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A, A representative diagram of the transduction efficiency evaluation of CART19s 5 days after lentivirus infection. B, Specific target cell lysis by CART19s. T cells or CART19s were co-cultured with K562-RFP cells or CD19-RFP-K562 cells at the indicated E:T ratio for overnight co-culture (24 hours). C, IFN-γ secretion measurements in supernatants in T cells or CART19 cells co-cultured with K562-RFP cells or CD19-RFP-K562 cells at the indicated E:T ratios for 24 hours.

Comparison of CART19 levels in different groups. A, Levels of CART19 cells in PB were shown as assessed by means of qPCR assay at serial time points before and after infusion of CART19 respectively. B, CAR DNA copies in BM and PB on day 7 to 9 after CART19 infusion were compared. CAR DNA copies in BM (Patient 2, 6, 11, 13) were higher than in PB. C, Paired measurements of CAR DNA copies in BM and PB on day 7 to 9 after CART19 infusion, percentage of leukemia cells after FC chemotherapy shows strong correlations (CAR DNA copies in BM VS in PB, Spearman r=0.956, p

Relapsed leukemia cells analysis by FACS.A, leukemia cells with bright CD19 expression obtained CR with MRD negative after CART19 therapy and relapsed with CD19 + leukemia cells (Patient 1). B, leukemia cells with dim CD19 expression obtained CR with MRD negative after CART19 therapy but relapsed with 2 subsets of CD19 + and - leukemia cells (Patient 2 and 3).

Supplementary Tables including Table 1, Table 2 and Table 3

CRS complication after CART19 therapy. A, the peak serum concentration of IL-6, IFN-γ, IL-10, CRP, D-dimer and ferritin of a representative patient (Patient 15) during CRS at the indicated time-points after CART19 infusion are showed. B, D, Peak serum levels of CRP, ferritin and D-dimer in patients who developed grade 3 CRS (n=6) compared with those without CRS or with 1 or 2 CRS (n=10). Data represented the mean{plus minus}SEM. The Mann-Whitney U test was used for statistical analysis. C, Paired measurements of peak serum IL-6, CRP, ferritin and D-dimer showed strong correlations (IL-6 VS CRP, Spearman r=0.617, p=0.014; IL-6 VS ferritin, Spearman r=0.574, p=0.028; IL-6 VS D-dimer, Spearman r=0.789, p

CART19 identification and quantification

The cumulative incidence of non-relapse mortality are shown.

Patient 13 with extramedullary leukemia relapse compromising testis obtained CR after CART19 infusion. A, Ultrasound showed complete elimination of extramedullary relapsed masses involved in testis (red arrows). Images are from before treatment and 90 days after CART19 infusion. B, Pathology showed complete elimination of extramedullary relapsed masses involved in testis. Images are from before treatment and 30 days after CART19 infusion. Left: 10×10, right: 10×40.

Purpose: Patients with relapsed/refractory acute lymphocytic leukemia (R/R ALL) have a poor prognosis. Chimeric antigen receptor–modified T cells against CD19 (CART19) have displayed anti-leukemia activities. However, data from systemic trials in Chinese patients are limited.Experimental Design: T cells transduced with CD19-directed CAR lentiviral vectors were infused in patients with R/R ALL under fludarabine- and cyclophosphamide-based lymphodepletion. The postinfusion responses, toxicities, expansion, and persistence of CART19s in enrolled patients were observed and monitored.Results: We enrolled 15 patients with R/R ALL. The median transduction efficiency of CART19s was 33%. In vitro cytotoxicity assays were conducted and showed prominent antileukemia activities with CART19s. The patients received CART19s infusion at doses of 1.1 × 106/kg to 9.8 × 106/kg. Twelve patients achieved complete remission 1 month after CART19s infusion. CART19s expanded and persisted in peripheral blood and bone marrow. At 150 days, the overall survival rate and leukemia-free survival rate were 65.5% and 37.8%, respectively. The cumulative incidence of relapse and the nonrelapse mortality rate were 54.5% and 7.7%, respectively. Four patients underwent subsequent haploidentical hematopoietic stem cell transplantation. In this trial, 10 patients experienced cytokine release syndrome (CRS). Grade 3 CRS developed in 40% of patients and was associated with a higher disease burden on day −1 and a higher number of previous relapses.Conclusions: This trial demonstrated potent antileukemia activities of CART19s in Chinese patients with R/R ALL. Disease relapse remained the main obstacle. However, patients with a high risk of relapse after CART19s might benefit from subsequent haploidentical hematopoietic stem cell transplantation. Clin Cancer Res; 23(13); 3297–306. ©2016 AACR.

Background: Chimeric antigen receptor (CAR) T-cell therapy has shown remarkable clinical efficacy in hematologic malignancies but limited success in solid tumors. GCC19CART, the first clinical candidate from the CoupledCAR solid tumor platform, is designed to overcome the limitations of conventional CAR T-cells in solid tumor malignancies by pairing solid tumor CAR T-cells with CD19 targeting CAR T-cells to amplify proliferation and activation of the solid tumor CAR T component. GCC19CART targets guanylate cyclase-C (GCC) which is expressed in the metastatic lesions of 70%-80% of subjects with colorectal cancers. A Phase 1 investigator-initiated clinical trial is underway in China for patients with relapsed or refractory metastatic colorectal cancer who have received at least 2 prior lines of therapy. Based on a data cutoff on October 20, 2022 21 subjects have been enrolled in 2 dose escalation groups at 5 hospitals in China. Methods: Subjects are screened for GCC expression by immunohistochemistry. Eligible subjects undergo leukapheresis, a single dose of lymphodepleting chemotherapy (fludarabine 30mg/m2 and cyclophosphamide 300mg/m2) 3 days prior to infusion, and then administration of a single infusion of GCC19CART at one of two preassigned doses: 1 × 106 or 2 × 106 CAR T-cells/kg. Endpoints are safety and preliminary evidence of efficacy as determined by CT or PET/CT per RECIST 1.1 or PERCIST 1.0. All responses were confirmed by an independent third-party imaging contract research organization (CRO). Results: 13 subjects have been enrolled to dose level 1 (1 × 106 cells/kg) and 8 subjects have been enrolled to dose level 2 (2 × 106 cells/kg). The most common adverse events were cytokine release syndrome (CRS) in 21/21 subjects (Grade 1 19/21 (90.48%) or Grade 2 2/21 (9.52%)) and diarrhea in 21/21 subjects (Grade 1 6/21 (28.57%) Grade 2 5/21 (23.81%) Grade 3 9/21 (42.86%) or Grade 4 1/21 (4.76%)). Neurotoxicity was observed in 2/21 (9.52%) subjects at Grade 3 or 4 and resolved with corticosteroids. The combined overall response rate (ORR) for both dose levels was 28.6% (6/21). For dose level 1, the overall response rate (ORR) per RECIST 1.1 was 15.4% (2/13). Two subjects demonstrated a partial response (PR) while 3 additional subjects had partial metabolic response (PMR) on PET/CT with stable disease (SD) or progressive disease (PD) per RECIST 1.1. For dose level 2, The ORR per RECIST 1.1 was 50% (4/8). 4 subjects demonstrated a PR (3 at month 1, 1 at month 3 after being SD at month 1) and 2 additional subjects had PMR on PET/CT with SD per RECIST 1.1. Conclusions: preliminary data show that GCC19CART has meaningful dose dependent clinical activity and an acceptable safety profile in relapsed or refractory metastatic colorectal cancer. This trial is ongoing and updated data will be presented. A Phase 1 trial of GCC19CART in the US under a cleared IND is expected to enroll patients from mid-2022. Citation Format: Naifei Chen, Chengfei Pu, Lingling Zhao, Ning Li, Chang Wang, Yusheng Huang, Suxia Luo, Xun Li, Zhenzhou Yang, Jun Bie, Ruihong Zhu, Xi Huang, Haiyang Tang, Tingting Liang, Yizhuo Wang, Beibei Jia, Dongqi Chen, Zhao Wu, Yongping Song, Victor Lu, Lei Xiao, Jiuwei Cui. A phase 1 dose escalation study of GCC19CART - a novel CoupledCAR therapy for subjects with metastatic colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1130.

