Trafficking circuit of CD8+ T cells between the intestine and bone marrow governs antitumour immunity.

Immunotherapy elicits a systemic antitumour immune response in peripheral circulating T cells. However, the T cell trafficking circuit between organs and their contributions to antitumour immunity remain largely unknown. Here we show in multiple mouse leukaemia models that high infiltration of leukaemic cells in bone marrow (BM) stimulates the transition of CD8+CD44+CD62L+ central memory T cells into CD8+CD44-CD62L- T cells, designated as inter-organ migratory T cells (TIM cells). TIM cells move from the BM to the intestine by upregulating integrin ß7 and downregulating C-X-C motif chemokine receptor 3 during leukaemogenesis. Upon immunogenic chemotherapy, these BM-derived TIM cells return from the intestine to the BM through integrin α4-vascular cell adhesion molecule 1 interaction. Blocking C-X-C motif chemokine receptor 3 function boosts the immune response against leukaemia by enhancing T cell trafficking. This phenomenon can also be observed in patients with leukaemia. In summary, we identify an unrecognized intestine-BM trafficking circuit of T cells that contributes to the antitumour effects of immunogenic chemotherapy.

LILRB4 regulates multiple myeloma development through STAT3-PFKFB1 pathway.

Although multiple myeloma (MM) responds well to immunotherapeutic treatment, certain portions of MM are still unresponsive or relapse after immunotherapy. Other immune molecules are needed for the immunotherapy of MM. Here, we revealed that leukocyte immunoglobulin-like receptor B4 (LILRB4) was highly expressed in multiple myeloma cell lines and patient samples and that the expression of LILRB4 was adversely correlated with the overall survival of MM patients. Knockdown of LILRB4 efficiently delayed the growth of MM cells both in vitro and in vivo. Mechanistically, IKZF1 transactivated LILRB4 expression to trigger the downstream of STAT3-PFKFB1 pathways to support MM cell proliferation. Blockade of LILRB4 signaling by blocking antibodies can effectively inhibit MM progression. Our data show that targeting LILRB4 is potentially an additional therapeutic strategy for the immunotherapeutic treatment of MM.

Impact of tocilizumab on anti-CD19 chimeric antigen receptor T-cell therapy in B-cell acute lymphoblastic leukemia.

BACKGROUND: Tocilizumab is commonly used for the management of chimeric antigen receptor (CAR) T-cell therapy-associated cytokine release syndrome (CRS). However, it remains unknown whether tocilizumab or its dosage affects the efficacy and safety of CAR T-cell therapy. The objective of this multicenter retrospective study was to explore the impact of tocilizumab on CAR T-cell therapy. METHODS: In total, 93 patients with B-cell acute lymphoblastic leukemia (B-ALL) receiving humanized anti-CD19 CAR T cells were recruited from May 2016 to November 2022. Forty-five patients received tocilizumab (tocilizumab group), whereas 48 patients did not (nontocilizumab group). Thirteen patients received >1 dose of tocilizumab. The primary end point was the effect of tocilizumab on the efficacy and safety of CAR T cells. Additionally, proliferation, killing, and cytokine assays of CAR T cells were performed in vitro in the presence of tocilizumab. RESULTS: The median age of the patients was 33 years, with 47 males and 46 females. Patients in the tocilizumab group showed similar complete response (CR) rate, overall survival (OS), and event-free survival (EFS) compared with the nontocilizumab group. Compared with patients who received ≤1 dose of tocilizumab, receiving >1 dose of tocilizumab did not affect their CR rate, OS, or EFS. In the tocilizumab group, all patients experienced CRS and 26.7% experienced immune effector cell-associated neurotoxicity syndrome (ICANS). In the nontocilizumab group, 64.6% of patients experienced CRS and 8.3% experienced ICANS. Up to 75% of ICANS and 87.5% of grade ≥3 ICANS occurred in the tocilizumab group. In vitro, tocilizumab did not impair the proliferation and killing effects of CAR T cells. CONCLUSIONS: Tocilizumab does not affect the efficacy of CAR T cells but may increase the likelihood of ICANS.

The DNA damage-independent ATM signalling maintains CBP/DOT1L axis in MLL rearranged acute myeloid leukaemia.

