Joseph Califano believes one
cancer cure could lie in the
erectile dysfunction drug
Most people associate the drug tadalafil (Cialis) with advertisements depicting middle-aged and older couples, all wine and intimate dinners, romance and seduction.
Outside of The Johns Hopkins Hospital, however, few people connect the erectile dysfunction (ED) drug with one of its lesser-known benefits: the potential to help patients who have head and neck cancer. Now, with a just-opened clinical trial and a growing battery of evidence showing the drug’s tumor-fighting benefits, head and neck surgeon Joseph Califano hopes he can change the narrow view of tadalafil from a purely ED-related medication to a drug that could possibly save lives. “From what we know and have seen so far,” Califano explains, “this drug weakens the tumor’s ability to evade immune system responses. We think that, for a lot of patients, immune suppression may be why their tumors are so aggressive.”
It makes sense that, in the fight against cancer, a strong immune system is crucial. But over time, Califano says, tumors have developed strategies for evading the body’s natural immune responses. By exploiting the nitric oxide produced by immune cells, tumors create a sort of fog that keeps them hidden from the lymphocytes (T-cells) that normally attack and rid the body of germs and disease. Impotence drugs, however, prevent the immune system from generating nitric oxide, allowing T-cells to detect and attack the tumor.
The link between ED drugs and cancer treatment was first discovered by Califano’s colleague, Hopkins oncology researcher Ivan Borrello. Together, the two have conducted studies in mice and human blood samples, all showing a marked improvement in the immune responses of subjects who received tadalafil. Some of that research also involved another popular ED drug, sildenafil (Viagra), which, though initially successful, had too short a half-life to offer the same benefits as tadalafil, with a half-life twice as long. Despite being a drug commonly thought of as specific to men, when it comes to cancer, tadalafil is a viable option for women too.
Califano and Borrello recently enrolled the first patient into the clinical trial, which is funded with a National Cancer Institute grant. The study protocol is simple and straightforward. Patients are given a once-daily dose of tadalafil for 10 to 14 days. At the end of the test period, their blood samples are examined to determine the drug’s success in boosting the immune system. Then patients proceed with traditional treatments such as surgery, chemotherapy or radiation therapy. “We’re able to evaluate this drug within the normal clinical treatment schedule,” Califano says. “Patients can enroll and still undergo standard therapies without delay. It’s a nice thing for patients, because they can participate in a clinical trial without sacrificing or delaying other treatment options.”
Right now, Califano is considering tadalafil primarily as a complement to other standard treatments. But, he says, with further investigation there exists the potential that the drug could eventually lessen or eliminate the need for chemo or radiation. “This is a great treatment option,” Califano says, “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.”
The Cialis cancer trial began enrolling patients in April 2009 and is expected to continue for the next year or longer. 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 this trial.
To find out more or to enroll, please call Zubair Khan at 410-955-3157.