The current pandemic of COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) highlights an urgent need to develop a safe, efficacious, and durable vaccine. Using a measles virus (rMeV) vaccine strain as the backbone, we developed a series of recombinant attenuated vaccine candidates expressing various forms of the SARS-CoV-2 spike (S) protein and its receptor binding domain (RBD) and evaluated their efficacy in cotton rat, IFNAR−/−mice, IFNAR−/−-hCD46 mice, and golden Syrian hamsters. We found that rMeV expressing stabilized prefusion S protein (rMeV-preS) was more potent in inducing SARS-CoV-2–specific neutralizing antibodies than rMeV expressing full-length S protein (rMeV-S), while the rMeVs expressing different lengths of RBD (rMeV-RBD) were the least potent. Animals immunized with rMeV-preS produced higher levels of neutralizing antibody than found in convalescent sera from COVID-19 patients and a strong Th1-biased T cell response. The rMeV-preS also provided complete protection of hamsters from challenge with SARS-CoV-2, preventing replication in lungs and nasal turbinates, body weight loss, cytokine storm, and lung pathology. These data demonstrate that rMeV-preS is a safe and highly efficacious vaccine candidate, supporting its further development as a SARS-CoV-2 vaccine.

Efforts to develop an effective vaccine against the hepatitis C virus (HCV; human hepacivirus) have been stymied by a lack of small animal models. Here, we describe an experimental rat model of chronic HCV-related hepacivirus infection and its response to T cell immunization. Immune-competent rats challenged with a rodent hepacivirus (RHV) develop chronic viremia characterized by expansion of non-functional CD8 + T cells. Single-dose vaccination with a recombinant adenovirus vector expressing hepacivirus non-structural proteins induces effective immunity in majority of rats. Resolution of infection coincides with a vigorous recall of intrahepatic cellular responses. Host selection of viral CD8 escape variants can subvert vaccine-conferred immunity. Transient depletion of CD8 + cells from vaccinated rats prolongs infection, while CD4 + cell depletion results in chronic viremia. These results provide direct evidence that co-operation between CD4 + and CD8 + T cells is important for hepacivirus immunity, and that subversion of responses can be prevented by prophylactic vaccination.

The spike (S) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the main target for neutralizing antibodies (NAbs). The S protein trimer is anchored in the virion membrane in its prefusion (preS) but metastable form. The preS protein has been stabilized by introducing two or six proline substitutions, to generate stabilized, soluble 2P or HexaPro (6P) preS proteins. Currently, it is not known which form is the most immunogenic. Here, we generated recombinant vesicular stomatitis virus (rVSV) expressing preS-2P, preS-HexaPro, and native full-length S, and compared their immunogenicity in mice and hamsters. The rVSV-preS-HexaPro produced and secreted significantly more preS protein compared to rVSV-preS-2P. Importantly, rVSV-preS-HexaPro triggered significantly more preS-specific serum IgG antibody than rVSV-preS-2P in both mice and hamsters. Antibodies induced by preS-HexaPro neutralized the B.1.1.7, B.1.351, P.1, B.1.427, and B.1.617.2 variants approximately two to four times better than those induced by preS-2P. Furthermore, preS-HexaPro induced a more robust Th1-biased cellular immune response than preS-2P. A single dose (10 4 pfu) immunization with rVSV-preS-HexaPro and rVSV-preS-2P provided complete protection against challenge with mouse-adapted SARS-CoV-2 and B.1.617.2 variant, whereas rVSV-S only conferred partial protection. When the immunization dose was lowered to 10 3 pfu, rVSV-preS-HexaPro induced two- to sixfold higher antibody responses than rVSV-preS-2P in hamsters. In addition, rVSV-preS-HexaPro conferred 70% protection against lung infection whereas only 30% protection was observed in the rVSV-preS-2P. Collectively, our data demonstrate that both preS-2P and preS-HexaPro are highly efficacious but preS-HexaPro is more immunogenic and protective, highlighting the advantages of using preS-HexaPro in the next generation of SARS-CoV-2 vaccines.

