p107 is a suppressor of retinoblastoma development in pRb-deficient mice

Hemizygosity for the retinoblastoma gene RB in man strongly predisposes to retinoblastoma. In the mouse, however, Rb hemizygosity leaves the retina normal, whereas in Rb^−/− chimeras pRb-deficient retinoblasts undergo apoptosis. To test whether concomitant inactivation of the Rb-related gene p107 is required to unleash the oncogenic potential of pRb deficiency in the mouse retina, we inactivated both Rb and p107 by homologous recombination in embryonic stem cells and generated chimeric mice. Retinoblastomas were found in five out of seven adult pRb/p107-deficient chimeras. The retinal tumors showed amacrine cell differentiation, and therefore originated from cells committed to the inner but not the outer nuclear layer. Retinal lesions were already observed at embryonic day 17.5. At this stage, the primitive nuclear layer exhibited severe dysplasia, including rosette-like arrangements, and apoptosis. These findings provide formal proof for the role of loss of Rb in retinoblastoma development in the mouse and the first in vivo evidence that p107 can exert a tumor suppressor function.     

Epithelioid trophoblastic tumor: clinicopathological features with an emphasis on uterine cervical involvement.

We report on the clinical and histological features of five cases of epithelioid trophoblastic tumor, with an emphasis on its involvement of the uterine cervix. All five patients were of reproductive age (median age 38.4 years) and all, except one, presented with vaginal bleeding 3 to 18 years after the most recent pregnancy. One patient presented with amenorrhea. Elevation of serum human chorionic gonadotropin (hCG) was seen in four cases. Pathologically, the tumor involved endocervix in three cases and involved uterine corpus in another two. All five tumors were invasive, nodular lesions consisting of epithelioid intermediate trophoblastic cells that were mononuclear with abundant eosinophilic cytoplasm, along with zones of hyaline material and necrotic debris. In three cases of cervical involvement, the neoplastic cells focally replaced endocervical surface and glandular epithelium, simulating high-grade squamous intraepithelial lesions. Immunohistochemically, all five tumors displayed focal positivity for human placental lactogen and hCG. Positive nuclear staining of p63 was seen in all five cases. All patients received total hysterectomy and various regimes of adjuvant chemotherapy. Three patients survived the tumor with no recurrences or metastases with follow-up periods of 3, 7 and 16 years. One patient is currently alive with lung metastasis 1 month after the surgery. One patient died of tumor metastasis 8 months after the diagnosis. In summary, with its unusual ability to simulate an invasive squamous cell carcinoma and other epithelioid neoplasms, epithelioid trophoblastic tumor frequently poses a diagnostic challenge, especially when involving the uterine cervix. High index of suspicion and an awareness of elevation of serum chorionic gonadotropin are crucial in reaching a correct diagnosis.     

Patent foramen ovale with paradoxical embolism: mid-term results of transcatheter closure in 256 patients

The purpose of this study was to assess the safety and feasibility of percutaneous interventional closure of patent foramen ovale (PFO) with or without atrial septal aneurysm (ASA) in symptomatic patients. Between June 1999 and June 2002, we performed transcatheter closure of PFO in 256 consecutive symptomatic patients (female/male = 1.45; mean age 48 +/- 16 years; range 14-75): ischemic stroke (n = 101), transient ischemic attack (n = 144), peripheral and coronary arterial embolism (n = 17); multiple events (n = 23); platypnea-orthodeoxia syndrome (n = 2); refractory hypoxemia (n = 1); and migraine aura (n = 27). The implanted devices were an Amplatzer PFO Occluder (n = 248), a Gore-HELEX Septal Occluder (n = 4), and PFO STAR (n = 4). Most procedures (n = 176.69%) were done under two-dimensional intracardiac echocardiography (ICE) guidance alone; in the last 30 patients, 3D/4D ICE reconstruction (TomTec Imaging Systems) 6mbH was obtained. In 30 cases, ICE and contrast enhanced-TCD have been used simultaneously in the catheterization laboratory. The devices were placed correctly in all patients. Mean fluoroscopy time was 9.45 +/- 5 minutes (range = 2.5-35 minutes); mean procedural time was 57 +/- 21 minutes (range = 15-135 minutes). Total occlusion rate at follow-up (mean 19 months, range 1-33) was 98.1%. No significant recurrent neurological events were observed. Transcatheter closure of PFO with or without ASA is a safe and effective, minimally invasive procedure that ensures high closure rate and avoids life-long anticoagulation. Mid-term follow-up results appear favorable with respect to recurrent thromboembolic events.     