Background: Chimeric antigen receptor (CAR) T-cell therapy has shown remarkable clinical efficacy in hematologic malignancies but limited success in solid tumors. GCC19CART, the first clinical candidate from the CoupledCAR® solid tumor platform, targets guanylate cyclase-C (GCC) which is expressed in colorectal cancers. A Phase 1 investigator-initiated dose escalation trial is underway in China for patients with relapsed or refractory metastatic colorectal cancer. Based on a data cutoff on September 10, 2021, 15 patients enrolled and 12 patients completed ≥1 evaluation of response and were evaluable. Methods: Subjects with relapsed or refractory metastatic colorectal cancer are screened for GCC expression, with 70% to 80% of subjects expected to demonstrate GCC per historical data. Subjects undergo leukapheresis, a single dose of lymphodepleting chemotherapy (fludarabine 30mg/m2 and cyclophosphamide 300mg/m2) 3 days prior to infusion, and then administration of a single infusion of GCC19CART at one of three doses from 1x106, or 2x106 cells/kg. Endpoints are safety and preliminary evidence of efficacy as determined by CT or PET/CT per RECIST1.1 or PERCIST 1.0. Results: 7 subjects have been enrolled to dose level 1 (1x106 cells/kg) and 5 subjects have been enrolled to dose level 2 (2x106 cells/kg) and have a 1 month post-infusion imaging study available for review. The most common adverse events were cytokine release syndrome (CRS) in 11/12 subjects (Grade 1 10/12 (83.33%) or Grade 2 1/12 (8.33%)) and diarrhea in 12/12 subjects (Grade 1 2/12 (16.67%) Grade 2 2/12 (16.67%) Grade 3 8/12 (66.67%)). Neurotoxicity was observed in 1/12 (8.33%) subjects at Grade 4 and resolved with corticosteroids. The combined overall response rate (ORR) for both dose levels was 41.67% (5/12). For dose level 1, the overall response rate (ORR) per RECIST 1.1 was 28.57% (2/7). Two subjects demonstrated a partial response (PR) while 2 additional subjects had partial metabolic response (PMR) on PET/CT with stable disease (SD) or progressive disease (PD) per RECIST 1.1. For dose level 2, The ORR per RECIST 1.1 was 60% (3/5). 3 subjects demonstrated a PR (2 at month 1, 1 at month 3 after being SD at month 1) and an additional subject had PMR on PET/CT with SD per RECIST 1.1. Conclusions: GCC19CART demonstrated meaningful clinical activity and an acceptable safety profile in relapsed or refractory metastatic colorectal cancer. This trial is ongoing and updated data will be presented. A United States based Phase 1 trial of GCC19CART is anticipated for early 2022. Citation Format: Naifei Chen, Chengfei Pu, Lingling Zhao, Chang Wang, Ruihong Zhu, Tingting Liang, Xi Huang, Haiyang Tang, Yizhuo Wang, Beibei Jia, Dongqi Chen, Eugene Kennedy, Zhao Wu, Lei Xiao, Jiuwei Cui. Novel coupledCAR࣪technology for treating colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2747.

One key hurdle for the CAR-T cell treatment of solid tumors is the limited accessibility of solid tumor antigens outside the tumor microenvironment, which prohibits the expansion of solid tumor-targeting CAR-T cells in patients. Here, we report the characterization of prostatic acid phosphatase (PAP) as a feasible CAR-T target for prostate cancer and a novel approach, named CoupledCAR, to expand solid tumor-targeting CAR-T cells lacking solid tumor antigens based on the observation of non-transduced T cells proliferating together with CD19 CAR-T cells during the treatment of acute lymphocyte leukemia. We demonstrated that CoupledCAR can significantly enhance the expansion and antitumor efficacy of PAP CAR-T cells both in vitro and in vivo. Furthermore, we showed that the expansion of solid tumor-targeting CAR-T cells does not depend on CAR/CD3ζ stimulation through direct antigen binding with CAR but enhances the memory status of CAR-T cells and causes little exhaustion. Since the CoupledCAR system does not rely on solid tumor antigens, we propose that it can be utilized in all CAR-T and T cell therapies for the treatment of solid tumors. Citation Format: Zhiyuan Cao, Chengfei Pu, Xianyang Jiang, Guiting Han, Yuzhe Peng, Wensheng Wang, Wei Ding, Xiaogang Shen, Dongqi chen, Beibei Jia, Xiaoqiang Xu, Zhipeng Huang, Xi Huang, Wenbi Liu, Ruihong Zhu, Lee Tian, Christopher Ballas, Victor.X Lu, Zhao Wu, Lei Xiao. Antigen-independent expansion enhances efficacy of CAR-T cells against solid tumor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2838.

Background Chimeric antigen receptor (CAR) T cell therapy has made significant progress in the treatment of blood cancers such as leukemia, lymphoma, and myeloma. However, the therapy faces many challenges in treating solid tumors. These challenges include physical barriers, tumor microenvironment immunosuppression, tumor heterogeneity, target specificity, and limited reactive cell expansion in vivo.Conventional CAR T cell therapy has thus far shown weak cell expansion in solid tumor patients and achieved little or no therapeutic responses. Here, we developed CAR T cells based on a novel CoupledCAR® technology to treat solid tumors. In contrast to conventional CAR T cells, CoupledCAR T cells significantly improved the expansion of the CAR T cells in vivo and enhanced the CAR T cells’ migration ability and resistance to immunosuppression by the tumor microenvironment. The enhanced migration ability and resistance allow the CAR T cells to infiltrate to tumor tissue sites and increase anti-tumor activities. Methods We designed a ‘CoupledCAR’ lentivirus vector containing a single-chain variable fragment (scFv) targeting human TSHR. The lentivirus was produced by transfecting HEK-293T cells with ‘CoupledCAR’ lentiviral vectors and viral packaging plasmids. Patient‘s CD3 T cells were cultured in X-VIVO medium containing 125U/mL 1interleukin-2 (IL-2), and transduced with ‘CoupledCAR’ lentivirus at certain MOI. Transduction efficiency and was evaluated at 7 to 9 days after ‘CoupledCAR’ lentivirus transduction, and quality controls for fungi, bacteria, mycoplasma, chlamydia, and endotoxin were performed. After infusion, serial peripheral blood samples were collected, and the expansion and the cytokine release of CART cells were detected by FACS and QPCR. The evaluation of response level for patients were performed at month 1,month 3,and month 6 by PET/CT. Results Specifically, we engineered CoupledCAR T cells with lentiviral vectors encoding an anti-GCC (guanylate cyclase 2C) CAR molecule. Furthermore, anti-GCC CAR T cells showed anti-tumor activities in vitro and in vivo experiments.To verify the safety and efficacy of CoupledCAR T cells for treating solid tumors, we conducted several clinical trials for different solid tumors, including seven patients with colorectal cancer. These seven patients failed multiple rounds of chemotherapy and radiotherapy. In the clinical trial, the patients were infused with autologous anti-GCC CoupledCAR T cells range from 4.9×105/kg to 2.9×106/kg. All patients using anti-GCC CoupledCAR T cells showed rapid expansion of CoupledCAR T cells and killing of tumor cells. Specifically, we observed that CoupledCAR T cells expanded significantly in the patients and infiltrated tumor tissue sites, demonstrating enhanced anti-tumor activities. PET/CT showed significant tumor shrinkage and SUV max declined, and the ongoing responses were monitored. Patient 3 achieved complete response and the best overall response rate (ORR, include complete remission, complete metabolic response, partial response, and partial metabolic response.) was 71.4% (5/7), complete remission (CR) rate was 14.3% (1/7). Conclusions The clinical data demonstrated that CoupledCAR T cells effectively expanded, infiltrated tumor tissue sites, and kill tumor cells in patients with colorectal cancer. We used immunotherapy to achieve complete remission in patients with advanced colorectal cancer for the first time. We are recruiting more colorectal cancer patients to further test the safety and efficacy of anti-GCC CoupledCAR T cells. Since our CoupledCAR® technology is a platform technology, we are expanding it to treat other solid tumors using different target tumor markers.

