Cheng, Qian

Abstract Background Despite CD19-directed chimeric antigen receptor T (CAR-T) therapy achieving remarkable remission rates in relapsed/refractory B-cell acute lymphoblastic leukemia (R/R B-ALL), long-term survival remains constrained by T-cell exhaustion and immunosuppressive microenvironments. Dasatinib, a tyrosine kinase inhibitor (TKI), has been shown to alleviate T cell exhaustion and enhance CAR-T cell persistence, demonstrating therapeutic synergy in newly diagnosed ALL. However, it may also suppress CAR-T cytotoxicity and is ineffective against BCR-ABLT315I mutations. Third-generation TKIs, including ponatinib and olverembatinib, effectively overcome T315I-mediated resistance, yet their impact on CAR-T cell function and immune modulation remains insufficiently defined. Methods and Results: We first established in vitro co-culture models of CD19 CAR-T cells with the B-ALL cell line NALM6 to evaluate the effects of dasatinib, ponatinib and olverembatinib on resting and tumor antigen-activated CAR-T cells. At clinically relevant concentrations, none of the TKIs affected resting CAR-T viability. In contrast, upon activation, all three TKIs significantly inhibited CAR-T activation, cytotoxicity, and cytokine secretion (IL-2, TNF-α, IFN-γ), while reducing activation-induced CAR-T cell apoptosis. TKIs treatment also downregulated exhaustion markers (eg. PD-1, TIM3, LAG3) and promoted differentiation toward naïve (TN) and central memory (TCM) subsets, while reducing terminal effector T cells. After the drug elution, CAR-T cells regained their cytolytic function in response to tumor targets. Notably, ponatinib-treated CAR-T cells exhibited higher levels of IFN-γ, TNF-α and IL-2 post-washout compared to other groups. Importantly, the TN/TCM phenotype and low exhaustion marker expression were preserved after washout in all TKI-treated groups. Transcriptomic profiling of CAR-T cells in vitro revealed that all three TKIs downregulated key exhaustion-associated genes, including PDCD1, HAVCR2, CTLA4 and NR4A1, along with upregulation of stemness- and memory-associated genes (eg. CCR7, TCF7, LEF1, IL7R). Gene set enrichment analysis showed inhibition of T-cell activation, apoptosis, glycolysis, and TGF-β signaling by all TKIs. Remarkably, ponatinib uniquely activated the IFN-γ pathway, suggesting superior immunostimulatory effects. Mechanistically, all three TKIs suppressed the phosphorylation of AKT, p38 MAPK, and NF-κB p65, indicating shared inhibition of downstream TCR signaling. Based on these findings, we evaluated ponatinib in a clinical setting. A prospective study (No. ChiCTR2000036350) enrolled three R/R B-ALL patients with the BCR-ABLT315I mutation. All the patients received CD19 CAR-T cell therapy followed by ponatinib maintenance, initiated two months post-infusion. All three patients remained progression-free during ponatinib maintenance. Notably, the DNA copies of CAR-T cells remained detectable at months 5 and 9 after ponatinib treatment in two patients, respectively. To further explore the in vivo effects of ponatinib on T cells and other immune cells,peripheral blood mononuclear cells were collected from these patients before and one month after ponatinib initiation for single-cell RNA sequencing. Ponatinib exposure led to an increased proportion of CD8+T cells and a decreased abundance of myeloid cells subsets. Within T cells, effector cells expanded while Tregs and exhausted T cells decreased. Differential gene analysis showed suppression of activation, adhesion, apoptosis, and PD-1/PD-L1 signaling, aligning with in vitro results. Functional scoring revealed enhanced cytotoxicity, IFN-γ responses, and reduced glycolysis, exhaustion, TGF-β, and Treg signatures. Furthermore, analysis of NK cell subsets showed enhanced cytolytic scores and enrichment of proliferation and immune activation pathways, suggesting that ponatinib preserves innate immune responses in vivo. Conclusions: This study provides preclinical and preliminary clinical evidence that third-generation TKIs, particularly ponatinib, can effectively alleviate CAR-T cell exhaustion, promote memory phenotypes, and remodel the immune microenvironment. Compared to dasatinib and olverembatinib, ponatinib uniquely enhances effector cytokine production and activates the IFN-γ pathway. These findings support ponatinib as a promising combinatorial agent with CAR-T therapy, offering a rational strategy for improving outcomes in patients with T315I-mutated R/R B-ALL.

