Immunotherapy for melanoma works over the long term: study
Treatment has strong effects; provincial reimbursement being requested
June 13, 2016
Drs. Frances Wright (left) and Teresa Petrella led a study that found patients with melanoma unable to be treated surgically had longer overall survival when given immunotherapy.
Melanoma is the most serious type of skin cancer that can spread to other organs. It develops in the cells, known as melanocytes, that produce melanin, the pigment that gives skin its colour. Melanocytes are found in the deepest part of the epidermis, the top layer of skin, and can reach the dermis, the layer underneath. From here, cancerous melanocytes can spread through the bloodstream and lymphatic vessels.
Although the number of cases is increasing each year, survival rates are high when melanoma is detected early. Surgery is the cornerstone of treatment.
“At the Odette Cancer Centre, we see about 20% of the province’s surgical melanoma [cases]. It’s a large program, the largest in Ontario by far,” says Dr. Frances Wright, a surgeon and scientist at Sunnybrook Research Institute (SRI).
Wright works with Dr. Teresa Petrella, a medical oncologist. One of their areas of research is in-transit disease.
“About 3% to 10% of patients with melanoma over one millimetre in depth will develop these deposits of disease on their skin that’s between the primary site and the nearest lymph nodal basin,” says Wright. “If you had a melanoma on your ankle, then the nearest lymph node basin would be your groin.” In-transit lesions would be deposits of melanoma between the ankle and the groin, Wright explains.
Therapies for these lesions include surgery, radiation, regional chemotherapy, and injection of immune-modulating agents and systemic therapies, drugs that treat the whole body to fight cancer cells.
The five-year survival rate for melanoma with in-transit disease is 50%; it plummets to 25% in those whose cancer has spread to the lymph nodes and have in-transit metastases.
Since 2009, Wright has been treating these patients using an agent called interleukin-2 (IL-2), which is injected into the lesions. This immunotherapy is used when surgery is no longer viable—that is, for patients who have many skin lesions or new lesions appearing weekly.
“It works well for patients, and for those that get a good response, it tends to last for a long time,” says Petrella.
We see about 20% of the province's surgical melanoma [cases]. It's the largest program in Ontario by far.
To understand better the long-term effects of IL-2 therapy, an unexplored area, Wright and Petrella co-authored a review of patients treated with IL-2 between 2009 and 2012 who had in-transit disease. Most were between 60 and 80 years of age with primary melanoma lesions from one millimetre to 20 mm deep.
Results suggested patients who had a good response to IL-2 had longer overall survival. “About one-third of all patients had a complete pathological response, meaning the IL-2 activated the immune system to get rid of the melanoma,” says Wright. “About 80% of those one-third did well in the long-term and are likely to live longer and be disease-free.” Patients were monitored for five years.
The study showed IL-2 decreases the size of the skin lesion or makes it disappear completely, says Petrella. Most side effects were minor, such as fever and chills.
These results paved the way for Wright to solicit support for IL-2 therapy to be covered by provincial funding. They submitted a request to the pan-Canadian Oncology Drug Review that, if successful, means patients will not have to pay.
“Each injection costs $600 every two weeks. You need about six to eight injections depending on how well the treatment is going,” says Petrella. “You can imagine by the end of the treatments, if you’re paying each time, [especially] for someone on a fixed income, it can get really expensive.”
Given the drug is already approved by Health Canada, Wright and Petrella say they are hopeful funding from the province will come through shortly.
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