Background CAR T therapy has achieved remarkable results in the treatment of hematological tumors such as leukemia, lymphoma, and multiple myeloma. However, there remains challenges in treating solid tumors. These challenges include physical barriers, tumor microenvironment immunosuppression, tumor heterogeneity and target specificity. Especially, due to tumor microenvironmental barriers, CAR T cells are not effectively exposed to tumor antigens and cannot activate co-stimulation signals on CAR molecules, thus conventional CAR T cell therapy has thus far shown weak cell expansion in solid tumor patients, achieved little or no therapeutic responses. Here, we developed CAR T cells based on a novel CoupledCAR® technology to overcome the lack of persistence of solid tumor CAR T cells in vivo. Methods We designed a ‘CoupledCAR’ lentivirus vector containing a single-chain variable fragment (scFv) targeting human TSHR. The lentivirus was produced by transfecting HEK-293T cells with ‘CoupledCAR’ lentiviral vectors and viral packaging plasmids. Patient‘s CD3 T cells were cultured in X-VIVO medium containing 125U/mL 1interleukin-2 (IL-2), and transduced with ‘CoupledCAR’ lentivirus at certain MOI. Transduction efficiency and was evaluated at 7 to 9 days after ‘CoupledCAR’ lentivirus transduction, and quality controls for fungi, bacteria, mycoplasma, chlamydia, and endotoxin were performed. After infusion, serial peripheral blood samples were collected, and the expansion and the cytokine release of CART cells were detected by FACS and QPCR. The evaluation of response level for patients were performed at month 1,month 3,and month 6 by PET/CT. Results We used prostatic acid phosphatase (PAP) as an exemplary CAR target for prostate cancer and demonstrated that our CoupledCAR® significantly enhanced the expansion of PAP CAR T cells in vitro and in vivo. Further, we observed that this expansion showed more memory-like phenotypes, and caused little exhaustion of PAP CAR T cells. Also, we find coupled solid tumor CAR T cells have stronger tumor killing ability. We demonstrated this simple expansion to enable the persistence of solid tumor CAR T cells and can be further applied to other kinds of T cell therapy like TCR T and TILs. Conclusions We developed a novel platform technology (CoupledCAR®) that allows solid tumor CAR T cells to rapidly expand. This initial CAR T cell expansion enabled enhanced trafficking and infiltration of the tumor tissue whereby further cell expansion occurred and thereby achieved tumor clearance. We have carried clinical trials and obtained early promising clinical data. We will further verify the safety and efficacy of this technology in the treatment of different kinds of solid tumors in the clinic research.

Background Chimeric antigen receptor modified T cells (CAR T) have demonstrated remarkable clinical efficacy in the treatment of B cell malignancies and multiple myeloma. Significant challenges restrict their application across solid tumors due to multiple obstacles, including the lack of robust in vivo CAR-T cell expansion and persistence, the immunosuppressive tumor microenvironment, and tumor escape due to heterogeneous tumor cell composition with a potential loss of the targeted tumor antigen.To address these difficulties, we generated CAR T cells using a novel CoupledCAR® technology. Specifically, we engineered CoupledCAR T cells with lentiviral vectors encoding an anti-thyroid stimulating hormone receptor (TSHR) CAR molecule. Immunohistochemistry (IHC) results showed that TSHR was highly expressed in thyroid cancer cells making it an ideal tumor-specific target antigen. In vitro co-culture experiments showed that TSHR CAR T cells specifically recognized and subsequently killed TSHR-positive tumor cells. Animal model experiments showed that TSHR CAR T cells inhibited the proliferation of TSHR-positive tumor cells. Methods We designed a ‘CoupledCAR’ lentivirus vector containing a single-chain variable fragment (scFv) targeting human TSHR. The lentivirus was produced by transfecting HEK-293T cells with ‘CoupledCAR’ lentiviral vectors and viral packaging plasmids. Patient‘s CD3 T cells were cultured in X-VIVO medium containing 125U/mL 1interleukin-2 (IL-2), and transduced with ‘CoupledCAR’ lentivirus at certain MOI. Transduction efficiency and was evaluated at 7 to 9 days after ‘CoupledCAR’ lentivirus transduction, and quality controls for fungi, bacteria, mycoplasma, chlamydia, and endotoxin were performed. After infusion, serial peripheral blood samples were collected, and the expansion and the cytokine release of CART cells were detected by FACS and QPCR. The evaluation of response level for patients were performed at month 1,month 3,and month 6 by PET/CT. Results To evaluate the clinical safety and efficacy of anti-TSHR CoupledCAR T cells on refractory or relapsed thyroid cancer, we treated refractory/relapsed post-thyroidectomy thyroid cancer patients according to an IRB approved protocol. We treated two patients using anti-TSHR CoupledCAR T cells and observed the rapid expansion of CAR T cells and enhanced the killing of tumor cells. One patient‘s best response was complete remission, and the other was near complete remission.Patient Profile:Patient 1 Male, 64Y, Papillary Thyroid Carcinoma. In May 2017, Thyroid cancer was diagnosed, bilateral total thyroidectomy, and right cervical lymph node functional dissection were performed in Jun 2018, followed by iodine 131 isotope therapy. In December 2018, bilateral multiple cervical lymph nodes were enlarged, especially on the right side. In February 2019, right neck lymphadenectomy was performed.Patient 2 Female, 60Y, Thyroid Carcinoma. In Aug 2013, a ‘double lobectomy of the thyroid gland’ was performed. From Oct 2013 to Jan 2014, she received iodine 131 isotope therapy. In Sep 2014, she was diagnosed with iodine - resistant thyroid cancer. From Sep to Jan 2016, 5 cycles of chemotherapy were performed. In Jun 2016, she enrolled in the Anlotinib experimental group. In Mar 2019, multiple metastases in both lungs and multiple enlarged lymph nodes in the mediastinum were observed.Observations and Results:Patient 1: One month after infusion (M1), the patient was evaluated as PR: lymph node metastasis became undetectable and the size of the thoracic paratracheal tumor nodules decreased significantly. Three months after infusion (M3), the patient was evaluated as CR, and the tumor tissue was substantially smaller than M1.Patient 2: M1, the patient was evaluated as PR (Partial Response): the tumor volume in the right lower lobe of the lung was reduced by approximately 67.51% (decreased from 65*55 mm to 42*39 mm). Three months after infusion (M3), compared with that before, the tumor volume was reduced by approximately 73.54% and SUV max value decreased from 14.9 to 2.8, therefore, the patient was evaluated as nCR (near complete remission). Conclusions We show that TSHR is a good target for treating thyroid cancer, and our anti-TSHR CoupledCAR T cells are safe and effective for treating thyroid cancer. Recruitment is ongoing to evaluate the safety and efficacy of our CoupledCAR T cells. Further, since our CoupledCAR® technology is a platform technology, we are developing it to treat other solid tumors using different target tumor markers.

Dysregulated B-cell activation plays pivotal roles in systemic lupus erythematosus (SLE), which makes B-cell depletion a potential strategy for SLE treatment. The clinical success of anti-CD19 CAR-T cells in treating B-cell malignancies has attracted the attention of researchers. In this study, we aimed to investigate the feasibility of applying anti-CD19 CAR-T cell therapy to SLE treatment in a mouse disease model. We constructed murine anti-CD19 CARs with either CD28 or 4-1BB as the intracellular costimulatory motif and evaluated the therapeutic function of the corresponding CAR-T cells by infusing them into MRL-lpr mice. Furthermore, anti-CD19 CAR-T cells were transferred to MRL-lpr mice before the onset of disease to determine their role in SLE prevention. According to our observations, compared with antibody treatment, the adoptive transfer of our anti-CD19 CAR-T cells showed a more sustained B-cell-depletion effect in MRL-lpr mice. The transfer of syngeneic anti-CD19 CAR-T cells not only prevented disease pathogenesis before the onset of disease symptoms but also displayed therapeutic benefits at a later stage after disease progression. We also tried to optimize the treatment strategy and found that compared with CAR-T cells with the CD28 costimulatory motif, CAR-T cells with the 4-1BB costimulatory motif showed better therapeutic efficiency without cell enrichment. Taken together, these results show that anti-CD19 CAR-T cell therapy was effective in the prevention and treatment of a murine model of SLE, indicating its potential for clinical use in patients.

