Health Rounds: Laser treatment before immunotherapy helps brain cancer patients live longer

By Nancy Lapid

March 3 (Reuters) - Hello Health Rounds readers! Today we report on a therapeutic combination that may provide hope for patients with an aggressive form of brain cancer and few options. We also feature a distressing analysis on the prevalence of diabetes and prediabetes among U.S. youth, and a possible explanation for long-term taste loss after COVID-19.

Laser heat may prolong survival with aggressive brain cancer

Adding a minimally invasive laser procedure to immunotherapy achieved dramatically improved survival in a small study of patients with recurrent high-grade astrocytoma, an aggressive brain cancer with few treatment options.

High-grade astrocytoma almost always returns after surgery. Patients with recurrent disease typically live another four to five months.

In a study of 45 patients with advanced recurrent high-grade astrocytoma, 42% of the 33 who received laser interstitial thermal therapy (LITT) to shrink their tumors, followed by Merck’s MRK.N immunotherapy drug Keytruda, were still alive at 18 months, and more than one-third lived more than three years.

None of the six patients who received conventional surgery followed by Keytruda were alive at the 18-month mark, according to a report of the study in Nature Communications.

“Patients with this type of advanced cancer have few remaining options and poor outcomes, and this approach could meaningfully extend their survival time and provide new hope for patients and their loved ones,” study leader Dr. David Tran from the University of Southern California said in a statement.

The randomized study was stopped early by an independent data and safety monitoring committee when the benefit of LITT developed by Monteris Medical became obvious. Such committees can halt trials before their conclusion if it becomes clear the drug or device being tested is clearly beneficial and should also be given to the control group, or if it raises safety concerns or is providing no benefit.

Drugs like Keytruda that use the immune system's T cells to attack cancer are approved for many types of the disease, but generally fail in brain tumors because the blood-brain barrier prevents them from reaching the intended target.

Researchers in earlier studies had seen that the heat produced by LITT can disrupt the blood–brain barrier for several weeks – long enough for T cells to pass through and target cancer cells once they have been activated by Keytruda.

Larger studies are needed before this can become a standard treatment, the researchers noted.

Nearly 1 in 3 US adolescents has prediabetes or diabetes

Nearly one-third of U.S. teens and preteens have type 2 diabetes or are at risk of developing it, a condition known as prediabetes, according to a large analysis.

Until the late 1990s, type 2 diabetes was rare in children. Childhood onset of the disease, in which the body loses its ability to use insulin properly, increases the risk of lifelong health complications.

Analyzing data collected between 2021 and 2023 from a nationally representative sample of nearly 2,000 children ages 10 to 19, researchers saw prediabetes or type 2 diabetes in 31%, as indicated by a hemoglobin A1c level of 5.7% or greater, or a fasting plasma glucose level of 100 mg/dL or more.

An A1c of more than 6.5% is the current American Diabetes Association A1c threshold for diagnosing type 2 diabetes.

Accumulation of fat around the abdomen, as measured by waist-to-height ratio, was the strongest independent predictor of prediabetes or diabetes, according to the report published in PLoS Global Public Health.

So-called central adiposity was a stronger predictor than body mass index, a ratio of weight-to-height, the researchers found.

“From a clinical and public health perspective, these findings suggest that screening strategies relying solely on BMI may miss high-risk adolescents,” they advised.

Integrating waist-to-height ratio into routine pediatric assessment could improve early diagnosis and allow for treatment before complications develop, they added.

Molecular cause of taste loss after COVID identified

Researchers have found evidence of molecular and structural changes to the taste buds of people who experience long-term taste loss after a bout of COVID-19, providing a likely explanation for the condition.

In biopsy samples from 20 patients with persistent taste disturbances more than a year after contracting COVID-19, the researchers discovered reduced levels of messenger RNA responsible for producing a protein called PLC beta2, they reported in Chemical Senses.

“PLC beta2 acts like a molecular amplifier inside taste cells,” study co-author Thomas Finger of the University of Colorado Anschutz said in a statement.

“It strengthens the signal before it's transmitted to the brain. When levels are reduced, the taste signal weakens.”

Some patients also showed altered taste-bud structure under microscopic examination.

“This suggests that both molecular and architectural changes may contribute to persistent taste dysfunction,” Finger said.

The discovery could lead to targeted therapies that might restore normal taste signaling if further research determines whether the molecular dysfunction can be fully reversed.