[CAR T-cell therapy for T cell malignancies: challenges and recent advances].

T cell malignancies pose several unique issues for CAR-T cell therapy that were not significant concerns with CAR-T cells for B-cell malignancies. A general problem to consider in the production of CAR-T cells is "on target-off tumor toxicity." This occurs when the antigen targeted by the CAR-T cells is also expressed on normal cells, not just tumor cells, which causes CAR-T cells to damage these normal cells. In CAR-T cell therapy for T cell tumors, antigens expressed on T cells (such as CD5, CD7, etc.) are the targets, which leads to a problem known as "fratricide," where CAR-T cells kill each other. Other issues include T cell aplasia and contamination of CAR-T cell products with tumor cells. However, several recent clinical trials have shown excellent outcomes for CAR-T cell therapy when genome editing technology is used to overcome these issues by knocking out target antigens or T cell receptors. This review article outlines these challenges and their solutions and discusses the results of recent clinical trials.

Mutational analysis of DNMT3A improves the prognostic stratification of patients with acute myeloid leukemia.

Nucleophosmin1 (NPM1) mutations are the most frequently detected gene mutations in acute myeloid leukemia (AML) and are considered a favorable prognostic factor. We retrospectively analyzed the prognosis of 605 Japanese patients with de novo AML, including 174 patients with NPM1-mutated AML. Although patients with NPM1-mutated AML showed a high remission rate, this was not a favorable prognostic factor for overall survival (OS); this is contrary to generally accepted guidelines. Comprehensive gene mutation analysis showed that mutations in codon R882 of DNA methyltransferase 3A (DNMT3AR882 mutations) were a strong predicative factor indicating poor prognosis in all AML (p < 0.0001) and NPM1-mutated AML cases (p = 0.0020). Furthermore, multivariate analysis of all AML cases showed that DNMT3AR882 mutations and the co-occurrence of internal tandem duplication in FMS-like tyrosine kinase 3 (FLT3-ITD), NPM1 mutations, and DNMT3AR882 mutations (triple mutations) were independent factors predicting a poor prognosis related to OS, with NPM1 mutations being an independent factor for a favorable prognosis (hazard ratios: DNMT3AR882 mutations, 1.946; triple mutations, 1.992, NPM1 mutations, 0.548). Considering the effects of DNMT3AR882 mutations and triple mutations on prognosis and according to the classification of NPM1-mutated AML into three risk groups based on DNMT3AR882 /FLT3-ITD genotypes, we achieved the improved stratification of prognosis (p < 0.0001). We showed that DNMT3AR882 mutations are an independent factor for poor prognosis; moreover, when confounding factors that include DNMT3AR882 mutations were excluded, NPM1 mutations were a favorable prognostic factor. This revealed that ethnological prognostic discrepancies in NPM1 mutations might be corrected through prognostic stratification based on the DNMT3A status.

Functional expression cloning of molecules inducing CD34 expression in bone marrow-derived stromal myofibroblasts.

We have previously shown a fraction of stromal fibroblasts/myofibroblasts (Fibs) from leukemic bone marrow cells expresses leukemia-specific transcripts along with hematopoietic and Fib-related markers. Normal bone marrow-derived Fibs (nFibs) do not express CD34 or CD45; however, nFibs may express hematopoietic markers with some specific stimulations. CD34 expression was detected in nFib cultures following the addition of a culture supernatant of blood mononuclear cells stimulated with phytohemagglutinin (PHA)-P. To identify the molecules responsible for inducing CD34 expression in nFibs, cDNA clones were isolated using functional expression cloning with a library constructed from PHA-P-stimulated human blood mononuclear cells. Positive clones inducing CD34 transcription in nFibs were selected. We confirmed that an isolated positive cDNA clone encoded human interleukin (IL)-1 beta (ß). CD34 expression was observed in the nFib cultures with recombinant human (rh) IL-1ß protein. And CD34 transcription was suppressed when a rhIL-1ß neutralizing antibody was added to the IL-1ß-stimulated nFib cultures. nFibs expressed gp130 and IL-6 receptors, and CD45 expression was detected in nFibs cultured with rhIL-1ß and rhIL-6. Chronic myelogenous leukemia (CML) cells reportedly respond well to IL-1ß. When CML-derived Fibs were cultured with rhIL-1ß and rhIL-6, CD45-positive cells increased in number. Cell fate may be influenced by an external specific stimulation without gene introduction.