Chimeric antigen receptor modified T cells against CD19 (CART19s) have potent anti-leukemia activities in patients with refractory/relapsed acute lymphoblastic leukemia (R/R ALL). This study was designed to investigate the correlation between safety/efficacy and therapeutic modalities including chemotherapy and CART19 therapy. Total 23 and 69 patients were enrolled in the CART19 group and in the chemotherapy group, respectively. The safety and efficacy profiles of 66 and 22 patients in the 2 groups were evaluated. The complete remission (CR) rate was higher in the CART19 group than that in the chemotherapy group (90.9 vs 37.9%, P = 0.000). For patients relapsed after allo-HSCT and chemotherapy, CR rates were 100% (8/8) vs 48.0% (12/25) (P = 0.009) and 85.7% (12/14) vs 31.7% (13/41) (P = 0.000), respectively. Moreover, a higher percentage in the CART19 group had results below the threshold for minimal residual disease (100 vs 7.58%, P = 0.000). In survival analysis, the overall survival rate at 12 months was higher in the CART19 group than that in the chemotherapy group (60.9 vs 10.1%, P = 0.000). For post-transplant patients achieving CR, 25.0% (2/8) and 75.0% (9/12) complicated with GVHD (P = 0.04) in the CART19 group and chemotherapy group, respectively. For all CR patients, the median duration of absolute neutrophil count less than 500/μL and platelet count less than 20,000/μL were longer in the CART19 group than in the chemotherapy group (p = 0.0047 and 0.0003, respectively). Our data demonstrated that patients with CART19s therapy acquired higher rates of remission and longer survival, confirming the encouraging application of CART19 therapy in R/R ALL.

Background: Chimeric antigen receptor (CAR) T-cell therapy has shown remarkable clinical efficacy in hematologic malignancies but limited success in solid tumors. GCC19CART, the first clinical candidate from the CoupledCAR ® solid tumor platform, targets guanylate cyclase-C (GCC) which is expressed in colorectal cancers. A Phase 1 investigator-initiated dose escalation trial is underway in China for patients with relapsed or refractory metastatic colorectal cancer. Data presented here are from a single participating institution. Methods: Subjects with relapsed or refractory metastatic colorectal cancer are screened for GCC expression, with 70% to 80% of subjects expected to demonstrate GCC per historical data. Subjects undergo leukapheresis, a single dose of lymphodepleting chemotherapy (fludarabine 30mg/m2 and cyclophosphamide 300mg/m2) 3 days prior to infusion, and then administration of a single infusion of GCC19CART at one of three doses of 1x10 6, 2x10 6, or 3x10 6 cells/kg. Endpoints are safety and preliminary evidence of efficacy as determined by CT or PET/CT per RECIST1.1 or PERCIST 1.0. Results: 5 subjects have been enrolled to dose level 1 (1x10 6 cells/kg) and 5 subjects have been enrolled to dose level 2 (2x10 6 cells/kg) and have a 1-month post-infusion imaging study available for review. The most common adverse events were cytokine release syndrome (CRS) in 10/10 subjects (Grade 1 9/10 (90%) or Grade 2 1/10 (10%)) and diarrhea in 10/10 subjects (Grade 1 3/10 (30%) Grade 2 1/10 (10%) Grade 3 6/10 (60%)). Neurotoxicity was observed in 1/10 (10%) subjects at Grade 4 and resolved with corticosteroids. The combined overall response rate (ORR) for both dose levels was 50% (5/10). For dose level 1, the overall response rate (ORR) per RECIST 1.1 was 40% (2/5). Two subjects demonstrated a partial response (PR) while an additional subject had partial metabolic response (PMR) on PET/CT with stable disease (SD) per RECIST 1.1. For dose level 2, The ORR per RECIST 1.1 was 60% (3/5). 3 subjects demonstrated a PR (2 at month 1, 1 at month 3 after being SD at month 1) and an additional subject had PMR on PET/CT with SD per RECIST 1.1. Conclusions: GCC19CART demonstrated meaningful clinical activity and an acceptable safety profile in relapsed or refractory metastatic colorectal cancer. This trial is ongoing and updated data will be presented. A United States based Phase 1 trial of GCC19CART is anticipated for early 2022. Disclosures Pu: Innovative Cellular Therapeutics: Current Employment. Zhu: Innovative Cellular Therapeutics: Current Employment. Huang: https://www.accme.org/accreditation-rules/standards-for-integrity-independence-accredited-ce/eligibility: Current Employment. Tang: Innovative Cellular Therapeutics: Current Employment. Jia: Innovative Cellular Therapeutics: Current Employment. Chen: Innovative Cellular Therapeutics: Current Employment. Kennedy: Innovative Cellular Therapeutics: Current Employment. Wu: Innovative Cellular Therapeutics: Current Employment. Xiao: Innovative Cellular Therapeutics: Current Employment.

Chimeric antigen receptor modified T cells (CAR T) have demonstrated remarkable clinical efficacy in the treatment of B cell malignancies and multiple myeloma. Significant challenges restrict their application across solid tumors due to multiple obstacles, including the lack of robust in vivo CAR-T cell expansion and persistence, the immunosuppressive tumor microenvironment.To address these difficulties, we generated CAR T cells using a novel CoupledCAR® technology. Specifically, we engineered CoupledCAR T cells with lentiviral vectors encoding an anti-thyroid stimulating hormone receptor (TSHR) CAR molecule. Immunohistochemistry (IHC) results showed that TSHR was highly expressed in thyroid cancer cells making it an ideal tumor-specific target antigen. In vitro co-culture experiments showed that TSHR CAR T cells specifically recognized and subsequently killed TSHR-positive tumor cells. Animal model experiments showed that TSHR CAR T cells inhibited the proliferation of TSHR-positive tumor cells.To evaluate the clinical safety and efficacy of anti-TSHR CoupledCAR T cells on refractory or relapsed thyroid cancer, we treated refractory/relapsed post-thyroidectomy thyroid cancer patients according to an IRB approved protocol. We treated two patients using anti-TSHR CoupledCAR T cells and observed the rapid expansion of CAR T cells and enhanced the killing of tumor cells. One patient's best response was complete remission, and the other was near complete remission.Patient 1 Male, 64Y, Papillary Thyroid Carcinoma. In May 2017, Thyroid cancer was diagnosed, bilateral total thyroidectomy, and right cervical lymph node functional dissection were performed in Jun 2018, followed by iodine 131 isotope therapy. In December 2018, bilateral multiple cervical lymph nodes were enlarged, especially on the right side. In February 2019, right neck lymphadenectomy was performed.Patient 2 Female, 60Y, Thyroid Carcinoma. In Aug 2013, a "double lobectomy of the thyroid gland” was performed. From Oct 2013 to Jan 2014, she received iodine 131 isotope therapy. In Sep 2014, she was diagnosed with iodine - resistant thyroid cancer. From Sep to Jan 2016, 5 cycles of chemotherapy were performed. In Jun 2016, she enrolled in the Anlotinib experimental group. In Mar 2019, multiple metastases in both lungs and multiple enlarged lymph nodes in the mediastinum were observed.Patient 1: One month after infusion (M1), the patient was evaluated as PR. Three months after infusion (M3), the patient was evaluated as CR, and the patient's CR lasted from M3 to M12 after infused anti-TSHR CoupledCAR T cells , and we are still following up.Patient 2: M1, the patient was evaluated as PR (Partial Response): the tumor volume in the right lower lobe of the lung was reduced by approximately 67.51% (decreased from 65*55mm to 42*39mm). Three months after infusion (M3), compared with that before, the tumor volume was reduced by approximately 73.54% and SUV max value decreased from 14.9 to 2.8, therefore, the patient was evaluated as nCR (near complete remission).We show that TSHR is a good target for treating thyroid cancer, and our anti-TSHR CoupledCAR T cells are safe and effective for treating thyroid cancer. Recruitment is ongoing to evaluate the safety and efficacy of our CoupledCAR T cells. Further, since our CoupledCAR® technology is a platform technology, we are developing it to treat other solid tumors using different target tumor markers. Citation Format: Lei Xiao, Xingchen Liu, Keshu Zhou, Yu Liu, Yong Huang, Chengfei Pu, Zhiyuan Cao, Ruihong Zhu, Haiyang Tang, Zhipeng Huang, Hang Yang, Xi Huang, Yongping Song, Renbin Liu, Zhao Wu, Victor Lu. CoupledCARTMtechnology for treating thyroid cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB145.

