Modern cancer drugs supercharge immune systems, target specific gene mutations and pack modified viruses into vaccines. Amid the increasing sophistication, one investigational treatment stands out for its simplicity.
Rose Bengal, a cheap industrial chemical that turns yarn and food bright red has been used as a diagnostic staining agent for some time. Now, some scientists are looking at its potential to fight various forms of cancer.
At the forefront is Provectus Biopharmaceuticals Inc, which is testing a reformulated version of the industrial dye on melanoma, the deadliest form of skin cancer.
The Knoxville, Tennessee, company reported promising results in a small melanoma study.
While some doctors are encouraged by the research, government approval is years off and not guaranteed. The company must replicate its early results on a bigger scale, and a US Food and Drug Administration decision is not expected before 2019.
Rose Bengal’s potential against cancer was discovered by accident. The salt was first patented in 1882 as a wool dye and has been used for years as a diagnostic stain in tests for jaundice in newborns and to detect eye damage.
In 1998, scientists who later founded Provectus were looking for a safe photoreactive agent to use in an investigation of lasers against cancer. Rose Bengal fit the bill.
As it turned out, the Rose Bengal solution appeared to work on its own to dissolve tumours when directed injected into them, recalled Provectus Chief Technology Officer Eric Wachter, a former scientist from Oak Ridge National Lab who co-founded the company. “It made the lasers obsolete.”
In a study of 80 people with advanced melanoma, half of the patients who had all of their lesions injected appeared cancer free after an average of two months. A year later, 11 percent continued to show no signs of cancer, according to a report published the Annals of Surgical Oncology.
The lesions were destroyed from the inside with no apparent harm to healthy tissue, researchers said. Reported side effects included injection site pain and blistering.
Final results from an ongoing 225-patient melanoma trial of the experimental drug compared to chemotherapy are expected in early 2018. The hope is that the drug, known as PV-10, will prevent melanoma from progressing beyond Stage III, in which the disease has spread but not yet to other organs, and allow patients with more advanced cancer to live longer.
“This is one of the really neat examples of what we call repurposing, taking drugs that been around for years … and suddenly realizing that they may have an oncologic value,” said Dr Vernon Sondak, head of cutaneous oncology at the Moffitt Cancer Center in Tampa, Florida. Sondak has been running clinical trials for Provectus.