SRCC cell lines in vitro. Immunofluorescent analysis with 95 clinical gastric cancer tissues revealed that MMP-3 was specifically abundant in E-cadherin-aberrant SRCC. In addition, CXCR4 molecules translocated onto the cell membrane after CDH1 KO. Addition of CXCL12, a ligand of CXCR4, to the culture medium prolonged cell survival of CDH1 KO hGO cells and was abolished by the inhibitor, AMD3100. In clinical SRCC samples, CXCL12-secreting fibroblasts showed marked infiltration into the cancer area. CONCLUSIONS: E-cadherin deficient SRCCs might gain cell motility through upregulation of MMPs. CXCL12-positive cancer-associated fibroblasts could serve to maintain cancer-cell survival as a niche. MMPs and the CXCL12/CXCR4 axis represent promising candidates as novel therapeutic targets for E-cadherin-deficient SRCC.

Risk factors for late cytomegalovirus infection after completing letermovir prophylaxis.

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.

Development and Validation of an LC-MS/MS Method to Quantify Gilteritinib and Its Clinical Application in Patients With FLT3 Mutation-Positive Acute Myelogenous Leukemia.

BACKGROUND: Gilteritinib, a novel oral tyrosine kinase inhibitor, is used to treat acute myeloid leukemia (AML) with FMS-like tyrosine kinase-3 (FLT3) mutations. Therapeutic drug monitoring (TDM) of gilteritinib is important for improving clinical outcomes and ensuring safety. Therefore, this study aimed to develop a simplified method for quantifying gilteritinib in human plasma using liquid chromatography-tandem mass spectrometry. METHODS: Liquid chromatography was performed by using an Acquity BEH C18 column (50 mm × 2.1 mm, 1.7 µm) and a gradient elution with 0.1% formic acid in water (A) and acetonitrile (B). Detection was performed by using a Shimadzu tandem mass spectrometer through multiple reaction monitoring in the positive-ion mode. RESULTS: The developed method enabled quantification of gilteritinib in 4 minutes and was validated by evaluating selectivity, calibration curve (10-1000 ng/mL, r 2 > 0.99), a lower limit of quantification (LLOQ), accuracy (overall bias -4.2% to 1.9%), precision (intraday CV ≤ 7.9%; interday CV ≤ 13.6%), carryover, recovery, matrix effect, dilution integrity, and stability according to the US Food and Drug Administration (FDA) guidelines. This method was successfully applied to the TDM of gilteritinib trough concentrations in 3 patients with AML. CONCLUSIONS: The developed method fulfilled the FDA guideline criteria and can easily be implemented to facilitate TDM in patients receiving gilteritinib in a clinical setting.

Genome-wide CRISPR-Cas9 screen identifies rationally designed combination therapies for CRLF2-rearranged Ph-like ALL.

Acute lymphoblastic leukemia (ALL) harboring the IgH-CRLF2 rearrangement (IgH-CRLF2-r) exhibits poor clinical outcomes and is the most common subtype of Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL). While multiple chemotherapeutic regimens, including ruxolitinib monotherapy and/or its combination with chemotherapy, are being tested, their efficacy is reportedly limited. To identify molecules/pathways relevant for IgH-CRLF2-r ALL pathogenesis, we performed genome-wide CRISPR-Cas9 dropout screens in the presence or absence of ruxolitinib using 2 IgH-CRLF2-r ALL lines that differ in RAS mutational status. To do so, we employed a baboon envelope pseudotyped lentiviral vector system, which enabled, for the first time, highly efficient transduction of human B cells. While single-guide RNAs (sgRNAs) targeting CRLF2, IL7RA, or JAK1/2 significantly affected cell fitness in both lines, those targeting STAT5A, STAT5B, or STAT3 did not, suggesting that STAT signaling is largely dispensable for IgH-CRLF2-r ALL cell survival. We show that regulators of RAS signaling are critical for cell fitness and ruxolitinib sensitivity and that CRKL depletion enhances ruxolitinib sensitivity in RAS wild-type (WT) cells. Gilteritinib, a pan-tyrosine kinase inhibitor that blocks CRKL phosphorylation, effectively killed RAS WT IgH-CRLF2-r ALL cells in vitro and in vivo, either alone or combined with ruxolitinib. We further show that combining gilteritinib with trametinib, a MEK1/2 inhibitor, is an effective means to target IgH-CRLF2-r ALL cells regardless of RAS mutational status. Our study delineates molecules/pathways relevant for CRLF2-r ALL pathogenesis and could suggest rationally designed combination therapies appropriate for disease subtypes.

Circulating CD34+ cells of primary myelofibrosis patients contribute to myeloid-dominant hematopoiesis and bone marrow fibrosis in immunodeficient mice.