Chimeric antigen receptor (CAR) T cell therapy has made significant progress in the treatment of blood cancers such as leukemia, lymphoma, and myeloma. However, the therapy faces many challenges in treating solid tumors. These challenges include physical barriers, tumor microenvironment immunosuppression, tumor heterogeneity, target specificity, and limited reactive cell expansion in vivo.Conventional CAR T cell therapy has thus far shown weak cell expansion in solid tumor patients and achieved little or no therapeutic responses. Here, we developed CAR T cells based on a novel CoupledCAR® technology to treat solid tumors. In contrast to conventional CAR T cells, CoupledCAR T cells significantly improved the expansion of the CAR T cells in vivo and enhanced the CAR T cells' migration ability and resistance to immunosuppression by the tumor microenvironment. The enhanced migration ability and resistance allow the CAR T cells to infiltrate to tumor tissue sites and increase anti-tumor activities.Specifically, we engineered CoupledCAR T cells with lentiviral vectors encoding an anti-GCC (guanylate cyclase 2C) CAR molecule. Furthermore, anti-GCC CAR T cells showed anti-tumor activities in vitro and in vivo experiments.To verify the safety and efficacy of CoupledCAR T cells for treating solid tumors, we conducted several clinical trials for different solid tumors, including seven patients with colorectal cancer. These seven patients failed multiple rounds of chemotherapy and radiotherapy. In the clinical trial, the patients were infused with autologous anti-GCC CoupledCAR T cells range from 4.9×10^5/kg to 2.9×10^6/kg. All patients using anti-GCC CoupledCAR T cells showed rapid expansion of CoupledCAR T cells and killing of tumor cells. Specifically, we observed that CoupledCAR T cells expanded significantly in the patients and infiltrated tumor tissue sites, demonstrating enhanced anti-tumor activities. PET/CT showed significant tumor shrinkage and SUV max declined, and the ongoing responses were monitored. Patient 3 achieved complete response and the best overall response rate (ORR, include complete remission, complete metabolic response, partial response, and partial metabolic response.) was 57.1% (4/7), complete remission (CR) rate was 14.3% (1/7).The clinical data demonstrated that CoupledCAR T cells effectively expanded, infiltrated tumor tissue sites, and kill tumor cells in patients with colorectal cancer. We used immunotherapy to achieve complete remission in patients with advanced colorectal cancer for the first time. We are recruiting more colorectal cancer patients to further test the safety and efficacy of anti-GCC CoupledCAR T cells. Since our CoupledCAR® technology is a platform technology, we are expanding it to treat other solid tumors using different target tumor markers. Citation Format: Lei Xiao, Song Li, Chengfei Pu, Zhiyuan Cao, Xinyi Yang, Ning Li, Youli Luo, Haiyan Zhao, Hang Yang, Xi Huang, Xiaogang Shen, Xiuwen Wang, Yongping Song, Junjie Mao, Pengfei Pang, Qun Hu, Zhao Wu, Victor Lu. Novel coupledCARTMtechnology for treating colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB146.

Purpose: Patients with relapsed/refractory acute lymphocytic leukemia (R/R ALL) have a poor prognosis. Chimeric antigen receptor–modified T cells against CD19 (CART19) have displayed anti-leukemia activities. However, data from systemic trials in Chinese patients are limited. Experimental Design: T cells transduced with CD19-directed CAR lentiviral vectors were infused in patients with R/R ALL under fludarabine- and cyclophosphamide-based lymphodepletion. The postinfusion responses, toxicities, expansion, and persistence of CART19s in enrolled patients were observed and monitored. Results: We enrolled 15 patients with R/R ALL. The median transduction efficiency of CART19s was 33%. In vitro cytotoxicity assays were conducted and showed prominent antileukemia activities with CART19s. The patients received CART19s infusion at doses of 1.1 × 106/kg to 9.8 × 106/kg. Twelve patients achieved complete remission 1 month after CART19s infusion. CART19s expanded and persisted in peripheral blood and bone marrow. At 150 days, the overall survival rate and leukemia-free survival rate were 65.5% and 37.8%, respectively. The cumulative incidence of relapse and the nonrelapse mortality rate were 54.5% and 7.7%, respectively. Four patients underwent subsequent haploidentical hematopoietic stem cell transplantation. In this trial, 10 patients experienced cytokine release syndrome (CRS). Grade 3 CRS developed in 40% of patients and was associated with a higher disease burden on day −1 and a higher number of previous relapses. Conclusions: This trial demonstrated potent antileukemia activities of CART19s in Chinese patients with R/R ALL. Disease relapse remained the main obstacle. However, patients with a high risk of relapse after CART19s might benefit from subsequent haploidentical hematopoietic stem cell transplantation. Clin Cancer Res; 23(13); 3297–306. ©2016 AACR.

e14507 Background: Chimeric antigen receptor modified T-cells (CAR-T) have demonstrated remarkable clinical efficacy in the treatment of B-cell malignancies. Significant challenges restrict their application across solid tumors due to multiple obstacles, including the lack of robust in vivo CAR-T cell expansion and persistence in the immunosuppressive tumor microenvironment. Methods: To address these difficulties, we generated CAR-T cells using a novel CoupledCAR technology. Specifically, we engineered CoupledCAR-T cells with lentiviral vectors encoding an anti-thyroid stimulating hormone receptor (TSHR) CAR molecule. In vitro co-culture experiments showed that TSHR CAR-T cells specifically recognized and subsequently killed TSHR-positive tumor cells. Animal model experiments showed that TSHR CAR-T cells inhibited the proliferation of TSHR-positive tumor cells. Results: Patient 1: Male, 64Y, Papillary Thyroid Carcinoma. In May 2017, his Thyroid cancer was diagnosed, bilateral total thyroidectomy, and right cervical lymph node functional dissection were performed in Jun 2018, followed by iodine 131 isotope therapy. In December 2018, bilateral multiple cervical lymph nodes were enlarged, especially on the right side. In February 2019, right neck lymphadenectomy was performed. One month after infusion (M1) of the anti-TSHR CoupledCAR-T cells, the patient was evaluated as PR. Three months after infusion (M3), the patient was evaluated as CR, and the patient's CR lasted from M3 to M12 after infusion of the CoupledCAR-T cells. We are still following the patient for long-term clinical effects. Patient 2: Female, 60Y, Thyroid Carcinoma: In Aug 2013, a "double lobectomy of the thyroid gland” was performed. From Oct 2013 to Jan 2014, she received iodine 131 isotope therapy. In Sep 2014, she was diagnosed with iodine-resistant thyroid cancer. From Sep to Jan 2016, 5 cycles of chemotherapy were performed. In Jun 2016, she enrolled in the Anlotinib experimental group. In Mar 2019, multiple metastases in both lungs and multiple enlarged lymph nodes in the mediastinum were observed. At month 1 (M1) post cell infusion, the patient was evaluated as PR (Partial Response): the tumor volume in the right lower lobe of the lung was reduced by approximately 67.51% (decreased from 65*55mm to 42*39mm). Three months after infusion (M3), the tumor volume was reduced by approximately 73.54% and SUV max value decreased from 14.9 to 2.8. Therefore, the patient was evaluated as nCR (near complete remission). Conclusions: In summary, we showed that TSHR is an attractive and specific target for treating thyroid cancer and our anti-TSHR CoupledCAR-T cells are safe and effective for treating thyroid cancer. Recruitment is ongoing to evaluate the safety and efficacy of our CoupledCAR-T cells. Further, since our CoupledCAR technology is a platform technology, we are developing additional CoulpledCAR-T cells to treat other solid tumors using different target tumor markers.

