New Drug Delivery System May Offer Clinical Advantages in Prostate Cancer Treatment

A potential new treatment under development for prostate cancer may offer clinical advantages, researchers reported at the annual meeting of the American Urological Association in Atlanta. The new therapy uses Atrix Laboratories’ innovative Atrigel drug delivery system to administer a sustained release of leuprolide (Lupron) subcutaneously, rather than intramuscularly, for 30 to 120 days.

“The intramuscular injections are often quite painful,” said Dr. Ramon Perez, director of research at the Urology Health Center in New Port Richey, Florida. Dr. Perez is conducting clinical studies with this new treatment. “Leuprolide acetate in the Atrigel system uses a smaller needle, and the subcutaneous delivery is far more comfortable for the patient,” he continued. “My patients who are now required to switch to the other formulations because of Atrix study completion voice a remarkable preference to stay on the new Atrix therapy.”

Less Invasive, Less Traumatic

Of the more than 180,000 American men diagnosed with prostate cancer annually, a large percentage tend to be older and without great muscle mass, making intramuscular injections more difficult.

“It is less traumatic and invasive to administer treatment in these patients subcutaneously and, assuming its effectiveness is comparable to current therapy, this is likely to make the Atrigel formulation an important new treatment option,” said Dr. Maury Jayson, a principal investigator with the Medical and Clinical Research Associates of Bay Shore, New York.

Dr. Perez noted that intramuscular injections have produced several instances of bothersome tissue bleeding in patients who are also receiving anticoagulant therapy, causing marked discomfort. “With patients on anticoagulants, we definitely prefer subcutaneous delivery,” he said. “In these patients, I like the 30-day release time because that means a smaller volume and thus a smaller needle.”

The new Atrigel formulation is injected subcutaneously as a liquid. Once administered, it solidifies and releases a predetermined systemic dose of leuprolide continuously as it is bioabsorbed. The sustained levels of leuprolide have been found to result in a marked decrease in testosterone levels, which, in turn, suppresses tumor growth in patients with hormone-responsive prostate cancer.

Further Trials

Atrix recently announced successful preliminary results of ongoing phase III trials of its 30-day leuprolide formulation, and has submitted investigational new drug applications to begin clinical trials of Atrigel formulations releasing leuprolide for 90 and 120 days, respectively. A single injection of the bioabsorbable Atrigel product has been shown to result in significant blood levels of the medication.

“The Atrigel drug delivery technology is not only easier for medical professionals to use and more acceptable to patients, but is much simpler and less costly to manufacture,” said David Bethune, chairman and chief executive officer of Atrix. “It allows for the sustained release of virtually any pharmaceutical, ranging from small molecules to complex peptides and proteins, and over times ranging from a few days to several months.”

According to the manufacturer, unlike microcapsules or microspheres, which are usually injected intramuscularly, the subcutaneously administered Atrigel can also be easily retrieved if treatment needs to be discontinued. Moreover, the system can be administered with a standard needle or syringe, and unlike many implants now used for long-acting drug delivery, it is bioabsorbable and does not require surgical removal.