Rose Bengal, an inexpensive chemical patented in 1882 as a wool dye, has shown some promise as a cancer treatment in a small, ongoing study involving melanoma patients published in Annals of Surgical Oncology.
The promising numbers come from the second phase of a study in which 80 patients with advanced melanoma had lesions treated with the injectable form of Rose Bengal called PV-10. Post-injection, the lesions were destroyed from the inside with no apparent damage to healthy tissue. Half of the patients injected appeared cancer-free after about two months. A year later, 11 percent still showed no signs of cancer.
According to a Reuters report, Rose Bengal's potential viability as a cancer drug was discovered by accident. Long after being patented and used as dye, the medical community began using the substance as a diagnostic stain to detect eye damage and examine jaundice in newborns. It was in 1998 when scientists needed a safe photoreactive agent to use in an investigation involving lasers as a cancer treatment. The Rose Bengal solution seemed to reduce the tumors unilaterally after being injected into them, rendering the presence of the lasers inconsequential.
Researchers have also noticed that in addition to the devastation of skin lesions, PV-10's positive effects seem to spread to untreated regions with lesions and tumors in areas as distant as the lungs.
"We've come to the conclusion that it is immune based," Sanjiv Agarwala, MD, chief of medical oncology and hematology at St. Luke's Cancer Center in Bethlehem, Pa., said, according to Rueters.
Researchers' greatest hopes for PV-10 are spurred by the observed potential of the drug to provoke an immune system response.
In the Reuters piece, Patrick Hwu, MD, an immunotherapy expert from MD Anderson Cancer Center in Houston, said, "The biggest value will be if it can affect distant disease."
While many are excited about these results, approval is years away and never surefire. Researchers will have to replicate this outcome on a significantly larger scale. PV-10 is being developed by Provectus Biopharmaceuticals Inc., based in Knoxville, Tenn.
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