Ewing sarcoma (EWS) is the second most common and aggressive type of metastatic bone tumor in adolescents and young adults. There is unmet medical need to develop and test novel pharmacological targets and novel therapies to treat EWS. Here, we found that EWS expresses high levels of a p53 isoform, delta133p53. We further determined that aberrant expression of delta133p53 induced HGF secretion resulting in tumor growth and metastasis. Thereafter, we evaluated targeting EWS tumors with HGF receptor neutralizing antibody (AMG102) in preclinical studies. Surprisingly, we found that targeting EWS tumors with HGF receptor neutralizing antibody (AMG102) in combination with GD2‐specific, CAR‐reengineered T‐cell therapy synergistically inhibited primary tumor growth and establishment of metastatic disease in preclinical models. Furthermore, our data suggested that AMG102 treatment alone might increase leukocyte infiltration including efficient CAR‐T access into tumor mass and thereby improves its antitumor activity. Together, our findings warrant the development of novel CAR‐T‐cell therapies that incorporate HGF receptor neutralizing antibody to improve therapeutic potency, not only in EWS but also in tumors with aberrant activation of the HGF/c‐MET pathway.

With the rapid increase in SARS-CoV-2 cases in children, a safe and effective vaccine for this population is urgently needed. The MMR (measles/mumps/rubella) vaccine has been one of the safest and most effective human vaccines used in infants and children since the 1960s. Here, we developed live attenuated recombinant mumps virus (rMuV)–based SARS-CoV-2 vaccine candidates using the MuV Jeryl Lynn (JL2) vaccine strain backbone. The soluble prefusion SARS-CoV-2 spike protein (preS) gene, stablized by two prolines (preS-2P) or six prolines (preS-6P), was inserted into the MuV genome at the P–M or F–SH gene junctions in the MuV genome. preS-6P was more efficiently expressed than preS-2P, and preS-6P expression from the P–M gene junction was more efficient than from the F–SH gene junction. In mice, the rMuV-preS-6P vaccine was more immunogenic than the rMuV-preS-2P vaccine, eliciting stronger neutralizing antibodies and mucosal immunity. Sera raised in response to the rMuV-preS-6P vaccine neutralized SARS-CoV-2 variants of concern, including the Delta variant equivalently. Intranasal and/or subcutaneous immunization of IFNAR1 −/− mice and golden Syrian hamsters with the rMuV-preS-6P vaccine induced high levels of neutralizing antibodies, mucosal immunoglobulin A antibody, and T cell immune responses, and were completely protected from challenge by both SARS-CoV-2 USA-WA1/2020 and Delta variants. Therefore, rMuV-preS-6P is a highly promising COVID-19 vaccine candidate, warranting further development as a tetravalent MMR vaccine, which may include protection against SARS-CoV-2.

The current pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to dramatic economic and health burdens. Although the worldwide SARS-CoV-2 vaccination campaign has begun, exploration of other vaccine candidates is needed due to the uncertainties of the current approved vaccines such as durability of protection, cross-protection against variant strains, and costs of long-term production, and storage. In this study, we developed a methyltransferase-defective recombinant vesicular stomatitis virus (mtdVSV)-based SARS-CoV-2 vaccine candidate. We generated mtdVSVs expressing SARS-CoV-2 full-length spike (S), S1, or its receptor binding domain (RBD). All these recombinant viruses grew to high titers in mammalian cells despite high attenuation in cell culture. SARS-CoV-2 S protein and its truncations were highly expressed by the mtdVSV vector. These mtdVSV-based vaccine candidates were completely attenuated in both immunocompetent and immunocompromised mice. Among these constructs, mtdVSV-S induced high levels of SARS-CoV-2 specific neutralizing antibodies (NAbs) and Th1-biased T cell immune responses in mice. Syrian golden hamsters immunized with mtdVSV-S triggered SARS-CoV-2 specific NAbs that were higher than convalescent plasma from convalescent COVID-19 patients. In addition, hamsters immunized with mtdVSV-S were completely protected against SARS-CoV-2 replication in lung and nasal turbinate tissues, cytokine storm, and lung pathology. Collectively, our data demonstrate that mtdVSV expressing SARS-CoV-2 S protein is a safe and highly efficacious vaccine candidate against SARS-CoV-2 infection. Significance Viral mRNA cap methyltransferase (MTase) is essential for mRNA stability, protein translation, and innate immune evasion. Thus, viral mRNA cap MTase activity is a novel target for development of live attenuated or live vectored vaccine candidates. Here, we developed a panel of MTase-defective recombinant recombinant vesicular stomatitis virus (mtdVSV)-based SARS-CoV-2 vaccine candidates expressing full-length S, S1, or several versions of the RBD. These mtdVSV-based vaccine candidates grew to high titers in cell culture and were completely attenuated in both immunocompetent and immunocompromised mice. Among these vaccine candidates, mtdVSV-S induces high levels of SARS-CoV-2 specific neutralizing antibody (Nabs) and Th1-biased immune responses in mice. Syrian golden hamsters immunized with mtdVSV-S triggered SARS-CoV-2 specific NAbs that were higher than convalescent plasma from COVID-19 recovered patients. Furthermore, hamsters immunized with mtdVSV-S were completely protected against SARS-CoV-2 challenge. Thus, mtdVSV is a safe and highly effective vector to deliver SARS-CoV-2 vaccine.

