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.