SARS-CoV-2-specific T cells are rapidly expanded for therapeutic use and target conserved regions of the membrane protein.

T-cell responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been described in recovered patients, and may be important for immunity following infection and vaccination as well as for the development of an adoptive immunotherapy for the treatment of immunocompromised individuals. In this report, we demonstrate that SARS-CoV-2-specific T cells can be expanded from convalescent donors and recognize immunodominant viral epitopes in conserved regions of membrane, spike, and nucleocapsid. Following in vitro expansion using a good manufacturing practice-compliant methodology (designed to allow the rapid translation of this novel SARS-CoV-2 T-cell therapy to the clinic), membrane, spike, and nucleocapsid peptides elicited interferon-γ production, in 27 (59%), 12 (26%), and 10 (22%) convalescent donors (respectively), as well as in 2 of 15 unexposed controls. We identified multiple polyfunctional CD4-restricted T-cell epitopes within a highly conserved region of membrane protein, which induced polyfunctional T-cell responses, which may be critical for the development of effective vaccine and T-cell therapies. Hence, our study shows that SARS-CoV-2 directed T-cell immunotherapy targeting structural proteins, most importantly membrane protein, should be feasible for the prevention or early treatment of SARS-CoV-2 infection in immunocompromised patients with blood disorders or after bone marrow transplantation to achieve antiviral control while mitigating uncontrolled inflammation.

Anti-BCMA immunotoxins produce durable complete remissions in two mouse myeloma models.

Multiple myeloma (MM) is a B cell malignancy for which new treatments are urgently needed. The B cell maturation antigen (BCMA) is a lineage-restricted differentiation protein highly expressed on myeloma. Recombinant immunotoxins (RITs) are proteins composed of the Fv or Fab portion of an antibody fused to a bacterial toxin. We previously treated H929 myeloma s.c. tumors with anti-BCMA immunotoxins, very active on killing cultured cells, and observed tumor growth inhibition but not complete tumor responses. To determine if immunotoxins were more active against cells growing in the bone marrow (BM), the normal location of myeloma cells, we developed a BM mouse model that is more relevant to human disease. H929 cells were transfected with luciferase and GFP, enriched by flow, recycled through the BM of a mouse, and injected IV into nonobese diabetic scid γ mice (NSG) mice. A second myeloma mouse model used the MM.1S-GFP-luc cell line. Mice were treated IV with immunotoxins, and the tumor burden was assessed using bioluminescence imaging. We achieved complete durable remissions when treating mice with H929-GFP-luc cells with anti-BCMA RITs both leptomycin B-75 (LMB-75) [anti-BCMA-disulfide-stabilized (ds)-Fv-PE24] (where PE represents Pseudomonas exotoxin A) or LMB-70 (anti-BCMA-Fab-PE24) given every other day for 5-d (QOD×5) doses beginning on day 4 or day 8. Mice were disease free at 3 months; untreated mice became moribund around day 40. We also achieved long-term responses using the MM.1S-GFP-luc myeloma cell line. Treatment with an 1.5 mg/kg LMB-75 QOD×5 anti-BCMA RIT beginning on day 4 caused the complete disappearance of tumors for 80 days. To summarize, LMB-75 and LMB-70, our anti-BCMA RITs, induced complete durable responses in two myeloma models.

Preclinical development of anti-BCMA immunotoxins targeting multiple myeloma.

BACKGROUND: Multiple myeloma (MM) is a B-cell malignancy that is incurable for the majority of patients. New treatments are urgently needed. Recombinant immunotoxins (RITs) are chimeric proteins that are composed of the Fv or Fab portion of an antibody fused to a bacterial toxin. B-cell maturation antigen (BCMA) is a lineage-restricted differentiation protein and an ideal target for antibody-based treatments for MM. METHODS: RITs were produced by expressing plasmids encoding the components of the anti-BCMA RITs in Escherichia coli followed by inclusion body preparation, solubilization, renaturation, and purification by column chromatography. The cytotoxic activity of RITs was tested in vitro by WST-8 assays. We also measured their binding to human and mouse serum albumins and to BCMA and measured their serum half-life in mice. RESULTS: Using Fvs from different anti-BCMA antibodies, we produced RITs that specifically kill BCMA-expressing MM cells in vitro. To increase the serum half-life in vivo, we generated RITs that are fused with albumin-binding domains (ABDs). All RITs with ABDs have some decreased activity compared to the parent RIT, which is not due to decreased binding to BCMA. CONCLUSIONS: Various new anti-BCMA immunotoxins were produced and evaluated. None of these were better than LMB-75 (anti-BCMA BM306-disulfide-stabilized Fv-LRggs) supporting the further preclinical development of LMB-75.

Loss of CENP-F Results in Dilated Cardiomyopathy with Severe Disruption of Cardiac Myocyte Architecture.

Centromere-binding protein F (CENP-F) is a very large and complex protein with many and varied binding partners including components of the microtubule network. Numerous CENP-F functions impacting diverse cellular behaviors have been identified. Importantly, emerging data have shown that CENP-F loss- or gain-of-function has critical effects on human development and disease. Still, it must be noted that data at the single cardiac myocyte level examining the impact of CENP-F loss-of-function on fundamental cellular behavior is missing. To address this gap in our knowledge, we analyzed basic cell structure and function in cardiac myocytes devoid of CENP-F. We found many diverse structural abnormalities including disruption of the microtubule network impacting critical characteristics of the cardiac myocyte. This is the first report linking microtubule network malfunction to cardiomyopathy. Importantly, we also present data demonstrating a direct link between a CENP-F single nucleotide polymorphism (snp) and human cardiac disease. In a proximate sense, these data examining CENP-F function explain the cellular basis underlying heart disease in this genetic model and, in a larger sense, they will hopefully provide a platform upon which the field can explore diverse cellular outcomes in wide-ranging areas of research on this critical protein.