Phase 1 open-label trial of intravenous administration of MVA-BN-brachyury-TRICOM vaccine in patients with advanced cancer.

BACKGROUND: MVA-BN-brachyury-TRICOM is a recombinant vector-based therapeutic cancer vaccine designed to induce an immune response against brachyury. Brachyury, a transcription factor overexpressed in advanced cancers, has been associated with treatment resistance, epithelial-to-mesenchymal transition, and metastatic potential. MVA-BN-brachyury-TRICOM has demonstrated immunogenicity and safety in previous clinical trials of subcutaneously administered vaccine. Preclinical studies have suggested that intravenous administration of therapeutic vaccines can induce superior CD8+ T cell responses, higher levels of systemic cytokine release, and stronger natural killer cell activation and proliferation. This is the first-in-human study of the intravenous administration of MVA-BN-brachyury-TRICOM. METHODS: Between January 2020 and March 2021, 13 patients were treated on a phase 1, open-label, 3+3 design, dose-escalation study at the National Institutes of Health Clinical Center. The study population was adults with advanced solid tumors and was enriched for chordoma, a rare sarcoma of the notochord that overexpresses brachyury. Vaccine was administered intravenously at three DLs on days 1, 22, and 43. Blood samples were taken to assess drug pharmacokinetics and immune activation. Imaging was conducted at baseline, 1 month, and 3 months post-treatment. The primary endpoint was safety and tolerability as determined by the frequency of dose-limiting toxicities; a secondary endpoint was determination of the recommended phase 2 dose. RESULTS: No dose-limiting toxicities were observed and no serious adverse events were attributed to the vaccine. Vaccine-related toxicities were consistent with class profile (ie, influenza-like symptoms). Cytokine release syndrome up to grade 2 was observed with no adverse outcomes. Dose-effect trend was observed for fever, chills/rigor, and hypotension. Efficacy analysis of objective response rate per RECIST 1.1 at the end of study showed one patient with a partial response, four with stable disease, and eight with progressive disease. Three patients with stable disease experienced clinical benefit in the form of improvement in pain. Immune correlatives showed T cell activation against brachyury and other tumor-associated cascade antigens. CONCLUSIONS: Intravenous administration of MVA-BN-brachyury-TRICOM vaccine was safe and tolerable. Maximum tolerated dose was not reached. The maximum administered dose was 109 infectious units every 3 weeks for three doses. This dose was selected as the recommended phase 2 dose. TRIAL REGISTRATION NUMBER: NCT04134312.

T-box transcription factor TBX1, targeted by microRNA-6727-5p, inhibits cell growth and enhances cisplatin chemosensitivity of cervical cancer cells through AKT and MAPK pathways.

Cervical cancer (CC) is the fourth most common cancers among women worldwide. T-box transcription factor 1 (TBX1), a member of the T-box family, has anti-tumor effects in some types of cancer, but its role in CC is yet unknown. The aim of this study is to investigate the functions and underlying mechanisms of TBX1 in CC. Online database UALCAN showed that TBX1 was down-regulated in CC tissues compared with normal tissues and patients with lower TBX1 expression level had a poor prognosis. TBX1 overexpression significantly decreased the proliferation, migration, and invasion of Hela and SiHa cells. Conversely, cell apoptosis and chemosensitivity to cisplatin were promoted in TBX1-overexpressing CC cells. Moreover, up-regulation of TBX1 inhibited both AKT and MAPK signaling pathways. Furthermore, dual luciferase report assay indicated that TBX1 could directly bind to miR-6727-5p. In addition, TBX1 expression was inhibited by miR-6727-5p mimic and up-regulated by miR-6727-5p inhibitor. Knockdown of TBX1 reversed the inhibitory effect of the miR-6727-5p inhibitor on CC cells. This study demonstrates that TBX1, a target gene of miR-6727-5p, acts as a tumor suppressor in CC, indicating that TBX1 may be a new target for CC therapy.

Tbx6 induces cardiomyocyte proliferation in postnatal and adult mouse hearts.