CD7 CAR T Cells for the Therapy of Acute Myeloid Leukemia.

Chimeric antigen receptor (CAR) T cell therapy for the treatment of acute myeloid leukemia (AML) has the risk of toxicity to normal myeloid cells. CD7 is expressed by the leukemic blasts and malignant progenitor cells of approximately 30% of AML patients but is absent on normal myeloid and erythroid cells. Since CD7 expression by malignant blasts is also linked with chemoresistance and poor outcomes, targeting this antigen may be beneficial for this subset of AML patients. Here, we show that expression of a CD7-directed CAR in CD7 gene-edited (CD7KO) T cells effectively eliminates CD7+ AML cell lines, primary CD7+ AML, and colony-forming cells but spares myeloid and erythroid progenitor cells and their progeny. In a xenograft model, CD7 CAR T cells protect mice against systemic leukemia, prolonging survival. Our results support the feasibility of using CD7KO CD7 CAR T cells for the non-myeloablative treatment of CD7+ AML.

Comprehensive Approach for Identifying the T Cell Subset Origin of CD3 and CD28 Antibody-Activated Chimeric Antigen Receptor-Modified T Cells.

The outcome of therapy with chimeric Ag receptor (CAR)-modified T cells is strongly influenced by the subset origin of the infused T cells. However, because polyclonally activated T cells acquire a largely CD45RO+CCR7- effector memory phenotype after expansion, regardless of subset origin, it is impossible to know which subsets contribute to the final T cell product. To determine the contribution of naive T cell, memory stem T cell, central memory T cell, effector memory T cell, and terminally differentiated effector T cell populations to the CD3 and CD28-activated CAR-modified T cells that we use for therapy, we followed the fate and function of individually sorted CAR-modified T cell subsets after activation with CD3 and CD28 Abs (CD3/28), transduction and culture alone, or after reconstitution into the relevant subset-depleted population. We show that all subsets are sensitive to CAR transduction, and each developed a distinct T cell functional profile during culture. Naive-derived T cells showed the greatest rate of proliferation but had more limited effector functions and reduced killing compared with memory-derived populations. When cultured in the presence of memory T cells, naive-derived T cells show increased differentiation, reduced effector cytokine production, and a reduced reproliferative response to CAR stimulation. CD3/28-activated T cells expanded in IL-7 and IL-15 produced greater expansion of memory stem T cells and central memory T cell-derived T cells compared with IL-2. Our strategy provides a powerful tool to elucidate the characteristics of CAR-modified T cells, regardless of the protocol used for expansion, reveals the functional properties of each expanded T cell subset, and paves the way for a more detailed evaluation of the effects of manufacturing changes on the subset contribution to in vitro-expanded T cells.

HBsAg-redirected T cells exhibit antiviral activity in HBV-infected human liver chimeric mice.

BACKGROUND: Chronic hepatitis B virus (HBV) infection remains incurable. Although HBsAg-specific chimeric antigen receptor (HBsAg-CAR) T cells have been generated, they have not been tested in animal models with authentic HBV infection. METHODS: We generated a novel CAR targeting HBsAg and evaluated its ability to recognize HBV+ cell lines and HBsAg particles in vitro. In vivo, we tested whether human HBsAg-CAR T cells would have efficacy against HBV-infected hepatocytes in human liver chimeric mice. RESULTS: HBsAg-CAR T cells recognized HBV-positive cell lines and HBsAg particles in vitro as judged by cytokine production. However, HBsAg-CAR T cells did not kill HBV-positive cell lines in cytotoxicity assays. Adoptive transfer of HBsAg-CAR T cells into HBV-infected humanized mice resulted in accumulation within the liver and a significant decrease in plasma HBsAg and HBV-DNA levels compared with control mice. Notably, the fraction of HBV core-positive hepatocytes among total human hepatocytes was greatly reduced after HBsAg-CAR T cell treatment, pointing to noncytopathic viral clearance. In agreement, changes in surrogate human plasma albumin levels were not significantly different between treatment and control groups. CONCLUSIONS: HBsAg-CAR T cells have anti-HBV activity in an authentic preclinical HBV infection model. Our results warrant further preclinical exploration of HBsAg-CAR T cells as immunotherapy for HBV.