2528 Background: Chimeric antigen receptor (CAR) T cell therapy has made significant progress in the treatment of blood cancers such as leukemia, lymphoma, and myeloma. However, the therapy faces many challenges in treating solid tumors. These challenges include physical barriers, tumor microenvironment immunosuppression, tumor heterogeneity, target specificity, and limited expansion in vivo. Methods: We designed a CAR lentivirus vector that consisted of a humanized CD19-specific single-chain variable fragment (scFv), a 4-1BB costimulatory domain, and a CD3ζ signaling domain.The lentivirus was produced by transfecting HEK-293T cells with CAR lentiviral vectors and viral packaging plasmids. Patient’s CD3 T cells was cultured in X-VIVO medium containing 125U/mL 1interleukin-2 (IL-2), and transduced with CAR lentivirus at certain MOI 24h after stimulated by anti-CD3/CD28 magnetic beads. Transduction efficiency was evaluated at 7 to 9 days after CAR lentivirus transduction, and quality controls for fungi, bacteria, mycoplasma, chlamydia, and endotoxin were performed. After infusion, serial peripheral blood samples were collected, and the expansion and the cytokine release of CART cells were detected by FACS and QPCR,respectively. The evaluation of response level for patients were performed at month 1,month 3,and month 6 by PET/CT. Results: We engineered CoupledCAR T cells with lentiviral vectors encoding an anti-GCC (guanylate cyclase 2C) CAR molecule. To verify the safety and efficacy of CoupledCAR-T cells for treating solid tumors, we conducted several clinical trials for different solid tumors, including seven patients with colorectal cancer. These seven patients failed multiple rounds of chemotherapy and radiotherapy. In the clinical trial, the metastatic colorectal cancer patients were infused with autologous anti-GCC CoupledCAR-T cells range from 4.9×105/kg to 2.9×106/kg. We observed that CoupledCAR-T cells expanded significantly in the patients and infiltrated tumor tissue sites, demonstrating enhanced anti-tumor activities. PET/CT showed significant tumor shrinkage and SUV max declined, and the ongoing responses were monitored. Patient 3 achieved complete response and the best overall response rate (ORR, include complete remission, complete metabolic response, and partial response.) was 57.1% (4/7), complete remission (CR) rate was 14.3% (1/7). Conclusions: In conclusion, the clinical data demonstrated that CoupledCAR-T cells effectively expanded, infiltrated tumor tissue sites, and kill tumor cells in patients with colorectal cancer. We used immunotherapy to achieve complete remission in patients with advanced colorectal cancer for the first time. We are recruiting more colorectal cancer patients to further test the safety and efficacy of anti-GCC CoupledCAR T cells. Since our CoupledCAR technology is a platform technology, we are expanding it to treat other solid tumors using different target tumor markers.

Chimeric antigen receptor (CAR) T cell therapy has made significant progress in the treatment of blood cancers such as leukemia, lymphoma, and myeloma. However, the therapy faces many challenges in treating solid tumors. These challenges include physical barriers, tumor microenvironment immunosuppression, tumor heterogeneity, target specificity, and limited reactive cell expansion in vivo. Conventional CAR T cell therapy has thus far shown weak cell expansion in solid tumor patients and achieved little or no therapeutic responses. Here, we developed CAR T cells based on a novel CoupledCAR® technology to treat solid tumors. In contrast to conventional CAR T cells, CoupledCAR T cells significantly improved the expansion of the CAR T cells in vivo and enhanced the CAR T cells' migration ability and resistance to immunosuppression by the tumor microenvironment. The enhanced migration ability and resistance allow the CAR T cells to infiltrate to tumor tissue sites and increase anti-tumor activities. Specifically, we engineered CoupledCAR T cells with lentiviral vectors encoding an anti-GCC (guanylate cyclase 2C) CAR molecule. Furthermore, anti-GCC CAR T cells showed anti-tumor activities in vitro and in vivo experiments. To verify the safety and efficacy of CoupledCAR T cells for treating solid tumors, we conducted several clinical trials for different solid tumors, including seven patients with colorectal cancer. These seven patients failed multiple rounds of chemotherapy and radiotherapy. In the clinical trial, the patients were infused with autologous anti-GCC CoupledCAR T cells range from 4.9×10^5/kg to 2.9×10^6/kg. All patients using anti-GCC CoupledCAR T cells showed rapid expansion of CoupledCAR T cells and killing of tumor cells. Specifically, we observed that CoupledCAR T cells expanded significantly in the patients and infiltrated tumor tissue sites, demonstrating enhanced anti-tumor activities. PET/CT showed significant tumor shrinkage and SUV max declined, and the ongoing responses were monitored. Patient 3 achieved complete response and the best overall response rate (ORR, include complete remission, complete metabolic response, partial response, and partial metabolic response.) was 71.4% (5/7), complete remission (CR) rate was 14.3% (1/7). The clinical data demonstrated that CoupledCAR T cells effectively expanded, infiltrated tumor tissue sites, and kill tumor cells in patients with colorectal cancer. We used immunotherapy to achieve complete remission in patients with advanced colorectal cancer for the first time. We are recruiting more colorectal cancer patients to further test the safety and efficacy of anti-GCC CoupledCAR T cells. Since our CoupledCAR® technology is a platform technology, we are expanding it to treat other solid tumors using different target tumor markers . Disclosures Xiao: Innovative Cellular Therapeutics: Other: stockholder.

CoupledCAR TM Technology for Treating Thyroid Cancer Chimeric antigen receptor modified T cells (CAR T) have demonstrated remarkable clinical efficacy in the treatment of B cell malignancies and multiple myeloma. Significant challenges restrict their application across solid tumors due to multiple obstacles, including the lack of robust in vivo CAR-T cell expansion and persistence, the immunosuppressive tumor microenvironment, and tumor escape due to heterogeneous tumor cell composition with a potential loss of the targeted tumor antigen. To address these difficulties, we generated CAR T cells using a novel CoupledCARTM technology. Specifically, we engineered CoupledCAR T cells with lentiviral vectors encoding an anti-thyroid stimulating hormone receptor (TSHR) CAR molecule. Immunohistochemistry (IHC) results showed that TSHR was highly expressed in thyroid cancer cells making it an ideal tumor-specific target antigen. In vitro co-culture experiments showed that TSHR CAR T cells specifically recognized and consequently killed TSHR-positive tumor cells. Animal experiments showed that TSHR CAR T cells inhibited the proliferation of TSHR-positive tumor cells. To evaluate the clinical safety and efficacy of anti-TSHR CoupledCAR T cells on refractory or relapsed thyroid cancer, we treated refractory/relapsed post-thyroidectomy thyroid cancer patients according to an IRB approved protocol. We treated two patients using anti-TSHR CoupledCAR T cells and observed the rapid expansion of CAR T cells and enhanced the killing of tumor cells. One patient's best response was complete remission, and the other was near complete remission. Patient Profile: Patient 1 Male, 64Y, Papillary Thyroid Carcinoma. In May 2017, Thyroid cancer was diagnosed, bilateral total thyroidectomy, and right cervical lymph node functional dissection were performed in June, followed by iodine 131 isotope therapy. In December 2018, bilateral multiple cervical lymph nodes were enlarged, especially on the right side. In February 2019, right neck lymphadenectomy was performed. Patient 2 Female, 60Y, Thyroid Carcinoma. In Aug 2013, a "double lobectomy of the thyroid gland" was performed. From Oct 2013 to Jan 2014, she received iodine 131 isotope therapy. In Sep 2014, she was diagnosed with iodine - resistant thyroid cancer. From Sep to Jan 2016, 5 cycles of chemotherapy were performed. In Jun 2016, she enrolled in the Anlotinib experimental group. In Mar 2019, multiple metastases in both lungs and multiple enlarged lymph nodes in the mediastinum were observed. Observations and Results: Patient 1: One month after infusion (M1), the patient was evaluated as PR: lymph node metastasis became undetectable and the size of the thoracic paratracheal tumor nodules decreased significantly. Three months after infusion (M3), the patient was evaluated as CR, and the tumor tissue was substantially smaller than M1. Patient 2: M1, the patient was evaluated as PR (Partial Response): the tumor volume in the right lower lobe of the lung was reduced by approximately 67.51% (decreased from 65*55mm to 42*39mm). Three months after infusion (M3), compared with that before, the tumor volume was reduced by approximately 73.54% and SUV max value decreased from 14.9 to 2.8, therefore, the patient was evaluated as nCR (near complete remission). We show that TSHR is a good target for treating thyroid cancer, and our anti-TSHR CoupledCAR T cells are safe and effective for treating thyroid cancer. Recruitment is ongoing to evaluate the safety and efficacy of our CoupledCAR T cells. Further, since our CoupledCARTM technology is a platform technology, we are developing it to treat other solid tumors using different target markers. Disclosures Xiao: Innovative Cellular Therapeutics: Other: stockholder.

