A single oral dose of an experimental therapy protected mice from otherwise lethal whole-body radiation while leaving radiation’s ability to attack cancer intact, according to a preclinical study from researchers at the Fralin Biomedical Research Institute at Virginia Tech. The treatment, called XOlacta, combines a therapeutic peptide known as alpha-CT11 with milk-derived extracellular vesicles, microscopic biological packages that naturally transport molecules between cells. In experiments, the formulation improved survival, reduced injury to radiation-sensitive organs, and preserved tumor control in mice with glioma. Although the findings remain preliminary and have not been demonstrated in humans, they point toward a possible way to address one of the most difficult problems in radiation medicine: shielding healthy tissue without shielding malignant cells.

Radiation therapy is used in roughly half of all cancer treatments, but the same ionizing radiation that damages tumor DNA can also injure normal organs. Radiation exposure produces highly reactive molecules that attack DNA, proteins, cell membranes, and the lining of the gastrointestinal tract. At sufficiently high doses, damage to the intestinal barrier and bone marrow can lead to severe dehydration, infection, bleeding, and immune-system collapse. These toxic effects limit how much radiation oncologists can safely deliver and can force physicians to interrupt treatment. Outside hospitals, a large-scale release of radiation from an accident, nuclear detonation, or other emergency could expose many people at once. Despite that risk, there are currently no U.S. Food and Drug Administration-approved medical countermeasures for severe whole-body radiation exposure.

The Virginia Tech team designed XOlacta to solve a practical delivery problem as well as a biological one. Alpha-CT11 is a peptide derived from connexin43, a protein involved in communication between neighboring cells and in tissue repair. Peptides can be rapidly broken down in the digestive tract, making many of them unsuitable as conventional oral medicines. To protect alpha-CT11, the researchers loaded it into extracellular vesicles obtained from milk. These naturally occurring membrane-bound particles can carry proteins, nucleic acids, and other signaling molecules through biological environments. Encapsulation may help the peptide survive passage through the stomach and intestine, allowing it to reach tissues after an oral dose rather than requiring injection or intravenous administration.

In the central survival experiment, mice received a radiation dose expected to be fatal and were given one oral dose of XOlacta approximately one hour later. Forty-two percent of treated animals survived for the full 30-day observation period, whereas untreated animals did not survive that interval. The therapy also retained protective activity when administration was delayed for as long as 24 hours after exposure, a potentially important feature for real-world emergencies in which people may not receive immediate medical attention. The researchers emphasized that the results were obtained in animals and do not establish an effective human dose, guarantee safety, or demonstrate that the treatment would work after the more variable exposures seen in accidents or nuclear events.

Tissue analyses suggested that XOlacta acted on organs particularly vulnerable to radiation injury. Treated mice showed less damage in the small intestine and bone marrow, tissues that are rapidly affected because they contain populations of actively dividing cells. Radiation can destroy intestinal stem cells, disrupting the renewal of the gut lining and allowing bacteria to cross into the bloodstream. In bone marrow, it can eliminate blood-forming cells, reducing the production of red cells, platelets, and immune cells. Imaging experiments indicated that the milk-derived vesicles accumulated preferentially in damaged regions, including the brain, intestine, and bone marrow. The researchers believe that radiation-induced changes in blood vessels and tissue architecture may help direct the vesicles toward injured sites, although the precise targeting mechanism remains under investigation.

The most significant finding for cancer care was that the treatment did not appear to protect tumors from radiation. In a mouse model of glioma, a difficult-to-treat brain cancer, XOlacta reduced injury to normal tissues while preserving radiation’s ability to suppress tumor growth. This distinction is essential because a broadly acting radioprotective drug could be dangerous if it also helped cancer cells repair radiation-induced damage. The investigators’ goal is therefore not simply to block radiation effects, but to support the recovery of normal tissues through biological pathways that tumors may not share or may be unable to exploit in the same way. Whether that separation can be maintained in diverse human cancers will require extensive testing.

The therapy’s proposed advantages also involve storage and emergency deployment. According to the researchers, the oral formulation remains stable at room temperature for a year or longer, potentially allowing it to be kept in hospitals, homes, military medical supplies, and emergency stockpiles. A stable tablet or oral dose could be distributed more easily than injectable medicines and administered without specialized equipment, an important consideration during disasters in which medical facilities, electricity, and trained personnel may be limited. The investigators also envision possible use alongside radiation therapy, where reducing damage to normal organs could help patients complete treatment or tolerate more intensive regimens. These applications remain hypothetical until larger studies establish manufacturing consistency, dosing, toxicity, and long-term effects.

Independent studies conducted by Lovelace Biomedical, a contract research organization, reportedly reproduced the mouse findings, and the therapy is now moving through additional safety and large-animal testing. The developers say the program is being advanced under the FDA’s Animal Rule, a regulatory pathway used for certain countermeasures whose efficacy cannot ethically be tested in humans. Under that framework, evidence from well-designed animal studies may contribute to approval when the biological mechanism is sufficiently understood, the animal models are considered predictive, and human safety and pharmacology data are available. The pathway does not eliminate the need for rigorous testing. Investigators must still determine whether the treatment causes unintended immune, cardiovascular, neurological, or reproductive effects and whether repeated doses are safe.

The work also carries commercial and intellectual-property interests that will need to be considered as the research progresses. Robert Gourdie and Spencer Marsh are officers and shareholders of Tiny Cargo Company, which is developing the technology, while Gourdie is also associated with Xequel Bio, a company developing related therapeutic peptides for wound healing. Virginia Tech, the Medical University of South Carolina, and Gourdie are connected with issued or pending patents involving alpha-CT1, alpha-CT11, and milk-derived extracellular vesicle technologies. The study involved researchers from Virginia Tech, the University of Virginia, and the Virginia-Maryland College of Veterinary Medicine, and was supported by federal and private organizations including the National Institutes of Health, the National Science Foundation, the National Cancer Institute, the Red Gates Foundation, The Fralin Family, and the Fralin Biomedical Research Institute. The results offer an intriguing preclinical signal, but the decisive test will be whether XOlacta can deliver the same tissue protection in larger animals and, eventually, in people without compromising cancer treatment or introducing new risks.

Subject of Research: Animals

Article Title: Oral connexin43–peptide–loaded milk extracellular vesicles mitigate lethal radiation injury while preserving tumour radiosensitivity

News Publication Date: 28 September 2026

Web References: https://doi.org/10.1016/j.canlet.2026.218686; https://www.sciencedirect.com/science/article/abs/pii/S0304383526004507

References: Cancer Letters, DOI: 10.1016/j.canlet.2026.218686

Image Credits: Virginia Tech

Keywords: radiation protection, radiation injury, cancer treatment, radiation therapy, glioma, alpha-CT11, connexin43, extracellular vesicles, exosomes, oral therapy, radioprotection, bone marrow, small intestine, medical countermeasures

Tags: alpha-CT11 peptide therapybiological packaging for radioprotectionexperimental oral radioprotective formulationsextracellular vesicles in radiation shieldingglioma radiation treatmentimmune system preservation in radiation therapynovel radiation shielding strategiesoral radioprotective agentspreclinical radiation injury mitigationradiation damage to healthy tissueradiation therapy protectiontumor preservation during radiation