Treatment of Acute Myeloid Leukemia with T Cells Expressing Chimeric Antigen Receptors Directed to C-type Lectin-like Molecule 1.

The successful immunotherapy of acute myeloid leukemia (AML) has been hampered because most potential antigenic targets are shared with normal hematopoietic stem cells (HSCs), increasing the risk of sustained and severe hematopoietic toxicity following treatment. C-type lectin-like molecule 1 (CLL-1) is a membrane glycoprotein expressed by >80% of AML but is absent on normal HSCs. Here we describe the development and evaluation of CLL-1-specific chimeric antigen receptor T cells (CLL-1.CAR-Ts) and we demonstrate their specific activity against CLL-1+ AML cell lines as well as primary AML patient samples in vitro. CLL-1.CAR-Ts selectively reduced leukemic colony formation in primary AML patient peripheral blood mononuclear cells compared to control T cells. In a human xenograft mouse model, CLL-1.CAR-Ts mediated anti-leukemic activity against disseminated AML and significantly extended survival. By contrast, the colony formation of normal progenitor cells remained intact following CLL-1.CAR-T treatment. Although CLL-1.CAR-Ts are cytotoxic to mature normal myeloid cells, the selective sparing of normal hematopoietic progenitor cells should allow full myeloid recovery once CLL-1.CAR-T activity terminates. To enable elective ablation of the CAR-T, we therefore introduced the inducible caspase-9 suicide gene system and we show that exposure to the activating drug rapidly induced a controlled decrease of unwanted CLL-1.CAR-T activity against mature normal myeloid cells.

CAR T Cells Administered in Combination with Lymphodepletion and PD-1 Inhibition to Patients with Neuroblastoma.

Targeting disialoganglioside (GD2) on neuroblastoma (NB) with T cells expressing a first-generation chimeric antigen receptor (CAR) was safe, but the cells had poor expansion and long-term persistence. We developed a third-generation GD2-CAR (GD2-CAR3) and hypothesized that GD2-CAR3 T cells (CARTs) would be safe and effective. This phase 1 study enrolled relapsed or refractory NB patients in three cohorts. Cohort 1 received CART alone, cohort 2 received CARTs plus cyclophosphamide and fludarabine (Cy/Flu), and cohort 3 was treated with CARTs, Cy/Flu, and a programmed death-1 (PD-1) inhibitor. Eleven patients were treated with CARTs. The infusions were safe, and no dose-limiting toxicities occurred. CARTs were detectable in cohort 1, but the lymphodepletion induced by Cy/Flu increased circulating levels of the homeostatic cytokine interleukin (IL)-15 (p = 0.003) and increased CART expansion by up to 3 logs (p = 0.03). PD-1 inhibition did not further enhance expansion or persistence. Antitumor responses at 6 weeks were modest. We observed a striking expansion of CD45/CD33/CD11b/CD163+ myeloid cells (change from baseline, p = 0.0126) in all patients, which may have contributed to the modest early antitumor responses; the effect of these cells merits further study. Thus, CARTs are safe, and Cy/Flu can further increase their expansion.

A T-cell-directed chimeric antigen receptor for the selective treatment of T-cell malignancies.