The chimeric antigen receptor (CAR) T cell treatment has been demonstrated as an effective therapy to treat relapsed/refractory B cell malignancy. However, tumor microenvironment influences and affects the efficacy of CAR T treatment. For example, programmed death ligand 1/2 (PDL1/2) may inhibit the CAR T cells via interaction with up-regulated programmed cell death protein 1 (PD1) after T cells activation, suppressing the tumor-killing capability of the CAR T cells. Thus, blockade of the PD1-PDL1/2 interaction may enhance the anti-tumor efficacy of CAR T therapy.Here, we generated CAR T expressed an anti-CD19 CAR molecule and a dominant-negative PD1 molecule. Compared with conventional CART cells, these “armored” CART cells showed the enhanced capability of tumor-killing and more “memory-like” phenotypes after multiple-round tumor challenging. These results suggest dominant-negative PD1 molecules may protect CART cells from exhaustion in the tumor microenvironment.Further, we reported the findings of a clinical trial for six relapsed or refractory B-cell non-Hodgkin lymphoma (NHLs) patients treated using our armored CAR T cells. These six patients failed multiple rounds of chemotherapy and radiotherapy. In the clinical trial, the patients were infused with autologous CAR T cells range from1×106/kg to 8×106/kg. PET/CT showed significant tumor shrinkage and SUV max declines in all six patients, and the ongoing responses were monitored. The best overall response rate (ORR)was 100%. Conclusion: The results of these six patients in the clinical trial showed that our armored CAR T cells achieved the significant anti-bulky lymphoma response while causing limited and tolerated cytokine release syndrome and central nervous system toxicity. Thus, dominant-negative PD1 molecules may increase CAR T cells persistence in patients, enhancing the efficacy of CAR T cells for treating blood cancer. Finally, dominant-negative PD1 can be used as a platform technology and may be applied to other adoptive cellular immunotherapies such as TCR-T or TIL in the treatment of solid tumors. We are continuing to monitor current patients and recruit more patients for the clinical trial. Citation Format: Yan Yuan, Liansheng Huang, Yang Su, Chengfei Pu, Tianling Ding, Xibin Xiao, Lina Jin, Zhiyuan Cao, Ting Wu, Tong Chen, Luying Ding, Xiaohong Zhang, Haifeng Lan, Zhao Wu, Lei Xiao. Dominant negative PD1 armored CAR-T cells induce remission in relapsed or refractory non-Hodgkin lymphoma (NHL) patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-379.

e15028 Background: The chimeric antigen receptor (CAR) T cell treatment has been demonstrated as an effective therapy to treat relapsed/refractory B cell malignancy. However, tumor microenvironment influences and affects the efficacy of CAR T treatment. For example, programmed death ligand 1/2 (PDL1/2) may inhibit the CAR T cells via interaction with up-regulated programmed cell death protein 1 (PD1) after T cells activation, suppressing the tumor-killing capability of the CAR T cells. Thus, blockade of the PD1-PDL1/2 interaction may enhance the anti-tumor efficacy of CAR T therapy. Methods: Here, we generated CAR T expressed an anti-CD19 CAR molecule and a dominant-negative PD1 molecule. Compared with conventional CART cells, these “armored” CART cells showed the enhanced capability of tumor-killing and more “memory-like” phenotypes after multiple-round tumor challenging. These results suggest dominant-negative PD1 molecules may protect CART cells from exhaustion in the tumor microenvironment. Results: Further, we reported the findings of a clinical trial for six relapsed or refractory B-cell non-Hodgkin lymphoma (NHLs) patients treated using our armored CAR T cells. These six patients failed multiple rounds of chemotherapy and radiotherapy. In the clinical trial, the patients were infused with autologous CAR T cells range from1×106/kg to 8×106/kg. PET/CT showed significant tumor shrinkage and SUV max declines in all six patients, and the ongoing responses were monitored. The best overall response rate (ORR)was 100%. Conclusions: The results of these six patients in the clinical trial showed that our armored CAR T cells achieved the significant anti-bulky lymphoma response while causing limited and tolerated cytokine release syndrome and central nervous system toxicity. Thus, dominant-negative PD1 molecules may increase CAR T cells persistence in patients, enhancing the efficacy of CAR T cells for treating blood cancer. Finally, dominant-negative PD1 can be used as a platform technology and may be applied to other adoptive cellular immunotherapies such as TCR-T or TIL in the treatment of solid tumors. We are continuing to monitor current patients and recruit more patients for the clinical trial.

Hypoxia-inducible factors (HIFs) are master regulators of adaptive responses to low oxygen, and their α-subunits are rapidly degraded through the ubiquitination-dependent proteasomal pathway after hydroxylation. Aberrant accumulation or activation of HIFs is closely linked to many types of cancer. However, how hydroxylation of HIFα and its delivery to the ubiquitination machinery are regulated remains unclear. Here we show that Rho-related BTB domain-containing protein 3 (RHOBTB3) directly interacts with the hydroxylase PHD2 to promote HIFα hydroxylation. RHOBTB3 also directly interacts with the von Hippel-Lindau (VHL) protein, a component of the E3 ubiquitin ligase complex, facilitating ubiquitination of HIFα. Remarkably, RHOBTB3 dimerizes with LIMD1, and constructs a RHOBTB3/LIMD1-PHD2-VHL-HIFα complex to effect the maximal degradation of HIFα. Hypoxia reduces the RHOBTB3-centered complex formation, resulting in an accumulation of HIFα. Importantly, the expression level of RHOBTB3 is greatly reduced in human renal carcinomas, and RHOBTB3 deficiency significantly elevates the Warburg effect and accelerates xenograft growth. Our work thus reveals that RHOBTB3 serves as a scaffold to organize a multi-subunit complex that promotes the hydroxylation, ubiquitination and degradation of HIFα.

Background: With the increase of chimeric antigen receptor-modified T (CAR-T) cell therapy, serious complications initiated by CAR-T cells have garnered wide attention. We have previously developed a 4-1BB/CD3-ζ-costimulated CAR-T cells against CD19 (CART19) for adult acute lymphoblastic leukemia (ALL). In this study, a preclinical safety assessment of CART19 was performed on NSG mice, to evaluate the preclinical toxicity along with its efficacy and tissue distribution. Methods: A total of 120 NSG mice were used for a combined pharmacodynamics and toxicity study for 56 days. Ninety-six mice of which were single dosed with Raji-Luc (5×10 5 per animal, i.p.) and different concentrations of CART19 (0.2×10 7 , 0.6×10 7 and 1.8×10 7 per animal, i.v.), while the rest were assigned to the Untreated group. Optical intensity of Raji-Luc in mice, clinical symptoms, body mass, hematological analysis, humanized cytokine, lymphocyte subset counting, necropsy and histopathological examinations were performed. In addition, a single dose of 0.6×10 7 CART19 was intravenously administered to 48 NSG mice, and the distribution of CART19 in different tissues was analyzed using quantitative PCR. Results: CART19 is widely distributed in organs well-perfused with blood, including the lungs, blood, bone marrow, liver and spleen. Significant proliferation of CART19 was also found in the blood by through recognition using humanized CD3+ for T lymphocytes. The survival rate and leukemia related clinical symptoms in mice administered CART19 were markedly ameliorated, and the proliferation of Raji cells in mice was effectively inhibited. However, CART19 had no obvious effects on either the mean body mass or the blood cell counts, and no cytokine release syndrome and graft versus host disease were observed. Conclusions: NSG mice given CART19 treatment demonstrated a longer survival period without significant immunotoxicity, suggesting encouraging clinical prospects for CART19 in patients with R/R ALL. Our study shed light on evaluation and supervision strategies for CAR-T products for the treatment of hematological diseases or leukemia.

