Purpose: CD7 chimeric antigen receptor T (CAR-T) therapy has potent antitumor activity against relapsed/refractory (R/R) T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL), however, immune reconstitution after CAR-T remains largely unknown. Patients and Methods: An open-label phase I clinical trial (ChiCTR2200058969) was initiated to evaluate safety and efficacy of donor-derived CD7 CAR-T cells in 7 R/R T-ALL/LBL patients. CAR-T cells were detected by flow cytometry and PCR. Cytokine levels were quantified by cytometric bead arrays. Single-cell RNA sequencing (scRNA-seq) was adopted to profile immune reconstitution. Results: Optimal complete remission (CR) was 100% on day 28, and median followed-up time was 4 months. Leukopenia, thrombocytopenia, and neutropenia were observed in 6 patients, and infections occurred in 5 patients. Two patients died of serious infection and one died of a brain hemorrhage. CAR-T cells expanded efficiently in all patients. CD7+ T cells were eliminated in peripheral blood on day 11 after infusion, and CD7− T cells dramatically expanded in all patients. scRNA-seq suggested that immunologic activities of CD7− T cells were stronger than those of T cells before infusion due to higher expression levels of T-cell function-related pathways, and major characters of such CD7− T cells were activation of autoimmune-related pathways. Monocyte loss was found in 2 patients who died of serious infections, indicating the main cause of the infections after infusion. S100A8 and S100A9 were identified as potential relapse markers due to their notable upregulation in leukocyte lineage in relapsed patients versus non-relapse controls. Conclusions: Our data revealed cellular level dynamics of immune homeostasis of CD7 CAR-T therapy, which is valuable for optimizing the treatment of R/R T-ALL/LBL.

BTK inhibitor (BTKi) Ibrutinib carries an increased bleeding risk compared to more selective BTKis Acalabrutinib and Zanubrutinib, however, its impact on vascular endothelium remains unknown. In this study, we found that Ibrutinib induced stronger cytotoxic effect on endothelial cells than Zanubrutinib, however, Acalabrutinib cytotoxicity was extremely weak. RNA-seq, followed by KEGG analysis and quantitative RT-PCR validation, was conducted to identify the differential apoptotic target genes of BTKis, leading to their distinct cytotoxic effects on endothelial cells, which showed that Ibrutinib and Zanubrutinib dramatically modulated the expression of critical apoptotic genes, GADD45B, FOS, and BCL2A1, among which FOS and GADD45B were upregulated more significantly by Ibrutinib than Zanubrutinib, however, Acalabrutinib downregulated BCL2A1 moderately and was not able to modulate the expression of FOS and GADD45B. Next, we performed in vitro angiogenesis assays and found that Ibrutinib was more able to induce endothelial dysfunction than Zanubrutinib via stimulating more BMP4 expression, however, Acalabrutinib had no such effect. Especially, the capacity of Ibrutinib to induce endothelial dysfunction can be antagonized by targeting BMP4. Accordingly, Ibrutinib, as an angiogenesis inhibitor, inhibited ovarian and breast cancer progression in vivo. Collectively, our findings addressed a novel molecular basis underlying Ibrutinib-induced endothelial cell dysfunction and suggested the potential application of Ibrutinib to treat angiogenesis-dependent cancers.

Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is an onco-embryonic antigen presented on chronic lymphocytic leukemia (CLL), but not on normal adult tissues, which promotes CLL-cell survival. Here, ROR1 was identified as a new client of Heat Shock Protein 90 (HSP90) via a mass spectrometry-based screen for ROR1-associated partners followed by co-immunoprecipitation (co-IP) analysis. A binding motif (ELHHPNIV) on ROR1 for HSP90 was revealed, which forms a αC-β4 loop and is necessary for HSP90-facilitated ROR1 stabilization. We also found that targeting HSP90 leads to ROR1 degradation in a ubiquitin-proteasome dependent pathway, by which pro-survival ROR1 signaling was attenuated in CLL. Based on our previous finding that a humanized monoclonal antibody against ROR1 increases the activity of Ibrutinib against CLL, which is currently undergoing evaluation in clinical trials for the treatment of B-cell lymphoid malignancies, we then provided evidence that treatment with HSP90 inhibitor (17-DMAG) enhances anti-CLL activity of Ibrutinib in vitro and in vivo, by down-modulating ROR1. iTRAQ-based quantitative proteomic analysis of other HSP90 oncogenic clients in addition to ROR1, followed by GO/KEGG enrichment analysis, showed that Bruton's Tyrosine Kinase (BTK), B-lymphoid Tyrosine Kinase (BLK), Lymphocyte-specific Protein Tyrosine Kinase (LCK), or LCK/YES-Related Novel Protein Tyrosine Kinase (LYN), as HSP90 clients, were significantly involved in 11 biological processes and 6 signaling pathways. However, immunoblotting validation confirmed that Ibrutinib treatment dramatically deprived HSP90 inhibitors, 17-DMAG, AUY922 or PU-H71, of inducing the degradation of BTK, BLK, LCK or LYN, but not ROR1. Collectively, our data suggested that depletion of ROR1 induced by targeting HSP90 might facilitate the enhancement of Ibrutinib activity against CLL.

T cell immune protection plays a pivotal role in the treatment of patients with hematological malignancies. However, T cell exhaustion might lead to the possibility of immune escape of hematological malignancies. Adoptive cell therapy (ACT) with chimeric antigen receptor T (CAR‐T) cells can restore the activity of exhausted T cell through reprogramming and is widely used in the treatment of relapsed/refractory (r/r) hematological malignancies. Of note, CD19, CD20, CD30, CD33, CD123, and CD269 as ideal targets have shown extraordinary potential for CAR‐T cell therapy and other targets such as CD23 and SLAMF7 have brought promising future for clinical trials. However, CAR‐T cells can also produce some adverse events after treatment of hematological malignancies, such as cytokine release syndrome (CRS), neurotoxicity, and on‐target/off‐tumor toxicity, which may cause systemic immune stress inflammation, destruction of the blood‐brain barrier, and even normal tissue damage. In this review, we aim to summarize the composition of CAR‐T cell and its application in the treatment of acute lymphocytic leukemia (ALL), chronic lymphocytic leukemia (CLL), non‐Hodgkin’s lymphoma (NHL), Hodgkin’s lymphoma (HL), multiple myeloma (MM), and acute myeloid leukemia (AML). Moreover, we will review the disadvantages of CAR‐T cell therapy and propose several comprehensive recommendations which might guide its development.

Purpose:CD7 chimeric antigen receptor T (CAR-T) therapy has potent antitumor activity against relapsed/refractory (R/R) T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL), however, immune reconstitution after CAR-T remains largely unknown.Experimental Design:An open-label phase I clinical trial (ChiCTR2200058969) was initiated to evaluate safety and efficacy of donor-derived CD7 CAR-T cells in 7 R/R T-ALL/LBL patients. CAR-T cells were detected by flow cytometry and PCR. Cytokine levels were quantified by cytometric bead arrays. Single-cell RNA sequencing (scRNA-seq) was adopted to profile immune reconstitution.Results:Optimal complete remission (CR) was 100% on day 28, and median followed-up time was 4 months. Leukopenia, thrombocytopenia, and neutropenia were observed in 6 patients, and infections occurred in 5 patients. Two patients died of serious infection and one died of a brain hemorrhage. CAR-T cells expanded efficiently in all patients. CD7+ T cells were eliminated in peripheral blood on day 11 after infusion, and CD7− T cells dramatically expanded in all patients. scRNA-seq suggested that immunologic activities of CD7− T cells were stronger than those of T cells before infusion due to higher expression levels of T-cell function-related pathways, and major characters of such CD7− T cells were activation of autoimmune-related pathways. Monocyte loss was found in 2 patients who died of serious infections, indicating the main cause of the infections after infusion. S100A8 and S100A9 were identified as potential relapse markers due to their notable upregulation in leukocyte lineage in relapsed patients versus non-relapse controls.Conclusions:Our data revealed cellular level dynamics of immune homeostasis of CD7 CAR-T therapy, which is valuable for optimizing the treatment of R/R T-ALL/LBL.