Viagra for Prostate Cancer? 10 Multi-Use Drugs
Sept. 28, 2010 -- Viagra is well recognized for its primary use. But who knew it would show promise as a cancer fighter, too?
Medical advances can be slow -- a fact frustrating to some who want the "latest and greatest" cure for their ailment, and don't want to wait out the testing process.
But once a drug has been approved for one use, doctors can prescribe it "off-label" when it is shown to be useful for something else. And an increasing number of drugs are prescribed in this manner. Off-label use of medicines accounts for about one-fifth of all prescriptions, according to a past study in the New England Journal of Medicine.
Viagra, for example, is a triple threat -- it's most commonly used to treat erectile dysfunction and is FDA-approved to treat pulmonary hypertension, but it can also be used to increase blood flow as a way to avoid amputations. And now, researchers may have found yet another use for the extremely popular drug: to help treat prostate cancer when used in combination with another cancer drug.
There are other drugs that perform double duty, including a skin cancer cream used to smooth out your facial wrinkles, a baldness drug to protect against prostate cancer, and a drug for enlarged prostate and possibly prostate cancer that may stop baldness.
Many of these off-label uses meet with controversy and questions about their value, particularly since the FDA has not yet approved the uses. (As a result, drug companies cannot advertise off-label uses.)
Though the hair loss drug finasteride is recommended by some medical organizations as a preventative measure against prostate cancer, many doctors say that such a use is inefficient and ill-advised.
But in many other cases, the alternative uses are well-known in the medical community -- though perhaps not among the general public -- and are regularly exploited.
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Researchers from Virginia Commonwealth University discovered that in mice, the combination of Viagra and doxorubicin effectively killed prostate cancer cells and also offered a protection against the well-known cardiac effects of doxorubicin, including cardiomyopathy and heart failure. The study is published in the latest issue of the journal Proceedings of the National Academy of Sciences.
"Doxorubicin has been used for more than 40 years and continues to be one of the most effective drugs against cancer, but the problem is the cardiac effects of this drug," said Rakesh Kukreja, professor of internal medicine at Virginia Commonwealth University in Richmond, Va., and one of the study's authors.
Kukreja said the drug combination was also effective against ovarian cancer and stomach cancer, and the findings show it has great potential as a cancer treatment.
Other experts are not convinced of that treatment potential.
"Everything works against mouse tumors," said Dr. Derek Raghavan, chair and director of the Cleveland Clinic Taussig Cancer Institute. He is not connected with the Viagra study.
"These types of data are what have been seen in the field for years and are doubtful to give a long and/or significant impact to tumor growth," said Robert Gertzenberg, professor of urology at the Johns Hopkins University School of Medicine. He is also not connected with the current research.
That Avodart would work makes some sense. Like Propecia, the drug targets the pathway that converts testosterone to DHT, which is the suspected culprit in hair loss.
"There are good studies that show it is effective," said Dr. Marc Avram, clinical associate professor of dermatology at Weill Medical College at Cornell Medical Center. "There are doctors who do give it out there for hair loss.
"Doctors are using it off-label for men," Avram said. "It absolutely should not be used off-label for women."
While women should not use the drug because of the risk of birth defects, questions also remain about its safety as a baldness remedy for men.
In a review article last October in the Journal of the American Academy of Dermatology, Avram and Dr. Nicole Rogers, a hair loss specialist with Old Metairie Dermatology in Metairie, La., wrote that "phase III FDA trials appear to be on hold for using dutasteride to treat male pattern hair loss. It is unclear exactly why, but we hypothesize it is because of concerns about side effects."
Dutasteride lasts much longer in the body than finasteride, and among the side effects the doctors noted was a reduced sperm count among men using the drug.
"The sexual side effect, if you get it, lasts a lot longer than with Propecia," Avram said. "If it affects sperm, they're going to need to do long-terms studies to approve it.
"My feeling is they [GSK] are not really going strong for approval, because to do that, they're going to have to prove that sperm is not affected in any long-term ways," he said.
Avram said he does not typically prescribe the drug.
"My feeling is Propecia works in most men, and between Propecia and Rogaine, we can stop their hair loss," he said.
Study participants who applied the cream twice daily for two weeks were able to reduce the number of potentially pre-cancerous spots on their faces. But in addition to this, researchers also found through clinical evaluation that the subjects enjoyed other improvements in aging-related damage, including fewer wrinkles, fewer dark skin spots and less hyperpigmentation.
The drug, of course, also had side effects -- primarily in the form of redness and irritation shortly after the application of the cream. And even though a number of currently available cosmetic skin treatments have similar or worse side effects, for some consumers these downsides could outweigh the benefits.
"It is possible that for some patients, topical fluorouracil may have an important role against photo-aging," lead study author Dr. Daniel Sachs of the University of Michigan Medical School in Ann Arbor said in a press release. "For others, however, it may not be cosmetically acceptable given that a standard course of therapy may last two to three weeks and the ensuing reaction can persist for several more weeks."
Still, the idea that the drug could one day enter the cosmetic armamentarium is not an outlandish one.
"Undoubtedly, there will be patients who desire a therapy such as topical fluorouracil for cosmetic purposes given the relatively low cost of this therapy compared with ... laser resurfacing," Sachs said.
Indeed, in a 2003 study involving 18,000 men, finasteride was shown to cut the risk of prostate cancer by around 8 percent.
"If a man is getting screened because he's worried about prostate cancer, taking the drug is a very rational thing to do along with screening," Dr. Otis Brawley, chief medical officer of the American Cancer Society, told ABC News.
