A group of researchers at Thomas Jefferson University have published their work “Radiation Protection of the Gastrointestinal Tract and Growth Inhibition of Prostate Cancer Xenografts by a Single Compound” in the Molecular Cancer Therapeutics journal, whereby they show a new cancer drug can help protect healthy cells from the effects of radiation therapy, while still efficiently targeting the tumor.
The compound, RTA-408, is being developed by REATA Pharmaceuticals, a privately held company located in Irving, Texas.
Even though radiation treatments have improved over the years, it is still a challenge to appropriately dose the tumor while minimizing radiation damage to the surrounding healthy tissue.
“It was a stroke of luck that the drug that most effectively protected normal cells and tissues against radiation also has anti-cancer properties, thus potentially increasing the therapeutic index of radiation therapy,” Ulrich Rodeck, M.D., Ph.D., Professor of Dermatology and Cutaneous Biology and Radiation Oncology at Thomas Jefferson University, and senior author on the study said in a press release.
The research team, led by first author Vitali Alexeev, Ph.D., Assistant Professor, Dermatology and Cutaneous Biology, tested five different compounds that had been demonstrated in previous research to have radiation-protective effects.
Using mice models, the team found the only robust radiation protector was RTA-408, which had comparable effects to the only currently FDA approved drug for the same purpose, amifostine, which carries a lot of undesired side-effects.
The team observed that sites which are usually affected by radiation damage, such as gut and blood cells in the bone marrow, were successfully protected in RTA-408 treated animals.
To assess whether RTA-408 was selectively protecting healthy tissue, the team used mice models injected with human prostate cancer cells, verifying that not only did the compound allow cancer cells to be targeted normally by radiation, it was able, by itself, to confer a degree of anti-tumoral protection, by slowing the growth of human prostate cancer transplants in these animals.
“It was really exciting to see that combining radiation and RTA-408 more effectively inhibited tumor growth compared to using either one or the other as single treatment modalities”, Dr. Rodeck added.
The results also demonstrated that RTA-408 might be useful for the treatment of accidental exposure to radiation. In fact, Reata is currently enrolling patients for a topical form of the drug applied to those who experience radiation dermatitis. The clinical trial, PRIMROSE, is a randomized, double-blind, vehicle-controlled, parallel-group Phase 2 study that will assess the efficacy, safety, pharmacokinetics, and pharmacodynamics of RTA 408 Lotion in the treatment of patients at risk for radiation dermatitis.
For more information on the PRIMROSE trial you can visit this website.