Cytotoxicity and exhaustion markers of chimeric antigen receptor T cells targeting BCMA in multiple myeloma cell lines between patients and healthy donors.

OBJECTIVES: Multiple myeloma (MM) accounts for 10% of hematologic malignancies. However, most of the patients suffered from relapsed/refractory disease. We would like to expand CAR T cell therapy to treat MM using our current platform. METHODS: BCMA CAR T lymphocytes were generated for volunteers or MM patients. The transduction efficiency was detected by the ddPCR technique. Immunophenotyping and exhaustion markers were monitored by flow cytometry. The efficacy of BCMA CAR T cells was tested using coculturing with BCMA CAR or mock, and the positive and negative targets, K562/hBCMA-ECTM and K562, respectively. RESULTS: BCMA CAR T cells were generated from consented volunteers or MM patients and could be detected CAR BCMA expression at a mean of 4.07 ± 1.95 or 4.65 ± 1.21 copies/cell, respectively. Those modified T cells were primarily effector memory T cells. Our BCMA CAR T cells could explicitly eradicate the K562/hBCMA-ECTM cell line while the K562 cell line survived. Interestingly, the BCMA CAR, mock T cells, and peripheral blood mononuclear cells from MM patients expressed similar levels of the exhaustion makers, TIM-3, LAG-3, and PD1. CONCLUSIONS: Our BCMA CAR T cells, mainly effector/effector memory, could eliminate BCMA-expressing cells in vitro and had similar levels of exhaustion markers among different populations.

Engineered U7 snRNA mediates sustained splicing correction in erythroid cells from ß-thalassemia/HbE patients.

Repair of a splicing defect of ß-globin pre-mRNA harboring hemoglobin E (HbE) mutation was successfully accomplished in erythroid cells from patients with ß-thalassemia/HbE disorder by a synthetic splice-switching oligonucleotide (SSO). However, its application is limited by short-term effectiveness and requirement of lifelong periodic administration of SSO, especially for chronic diseases like thalassemias. Here, we engineered lentiviral vectors that stably express U7 small nuclear RNA (U7 snRNA) carrying the splice-switching sequence of the SSO that restores correct splicing of ßE-globin pre-mRNA and achieves a long-term therapeutic effect. Using a two-step tiling approach, we systematically screened U7 snRNAs carrying splice-switching SSO sequences targeted to the cryptic 5' splice site created by HbE mutation. We tested this approach and identified the most responsive element for mediating splicing correction in engineered U7 snRNAs in HeLa-ßE cell model cell line. Remarkably, the U7 snRNA lentiviral vector (U7 ßE4+1) targeted to this region effectively restored the correctly-spliced ßE-globin mRNA for at least 5 months. Moreover, the effects of the U7 ßE4+1 snRNA lentiviral vector were also evident as upregulation of the correctly-spliced ßE-globin mRNA in erythroid progenitor cells from ß-thalassemia/HbE patients treated with the vector, which led to improvements of pathologies in erythroid progenitor cells from thalassemia patients. These results suggest that the splicing correction of ßE-globin pre-mRNA by the engineered U7 snRNA lentiviral vector provides a promising, long-term treatment for ß-thalassemia/HbE.

A novel anti-membrane CD30 single-chain variable fragment discovered from the human phage library: A potential targeted immunotherapy.

Hodgkin's lymphoma and anaplastic large cell lymphoma, especially relapsed or refractory diseases, could recently be cured by CD30-targeted immunotherapy. However, the CD30 antigen releases the soluble ectodomain of CD30, which might obscure the targeted therapy. Therefore, the membrane epitope of CD30 (mCD30), left on the cancer cells, might be a prospective target for lymphoma treatment. The discovery of novel mCD30 monoclonal antibodies (mAbs) using phage technology yielded 59 potential human single-chain variable fragments (HuscFvs). Ten candidate HuscFv clones have been selected based on various methods, i.e., direct PCR, ELISA and western blot assays, and nucleotide sequencing techniques. Fortunately, only one potential HuscFv clone, clone #A4, was determined by the prediction of HuscFv-peptide molecular docking and the binding affinity test using isothermal titration calorimetry. Finally, we proved that the HuscFv #A4, which had a binding affinity (Kd) of 421e-9 ± 2.76e-6 M, might be the novel mCD30 mAb. We generated chimeric antigen receptor-modified T lymphocytes using HuscFv #A4 as an antigen detection part (anti-mCD30-H4CART). The cytotoxicity assay of anti-mCD30-H4CART cells showed significant eradication of the CD30-expressing cell line, K562 (p = 0.0378). We found a novel mCD30 HuscFv using human phage technology. We systematically examined and proved that our HuscFv #A4 could specifically eradicate CD30-expressing cancers.