But at the estimated cost of $90 a month, the drug is expensive. And in the earlier trials there was some evidence that the drug might cause high-grade cancers. While proponents have denied such findings, other doctors have voiced their concern over this potential use of the drug.
"There are way too many side effects, and I believe that if they get cancer on finasteride, it's going to be biologically more aggressive," said Dr. Aaron Katz, director of the Center for Holistic Urology at Columbia University. "This is not the way to prevent cancer of the prostate."
"I still do not feel that this is ready for prime time," agreed Robert Getzenberg, director of urology research at the Brady Urology Institute at Johns Hopkins Hospital. "There are too many important questions that are unanswered."
Dr. Peter Lin, Schanbaum's doctor, who treated her at St. Joseph's hospital outside of Houston, said his team used the drug to see if it would be possible to spare Schanbaum the extensive amputations some physicians suggested as the only way to control the gangrene in her arms and legs.
"Viagra stimulates blood flow," Lin told ABCNews.com. "We wanted as much blood flow to get to the damaged area as possible."
While Viagra's usefulness in this regard has yet to be confirmed, an Australian study this year looked at the possibility that the drug might help increase blood flow to the uterus in pregnant women, which could in turn help developing fetuses receive more oxygen. Other studies have also taken a look at whether the drug could one day be used to increase blood flow to the brains of patients with multiple sclerosis, as well as whether it could help travelers deal with jet lag.
However, the reputation of the drug changed forever in 2002 when the U.S. Food and Drug Administration approved it for the treatment of facial frown lines. Injecting the solution into the faces of their patients, doctors could selectively paralyze certain muscles implicated in the formation of wrinkles.
Now, doctors are further stretching the drug's usefulness by treating patients who experience certain type of hyperlacrimation -- in other words, the overproduction of tears in response to certain stimuli.
For 58-year-old Patricia Webster of Maidstone, England, who had been living with the degenerative nerve condition known as Guillain-Barre syndrome, the occasional shot straight into her tear ducts means freedom from an embarrassing symptom of her condition in which she would appear to cry whenever she ate.
"For the last 18 years of my life I've done nothing, and the embarrassment of my eyes was a major part of this," she told ABCNews.com.
Still, even Webster was skeptical when her doctor first offered up the treatment.
"Of course, I'm thinking, 'Botox ... it's a cosmetic treatment.' I thought, 'He's not worried about my eye, he's telling me that I'm wrinkly,'" Webster said.
In addition to hyperlacrimation, some doctors are also using Botox to help relieve chronic pain.
Dr. Scott Whitcup, Allergan's executive vice president of research and development, told ABCNews.com that researchers noted the eyelash-enhancing side effects of the eye drops during the Phase 3 trials for the drug.
"At the time, we began thinking of developing Lumigan as a treatment for eyelash growth," Whitcup said.
Essentially, the drug works by keeping hairs in their growth phase -- the phase during which they become longer, thicker and darker. Of course, the eyelash-enhancing effects of Latisse are not permanent once the drug is discontinued. And at $120 for a 30-day supply, Latisse is not cheap. But it is still far cheaper (and most likely less risky) than surgical procedures designed to achieve the same end.
So far there is no reliable evidence to show that the syrup does much, if anything, to increase the odds of a woman getting pregnant. The theory, however, is that in much the same way the drug can thin the mucus in your nose and throat, it may also thin the cervical mucus. Thinner cervical mucus means that sperm may have an easier time making it into the uterus to fertilize a waiting egg.
While proof of this remedy remains elusive, it is far from the only home-grown cure that many women look to when it comes to getting pregnant. Some aspiring moms try dietary changes, for example. But because so many factors contribute to a woman's ability to conceive, doctors warn that changing any one variable is not likely to have a huge overall effect on the chances of pregnancy.
"There is really not a single scientific study to show that it definitely works," Dr. Malcolm Roth, director of plastic surgery at Maimondes Medical Center in Brooklyn, N.Y., told ABCNews.com. "Are these chemicals safe when injected into fat? And what happens to this fat? Where does it go?"
Despite the dangers of the procedure, however, the growing number of clinics offering the treatment is a testament to its continued legal status in the United States. Still, the procedure is banned for cosmetic purposes in Brazil and other countries.
"Most physicians performing this procedure do not have training in liposuction, plastic surgery or dermatologic surgery," said Dr. Carolyn Jacob, a board-certified dermatologist in Chicago. "Even dentists are doing it."
In 2004, despite the illegality of the drug, the U.S. government authorized a human study of its potential to help those suffering from the emotional scars of a traumatic event.
However, while some patients in the study felt that they had benefited from the drug, today it remains on the government's list of Schedule I drugs -- a classification that includes heroin, cocaine and methamphetamines. Still, some hope that the restrictions on the drug's use may one day be lifted to help soldiers returning from war deal with psychological trauma.
Despite these tragic and high-profile outcomes, a small group of patients did benefit from using the drug -- those with a severe and debilitating leprosy-associated complication known as erythema nodosum leprosum (ENL).
Considering the small number of people today who live with leprosy, it may come as little surprise that the silver lining of this devastating drug remains relatively secret. And the World Health Organization still recommends against the use of the drug to treat the ravages of ENL due to birth defects.
Nonetheless, in 1998 the FDA cleared the drug's use for leprosy under strict supervision. Women who are candidates for receiving the drug are required to undergo pregnancy testing both before and during their treatment with the drug. Men using the drug are required to use a condom whenever they have sex with a woman, and all patients are limited to a 28-day supply and must see a doctor before getting more of the drug.
Reports from Emily Friedman, Radha Chitale and Bob Woodruff contributed to this report.
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