Cardiovascular disease is a leading cause of death worldwide. Mammalian cardiomyocytes (CMs) proliferate during embryonic development, whereas they largely lose their regenerative capacity after birth. Defined factors expressed in cardiac progenitors or embryonic CMs may activate the cell cycle and induce CM proliferation in postnatal and adult hearts. Here, we report that the overexpression of Tbx6, enriched in the cardiac mesoderm (progenitor cells), induces CM proliferation in postnatal and adult mouse hearts. By screening 24 factors enriched in cardiac progenitors or embryonic CMs, we found that only Tbx6 could induce CM proliferation in primary cultured postnatal rat CMs. Intriguingly, it did not induce the proliferation of cardiac fibroblasts. We next generated a recombinant adeno-associated virus serotype 9 vector encoding Tbx6 (AAV9-Tbx6) for transduction into mouse CMs in vivo. The subcutaneous injection of AAV9-Tbx6 into neonatal mice induced CM proliferation in postnatal and adult mouse hearts. Mechanistically, Tbx6 overexpression upregulated multiple cell cycle activators including Aurkb, Mki67, Ccna1, and Ccnb2 and suppressed the tumor suppressor Rb1. Thus, Tbx6 promotes CM proliferation in postnatal and adult mouse hearts by modifying the expression of cell cycle regulators.

Transcriptional suppression of connexin43 by TBX18 undermines cell-cell electrical coupling in postnatal cardiomyocytes.

T-box transcription factors figure prominently in embryonic cardiac cell lineage specifications. Mesenchymal precursor cells expressing Tbx18 give rise to the heart's pacemaker, the sinoatrial node (SAN). We sought to identify targets of TBX18 transcriptional regulation in the heart by forced adenoviral overexpression in postnatal cardiomyocytes. Neonatal rat cardiomyocytes (NRCMs) transduced with GFP showed sarcolemmal, punctate Cx43 expression. In contrast, TBX18-transduced NRCMs exhibited sparse Cx43 expression. Both the transcript and protein levels of Cx43 were greatly down-regulated within 2 days of TBX18 transduction. Direct injection of TBX18 in the guinea pig heart in vivo inhibited Cx43 expression. The repressor activity of TBX18 on Cx43 was highly specific; protein levels of Cx45 and Cx40, which comprise the main gap junctions in the SAN and conduction system, were unchanged by TBX18. A reporter-based promoter assay demonstrated that TBX18 directly represses the Cx43 promoter. Phenotypically, TBX18-NRCMs exhibited slowed intercellular calcein dye transfer kinetics (421 ± 54 versus control 127 ± 43 ms). Intracellular Ca(2+) oscillations in control NRCM monolayers were highly synchronized. In contrast, TBX18 overexpression led to asynchronous Ca(2+) oscillations, demonstrating reduced cell-cell coupling. Decreased coupling led to slow electrical propagation; conduction velocity in TBX18 NRCMs slowed by more than 50% relative to control (2.9 ± 0.5 versus 14.3 ± 0.9 cm/s). Taken together, TBX18 specifically and directly represses Cx43 transcript and protein levels. Cx43 suppression leads to significant electrical uncoupling, but the preservation of other gap junction proteins supports slow action potential propagation, recapitulating a key phenotypic hallmark of the SAN.

Microarray analysis of Tbx2-directed gene expression: a possible role in osteogenesis.

Tbx2 is a member of the developmentally important transcriptional regulatory T-box gene family, whose target genes have not been well characterized. In an attempt to identify genes that may be regulated by Tbx2, mouse cDNA microarrays were used to analyze differential gene expression profiles, comparing stably transfected NIH3T3 cells overexpressing Tbx2 and vector-transfected controls. Among 8734 genes, 107 genes were up-regulated by 2-fold or greater, and 66 genes were down-regulated by 2-fold or greater. Caveolin, pleiotrophin (osf-1), osteoblast-specific factor-2 (osf-2) and collagen type I alpha were among the genes upregulated in the Tbx2-overexpressing cells, whereas cadherin 3, tenascin C, and insulin-like growth factor binding protein 10/CYR61 (IBP10) were among the genes downregulated. Northern blot analysis confirmed the correlation of expression of several genes, including IBP10 and osf-2, in fibroblast NIH3T3 and rat osteosarcoma ROS17/2.8 cells differentially expressing Tbx2. In ROS17/2.8 cells transfected with antisense Tbx2, osf-2 was downregulated, whereas transfection of sense Tbx2 upregulated this gene. Interestingly, the expression of pleiotrophin (osf-1) and collagen I alpha with Tbx2 transfection showed an inverse regulatory correlation between NIH3T3 and ROS17/2.8 cells. Thus, Tbx2 can act as both a repressor and activator, and the cellular context can influence the effect on gene expression. Although the data do not address whether Tbx2 directly mediates the transcriptional effect, a number of candidate genes possess putative T-box gene regulatory elements. The results support the hypothesis that Tbx2 may be an important modulator of bone development. Further functional cluster analysis indicates that Tbx2 might also be involved in the regulation of cell cycle and cell adhesion.