Background Glioblastoma (GBM) remains one of the least successfully treated cancers. It is essential to understand the basic biology of this lethal disease and investigate novel pharmacological targets to treat GBM. The aims of this study were to determine the biological consequences of elevated expression of ΔNp73, an N-terminal truncated isoform of TP73, and to evaluate targeting of its downstream mediators, the angiopoietin 1 (ANGPT1)/tunica interna endothelial cell kinase 2 (Tie2) axis, by using a highly potent, orally available small-molecule inhibitor (rebastinib) in GBM. Methods ΔNp73 expression was assessed in glioma sphere cultures, xenograft glioblastoma tumors, and glioblastoma patients by western blot, quantitative reverse transcription PCR, and immunohistochemistry. Immunoprecipitation, chromatin immunoprecipitation (ChiP) and sequential ChIP were performed to determine the interaction between ΔNp73 and E26 transformation-specific (ETS) proto-oncogene 2 (ETS2) proteins. The oncogenic consequences of ΔNp73 expression in glioblastomas were examined by in vitro and in vivo experiments, including orthotopic zebrafish and mouse intracranial-injection models. Effects of rebastinib on growth of established tumors and survival were examined in an intracranial-injection mouse model. Results ΔNp73 upregulates both ANGPT1 and Tie2 transcriptionally through ETS conserved binding sites on the promoters by interacting with ETS2. Elevated expression of ΔNp73 promotes tumor progression by mediating angiogenesis and survival. Therapeutic targeting of downstream ΔNp73 signaling pathways by rebastinib inhibits growth of established tumors and extends survival in preclinical models of glioblastoma. Conclusion Aberrant expression of ΔNp73 in GBM promotes tumor progression through autocrine and paracrine signaling dependent on Tie2 activation by ANGPT1. Disruption of this signaling by rebastinib improves tumor response to treatment in glioblastoma.

The pre-metastatic niche (PMN) represents an abnormal microenvironment devoid of cancer cells, but favoring tumor growth. Little is known about the mechanisms that generate the PMN or their effects on host cells within metastasisprone organs. Here, we investigated by using spontaneous metastatic models whether lung epithelial cells are essential for primary tumor induced neutrophil recruitment in lung and subsequently initiating PMN formation in osteosarcoma. We found that serum levels of ANGPTL2 in osteosarcoma patients are significantly higher compared to those in healthy controls and that ANGPTL2 secretion by tumor cells plays an essential role in osteosarcoma metastasis. We determined that tumor-derived ANGPTL2 stimulates lung epithelial cells, which is essential for primary tumor-induced neutrophil recruitment in lung and subsequent pre-metastatic niche formation. Lastly, we identified that a p63 isoform, ΔNp63, drives high level of ANGPTL2 secretion and pharmaceutical inhibition of ANGPTL2 signaling by a non-RGD-based integrin binding peptide (ATN-161) diminished metastatic load in lungs likely due to reduction of the lung pre-metastatic niche formation.