e19028 Background: The chimeric antigen receptor (CAR) T cell treatment has been demonstrated as an effective therapy to relapse/refractory B cell malignancy. However, tumor microenvironment influences and affects CAR T treatment. For example, programmed death ligand 1/2 (PDL1/2) may inhibit the CAR T cells via interaction with up-regulated Programmed cell death protein 1 (PD1) during T cells activation, suppressing the tumor-killing capability of the CAR T cells. Thus, blockade of the PD1-PDL1/2 interaction may enhance the anti-tumor efficacy of CAR T therapy. Methods: We generated CAR T cells including an anti-CD19 second generation (2G) CAR molecule and a dominant negative PD1 molecule (Figure A). Compared with conventional CART cells, these “armored” CART cells show the enhanced capability of tumor killing after multiple-round tumor challenging and more “memory-like” phenotypes (Figure B). These results suggest dominant negative PD1 molecules may protect CART cells from exhaustion in the tumor microenvironment. Results: We report clinical trials of three refractory diffuse large B cell lymphomas (DLBCLs) patients that were successfully treated using the armored CAR T cells described above. All of these three patients failed to achieve response after multiple rounds of chemotherapy and radiotherapy. However, after infused with autologous CART cells at 5.23×10^6/kg and 1.97×10^6/kg, respectively, they showed significant tumor mass decrease and SUV max declines in PET/CT results and ongoing responses (e.g., from 34.48 to 3.89 at day 27, from 25.02 to 2.38 at day 31, respectively, see Figure C). Conclusions: These three clinical trials revealed the significant anti-bulky lymphoma response with respect to these armored CAR T cells and limited and tolerated cytokine release syndrome and central nervous system toxicity. Also, dominant negative PD1 molecules may augment CAR T cells persistence in patients after activation by lymphoma cells, thus enhancing the efficacy of CAR T cells in the treatment of hematomas. Finally, the techniques described herein are a platform technology and may be applied to other adoptive cellular immunotherapies such as TCR-T or TIL in the treatment of solid tumors. We are continuing to recruit more patients for the clinical trials. Clinical trial information: ChiCTR1900021295.

Supplemental Digital Content is available in the text, Rationale: The presence of the Philadelphia chromosome (Ph) in acute lymphoblastic leukemia (ALL) has been associated with a high risk of disease relapse and a poor prognosis. Allogeneic hematopoietic stem cell transplantation (HSCT) is an established treatment for adults with Ph-positive ALL, but relapse remains the primary cause of treatment failure, and is associated with an extremely poor prognosis. The emergence of resistance to tyrosine kinase inhibitors (TKIs) poses a challenge for patients with disease relapses after initial treatment with TKI-containing regimens. Patient concerns: Two patients with TKI-resistant recurrent Ph-positive ALL. Diagnoses: Ph-positive ALL. Interventions: Anti-CD19 CAR T-cell infusion. Outcomes: One patient's bone marrow blasts decreased significantly, and the other reached negative minimal residual disease (MRD). However, we first recorded the development of new-onset acute graft-versus-host disease (aGVHD) after anti-CD19 CAR T-cell infusion in a patient who received allogeneic HSCT. Our 2 case reports also demonstrate the efficacy of anti-CD19 CAR T-cell therapy in the treatment of TKI-resistant Ph-positive ALL. Lessons: Our report suggests that anti-CD19 CAR T-cell therapy may be a promising option for the treatment of relapsed Ph-positive ALL after conventional chemotherapy or allogeneic HSCT. However, caution is due given the possibility of the adverse effects of cytokine release syndrome (CRS)-induced aGVHD for patients receiving allogeneic HSCT.

Preparation of chimeric antigen receptor-modified (CAR) T cells targeting CD19 (CART19). (DOCX 16.7 KB)

Detailed patient information and procedures of diagnosis and treatment. (DOCX 17.2 KB)

Introduction Primary disease relapse remains the leading causeof death inadult acute lymphocytic leukemia (ALL) patients despite the availability of high-dose chemotherapy, targeted drugs and allogeneic hematopoietic stem cell transplantation. Relapsed or refractoryALL especially with high leukemia burden has very poor prognosis. Chimeric antigen receptor-modified T cells (CAR-T) targeting CD19 may overcome many limitations of conventional therapies and induce remission in patients with refractory disease. Patients and Methods Refractory or relapsed CD19+ ALL adult patients with more than 60% blast cells in the bone marrow at the time of evaluation were enrolled. Eligible patients underwent leukapheresis, and T cells were transduced with a Lenti-virus encoding a CAR construct composed of anti-CD19 scFV linked to 4-1BB and CD3¦Æ signaling domains. To enhance the activity of the transferred CAR-T cells, all patients received lymphodepleting chemotherapy with fludarabine (30mg/m2/day Days -4, -3, -2) and cyclophosphamide (1000mg/m2/day Days -3, -2) followed with 1x10E6 to 10x10E6 CD19CAR-T cells/kg 2 days later. The primary objective of the study was to evaluate the safety and anti-tumor activity of CD19CAR-T cells in ALL. Peripheral blood and bone marrow samples were collected for immunophenotypic, cytokine, and molecular studies at pre-specified times after CD19CART cell infusion. Results 2 patients were enrolled. The patient characteristics are listed in Table 1. All the 2 patients had once achieved complete remission, with MRD Conclusion Our study revealed that CD19CAR-T cells could express robust expansion and anti-leukemia activity in relapsed and refractory ALL patients with high tumor burden. All the 2 patients achieved CR with negative MRD within 12 days after CART cell infusion. No uncontrollable clinical toxicities were manifested. The robust anti-leukemia activity of CD19CAR-T and high-dose CTX chemotherapy might contribute to the good therapeutic efficacy in our clinical trial. More patients will be enrolled in this trial and results will be reported in ASH meeting this year. Table 1. Patient characteristics Patient Age/sex Number of prior therapies Lymphodepleting chemotherapy Marrow blast Toxicities Pre-CAR Post-CAR 1 51y/M 3 Flu(30mg/m2/d -4 to -2) and CTX(1g/m2/d -3, -2) 66% Disclosures No relevant conflicts of interest to declare.

Chimeric antigen receptor-modified (CAR) T cells targeting CD19 (CART19) have shown therapeutical activities in CD19+ malignancies. However, the etiological nature of neurologic complications remains a conundrum. In our study, the evidence of blood-brain barrier (BBB)-penetrating CAR T cells as a culprit was revealed. A patient with acute lymphocytic leukemia developed sustained pyrexia with tremors about 6 h after CART19 infusion, followed by a grade 2 cytokine release syndrome (CRS) and neurological symptoms in the next 3 days. Contrast-enhanced magnetic resonance showed signs of intracranial edema. Lumbar puncture on day 5 showed an over 400-mmH2O cerebrospinal pressure. The cerebrospinal fluid (CSF) contained 20 WBCs/μL with predominant CD3+ T cells. qPCR analysis for CAR constructs showed 3,032,265 copies/μg DNA in CSF and 988,747 copies/μg DNA in blood. Cytokine levels including IFN-γ and IL-6 in CSF were extremely higher than those in the serum. Methyprednisone was administrated and the symptoms relieved gradually. The predominance of CART19 in CSF and the huge discrepancies in cytokine distributions indicated the development of a cerebral CRS, presumably featured as CSF cytokines largely in situ produced by BBB-penetrating CAR T cells. For the first time, we reported the development of cerebral CRS triggered by BBB-penetrating CAR T cells. Trial registration: ChiCTR-OCC-15007008. Electronic supplementary material The online version of this article (doi:10.1186/s13045-016-0299-5) contains supplementary material, which is available to authorized users.