INTRODUCTION: Primary myelofibrosis (PMF) is a clonal stem cell disorder characterized by myeloid dominant hematopoiesis and dysregulated proliferation of fibroblasts in the bone marrow. However, how these aberrant myeloid cells and fibroblasts are produced remains unclear. AIM AND METHODS: In this study, we examined in vivo engraftment kinetics of PMF patient-derived CD34+ cells in immunecompromised NOD/SCID/IL2rgKO (NSG) mice. Engrafted human cells were analyzed with flow cytometry, and proliferation of fibroblastic cells and bone marrow fibrosis were assessed with the histo-pathological examination. RESULTS: Transplantation of PMF patient-derived circulating CD34+ fractions into NSG newborns recapitulates clinical features of human PMF. Engraftment of human CD45+ leukocytes resulted in anemia and myeloid hyperplasia accompanied by bone marrow fibrosis by six months post-transplantation. Fibrotic bone marrow contained CD45-vimentin+ cells of both human and mouse origin, suggesting that circulating malignant CD34+ subsets contribute to myelofibrotic changes in PMF through direct and indirect mechanisms. CONCLUSION: A patient-derived xenotransplantation (PDX) model of PMF allows in vivo examination of disease onset and propagation originating from immature CD34+ cells and will support the investigation of pathogenesis and development of therapeutic modalities for the disorder.

Incidence of refractory cytomegalovirus infection after allogeneic hematopoietic stem cell transplantation.

Post-transplant cytomegalovirus (CMV) disease can be almost completely avoided by current infection control procedures. However, CMV reactivation occurs in more than half of patients, and some patients can develop clinically resistant CMV infections. Whether resistance is due to the host's immune status or a viral resistance mutation is challenging to confirm. Therefore, a prospective observational analysis of refractory CMV infection was conducted in 199 consecutive patients who received allogeneic hematopoietic stem cell transplantation at a single institution. Among them, 143 (72%) patients received anti-CMV drugs due to CMV reactivation, and only 17 (8.5%) exhibited refractory CMV infection. These patients had clinically refractory infection. However, viral genome analysis revealed that only one patient exhibited a mutation associated with the anti-CMV drug resistance. Clinical resistance was mainly correlated with host immune factors, and the incidence of resistance caused by gene mutations was low at the early stage after a transplantation.

Targeting leukemia-specific dependence on the de novo purine synthesis pathway.

Acute myeloid leukemia (AML) is a devastating disease, and clinical outcomes are still far from satisfactory. Here, to identify novel targets for AML therapy, we performed a genome-wide CRISPR/Cas9 screen using AML cell lines, followed by a second screen in vivo. We show that PAICS, an enzyme involved in de novo purine biosynthesis, is a potential target for AML therapy. AML cells expressing shRNA-PAICS exhibited a proliferative disadvantage, indicating a toxic effect of shRNA-PAICS. Treatment of human AML cells with a PAICS inhibitor suppressed their proliferation by inhibiting DNA synthesis and promoting apoptosis and had anti-leukemic effects in AML PDX models. Furthermore, CRISPR/Cas9 screens using AML cells in the presence of the inhibitor revealed genes mediating resistance or synthetic lethal to PAICS inhibition. Our findings identify PAICS as a novel therapeutic target for AML and further define components of de novo purine synthesis pathway and its downstream effectors essential for AML cell survival.

Granulocyte collection by polymorphonuclear cell-targeting apheresis with medium-molecular-weight hydroxyethyl starch.

Granulocyte transfusion (GTX) is a therapeutic option for patients with prolonged neutropenia suffering from severe infections. Efficient granulocyte collection by apheresis from donors requires clear separation of granulocytes from red blood cells (RBCs), and infusion of high-molecular-weight (MW) hydroxyethyl starch (HES) facilitates RBC sedimentation. Recent research has shown that apheresis with medium-MW HES may prevent adverse effects of high-MW HES on donors, but the rationale for collection with medium-MW HES has yet to be evaluated. To validate the use of medium-MW HES, we first performed experiments with whole blood samples to determine how efficiently high-, medium- and low-MW HES separated granulocytes from RBCs, and found that medium-MW HES was just as efficient as high-MW HES. We also reviewed clinical data of granulocyte apheresis at our institution to evaluate granulocyte yields. Retrospective analysis of granulocyte collection revealed that apheresis with medium-MW HES yielded sufficient granulocytes for GTX and that donor anemia reduced collection efficiency. These results collectively may help us to establish a safer method for apheresis targeting polymorphonuclear granulocytes as an alternative to high-MW HES.

Optimization of lymphapheresis for manufacturing autologous CAR-T cells.

Collection of CD3+ lymphocytes via lymphapheresis is essential for manufacturing autologous chimeric antigen receptor (CAR) T cells. Optimization of timing and procedures for lymphapheresis for each patient is critical because patients often have progressive diseases and receive medications that could reduce T cell counts. We conducted a retrospective study of clinical data from 28 patients who underwent lymphapheresis for CD19-directed CAR-T therapy with tisagenlecleucel to identify factors that could affect CD3+ lymphocyte yields. The numbers of CD3+ cells in peripheral blood were significantly correlated with CD3+ cell yields (correlation coefficient r = 0.84), which enabled us to estimate the volume of blood to process before apheresis. We also found that small cell ratio (SCR) at the apheresis site precisely reflected the proportion of lymphocytes, especially in patients without circulating blasts (coefficient of determination: r2 = 0.9). We were able to predict the CD3+ cell yield and prevent excessive apheresis by measuring pre-apheresis circulating CD3+ cell counts and monitoring SCR. Collectively, these results will help us to establish a strategy for optimization of lymphapheresis procedures for CAR-T cell production on a patient-by-patient basis.