Patients with advanced melanoma face the possibility they could survive much longer with drugs that fire up their immune system to fight cancer but steep odds the therapy will work for them.
Less than 20 percent of patients with the deadly skin cancer respond to the treatment, which is known as immunotherapy, according to the Melanoma Research Foundation.
New research out of Moffitt Cancer Center at the University of South Florida takes another step toward identifying patients who should try the therapy and which ones should initially concentrate on other treatments.
Moffitt researchers identified a unique group of genes, known as a "gene signature," linked to the presence of lymph node-like structures on melanoma tumors from some patients.
Previous research has shown those lymph node-like structures are associated with higher survival rates among cancer patients. It's unclear why, but Moffitt researchers speculate that the structures play an important role in fighting tumors.
Patients with such internal tumor fighters might be the best candidates for immunotherapy, researchers say.
Being able to direct advanced melanoma patients to the most promising treatment would be huge, given that time is such a critical issue, said senior Moffitt researcher James Mule.
"Why hold up a patient on a therapy when you don't know if it's going to work or not?" he said.
The Moffitt study analyzed 15,000 tumors of different types, including metastatic melanoma. Because immunotherapy is used most often in melanoma patients, the work will initially focus on that cancer. But Moffitt hopes future findings may be applied to lung, colorectal and ovarian cancers.
The study was published in Scientific Reports, a journal from Nature Publishing Group. Moffitt has begun running experimental clinical trials to see how melanoma patients with the gene signature respond to immunotherapy.
For late-stage melanoma patients, the traditional method of fighting cancer -- chemotherapy -- is rarely effective, said Tim Turnham, executive director at the Melanoma Foundation.
So treatment is focused on immunotherapy and so-called "targeted therapy," which uses drugs that block the growth and spread of cancer by working at a cellular level. Trials are starting to combine the two treatments as well, he said.
Fewer patients respond to immunotherapy than targeted therapy, said Turnham. But the ones who do respond well are living much longer than other patients.
"One of the Holy Grails in immunotherapy is, 'Can we find some biomarker?' " to predict who might respond best, he said.
Turnham said the latest Moffitt research is a positive development toward doing just that. "That's why this kind of work is very, very important," he said.
After all, he said, the average lifespan of a patient with metastatic melanoma is 10 months. "You don't have time to wait," he said.