Older drug reprograms white blood cells, improves blood sugar in type 1 diabetes

(Reuters) - We also report on promising early data that could produce a better option for treating C. difficile-caused diarrhea, and the first vaccine for preventing Lassa fever. 

Old immunotherapy helps type 1 diabetes blood sugar control

In adults with type 1 diabetes since childhood, a decades-old immune system treatment reprogrammed their white blood cells and dramatically improved blood sugar control even without a functioning pancreas, a small trial found. 

Patients with long-standing juvenile-onset type 1 diabetes who received six Bacillus Calmette-Guérin (BCG) shots over five years had significant reductions in levels of HbA1c, a measure of blood-glucose levels over time, the researchers reported at the American Diabetes Association meeting in New Orleans.

BCG treatment, which was developed in 1921 and is widely used to prevent tuberculosis, also significantly reduced insulin use. Continuous glucose monitoring showed up to a 183.7% improvement over baseline in time spent with blood sugar in the normal range, without increased episodes of low blood sugar.

"Many patients in the trial were able to normalize their blood sugar levels,” the researchers reported.

Research into the use of immunotherapy for treating type 1 diabetes has been focused on halting the body’s autoimmune attack on the pancreas, which produces insulin.

But type 1 diabetes is not just an autoimmune disease, said study leader Dr. Denise Faustman of Massachusetts General Hospital. 

“White blood cells in people with type 1 diabetes have a metabolic defect,” she said. “Their white blood cells consume fat in the blood for fuel." In healthy people, white blood cells consume sugar, she noted. 

If white blood cells are not utilizing and regulating blood sugars, “you have abnormal blood sugar levels that are independent of the pancreas,” Faustman said. 

In the mid-stage trial, 34 adults received the BCG shots and 24 volunteers with the disease got placebo shots. 

The BCG immunotherapy activated a cascade of events that ultimately reprogrammed the malfunctioning white blood cells, Faustman said. 

The improvements were not seen in the control group. 

Unlike injections of insulin, which can cause blood sugar levels to drop precipitously and then rebound, properly functioning white cells keep blood sugar levels closer to normal for longer periods, Faustman said. 

“This is the first time an immunotherapy has worked in people with long-standing type 1 diabetes,” she said, noting that it works independent of the pancreas.

"And it's a safe drug that with limited dosing restores blood sugars to a normal range. In the long term, that will prevent complications.”

More than 100 million newborns receive the BCG vaccine each year, according to the World Health Organization.

Lab-grown bacteria treats C. diff-caused diarrhea

Factory-produced bacteria may someday replace bacteria cultured from feces for treating severe recurrent diarrhea caused by Clostridioides difficile, researchers say. 

The diarrhea often begins after patients have been treated with antibiotics that disrupt their gut bacteria, allowing the C. difficile bacteria to thrive.

Patients with multiple recurrences often receive fecal microbiota transplants, which deliver bacteria cultured from healthy donors’ stool in order to restore a safe balance of intestinal organisms.

In a pilot study, researchers tested a new treatment made from 15 strains of healthy bacteria originally cultured from donors but then mass-reproduced in a laboratory.

Eight weeks after treatment, recurrence of C. difficile diarrhea was prevented in seven of nine patients who got the lab-grown bacteria and in eight of nine who received standard fecal microbiota, according to a report of the study published in Nature Medicine. 

There were no treatment-related adverse events.

Researchers said the lab-grown version could be easier to manufacture and standardize than stool-based treatments because carefully selected bacteria would be produced under controlled conditions.

“Our goal was to move beyond stool-based therapies toward something more precise and reproducible,” said study leader Dr. Ari Grinspan of the Icahn School of Medicine at Mount Sinai in New York. “By defining exactly which bacterial strains are included, we can better understand how these therapies work and potentially improve safety, quality control, and scalability.”

Lassa fever vaccine promising in first-in-human trial

An experimental vaccine against Lassa fever and rabies safely induced immune responses against both viruses, researchers reported in Nature Medicine. 

There are no vaccines against Lassa fever on the market. The World Health Organization has identified Lassa virus as a public health threat in western Africa. Like Ebola, it can trigger severe illness. 

Regions where Lassa fever is common also have a high burden of rabies.

The randomized U.S. trial tested various doses of the vaccine in 54 healthy volunteers. 

There were no serious adverse events reported, and it induced rapid and robust antibody responses against both Lassa and rabies viruses, the researchers said.

Vaccine safety and participants’ immune responses will be studied for roughly 13 months post-vaccination. If the vaccine’s effects are persistent, the researchers will proceed with larger trials.

The investigational vaccine can be freeze-dried for storage, enabling distribution to regions where it can be difficult to maintain cold storage, the researchers said.

Last year, before results were available, the trial was highlighted by Nature Medicine in its feature, “Eleven clinical trials that will shape medicine in 2026,” which identified studies to watch based on their potential to address major unmet health needs.