A new clinical trial aims to find out if the drug's tumor-fighting benefits have the potential to help those fighting head and neck cancer. So far, doctors at John Hopkins have found Cialis weakens the tumors' ability to evade immune system responses. "We think that, for a lot of patients, immune suppression may be why their tumors are so aggressive," Joseph Califano, M.D., professor in the Department of Otolaryngology-Head and Neck Surgery at Johns Hopkins Hospital in Baltimore, Md., told Ivanhoe.
When someone is fighting cancer, doctors say over time tumors develop strategies for evading the body's natural immune system. By exploiting the nitric oxide produced by immune cells, tumors create a shield that keeps them hidden from the T-cells, or lymphocytes that normally attack germs and disease. Erectile dysfunction drugs are proving they can prevent the immune system from generating nitric oxide, allowing T-cells to detect and attack the tumor. In a future stage of the study, Dr. Califano will aim to find out if drugs like Cialis can also directly cause the tumors to shrink.
The link between erectile dysfunction drugs and cancer treatment was first discovered by Dr. Califano's colleague, Johns Hopkins oncology researcher Ivan Borrello. Together, the two have conducted studies in mice and human blood samples, all showing improvement in the immune response of patients who received Cialis. Other research also involved sildenafil (Viagra), which was successful, as well. However, researchers believe it has too short of a half-life to offer the same benefits as Cialis, with a half-life twice as long.
Drs. Califano and Borrello are enrolling patients in the clinical trial, which is funded by a National Cancer Institute grant. Patients are given a once-daily dose of Cialis for 10 to 14 days. At the end of the test period, their blood samples are looked at to figure the drug's success in boosting the immune system. Then patients proceed with their recommended treatment protocol, whether it's surgery, chemotherapy or radiation. Doctors say that's one of the benefits of this study ? patients can participate in the clinical trial without forgoing or slowing down their other treatment options.
Right now, doctors conducting the study consider Cialis primarily as a complement to other standard therapy; however, in the future, there is potential that the drug could lessen or eliminate the need for chemo or radiation. "It would be great if instead of radiation, I could take a pill with some pleasant side effects," one cancer patient told Ivanhoe.
"This is a great treatment option because it's an incredibly safe drug -- one of the safest drugs around -- and to be honest, some patients really like the idea of being on tadalafil," said Dr. Califano.
The Cialis cancer trial is expected to continue for about the next year. Both men and women with head and neck cancers are eligible to participate. Patients who have had a recent heart attack or who are taking nitrates are not eligible for the trial.
FOR MORE INFORMATION, PLEASE CONTACT:
Johns Hopkins Medicine