Abstract Background: For patients with B-cell acute lymphoblastic leukemia (B-ALL), extramedullary relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT) carries an extremely unfavorable prognosis. As a new immunotherapy, chimeric antigen receptor T (CAR-T) cell therapy has shown remarkable effects in refractory or relapsed B-ALL (r/r B-ALL). However, there is still a lack of evidence for its efficacy and safety in patients with extramedullary relapse after allo-HSCT. The aim of this study was to evaluate the safety and efficacy of allogeneic CAR-T in such high-risk populations. Method: We conducted a prospective clinical study, during which 7 patients with B-ALL who experienced extramedullary relapse after allo-HSCT were enrolled between October 2019 and January 2025. These patients all received allogeneic CD19 CAR-T cell therapy. We prospectively evaluated the safety, efficacy, and survival outcomes following CAR-T treatment. This study was registered at www.chictr.org.cn (No. ChiCTR2000036350). Results: This study included 7 patients with extramedullary relapse after allo-HSCT. Median age was 21 years (range: 15 - 46 years), and the median follow-up time was 415 days (range: 130 - 1320 days). The last follow-up was conducted until July 5, 2025. All the patients were classified as high-risk patients before transplantation. Four of them were Philadelphia chromosome/BCR-ABL positive (Ph+). The sites of extramedullary relapse included: 5 cases of central nervous system (among which 2 cases were accompanied by BCR-ABL molecular relapse in the bone marrow), 1 case of testicular relapse, and 1 case of extensive extramedullary relapse. The median interval from transplantation to extramedullary relapse was 628 days (44 - 1225 days). All patients received chemotherapy, radiotherapy or targeted therapy to reduce tumor burden before infusion. The infusion dose of CAR-T cells was 4 - 10 × 10⁶/kg. After infusion, one patient developed grade 3 cytokine release syndrome (CRS) and grade 4 immune effector cell-related neurotoxicity syndrome (ICANS), while the remaining patients did not experience grade 2 or higher CRS or ICANS. No patients developed graft-versus-host disease (GVHD), and all adverse events were resolved. In terms of therapeutic efficacy, one patient was considered unresponsive at the first assessment after infusion (54 days after infusion). The remaining 6 patients all achieved complete remission (CR) efficacy. The median duration of CR was 275 days (range: 120 - 1305 days). During the follow-up period, one patient suffered from central nervous system relapse again at 275 days post-infusion, while the other 5 maintained a continuous CR. The expansion of CAR-T cells in peripheral blood peaked between days 8 to 15 post-infusion, with a median peak of 1.90E+05 copies/μg DNA (range: 1.78E+04 – 3.18E+05 copies/μg DNA), and the longest duration of detectable expansion was 1320 days. Furthermore, CAR-T cells were detected in the cerebrospinal fluid of three patients, indicating their capability for targeted migration and central nervous system infiltration. Conclusion: Overall, allogeneic CAR-T therapy has demonstrated excellent safety and durable anti-leukemia effects in high-risk ALL patients with extramedullary relapse after transplantation.

Multiple myeloma (MM), an incurable hematologic malignancy, presents significant challenges in managing its recurrence. The bone marrow tumor microenvironment (BM-TME) is critical to MM progression. However, classical immune checkpoint blockade (ICB) therapies, like anti-PD1, have shown limited efficacy in MM. Therefore, elucidating the compositional features and regulatory mechanisms of the TIME in MM is crucial for developing novel immunotherapeutic targets. Tissue-resident memory CD8+ T cells (CD8+ TRMs) reside indefinitely at multiple anatomical locations like the skin, intestine, and bone marrow, functioning as frontline responders against reencountered pathogens and tumors. Whether CD8+ TRMs within BM-TME are involved in the MM cell immune escape and pathogenesis has not been systematically elucidated. Firstly, we leverage single-cell RNA sequencing (scRNA-seq) to dissect the BM CD8+ T cells across patients at different stages of MM, and identify that CD69+CD8+ T subsets were BM residents, and the proportion of BM CD8+ TRMs between health donors and MM patients was comparable. Moreover, our findings indicated that BM CD8+ TRMs exhibit exhausted features and enrichment of NK genes with MM progresses. Importantly, we observed a considerable elevation of the NK gene KLRB1 and its encoded protein CD161 in BM CD8+ TRMs in MM patients. Immunofluorescence labeling of BM biopsy samples from MM patients confirmed the infiltration of the BM-TME with CD3+CD8+CD69+CD161+ cells. Then, we found that KLRB1 expression in BM CD8+ TRMs was higher than that of other classical inhibitory receptor genes (e.g., PDCD1, CTLA4, LAG3), and CLEC2D (encodes the ligand of CD161) was also markedly expressed in patients' MM cells, exhibiting considerably higher than classical immunosuppressive receptor ligand genes (e.g., PDL1, CD80, CD86). Moreover, patients with higher CLEC2D expression had unfavorable overall survival. We further found that the CD161 expression was higher in CD69+CD8+ TRMs compared to circulating CD69-CD8+ T cells, and the percentage of BM CD161+CD8+ TRMs in MM patients was significantly higher than in healthy donors, while there was no difference for PD-1, LAG3, and TIM3 expression. Notably, only a small fraction of BM CD8+ TRMs have mucosal-associated invariant T cell phenotypes (identified by CD161+TCR-Vα7.2+). Additionally, the CLEC2D expression of BM cells was