The TCR γδ repertoire and relative gene expression characteristics of T-ALL cases with biclonal malignant Vδ1 and Vδ2 T cells

Single-Cell Multiomics Reveals TCR Clonotype-Specific Phenotype and Stemness Heterogeneity of T-ALL Cells

T-cell acute lymphoblastic leukaemia (T-ALL) is a heterogeneous malignant disease with high relapse and mortality rates. To characterise the multiomics features of T-ALL, we conducted integrative analyses using single-cell RNA, TCR and chromatin accessibility sequencing on pre- and post-treatment peripheral blood and bone marrow samples of the same patients. We found that there is transcriptional rewiring of gene regulatory networks in T-ALL cells. Some transcription factors, such as TCF3 and KLF3, showed differences in activity and expression levels between T-ALL and normal T cells and were associated with the prognosis of T-ALL patients. Furthermore, we identified multiple malignant TCR clonotypes among the T-ALL cells, where the clonotypes consisted of distinct combinations of the same TCR α and β chain per patient. The T-ALL cells displayed clonotype-specific immature thymocyte cellular characteristics and response to chemotherapy. Remarkably, T-ALL cells with an orphan TCRβ chain displayed the strongest stemness and resistance to chemotherapy. Our study provided transcriptome and epigenome characterisation of T-ALL cells categorised by TCR clonotypes, which may be helpful for the development of novel predictive markers to evaluate treatment effectiveness for T-ALL.

γδ T Cells for Leukemia Immunotherapy: New and Expanding Trends

Recently, many discoveries have elucidated the cellular and molecular diversity in the leukemic microenvironment and improved our knowledge regarding their complex nature. This has allowed the development of new therapeutic strategies against leukemia. Advances in biotechnology and the current understanding of T cell-engineering have led to new approaches in this fight, thus improving cell-mediated immune response against cancer. However, most of the investigations focus only on conventional cytotoxic cells, while ignoring the potential of unconventional T cells that until now have been little studied. γδ T cells are a unique lymphocyte subpopulation that has an extensive repertoire of tumor sensing and may have new immunotherapeutic applications in a wide range of tumors. The ability to respond regardless of human leukocyte antigen (HLA) expression, the secretion of antitumor mediators and high functional plasticity are hallmarks of γδ T cells, and are ones that make them a promising alternative in the field of cell therapy. Despite this situation, in particular cases, the leukemic microenvironment can adopt strategies to circumvent the antitumor response of these lymphocytes, causing their exhaustion or polarization to a tumor-promoting phenotype. Intervening in this crosstalk can improve their capabilities and clinical applications and can make them key components in new therapeutic antileukemic approaches. In this review, we highlight several characteristics of γδ T cells and their interactions in leukemia. Furthermore, we explore strategies for maximizing their antitumor functions, aiming to illustrate the findings destined for a better mobilization of γδ T cells against the tumor. Finally, we outline our perspectives on their therapeutic applicability and indicate outstanding issues for future basic and clinical leukemia research, in the hope of contributing to the advancement of studies on γδ T cells in cancer immunotherapy.

γδ T Cells: The Ideal Tool for Cancer Immunotherapy

γδ T cells have recently gained considerable attention as an attractive tool for cancer adoptive immunotherapy due to their potent anti-tumor activity and unique role in immunosurveillance. The remarkable success of engineered T cells for the treatment of hematological malignancies has revolutionized the field of adoptive cell immunotherapy. Accordingly, major efforts are underway to translate this exciting technology to the treatment of solid tumors and the development of allogeneic therapies. The unique features of γδ T cells, including their major histocompatibility complex (MHC)-independent anti-cancer activity, tissue tropism, and multivalent response against a broad spectrum of the tumors, render them ideal for designing universal 'third-party' cell products, with the potential to overcome the challenges of allogeneic cell therapy. In this review, we describe the crucial role of γδ T cells in anti-tumor immunosurveillance and we summarize the different approaches used for the ex vivo and in vivo expansion of γδ T cells suitable for the development of novel strategies for cancer therapy. We further discuss the different transduction strategies aiming at redirecting or improving the function of γδ T cells, as well as, the considerations for the clinical applications.

Treatment response and outcome of children with T-cell acute lymphoblastic leukemia expressing the gamma-delta T-cell receptor

T-cell malignancies expressing the γδ T-cell receptor (TCR) are often associated with poor prognosis. Here, we determined the clinical outcome of pediatric patients with T-cell acute lymphoblastic leukemia (T-ALL) expressing the γδ TCR. Of 100 newly diagnosed T-ALL patients, 93 had γδ TCR analysis performed at diagnosis. Repertoire was evaluated by paired sequencing of the rearranged TCR. All patients received intensified chemotherapy and those with minimal residual disease (MRD) ≥ 1% on day 42-46 became candidates for hematopoietic cell transplantation. Of the 93 T-ALL patients, 12 (13%) had γδ T-ALL and 11 (12%) had early T-cell precursor (ETP) ALL. Compared to the remaining 70 T-ALL patients, the γδ T-ALL patients were more likely to have MRD ≥ 1% on day 15-19 (67% vs. 33%, P = 0.03) and day 42-49 (33% vs. 7%; P = 0.007) of remission induction. The 10-year overall survival for γδ T-ALL patients (66.7% ± 22.2%) were lower than that of T-ALL patients (93.3% ± 7.3%, P = 0.001). TCR analysis demonstrated a conserved clonotype. In conclusion, the data suggest that children with γδ T-ALL may have a poor response to remission induction, based on MRD levels and decreased survival than the other T-ALL patients, despite receiving risk-directed therapy.

