Day: November 4, 2022

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Stopping Prostate Tumours from Evading Androgen Suppression Therapy

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Credit: Darryl Leja / National-Human-Genome Research Institute / National Institutes of Health

Researchers have identified an investigational therapeutic approach that could be effective against treatment-resistant prostate cancer. Results of the Phase II clinical trial performed by Cedars-Sinai Cancer investigators and published in Molecular Therapy, have led to a larger, multicentre trial that will soon be underway.

Cancer of the prostate is the second-leading cause of cancer-related death in men. Many prostate tumours are not aggressive and may require no or minimal treatment. Aggressive tumours are initially treated with surgery or radiation therapy.

In roughly a third of patients, the cancer comes back after initial treatment, said Neil Bhowmick, PhD, research scientist at Cedars-Sinai Cancer, professor of Medicine and Biomedical Sciences and senior author of the study. Those patients are usually treated with medications that suppress the actions of testosterone and other androgens, which promote prostate tumour growth.

“Patients do really well until the tumour figures a way around the androgen-suppressing therapy,” Bhowmick said. “One way that it can do this is to cause cells to make only part of the protein that the drug binds to, rendering the drug useless. The partial proteins are called splice variants.”

Through research with human cells and laboratory mice, study first author Bethany Smith, PhD, figured out that the cancer cells were using a protein called CD105 to signal to the surrounding supportive cells to make these slice variant proteins. Investigators then conducted a trial in human patients to test a drug that they hoped would keep those partial proteins from forming by inhibiting CD105.

In the trial, 9 patients whose tumours were resistant to androgen-blocking therapy continued that therapy but were also given a CD105 inhibitor called carotuximab. Forty percent of those patients experienced progression-free survival, based on radiographic imaging.

“Every single one of the patients in our trial was totally resistant to at least one androgen suppressor, and the normal course of action would be to simply try a different one or chemotherapy, which research has shown generally doesn’t stop tumor growth for more than about three months,” Bhowmick said. “Carotuximab prevented the cancer’s workaround and made the tumor sensitive to androgen-suppressing therapy.”

Importantly, Bhowmick said, carotuximab also appears to prevent androgen receptor splice variants in the supporting cells surrounding tumours, further sensitising the tumour to the androgen suppressor.

“We found that this therapy may be able to, especially in early cancers, resensitize select patients to androgen suppression. This could allow patients to avoid or delay more toxic interventions such as cytotoxic chemotherapy,” said Edwin Posadas, MD, associate professor of Medicine at Cedars-Sinai and a co-author of the study. “We also hope to find ways of predicting which patients are most likely to benefit from this approach by testing blood and tissue samples using next-generation technologies housed at Cedars-Sinai Cancer.”

Study co-author Sungyong You, PhD, director of the Urologic Oncology Bioinformatics Group, pinpointed three biomarkers that could help indicate which patients will respond to this investigational therapy, and the team will validate those markers in a new clinical trial. This will allow future studies to target patients most likely to be helped by this intervention, Bhowmick said.

Source: Cedars-Sinai Medical Center

Categories : Respiratory DiseasesTags : Leave a comment

Modern Ventilators Shown to Overstretch Lung Tissue

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In pulmonary medicine, it has long been debated as to whether ventilator overstretches lung tissue, and now new research published in the American Journal of Respiratory and Critical Care Medicine has proven that they do in fact cause overstretching.

The University of California Riverside researchers showed that there were major differences between natural breathing versus the forced breathing from ventilators. These results are critical, particularly in context of the COVID pandemic and the rush to build ventilators.

“Using novel techniques, we observed that ventilators can overextend certain regions of the lungs,” said Mona Eskandari, assistant professor of mechanical engineering, who led the research. These results may explain why lung health declines for patients the longer they spend on the machines, especially in the case of disease.

Eskandari’s bMECH lab pioneered a technique to study lungs as they are made to breathe. On a custom-built ventilator designed in their lab, the researchers imitated both natural and artificial breathing. Then, they observed isolated lungs involved in both types of breathing using multiple cameras collecting fast, high-resolution images, a method called digital image correlation.

“Our setup allows us to imitate both physiological and artificial breathing on the same lung with the switch of a button,” Eskandari said. “The unique combination of our ventilator with digital image correlation gives us unprecedented insights into the way specific regions of the lungs work in concert with the whole.”

Using their innovative method to interface these two systems, UCR researchers collected evidence demonstrating that natural breathing stretches certain parts of the lung as little as 25% while those same regions stretch to as much as 60% when on a ventilator.

Scholars traditionally model the lungs like balloons, or what they refer to as thin-walled pressure vessels, where pushing air in and pulling air out are understood to be mechanically equivalent.

To explain what they observed in this study, the researchers propose moving away from thin-walled pressure vessel models and instead towards thick-walled models. Unlike thin-walled pressure vessels theory, a thick-walled model accounts for the differing levels of stress in airways resulting from ventilators pushing air in versus natural breathing, which pulls air in. This helps to explain how airways are more engaged and air is more evenly distributed in the lung during physiological breathing.