analyzed, and the highest level of CLEC2D expression was observed in B cells from MM patients, followed by plasma cells. Importantly, CLEC2D expression in MM patients was significantly higher than in plasma cells from healthy donors. Next, to investigate whether the blockade of CD161 could restore the function of CD8+ TRMs, the primary BM cells from MM patients were isolated and stimulated ex vivo. Compared to the anti-PD-1 and isotype group, CD161 blocking presents enhanced CD8+ TRMs proliferation and cytokine secretion levels (TNF-α, IFN-γ, IL2), increasing MM cells apoptosis. Chimeric antigen receptor T (CAR-T) cell therapy has achieved impressive success in treating relapsed/refractory MM. How to prevent CAR-T cell exhaustion and enhance function remains a significant challenge. Therefore, we next set out to investigate the impact of CD161 on CAR-T cells. Our results demonstrated that CD161 was highly expressed in early peripheral blood (PB) CAR-T cells after infusion in MM patients but decreased with time. Moreover, the CD161 expression of CAR-T cells was considerably higher than endogenous T cells. Notably, BM-derived CAR-T cells have higher CD161 expression than PB counterparts for the same patient, suggesting CD161 may have BM-specific expression enrichment. After co-culturing MM and CAR-T cells in vitro for 24 hours, we found that blocking CD161 led to an augmented proportion of CAR-T cells, increased IFN-γ secretion, and a notable elevation in tumor cell apoptosis compared to the anti-PD-1 and isotype groups. Taken together, we demonstrated that CD8+ TRMs constitute a vital anti-tumor cell subset in the MM BM-TME, which exhibits a high expression of the inhibitory CD161 receptor, binding to the CLEC2D expressed by MM cells, thereby mediating the dysfunction of CD8+ TRMs. Blocking the CD161-CLEC2D pathway is expected to become a novel target for MM immunotherapy. The combination of CD161 inhibitors and CAR-T cell therapy can potentially enhance the anti-myeloma function of CAR-T cells.

Background : Rituximab is a monoclonal antibody that targets CD20 and can significantly improve the prognosis of patients with CD20-positive B-cell non-Hodgkin lymphoma (B-NHL). Nonetheless, a significant number of patients experience disease progression or relapse post-rituximab therapy. CD19-chimeric antigen receptor (CAR) T cells have demonstrated remarkable efficacy in B-NHL treatment. However, few studies have focused on the efficacy and safety of CD20 CAR-T cells in rituximab-refractory/relapsed (R/R) B-NHL patients, particularly those treated with rituximab for a short time. Here, we conducted a prospective study, aimed to assess the long-term remission and survival in patients with rituximab-R/R B-NHL after treatment with U16 (CD20 CAR-T cells). Methods : This first-in-human study is an open-label, single center investigator-initiated trial (IIT) to determine the safety and efficacy of CD20 CAR-T in R/R B-NHL after previous rituximab treatment failure (no. ChiCTR2000036350). CD20 CAR-T was administered at a target dose of 1.0×107 CAR-T cells/kg after a 3-day conditioning chemotherapy with fludarabine and cyclophosphamide. The primary objective was to assess the safety and tolerability of CD20 CAR-T. Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) were graded according to ASTCT 2019 criteria. The secondary objectives were to evaluate efficacy and pharmacokinetics (PK). Response was assessed per Lugano 2014 criteria. Results:A total of 16 patients with R/R B-NHL were enrolled.The median age was 49 years (range, 28-66). Median number of prior lines of therapy was 3 (range, 2-5). All patients had received rituximab therapy; of these, 9 had done so within the 3 months before CAR-T infusion. CRS occurred in all patients, with 11 patients (68.75%) experiencing grade 1 or 2 CRS and 5 patients (31.25%) experiencing grade 3 CRS. No patient developed grade 4 CRS , and only one patient had ICANS.The most common grade 3 or higher adverse events observed after infusion included leukopenia (93.3%), anemia (40%) and thrombocytopenia (60%). An overall response rate of 100% was observed among enrolled patients, with 11 patients (68.75%) achieving complete remission(CR) and 5 patients (32.25%) achieving partial remission(PR) within 3 months. The median follow-up time was 11.7 months(range 0.69-47.47). The median overall survival was not reached, and the median progression-free survival was 14.5 months. 9 patients remained CR or PR for 12 months, with 7 of them continuing in CR for up to 24 months. The pharmacokinetics of CD20 CAR-T cells were assessed using quantitative PCR to determine the expansion and persistence ability. Peak CAR amplification were detected 7-14 days after infusin. Patients 1, 2 and 4 achieved long-term remission, and persistent positive CAR-T cell copy numbers were detected for 15 months, 30 months and 26 months, respectively. However, patients 7, 8 and 12 relapsed within 3 months, and the CAR-T cell copies of all three patients were reduced to fewer than 1×103 copies/μg of DNA within 3 months. The qPCR results indicated that the maintenance of efficacy was closely related to the persistence of CAR-T cells. Notably, patients who received rituximab less than 3 months before CAR-T infusion had a poorer prognosis, with higher relapse rates (77.8% vs. 28.6%) and shorter progression-free survival, regardless of the degree of response. Conclusion : Long-term follow-up demonstrated that CD20 CAR-T therapy can produce a deep and durable response with a favorable safety profile in patients with rituximab-refractory/relapsed B-NHL. Notably, patients who had received rituximab within 3 months had a poorer prognosis.