Options for targeted therapy of T-cell malignancies remain scarce. Recent clinical trials demonstrated that chimeric antigen receptors (CARs) can effectively redirect T lymphocytes to eradicate lymphoid malignancies of B-cell origin. However, T-lineage neoplasms remain a more challenging task for CAR T cells due to shared expression of most targetable surface antigens between normal and malignant T cells, potentially leading to fratricide of CAR T cells or profound immunodeficiency. Here, we report that T cells transduced with a CAR targeting CD5, a common surface marker of normal and neoplastic T cells, undergo only limited fratricide and can be expanded long-term ex vivo. These CD5 CAR T cells effectively eliminate malignant T-cell acute lymphoblastic leukemia (T-ALL) and T-cell lymphoma lines in vitro and significantly inhibit disease progression in xenograft mouse models of T-ALL. These data support the therapeutic potential of CD5 CAR in patients with T-cell neoplasms.

Optimization of anti-TIM3 chimeric antigen receptor with CD8α spacer and TNFR-based costimulation for enhanced efficacy in AML therapy.

CAR T cell therapy for AML remains limited due to the lack of a proper target without on-target off-tumor toxicity. TIM3 is a promising target due to its high expression on AML cells and absence in most normal hematopoietic cells. Previous reports have shown that each CAR component impacts CAR functionality. Here, we optimized TIM-3 targeting CAR T cells for AML therapy. We generated CARs targeting TIM3 with two different non-signaling domains: an IgG2-CH3 spacer with CD28 transmembrane domain (CH3/CD28) and a CD8α spacer with CD8α transmembrane domain (CD8/CD8), and evaluated their characteristics and function. Incorporating the non-signaling CH3/CD28 domain resulted in unstable CAR expression in anti-TIM3 CAR T cells, leading to lower surface CAR expression over time and reduced cytotoxic function compared to anti-TIM3 CARs with the CD8/CD8 domain. Both types of anti-TIM3 CAR T cells transiently exhibited fratricide, which subsided overtime, and both CAR T cells achieved substantial T cell expansion. To further optimize the design, we explored the effects of different costimulatory domains. Compared with CD28 costimulation, 4-1BB and CD27 combined with a CD8/CD8 non-signaling domain showed higher cytokine secretion, superior antitumor activity, and enhanced T-cell persistence after repeated antigen exposure. These findings emphasize the impact of the optimal design of CAR constructs that provide efficient function. In the context of anti-TIM3 CAR T cells, using a CD8α spacer and transmembrane domain with TNFR-based costimulation is a promising CAR design to improve anti-TIM3 CAR T cell function for AML therapy.

Type 1 diabetes mellitus after cord blood transplantation from an unrelated donor with a disease-sensitive haplotype.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT), a curative treatment for hematopoietic neoplasms, often causes various autoimmune disease-like conditions. In contrast, allo-HSCT-related type 1 diabetes mellitus is extremely rare. Herein, we report a case of allo-HSCT-related type 1 diabetes mellitus in a patient who had undergone cord blood transplantation (CBT) as a treatment for acute myeloid leukemia. The patient's human leukocyte antigen was replaced with the donor type after transplantation. The donor had a disease-sensitive haplotype. To the best of our knowledge, this is the first reported case of type 1 diabetes mellitus following CBT.

Primary diffuse large B cell lymphoma of the prostate in a patient with HIV infection.

Introduction: Primary prostate lymphomas are very rare; however, the incidence of malignant lymphoma is high among HIV-infected patients. Herein, we report a case of primary diffuse large B-cell lymphoma (DLBCL) of the prostate in an HIV-infected patient. Case presentation: A 47-year-old man presented with miction pain and back pain. Abdominal CT revealed a huge prostate mass extending to the left retroperitoneum. Serum sIL-2R level was abnormally high (2896 U/mL), whereas PSA level was normal. HIV antigen and antibody tests were positive. The patient was diagnosed with DLBCL after a prostate biopsy. Systemic treatments were administered; however, the tumor was refractory, and the patient died 9 months after diagnosis. Conclusion: Prostate malignant lymphomas are rare but should be considered in patients with enlarged prostates and normal PSA levels. It should be noted that HIV patients have a high incidence of malignant lymphomas.

