Researcher examining malignant melanoma in horses

Malignant melanoma is a dangerous, aggressive form of cancer and approximately 54,000 new cases are diagnosed every year, according to the American Cancer Society. Interestingly, there are many similarities between malignant melanoma in horses and malignant melanoma in people.

Recognizing the extraordinary opportunity for translational research that the disease represents, Dr. John L. Robertson, a professor in the Virginia-Maryland Regional College of Veterinary Medicine at Virginia Tech and director of the college’s Center for Comparative Oncology (CECO), has been looking at one experimental treatment.

During a presentation before a regional meeting of the American Cancer Society in Roanoke, Va., Robertson detailed some of the work he is doing with the use of Frankincense oil as a possible treatment for malignant melanoma in horses.

The risk factors for malignant melanoma in people and horses are very similar, according to Robertson. In people, risk factors include pale complexion and hair, exposure to excessive sunlight and sunburns and aging. Horses at risk also have a pale coat of grey to white and there seems to be a correlation to aging, which could be a result of chronic exposure to sunlight, he said. In each, the disease is an infiltrated pigmented malignancy that is difficult to manage. Conventional therapies include chemotherapy, radiation, immunotherapy, and surgery.

The disease often affects horses with the development of lesions on the lips, neck, and perineal area.

Robertson presented the story of Chili, a handsome, 11-year old Thoroughbred and champion jumper that was diagnosed with multi-centric malignant melanoma at the age of seven. Told by her local practitioner that there was not much that could be done for Chili and aware of Robertson’s interest in evaluating an experimental therapy, Chili’s owner asked if Robertson would work with Chili.

That experimental therapy involved the use of frankincense oil, a compound known as a valuable treatment for wounds for more than 2,000 years, and one people are reminded of every Christmas when they recall the Gifts of the Magi brought to the Christ-child.

Frankincense oil is a fragrant botanical oil distillate made from fermented plants, explains Robertson, who adds that it contains hundreds of constituents, including boswellic acid, a component that is known to have anti-neoplastic properties. Scientists have demonstrated that the oil has potent anti-inflammatory effects and anti-tumor properties when evaluated in tissue culture with tumors such as astrocytomas, melanomas, and fibrosarcomas. Furthermore, he said, it appears to have fairly selective anti-tumor activity and does not appear to disrupt normal cells. But much about how it affects actual cancer patients is unknown.

Chili’s experimental protocol involved daily injections of medicinal grade, sterile frankincense oil directly into his tumors and the application of oil on topical tumors, while Chili’s comfort and well-being was carefully maintained through pain and nutritional management, including copious amounts of his favorite peeled baby carrots and peppermints.

The lesions were observed, measured, photographed, and periodically biopsied, according to Robertson. Those tumor biopsies demonstrated that some small tumor cells were destroyed by the treatment and those treated topically were reduced in size. Unfortunately, however, Chili passed away on October 18, 2005 as a result of the progressive and relentless growth of the non-treated tumors.

Chili’s involvement with CeCO and the experimental protocol did result in some important achievements, according to Robertson.

“I think this research on frankincense oil suggests that this ancient medicine may have significant modern uses for chemotherapy of non-resectable malignancies,” said Robertson, a professor in the Department of Biomedical Sciences and Pathobiology. “This research showed that equine melanomas respond to this therapy.”

Information gleaned from this Phase I-II National Cancer Institute format clinical trial has supported the development of grant applications and helped in the treatment of five additional horses, Robertson said. A collaboration with the Clinical Research Program at Wake Forest University’s Comprehensive Cancer Center is being discussed.