The long-term maintenance of leukaemia stem cells (LSCs) is responsible for the high degree of malignancy in MLL (mixed-lineage leukaemia) rearranged acute myeloid leukaemia (AML). The DNA damage response (DDR) and DOT1L/H3K79me pathways are required to maintain LSCs in MLLr-AML, but little is known about their interplay. This study revealed that the DDR enzyme ATM regulates the maintenance of LSCs in MLLr-AML with a sequential protein-posttranslational-modification manner via CBP-DOT1L. We identified the phosphorylation of CBP by ATM, which confers the stability of CBP by preventing its proteasomal degradation, and characterised the acetylation of DOT1L by CBP, which mediates the high level of H3K79me2 for the expression of leukaemia genes in MLLr-AML. In addition, we revealed that the regulation of CBP-DOT1L axis in MLLr-AML by ATM was independent of DNA damage activation. Our findings provide insight into the signalling pathways involoved in MLLr-AML and broaden the understanding of the role of DDR enzymes beyond processing DNA damage, as well as identigying them as potent cancer targets.

Phase II study of novel orally PI3Kα/δ inhibitor TQ-B3525 in relapsed and/or refractory follicular lymphoma.

This registration study assessed clinical outcomes of TQ-B3525, the dual phosphatidylinositol-3-kinase (PI3K) α/δ inhibitor, in relapsed and/or refractory follicular lymphoma (R/R FL). This phase II study (ClinicalTrials.gov NCT04324879. Registered March 27, 2020) comprised run-in stage and stage 2. R/R FL patients after ≥2 lines therapies received oral 20 mg TQ-B3525 once daily in a 28-day cycle until intolerable toxicity or disease progression. Primary endpoint was independent review committee (IRC)-assessed objective response rate (ORR). Based on results (ORR, 88.0%; duration of response [DOR], 11.8 months; progression-free survival [PFS], 12.0 months) in 25 patients at run-in stage, second stage study was initiated and included 82 patients for efficacy/safety analysis. Patients received prior-line (median, 3) therapies, with 56.1% refractory to previous last therapies; 73.2% experienced POD24 at baseline. At stage 2, ORR was 86.6% (71/82; 95% CI, 77.3-93.1%), with 28 (34.2%) complete responses. Disease control rate was 95.1% due to 7 (8.5%) stable diseases. Median time to response was 1.8 months. Among 71 responders, median DOR was not reached; 18-month DOR rate was 51.6%. with median follow-up of 13.3 months, median PFS was 18.5 (95% CI, 10.2-not estimable) months. Median overall survival (OS) was not reached by cutoff date; 24-month OS rate was estimated as 86.1%. Response rates and survival data were consistent across all subgroups. Grade 3 or higher treatment-related adverse events were observed in 63 (76.8%) cases, with neutropenia (22.0%), hyperglycemia (19.5%), and diarrhea (13.4%) being common. TQ-B3525 showed favorable efficacy and safety for R/R FL patients after ≥2 lines prior therapies.

Indicators describing the tumor lesion aggregation and dissemination and their impact on the prognosis of patients with diffuse large B cell lymphoma receiving chimeric antigen receptor T cell therapy.