Incidence and predictors of recurrent sick leave in survivors who returned to work after allogeneic hematopoietic cell transplantation.

BACKGROUND: Although rather favorable probabilities of return to work have been reported after allogeneic hematopoietic cell transplantation (allo-HCT), survivors often have difficulty continuing to work because of their immunocompromised status and diverse late effects after allo-HCT. We evaluated the incidence of and risk factors for recurrent sick leave in allo-HCT survivors after they initially returned to work. METHODS: We targeted allo-HCT survivors who were employed at diagnosis, aged 20-64 at survey, and survived for ≥ 2 years without relapse. Of the 1904 survivors who were informed of the study, 1148 returned the questionnaire (60%), and 1048 eligible participants were included in the overall analysis. In the present study that considered recurrent sick leave after return to work, we targeted 896 participants who returned to work at least once after allo-HCT. Participants stated if they had recurrent sick leave after returning to work and its reasons, as well as associated patient-, HCT/HCT center-, and work-related factors and clinical events after allo-HCT. A logistic regression analysis was conducted to explore correlated factors for recurrent sick leave. RESULTS: In survivors who returned to work, 30% required recurrent sick leave. The most frequent causes of recurrent leave were physical issues (72%), and analysis of free descriptions demonstrated that these were mainly associated with graft-versus-host disease, infection, or readmission. Other reasons included work-related issues such as gap between physical and working conditions. Multivariate analysis showed that cord blood transplantation, longer employment duration, and counseling from healthcare professionals were associated with a lower risk of recurrent leave. Readmission, immunosuppressant use, and symptoms involving the respiratory system, gut, and joints and muscles were associated with a higher risk. CONCLUSIONS: Our results drawn from a large cohort study should help healthcare professionals identify and assist at-risk patients. Multi-professional teams that provide continuous support and effective communication with the workplace are necessary to improve long-term outcomes after allo-HCT. IMPLICATIONS FOR CANCER SURVIVORS: In order to continue working after the initial return to work, it is important to receive counseling from healthcare professionals and obtain reasonable accommodation from workplace.

The FLT3 internal tandem duplication mutation at disease diagnosis is a negative prognostic factor in myelodysplastic syndrome patients.

The role of the FMS-like tyrosine kinase 3 (FLT3) gene in acute myeloid leukemia (AML) has been well documented and the FLT3-internal tandem duplication (FLT3-ITD) mutation has been identified as a prognostic factor in AML. Due to its low incidence, the role of the FLT3 mutation remains unclear in myelodysplastic syndrome (MDS) patients. To investigate the impact of the FLT3-ITD status on the prognosis of MDS at diagnosis, we retrospectively analyzed 72 MDS patients admitted to Teikyo University Hospital. FLT3-ITD was examined by a reverse transcription-polymerase chain reaction using complementary DNA synthesized from mRNA extracted from bone marrow mononuclear cells at the diagnosis of MDS. Fifteen patients (20.8 %) were positive for FLT3-ITD and had significantly worse overall survival (OS) and progression-free survival (PFS) than patients who were negative (P < 0.001 and P < 0.001, respectively) in a multivariate analysis. We also investigated whether the Wilms' tumor gene-1 (WT-1) copy number was associated with the FLT3-ITD mutational status using data available on WT-1 from 57 patients. A WT-1 transcript copy number ≥50/µg total mRNA in peripheral blood was detected in 35 patients (61.4 %). All FLT3-ITD-positive patients showed WT-1 ≥50. The FLT3-ITD-positive group showed significantly higher WT-1 transcription levels than the negative group. These results indicate that the FLT3-ITD mutation has a prognostic impact at the diagnosis of MDS and is associated with a high level of WT-1.

Serum high-density lipoprotein cholesterol level has a significant prognostic impact on outcomes of follicular lymphoma patients.