γδ T-Cell Acute Lymphoblastic Leukemia/Lymphoma: Discussion of Two Pediatric Cases and Its Distinction from Other Mature γδ T-Cell Malignancies

Gamma delta (γδ) T-cell antigen receptor (TCR) expression and its related T-cell differentiation are not commonly reported in T-cell acute lymphoblastic leukemia/lymphoma (T-ALL). Here we report two pediatric T-ALL cases and present their clinical features, histology, immunophenotypes, cytogenetics, and molecular diagnostic findings. The first patient is a two-year-old girl with leukocytosis, circulating lymphoblasts, and a cryptic insertion of a short-arm segment at 10p12 into the long-arm segment of 11q23 resulting in an MLL and AF10 fusion transcript, which may be the first reported in γδ T-ALL. She responded to the chemotherapy protocol poorly and had persistent diseases. Following an allogeneic bone marrow transplant, she went into remission. The second patient is an eleven-year-old boy with a normal white cell count, circulating blasts, and a normal karyotype, but without any immature cellular markers by flow cytometric analysis. He responded to the chemotherapy well and achieved a complete remission. These cases demonstrate the diverse phenotypic, cytogenetic, and molecular aspects of γδ T-ALL. Early T-precursor- (ETP-) ALL and their differential diagnosis from other mature γδ T-cell leukemia/lymphomas are also discussed.

Persistent donor derived Vδ4 T cell clones may improve survival for recurrent T cell acute lymphoblastic leukemia after HSCT and DLI

The outcome for T-cell acute lymphoblastic leukemia (T-ALL) in relapse after hematopoietic stem cell transplantation (HSCT) is quite poor, while, both donor lymphocytes infusion (DLI) and adoptively infusion of γδ T cells in leukemia patients after HSCT have demonstrated good results in prolonging survival time of patients. Here, we reported a T-ALL case who experienced three relapses and received HSCT and DLI with an overall survival (OS) time lasting for more than seven years. Based on our previous identification of a leukemic and reactive clone in this patient, continual γδ T cell repertoire monitoring affirmed that the same Vδ5 leukemic clone existed in most samples from the patient, particularly including a sample taken at the time of the third T-ALL relapse, while it could not be detected in the donor sample. In addition, an identical Vδ4 monoclonal T cell that proliferated in the recipient for several years was confirmed to come from the donor graft, and its expression level significantly increased in third leukemia recurrence. These results indicate that clonally expanded Vδ4 T cells may represent a reconstituted γδ T cell repertoire after HSCT, which also hints to a relatively better outcome for this case. Based on this case study, we recommend DLI should be as a treatment strategy for patients who achieve CR or relapse from HSCT. Moreover, dynamically monitoring the TCR repertoire in patients who receive HSCT will benefit in supervising of malignant clone evolution and residue, identifying T cell clones mediate anti-infection, GvHD or GvL.

Arsenic induced complete remission in a refractory T-ALL patient with a distinct T-cell clonal evolution without molecular complete remission: A case report

Currently, arsenic trioxide therapy is widely used for the treatment of acute promyelocytic leukemia (APL), relapsed and refractory adult T-cell leukemia/lymphoma and myelodysplastic syndrome. Regarding the broad antitumor activity of arsenic, certain studies have been undertaken to test its efficacy in treating acute T-cell lymphoblastic leukemia (T-ALL) cell lines and patients; however, to the best of our knowledge, no reports document that arsenic is able to induce the remission of T-ALL patients. The present study reports the case of young male patient diagnosed with T-ALL, with no significant response to common chemotherapy regimens, who finally achieved complete remission without minimal residual disease (as detected by flow cytometry) due to arsenic treatment. This result is encouraging, and the present study has shown that malignant TCRαβ⁺ cell clones can be detected at the molecular level using reverse transcription-polymerase chain reaction (PCR) combined with the GeneScan technique. The result is mainly based on the T-cell receptor (TCR) Vβ1 clone (a 190-base pair PCR product that with the same complementarity determining region 3 length can be detected for all samples collected during various statuses) and on undetectable TCR Vγ subfamily members, at the time of disease diagnosis. It is important to analyze the dynamically changing TCR pool in leukemia patients during therapy. Although the molecular mechanism through which arsenic contributes to malignant clone elimination remains unclear in the case presented, the use of arsenic is expected to be effective for clinically treating refractory and relapsed T-ALL patients.

