Enhancing Therapeutic Efficacy of Double Negative T Cells against Acute Myeloid Leukemia Using Idelalisib

DNT cells mediate resistance to CAR-T cells therapy in a pediatric patient with relapsed and refractory B-ALL

Chimeric antigen receptor T (CAR-T) cells therapy is a milestone achievement in the immunotherapy of relapsed and refractory (R/R) B cell acute lymphoblastic leukemia (B-ALL). However, some patients treated with CAR-T cells do not achieve complete remission, the mechanisms of which have not been elucidated. In the present study, we report a 9-year-old pediatric patient with refractory B-ALL received a triple infusion of autologous CD19 CAR-T cells therapy after the second relapse. CAR-T cells expanded in the peripheral blood and bone marrow. However, the patient did not achieve complete remission, indicating a lack of response to CAR-T cells therapy. Analysis of etiological factors revealed that the number of CD4 and CD8 double-negative T (DNT) cells was significantly upregulated in the peripheral blood, bone marrow, and autologous CAR-T cells products. In conclusiont, these findings indicate that DNT cells mediated resistance to CAR-T cells therapy in this pediatric patient with R/R B-ALL.

Allogeneic CAR-T Therapy Technologies: Has the Promise Been Met?

This last decade, chimeric antigen receptor (CAR) T-cell therapy has become a real treatment option for patients with B-cell malignancies, while multiple efforts are being made to extend this therapy to other malignancies and broader patient populations. However, several limitations remain, including those associated with the time-consuming and highly personalized manufacturing of autologous CAR-Ts. Technologies to establish "off-the-shelf" allogeneic CAR-Ts with low alloreactivity are currently being developed, with a strong focus on gene-editing technologies. Although these technologies have many advantages, they have also strong limitations, including double-strand breaks in the DNA with multiple associated safety risks as well as the lack of modulation. As an alternative, non-gene-editing technologies provide an interesting approach to support the development of allogeneic CAR-Ts in the future, with possibilities of fine-tuning gene expression and easy development. Here, we will review the different ways allogeneic CAR-Ts can be manufactured and discuss which technologies are currently used. The biggest hurdles for successful therapy of allogeneic CAR-Ts will be summarized, and finally, an overview of the current clinical evidence for allogeneic CAR-Ts in comparison to its autologous counterpart will be given.

Targeting T-cell malignancies using allogeneic double-negative CD4-CAR-T cells

BACKGROUND

Patients with relapsed/refractory T-cell malignancies have limited treatment options. The use of chimeric antigen receptor (CAR)-T cell therapy for T-cell malignancies is challenging due to possible blast contamination of autologous T-cell products and fratricide of CAR-T cells targeting T-lineage antigens. Recently, allogeneic double-negative T cells (DNTs) have been shown to be safe as an off-the-shelf adoptive cell therapy and to be amendable for CAR transduction. Here, we explore the antitumor activity of allogeneic DNTs against T-cell malignancies and the potential of using anti-CD4-CAR (CAR4)-DNTs as adoptive cell therapy for T-cell malignancies.

METHODS

Healthy donor-derived allogeneic DNTs were ex vivo expanded with or without CAR4 transduction. The antitumor activity of DNTs and CAR4-DNTs against T-cell acute lymphoblastic leukemia (T-ALL) and peripheral T-cell lymphoma (PTCL) were examined using flow cytometry-based cytotoxicity assays and xenograft models. Mechanisms of action were investigated using transwell assays and blocking assays.

RESULTS

Allogeneic DNTs induced endogenous antitumor cytotoxicity against T-ALL and PTCL in vitro, but high doses of DNTs were required to attain therapeutic effects in vivo. The potency of DNTs against T-cell malignancies was significantly enhanced by transducing DNTs with a third-generation CAR4. CAR4-DNTs were manufactured without fratricide and showed superior cytotoxicity against CD4+ T-ALL and PTCL in vitro and in vivo relative to empty-vector transduced-DNTs. CAR4-DNTs eliminated T-ALL and PTCL cell lines and primary T-ALL blasts in vitro. CAR4-DNTs effectively infiltrated tumors, delayed tumor progression, and prolonged the survival of T-ALL and PTCL xenografts. Further, pretreatment of CAR4-DNTs with PI3Kδ inhibitor idelalisib promoted memory phenotype of CAR4-DNTs and enhanced their persistence and antileukemic efficacy in vivo. Mechanistically, LFA-1, NKG2D, and perforin/granzyme B degranulation pathways were involved in the DNT-mediated and CAR4-DNT-mediated killing of T-ALL and PTCL.

CONCLUSIONS

These results demonstrate that CAR4-DNTs can effectively target T-ALL and PTCL and support allogeneic CAR4-DNTs as adoptive cell therapy for T-cell malignancies.

T-cell receptor αβ+ double-negative T cells in the kidney are predominantly extravascular and increase in abundance in response to ischemia-reperfusion injury

T-cell receptor+ CD4- CD8- double-negative (DN) T cells are a population of T cells present in low abundance in blood and lymphoid organs, but enriched in various organs including the kidney. Despite burgeoning interest in these cells, studies examining their abundance in the kidney have reported conflicting results. Here we developed a flow cytometry strategy to clearly segregate DN T cells from other immune cells in the mouse kidney and used it to characterize their phenotype and response in renal ischemia-reperfusion injury (IRI). These experiments revealed that in the healthy kidney, most DN T cells are located within the renal parenchyma and exhibit an effector memory phenotype. In response to IRI, the number of renal DN T cells is unaltered after 24 h, but significantly increased by 72 h. This increase is not related to alterations in proliferation or apoptosis. By contrast, adoptive transfer studies indicate that circulating DN T cells undergo preferential recruitment to the postischemic kidney. Furthermore, DN T cells show the capacity to upregulate CD8, both in vivo following adoptive transfer and in response to ex vivo activation. Together, these findings provide novel insights regarding the phenotype of DN T cells in the kidney, including their predominant extravascular location, and show that increases in their abundance in the kidney following IRI occur in part as a result of increased recruitment from the circulation. Furthermore, the observation that DN T cells can upregulate CD8 in vivo has important implications for detection and characterization of DN T cells in future studies.

Application of double-negative T cells in haematological malignancies: recent progress and future directions

Haematologic malignancies account for a large proportion of cancers worldwide. The high occurrence and mortality of haematologic malignancies create a heavy social burden. Allogeneic haematopoietic stem cell transplantation is widely used in the treatment of haematologic malignancies. However, graft-versus-host disease and relapse after allogeneic haematopoietic stem cell transplantation are inevitable. An emerging treatment method, adoptive cellular therapy, has been effectively used in the treatment of haematologic malignancies. T cells, natural killer (NK) cells and tumour-infiltrating lymphocytes (TILs) all have great potential in therapeutic applications, and chimeric antigen receptor T (CAR-T) cell therapy especially has potential, but cytokine release syndrome and off-target effects are common. Efficient anticancer measures are urgently needed. In recent years, double-negative T cells (CD3⁺CD4^-CD8^-) have been found to have great potential in preventing allograft/xenograft rejection and inhibiting graft-versus-host disease. They also have substantial ability to kill various cell lines derived from haematologic malignancies in an MHC-unrestricted manner. In addition, healthy donor expanded double-negative T cells retain their antitumour abilities and ability to inhibit graft-versus-host disease after cryopreservation under good manufacturing practice (GMP) conditions, indicating that double-negative T cells may be able to be used as an off-the-shelf product. In this review, we shed light on the potential therapeutic ability of double-negative T cells in treating haematologic malignancies. We hope to exploit these cells as a novel therapy for haematologic malignancies.