We investigated the potential of nutritional and inflammatory parameters as prognostic factors for follicular lymphoma (FL), and also examined the predictive value of the early progression of disease within 24 months of first-line chemo-immunotherapy (POD24). We retrospectively analyzed 46 patients with FL admitted to Teikyo University Hospital and treated with chemo-immunotherapy between May 2009 and July 2019. Physical characteristics, blood parameters, and markers or scores for consumptive/inflammatory and nutritional conditions were used as variables. Nine parameters correlated with poor overall survival (OS) in univariate analysis: An Eastern Cooperative Oncology Group (ECOG) scale performance status (PS) ≥2, five or more involved nodal sites, positive bone marrow (BM) involvement, a serum albumin level <3.5 g/dL, CRP >0.5 mg/dL, lactate dehydrogenase (LD) higher than the upper normal limit (UNL), high-density lipoprotein cholesterol (HDL-C) <40 mg/dL, modified Glasgow prognostic score of 1-2, and the geriatric nutritional risk index <82. In multivariate analysis, ECOG PS ≥2, positive BM involvement, and a serum HDL-C level <40 mg/dL remained significant for poor progression-free survival. One-year OS rate after receiving salvage chemotherapy was lower in the POD24 group (50%) and POD24 correlated with ECOG PS ≥2, positive BM involvement, a serum lactate dehydrogenase >UNL, and HDL-C <40 mg/dL by Fisher's exact test. These results indicate that low serum HDL-C levels appear to be important for predicting the risk of POD24 and the worse prognosis of FL.

Budd-Chiari Syndrome during Long-term Follow-up after Allogeneic Umbilical Cord Blood Transplantation.

A series of abdominal computed tomography scans of an asymptomatic 40-year-old woman with a history of umbilical cord blood transplantation (CBT) for leukemia at 19 years old revealed the long-term gradual development of a right hepatic vein thrombus and stenosis of the inferior vena cava, leading to a diagnosis of Budd-Chiari syndrome. The Budd-Chiari syndrome in this case might have been influenced by the patient's history of multiple liver abscesses after CBT and associated thrombus formation, in addition to the hormone replacement therapy with estradiol and dydrogesterone she was taking. This case provides insight into the development of Budd-Chiari syndrome.

Allogeneic Hematopoietic Cell Transplantation for Patients with Relapsed Acute Promyelocytic Leukemia.

Although autologous hematopoietic cell transplantation (HCT) is an established therapy for patients with relapsed acute promyelocytic leukemia (APL) after returning to complete remission (CR), the role of allogeneic HCT remains unclear for treating relapsed APL. This study aimed to investigate allogeneic HCT outcomes in patients with relapsed APL, focusing particularly on those who underwent transplantation in non-CR and those who had relapsed after prior autologous HCT. We retrospectively analyzed Japanese nationwide transplantation registry data of patients with relapsed APL age ≥16 years who underwent allogeneic HCT between 2006 and 2020. A total of 195 patients were eligible for this analysis, including 69 who underwent transplantation in non-CR and 55 who relapsed after prior autologous HCT. The median duration of follow-up for survivors was 5.4 years. Multivariate analysis revealed that both non-CR at transplantation (hazard ratio [HR], 1.74; 95% confidence interval [CI], 1.12 to 2.71; P = .014) and prior autologous HCT (HR, 2.10; 95% CI, 1.28 to 3.44; P = .013) were associated with higher risks of overall mortality. The 5-year overall survival (OS) rates for patients who underwent transplantation in CR and non-CR were 58% and 39%, respectively (P = .085), if they did not have a history of prior autologous HCT. In the patients who had relapsed after prior autologous HCT, the 5-year OS rate was 47% for those who underwent allogeneic HCT in CR and 6% for those who did so in non-CR (P = .001). Allogeneic HCT still provides an opportunity for long-term survival for certain patients with relapsed APL for whom autologous HCT is unlikely to be effective. The dismal outcome of those with prior autologous HCT who underwent allogeneic HCT in non-CR poses a significant therapeutic challenge.