Analysis of the expression of PHTF1 and related genes in acute lymphoblastic leukemia

Background

Previous study showed that downregulated BCL11B expression in T cell acute lymphoblastic leukemia (T-ALL) cell line Molt-4 inhibited cell proliferation and induce apoptosis, which may be related to PHTF1 gene overexpression. The objective of this study was to investigate the expression of PHTF1 and related genes in ALL and further explore its function in T-ALL cell lines.

Methods

Real-time PCR was used to determine the gene expression level of PHTF1 in hematologic malignancies. The PHTF1, BCL11B, FEM1B and Apaf-1 gene expression levels and correlations were analyzed in patients with primary ALL (including T-ALL and B-ALL) and healthy individuals (HIs). Inhibition and overexpression of PHTF1 by lentiviral transduction were performed using the Molt-4 and Jurkat cell lines. Cell growth and apoptosis were measured by the Cell Counting Kit-8 assay and flow cytometry, respectively. Upon PHTF1 overexpression, the BCL11B, FEM1B and Apaf-1 gene expression levels were determined by real-time PCR.

Results

PHTF1 overexpression was found in both T-ALL (p = 0.004) and B-ALL (p < 0.001) groups compared with HIs group. A trend toward a negative correlation between the PHTF1 and BCL11B genes was detected for the T-ALL group, while positively correlated expression was found for the PHTF1 and BCL11B genes in HIs (P = 0.001). FEM1b and Apaf-1 overexpression was found in recently diagnosed ALL patients compared with HIs (p < 0.05). Positively correlated expression was found for the PHTF1, FEM1b and Apaf-1 genes in patients with ALL (p < 0.05) and HIs (p < 0.05). Direct up-regulation of PHTF1 expression inhibited the proliferation of Jurkat and Molt-4 cells and effectively induced apoptosis in Molt-4 cells. Direct inhibition of PHTF1 expression had no significant effect on the proliferation or apoptosis of Jurkat and Molt-4 cells. FEM1b and Apaf-1 overexpression, which did not obviously alter the BCL11B expression level, was detected in PHTF1-transduced T-ALL cell lines.

Conclusions

PHTF1 overexpression is responsible for regulating cell proliferation and apoptosis in T-ALL cell lines. PHTF1 may be a tumor-suppressor like gene and a therapeutic target for triggering the PHTF1-FEM1b-Apaf-1 apoptosis pathway.

Characteristics of CARMA1-BCL10-MALT1-A20-NF-κB expression in T cell-acute lymphocytic leukemia

Background

Knowledge of the oncogenic signaling pathways of T-cell acute lymphoblastic leukemia (T-ALL) remains limited. Constitutive aberrant activation of the nuclear factor kappa B (NF-κB) signaling pathway has been detected in various lymphoid malignancies and plays a key role in the development of these carcinomas. The zinc finger-containing protein, A20, is a central regulator of multiple NF-κB-activating signaling cascades. A20 is frequently inactivated by deletions and/or mutations in several B-and T-cell lymphoma subtypes. However, few A20 mutations and polymorphisms have been reported in T-ALL. Thus, it is of interest to analyze the expression characteristics of A20 and its regulating factors, including upstream regulators and the CBM complex, which includes CARMA1, BCL10, and MALT1.

Methods

The expression levels of CARMA1, BCL10, MALT1, A20, and NF-κB were detected in peripheral blood mononuclear cells (PBMCs) from 21 patients with newly diagnosed T-ALL using real-time PCR, and correlations between the aberrant expression of these genes in T-ALL was analyzed. Sixteen healthy individuals, including 10 males and 6 females, served as controls.

Results

Significantly lower A20 expression was found in T-ALL patients (median: 4.853) compared with healthy individuals (median: 8.748; P = 0.017), and significantly increased expression levels of CARMA1 (median: 2.916; P = 0.034), BCL10 (median: 0.285; P = 0.033), and MALT1 (median: 1.201; P = 0.010) were found in T-ALL compared with the healthy individuals (median: 1.379, 0.169, and 0.677, respectively). In contrast, overexpression of NF-κB (median: 0.714) was found in T-ALL compared with healthy individuals (median: 0.335; P = 0.001). A negative correlation between the MALT1 and A20 expression levels and a positive correlation between CARMA1 and BCL10 were found in T-ALL and healthy individuals. However, no negative correlation was found between A20 and NF-κB and the MALT1 and NF-κB expression level in the T-ALL group.

Conclusions

We characterized the expression of the CARMA-BCL10-MALT1-A20-NF-κB pathway genes in T-ALL. Overexpression of CARMA-BCL10-MALT in T-ALL may contribute to the constitutive cleavage and inactivation of A20, which enhances NF-κB signaling and may be related to T-ALL pathogenesis.