Oral squamous cell carcinoma is a deadly cancer that, even when treated successfully, often leaves patients permanently disfigured. Other than radical surgery, there are few known treatments.
Researchers at Ohio State University, however, report a Phase I/II trial demonstrating that a gel made from black raspberries shows promise in preventing or slowing the malignant transformation of precancerous oral lesions.
“Black raspberries are full of anthocyanins, potent antioxidants that give the berries their rich, dark color, and our findings show these compounds have a role in silencing cancerous cells,” said Susan Mallery, D.D.S., Ph.D., professor in the Department of Oral Maxillofacial Surgery and Pathology at Ohio State University’s College of Dentistry. “This gel appears to be a valid means of delivering anthocyanins and other cancer-preventing compounds directly to precancerous cells, since it slowed or reduced lesion progression in about two-thirds of study participants.”
According to American Cancer Society statistics, oral cancer is one of the deadliest of all cancers, with about 35,000 new cases each year in the United States and 7,500 deaths annually. These cancers generally begin as small, often unnoticed, lesions inside the mouth. “More than a third of untreated precancerous oral lesions will undergo malignant transformation into squamous cell cancer, but we do not have the capability to predict which lesions will progress,” Mallery said.
The National Cancer Institute-funded trial included 30 participants, 20 of whom had identifiable precancerous lesions, and 10 normal controls. Each of the participants was instructed to gently dry the lesion sites (or a pre-selected control site for the normal participants) and rub the gel into the area four times a day, once after each meal and at bedtime.
After six weeks, about 35 percent of the trial participants’ lesions showed an improvement in their microscopic diagnosis, while another 45 percent showed that their lesions had stabilized. About 20 percent showed an increase in their lesional microscopic diagnoses. Importantly, none of the participants experienced any side effects from the gel.
“The trial was designed to test the safety of the gel and detect any possible toxicity, but the next obvious step is a multicenter, double-blind, placebo-controlled Phase II study,” Mallery said. “Such a study would enable us to determine that the black raspberries are the active factor and not just the gel base or the act of drying and rubbing the lesions.”
The researchers also collected cell samples from the lesion sites of each participant before and after treatment in order to study the genetics and biology of the lesions. The majority of patients with precancerous lesions at the start of the trial showed elevated levels of COX-2 and iNOS, two proteins closely correlated with inflammation and malignant progression. Following treatment, Mallery says, levels of those proteins in the treated lesional epithelial cells decreased dramatically.
Mallery and her colleagues also examined samples for three tumor suppressor genes in order to determine what researchers call “loss of heterozygosity,” whether or not a cancer cell has lost one of its two copies of the gene. Such loss greatly increases a cell’s chances of losing the benefit of the tumor suppressor genes due to a second mutation or gene silencing event. Following the trial, the researchers noted that many lesions returned to normal, retaining both copies of each tumor suppressor gene. “We speculate that the chemopreventive compounds in black raspberries assist in modulating cell growth by promoting programmed cell death or terminal differentiation, two mechanisms that help “reeducate” precancerous cells,” Mallery said.
“Oral cancer is a debilitating disease and there is a desperate need for early detection and management of precancerous lesions,” Mallery said. “While screening can help detect the disease early – and survival rates are definitely improved the earlier the disease is caught – many of these precancerous lesions recur despite complete surgical removal. There are currently no effective chemopreventive treatments which could conceivably serve as either adjunctive or alternative approaches to surgery.”
According to Mallery, the development of black raspberries as potential cancer-fighters is the result of decades of research into identification of naturally derived chemopreventive compounds by Ohio State researcher Gary D. Stoner, Ph.D., an emeritus professor at Ohio State University’s College of Medicine and Public Health. Clinical studies stemming from his research are currently underway for oral, esophageal and colorectal cancer.
The gel looks deceptively like black raspberry jam, but it certainly does not taste like something you would want to spread on toast, Mallery says. The bioadhesive gel, which contains 10 percent freeze dried black raspberries, is devoid of many of the tasty sugars found in native berries.
The black raspberry gel was manufactured by the University of Kentucky’s Good Manufacturing Production (GMP) facility. NanoMed Pharmaceuticals is partnering with OSU investigators Mallery, Stoner and Peter E. Larsen D.D.S. and Russell J. Mumper, Ph.D., of the University of North Carolina, in product development. -American Association for Cancer Research
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