Immunomodulation of transplant rejection using monoclonal antibodies and soluble receptors

The main objective of our studies has been to optimize the effects of monoclonal antibodies (MAbs) and other immunosuppressive reagents to enhance organ graft survival. One such agent is OKT3, a MAb that is directed against the CD3 component of the human T-cell receptor (TCR) complex. Treatment of a rejection episode with OKT3 results in a rapid and efficient clearing of circulating T cells and reversal of most rejection episodes. Its wider use in transplantation and in the treatment of immune-mediated disease is limited by adverse reactions that follow the initial dose, the production of neutralizing Abs, and the transient nature of the immunosuppression. We have engineered CDR-grafted humanized anti-CD3 MAbs that lack Fc-receptor binding activity through mutagenesis of amino acids in the Fc portion of the MAb. This results in an immunosuppressive anti-CD3 MAb that is less antigenic and one that does not induce the first-dose side effects. In addition, we have pursued a goal of developing a therapy that will induce donor-specific tolerance while maintaining overall recipient immune competency. Because antigen-specific T-cell activation depends not only on TCR-ligand interaction, but also on additional costimulatory signals mediated by accessory molecules such as CD28, blocking the binding of CD28 on T cells to its ligand B7, during TCR engagement, might modulate transplantation responses. Using a soluble fusion protein of human CTLA4, CTLA4-Ig, that binds B7 with high affinity, inhibition of human pancreatic islet rejection that occurs, at least in part, by affecting T-cell recognition of human B7⁺ antigen-presenting cells has been demonstrated. In addition, CTLA4-Ig induces long-term, donor-specific unresponsiveness.     

Protective Immunity against Recurrent Staphylococcus aureus Skin Infection Requires Antibody and Interleukin-17A

Although many microbial infections elicit an adaptive immune response that can protect against reinfection, it is generally thought that Staphylococcus aureus infections fail to generate protective immunity despite detectable T and B cell responses. No vaccine is yet proven to prevent S. aureus infections in humans, and efforts to develop one have been hampered by a lack of animal models in which protective immunity occurs. Our results describe a novel mouse model of protective immunity against recurrent infection, in which S. aureus skin and soft tissue infection (SSTI) strongly protected against secondary SSTI in BALB/c mice but much less so in C57BL/6 mice. This protection was dependent on antibody, because adoptive transfer of immune BALB/c serum or purified antibody into either BALB/c or C57BL/6 mice resulted in smaller skin lesions. We also identified an antibody-independent mechanism, because B cell-deficient mice were partially protected against secondary S. aureus SSTI and adoptive transfer of T cells from immune BALB/c mice resulted in smaller lesions upon primary infection. Furthermore, neutralization of interleukin-17A (IL-17A) abolished T cell-mediated protection in BALB/c mice, whereas neutralization of gamma interferon (IFN-γ) enhanced protection in C57BL/6 mice. Therefore, protective immunity against recurrent S. aureus SSTI was advanced by antibody and the Th17/IL-17A pathway and prevented by the Th1/IFN-γ pathway, suggesting that targeting both cell-mediated and humoral immunity might optimally protect against secondary S. aureus SSTI. These findings also highlight the importance of the mouse genetic background in the development of protective immunity against S. aureus SSTI.     

Expression of the gp150 maedi visna virus envelope precursor protein by mammalian expression vectors

There are very few previous reports of expression of native full-length maedi visna virus (MVV) Env gp150 protein in the literature. Therefore the use of different plasmid and viral expression vectors to obtain full-length gp150 was investigated. A mammalian expression plasmid, pN3-Env, was constructed containing the MVV env gene encoding the precursor protein gp150 Env. The functionality of the recombinant plasmid was tested for expression in HEK293 cells. A recombinant modified vaccinia Ankara virus, MVA-Env, with expression detected in avian cells was also made. The expression of the MVV gp150 Env precursor protein was shown for the first time upon transfection of the eukaryotic HEK293 cells by the pN3-Env plasmid DNA as demonstrated by Western blot analysis. These plasmid or viral expression vectors are of potential use in MVV vaccines.     

Tivozanib for the treatment of renal cell carcinoma

Introduction: Renal cell carcinoma (RCC) represents a heterogeneous group of cancers with distinct histological features, molecular alterations, prognosis, and response to therapy. Target agents directed against vascular endothelial growth factor and its receptor and mammalian target of rapamycin (mTOR) inhibitors have completely changed the landscape of RCC. However, the rate of complete response is still low, thus supporting the research of novel therapeutic agents.

Area covered: The authors describe the chemical features of tivozanib, its pharmacodynamic and pharmacokinetic properties, and the results obtained in human phase I–III clinical trials. Tivozanib received its first global approval in EU, Iceland, and Norway on 28 August 2017 for the first-line treatment of adult patients with advanced RCC and for adult patients who are VEGFR and mTOR inhibitor-naive following disease progression after one prior treatment with cytokines.

Expert opinion: The US Food and Drug Administration did not approve tivozanib due to the lack of a significant advantage in terms of survival compared to sorafenib. To date, the role of tivozanib in the pharmaceutical landscape of mRCC appears to be very limited. However, ongoing trials on the association between tivozanib and immunotherapy may represent a promising strategy to be assessed in future clinical trials.