The COVID-19 pandemic caused by SARS-CoV-2 has made the development of safe and effective vaccines a critical priority. To date, four vaccines have been approved by European and American authorities for preventing COVID-19, but the development of additional vaccine platforms with improved supply and logistics profiles remains a pressing need. Here we report the preclinical evaluation of a novel COVID-19 vaccine candidate based on the electroporation of engineered, synthetic cDNA encoding a viral antigen in the skeletal muscle. We constructed a set of prototype DNA vaccines expressing various forms of the SARS-CoV-2 spike (S) protein and assessed their immunogenicity in animal models. Among them, COVID-eVax-a DNA plasmid encoding a secreted monomeric form of SARS-CoV-2 S protein receptor-binding domain (RBD)induced the most potent anti-SARS-CoV-2 neutralizing antibody responses (including against the current most common variants of concern) and a robust T cell response. Upon challenge with SARS-CoV-2, immunized K18-hACE2 transgenic mice showed reduced weight loss, improved pulmonary function, and lower viral replication in the lungs and brain. COVID-eVax conferred significant protection to ferrets upon SARS-CoV-2 challenge. In summary, this study identifies COVID-eVax as an ideal COVID-19 vaccine candidate suitable for clinical development. Accordingly, a combined phase I-II trial has recently started.

Olaparib (AZD-2281, Ku-0059436) is an orally bioavailable and well-tolerated poly(ADP-ribose) polymerase (PARP) inhibitor currently under investigation in patients with solid tumors. To study the clinical potential of olaparib as a single-agent for the treatment of acute myeloid leukemia (AML) patients, we analyzed the in vitro sensitivity of AML cell lines and primary blasts. Clinically achievable concentrations of olaparib were able to induce cell death in the majority of primary AML case samples (88%) and tested cell lines. At these concentrations, olaparib preferentially killed leukemic blasts sparing normal lymphocytes derived from the same patient and did not substantially affect the viability of normal bone marrow and CD34-enriched peripheral blood cells obtained from healthy donors. Most primary AML analyzed were characterized by low BRCA1 mRNA level and undetectable protein expression that likely contributed to explain their sensitivity to olaparib. Noteworthy, while PARP1 over-expression was detected in blasts not responsive to olaparib, phosphorylation of the histone H2AFX (γH2AX) was associated with drug sensitivity. As to genetic features of tested cases the highest sensitivity was shown by a patient carrying a 11q23 deletion. The high sensitivity of AML blasts and the identification of biomarkers potentially able to predict response and/or resistance may foster further investigation of olaparib monotherapy for AML patients unfit to conventional chemotherapy.

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide, and several molecular pathways that underlie the molecular tumorigenesis of HNSCC have been identified. Among them, amplification or overexpression of ΔNp63 isoforms is observed in the majority of HNSCCs. Here, we unveiled a ΔNp63-dependent transcriptional program able to regulate the metabolism and the signaling of hyaluronic acid (HA), the major component of the extracellular matrix (ECM). We found that ∆Np63 is capable of sustaining the production of HA levels in cell culture and in vivo by regulating the expression of the HA synthase HAS3 and two hyaluronidase genes, HYAL-1 and HYAL-3. In addition, ∆Np63 directly regulates the expression of CD44, the major HA cell membrane receptor. By controlling this transcriptional program, ∆Np63 sustains the epithelial growth factor receptor (EGF-R) activation and the expression of ABCC1 multidrug transporter gene, thus contributing to tumor cell proliferation and chemoresistance. Importantly, p63 expression is positively correlated with CD44, HAS3, and ABCC1 expression in squamous cell carcinoma datasets and p63-HA pathway is a negative prognostic factor of HNSCC patient survival. Altogether, our data shed light on a ∆Np63-dependent pathway functionally important to the regulation of HNSCC progression.

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In this study, we explored whether Nutlin-3a, a well-known, nontoxic small-molecule compound antagonizing the inhibitory interaction of MDM2 with the tumor suppressor p53, may restore ligands for natural killer (NK) cell–activating receptors (NK-AR) on neuroblastoma cells to enhance the NK cell–mediated killing. Neuroblastoma cell lines were treated with Nutlin-3a, and the expression of ligands for NKG2D and DNAM-1 NK-ARs and the neuroblastoma susceptibility to NK cells were evaluated. Adoptive transfer of human NK cells in a xenograft neuroblastoma-bearing NSG murine model was assessed. Two data sets of neuroblastoma patients were explored to correlate p53 expression with ligand expression. Luciferase assays and chromatin immunoprecipitation analysis of p53 functional binding on PVR promoter were performed. Primary neuroblastoma cells were also treated with Nutlin-3a, and neuroblastoma spheroids obtained from one high-risk patient were assayed for NK-cell cytotoxicity. We provide evidence showing that the Nutlin-3a–dependent rescue of p53 function in neuroblastoma cells resulted in (i) increased surface expression of ligands for NK-ARs, thus rendering neuroblastoma cell lines significantly more susceptible to NK cell–mediated killing; (ii) shrinkage of human neuroblastoma tumor masses that correlated with overall survival upon adoptive transfer of NK cells in neuroblastoma-bearing mice; (iii) and increased expression of ligands in primary neuroblastoma cells and boosting of NK cell–mediated disaggregation of neuroblastoma spheroids. We also found that p53 was a direct transcription factor regulating the expression of PVR ligand recognized by DNAM-1. Our findings demonstrated an immunomodulatory role of Nutlin-3a, which might be prospectively used for a novel NK cell–based immunotherapy for neuroblastoma.