Tag Archives: immunity

Cancer Vaccine Boosted

Scientists at Thomas Jefferson University who are developing a cancer vaccine to prevent recurrences of gastric, pancreatic, esophageal, and colon cancers say they have added a component that would make the vaccine more effective. The change makes the vaccine less prone to being cleared by the immune system before it can generate immunity against the tumor components.

The preclinical studies pave the way for a Phase II clinical trial opening to patients this fall, according to Adam Snook, PhD, assistant professor in the department of pharmacology and experimental therapeutics and researcher at the NCI-Designated Sidney Kimmel Cancer Center (SKCC)—Jefferson Health.

Our data show strong immune responses in mice that might otherwise clear the vaccine, and suggests this approach will be more effective in the human trials we are starting shortly,” he said. “Adenovirus serotype 5 (Ad5) is a commonly used viral vector for transient delivery of transgenes, primarily for vaccination against pathogen and tumor antigens. However, endemic infections with Ad5 produce virus-specific neutralizing antibodies (NAbs) that limit transgene delivery and constrain target-directed immunity following exposure to Ad5-based vaccines

Indeed, clinical trials have revealed the limitations that virus-specific NAbs impose on the efficacy of Ad5-based vaccines. In that context, the emerging focus on immunological approaches targeting cancer self-antigens or neoepitopes underscores the unmet therapeutic need for more efficacious vaccine vectors.

“Here, we evaluated the ability of a chimeric adenoviral vector (Ad5.F35) derived from the capsid of Ad5 and fiber of the rare adenovirus serotype 35 (Ad35) to induce immune responses to the tumor-associated antigen guanylyl cyclase C (GUCY2C).

In the absence of pre-existing immunity to Ad5, GUCY2C-specific T-cell responses and antitumor efficacy induced by Ad5.F35 were comparable to Ad5 in a mouse model of metastatic colorectal cancer. Furthermore, like Ad5, Ad5.F35 vector expressing GUCY2C was safe and produced no toxicity in tissues with, or without, GUCY2C expression. Importantly, this chimeric vector resisted neutralization in Ad5-immunized mice and by sera collected from patients with colorectal cancer naturally exposed to Ad5.

“These data suggest that Ad5.F35-based vaccines targeting GUCY2C, or other tumor or pathogen antigens, may produce clinically relevant immune responses in more (≥90%) patients compared with Ad5-based vaccines (~50%).”

Novavax’s Coronavirus Vaccine Generates Promising Immune Response

Novavax announced Tuesday that its potential vaccine to prevent Covid-19 generated a promising immune response in an early stage clinical trial, but the biotech company’s stock fell briefly on concerns about its safety.

The phase one trial included 131 healthy participants between the ages 18 and 59 at two sites in Australia. Novavax said 106 participants received one of four dose levels of the potential vaccine, named NVX-CoV2373, with or without an adjuvant, which is an ingredient designed to enhance the immune response. The remaining 25 patients received a placebo. Participants received two doses of the potential vaccine via intramuscular injection approximately 21 days apart, the company reported. The vaccine produced neutralizing antibodies, which researchers believe are necessary to build immunity to the virus, and killer T-cells, the company said. Additionally, the neutralizing antibodies that were produced were higher than those seen in people who have recovered from Covid-19, Novavax underscored. The immune response was also stronger for those who had the adjuvant, the company said.

Novavax explained that the vaccine was well tolerated with no serious adverse events reported. Most patients reported tenderness and pain at the injection after the first dose, with some patients also reporting headaches, fatigue or muscle aches. Only one participant in the trial experienced a mild fever after a second dose, the company noted. Earlier media reports and analysts cited eight possible hospitalizations related to the study, but the company said no patients were hospitalized.

https://www.cnbc.com/

New Coronavirus Antibody Test Highly Accurate

Abbott Laboratories’ antibody test for the new coronavirus is highly likely to correctly determine whether people have ever been infected with the fast-spreading virus, the company said, citing a U.S. study.

Researchers at the University of Washington School of Medicine report in the Journal of Clinical Microbiology  that Abbott‘s test had a specificity of 99.9% and a sensitivity of 100%, suggesting very few false positives and no false negatives.

Antibody tests can tell whether a person has ever been infected and are considered crucial in efforts to get Americans back to work safely as the presence of antibodies to the virus indicates possible immunity to future infection.

Abbott’s test was launched last month under the U.S. Food and Drug Administration’s relaxed rules for some coronavirus tests, allowing their distribution before regulatory clearance. It has since received emergency use authorization from the FDA.

Abbott has already shipped more than 10 million antibody tests to hospitals and labs.

Source: bit.ly/2SKTVcQ
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https://www.reuters.com/