INTRODUCTION: Chimeric antigen receptor (CAR) T cell therapy has markedly improved the prognosis of patients with diffuse large B-cell lymphoma (DLBCL). The relative positioning of tumor lesions in lymphoma varies among patients, manifesting as either aggregation (clumped together) or dissemination (spread throughout the body). Prognostic significance of factors indicating the relative positioning of tumor lesions in CAR T cell therapy remains underexplored. For aggregation, prior research proposed the tumor volume surface ratio (TVSR), linking it to prognosis in chemotherapy. Regarding dissemination, indicators such as disease stage or extranodal involvement, commonly used in clinical practice, have not demonstrated prognostic significance in CAR T cell therapy. This study aims to analyze current indicators of tumor aggregation or dissemination and introduce a novel indicator to assess the prognostic value of tumor lesions' relative positioning in DLBCL patients undergoing CAR T cell therapy. METHODS: This retrospective study included 42 patients receiving CAR T cell therapy. Lesion image information was obtained from the last PET/CT scan prior to CAR T cell infusion, including total metabolic tumor volume, total tumor surface, diameter of lymphoma masses, and the sites of tumor lesions. We evaluated TVSR and bulky disease as descriptors of tumor aggregation. We refined existing indicators, stage III&IV and >1 site extranodal involvement, to distill a new indicator, termed 'extra stage', to better represent tumor dissemination. The study examined the prognostic significance of tumor aggregation and dissemination. RESULTS: Our findings indicate that TVSR, while prognostically valuable in chemotherapy, lacks practical prognostic value in CAR T cell therapy. Conversely, bulky disease emerged as an optimal prognostic indicator of tumor aggregation. Both bulky disease and extra stage were associated with poor prognosis and exhibiting synergistic prognostic impact in CAR T cell therapy. CONCLUSIONS: Overall, the relative positioning of tumor lesions significantly influences the prognosis of patients with DLBCL receiving CAR T cell therapy. The ideal scenario involves tumors with minimal dissemination and no aggregation.

Serine and Arginine-Rich Splicing Factor 3 Promotes the Activation of Quiescent Mouse Neural Stem Cells.

The quiescence and activation of adult stem cells are regulated by many kinds of molecular mechanisms, and RNA alternative splicing participates in regulating many cellular processes. However, the relationship between stem cell quiescence and activation regulation and gene alternative splicing has yet to be studied. In this study, we aimed to elucidate the regulation of stem cell quiescence and activation by RNA alternative splicing. The upregulated genes in activated mouse neural stem cells (NSCs), muscle stem cells, and hematopoietic stem cells were collected for Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis. The genes from three tissue stem cells underwent Venn analysis. The mouse NSCs were used for quiescence and reactivation induction. The immunostaining of cell-specific markers was performed to identify cell properties. The reverse transcription-polymerase chain reaction and western blotting were used to detect the gene expression and protein expression, respectively. We found that the upregulated genes in activated stem cells from three tissues were all enriched in RNA splicing-related biological processes; the upregulated RNA splicing-related genes in activated stem cells displayed tissue differences; mouse NSCs were successfully induced into quiescence and reactivation in vitro without losing differentiation potential; serine and arginine-rich splicing factor 3 (Srsf3) was highly expressed in the activated mouse NSCs, and the overexpression of SRSF3 protein promoted the activation of quiescent mouse NSCs and increased the neural cell production. Our data indicate that the alternative splicing change may underline the transition of quiescence and activation of stem cells. The manipulation of the splicing factor may benefit tissue repair by promoting the activation of quiescent stem cells.

CAR-Aptamers Enable Traceless Enrichment and Monitoring of CAR-Positive Cells and Overcome Tumor Immune Escape.

Chimeric antigen receptor (CAR)-positive cell therapy, specifically with anti-CD19 CAR-T (CAR19-T) cells, achieves a high complete response during tumor treatment for hematological malignancies. Large-scale production and application of CAR-T therapy can be achieved by developing efficient and low-cost enrichment methods for CAR-T cells, expansion monitoring in vivo, and overcoming tumor escape. Here, novel CAR-specific binding aptamers (CAR-ap) to traceless sort CAR-positive cells and obtain a high positive rate of CAR19-T cells is identified. Additionally, CAR-ap-enriched CAR19-T cells exhibit similar antitumor capacity as CAR-ab (anti-CAR antibody)-enriched CAR-T cells. Moreover, CAR-ap accurately monitors the expansion of CAR19-T cells in vivo and predicts the prognosis of CAR-T treatment. Essentially, a novel class of stable CAR-ap-based bispecific circular aptamers (CAR-bc-ap) is constructed by linking CAR-ap with a tumor surface antigen (TSA): protein tyrosine kinase 7 (PTK7) binding aptamer Sgc8. These CAR-bc-aps significantly enhance antitumor cytotoxicity with a loss of target antigens by retargeting CAR-T cells to the tumor in vitro and in vivo. Overall, novel CAR-aptamers are screened for traceless enrichment, monitoring of CAR-positive cells, and overcoming tumor cell immune escape. This provides a low-cost and high-throughput approach for CAR-positive cell-based immunotherapy.