Iron lungs, the gigantic ventilators used during the late 1940s polio outbreak, acted more like a human chest cavity, expanding the lung as it naturally would. This creates a vacuum effect that pulls air into the lungs. Though this action is gentler for the lungs, these bulky systems prevented easy access to monitoring other organs in hospital care.

By contrast, modern ventilators are more portable and easier for caretakers to work with. However, they push air into the lungs that is not evenly distributed, overstretching some parts and causing a decline in lung health over time.

While it is unlikely that hospitals will return to the iron lung models, it is possible that modern machines can be altered to reduce injury.

“Now that we know about excessive strain when air is delivered to the lungs, the question for us becomes about how we can improve ventilation strategies by emulating natural breathing,” Eskandari said.

Source: University of California – Riverside

Categories : Antibiotics Cardiovascular DiseaseTags : Leave a comment

Antibiotics Reduce the Gastrointestinal Bleeding Risk of Long-term Aspirin

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Bottle of pills
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A major clinical trial found that the risk of gastrointestinal bleeding caused by long-term aspirin use can be reduced with a short course of antibiotics, potentially improving the safety of aspirin when used to prevent heart attacks, strokes and possibly some cancers.

The results of the HEAT (Helicobacter pylori Eradication Aspirin) trial, which was led by Professor Chris Hawkey from the University of Nottingham, are published in The Lancet.

Aspirin in low doses is a very useful preventative drug in people at high risk of strokes or heart attacks. However, on rare occasions, its blood thinning effect can provoke internal ulcer bleeding. These ulcers may be caused by Helicobacter pylori.

The STAR (Simple Trials for Academic Research) team from the University of Nottingham investigated whether a short course of antibiotics to remove these bacteria would reduce the risk of bleeding in aspirin users.

The HEAT trial, conducted in 1208 UK general practices, was a real-life study which used clinical data routinely stored in GP and hospital records, instead of bringing patients back for follow up trial visits.

The researchers recruited 30 166 who were taking aspirin. Those who tested positive for H. pylori were randomised to receive antibiotics or placebos (dummy tablets) and were followed for up to 7 years.

Over the first two and a half years, those who had antibiotic treatment were less likely to be hospitalised for ulcer bleeding than those taking placebo (6 versus 17). Protection occurred rapidly: with the placebo group, the first hospitalisation for ulcer bleeding occurred after 6 days, compared to 525 days following antibiotic treatment.

Over a longer time period, protection appeared to wane. However, the overall rate of hospitalisation for ulcer bleeding was lower than expected and this in line with other evidence that ulcer disease is on the decline. Risks for people already on aspirin are low. Risks are higher when people first start aspirin, when searching for H. pylori and treating it is probably worthwhile.

Aspirin has many benefits in terms of reducing the risk of heart attacks and strokes in people at increased risk. There is also evidence that it is able to slow down certain cancers. The HEAT trial is the largest UK-based study of its kind, and we are pleased that the findings have shown that ulcer bleeding can be significantly reduced following a one-week course of antibiotics. The long-term implications of the results are encouraging in terms of safe prescribing.

Professor Chris Hawkey, University of Nottingham’s School of Medicine and Nottingham Digestive Diseases Centre

Source: University of Nottingham

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Reawakening a Foetal Gene Promotes Diabetic Wound Healing

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Photo by Diana Polekhina on Unsplash

In the journal Molecular Therapy, researchers report that it may be possible to heal wounds by using a healing protein that is active in foetuses, but largely inactive in adults and absent in diabetic adults.

“We already know from previous studies at other institutions that if a foetus is wounded, it can regenerate the tissue, or repair it to be like new,” said Chandan K. Sen, PhD, at Indiana University School of Medicine. “But after birth, such regenerative wound healing ability is lost. Healing in adults is relatively inefficient often associated with undesirable scar formation.”

In the study,  the team focused on a protein called nonselenocysteine-containing phospholipid hydroperoxide glutathione peroxidase, or NPGPx. NPGPx is active in foetal tissue but becomes mostly inactive in the skin after birth.

“Nature essentially hides this foetal regenerative repair pathway in the adult body,” Sen said. “We spotted its absence, and then activated it to improve healing of diabetic wounds.”

Researchers used tissue ‘nanotransfection’ technology to deliver the NPGPx gene to the wound site. Diabetic wounds, which are complicated skin injuries in people with diabetes, are particularly difficult to treat and often lead to amputations or other complications because of how easily they can become infected.

“This is an exciting new approach to harness foetal repair mechanisms to close diabetic wounds in adults,” Sen said. “The study results show that while NPGPx has been known to be abundant in the foetal skin, but not after birth, it can be reactivated in the skin after an injury. We look forward to continued study aiming to achieve a more complete regenerative repair by improving our understanding of how NPGPx functions.”

Source: Indiana University School of Medicine