Purdue University scientists have developed a new molecule that is capable of carrying a pharmaceutical load straight into prostate tumor cells. For now only confirmed in laboratory studies, the new particles will soon be tested in clinical trials when scientists couple them with new imaging agents that can also come along for a ride.
Purdue press office explains:
The molecule Low’s team created [Philip Low, the Ralph C. Corley Distinguished Professor of Biochemistry –ed.] attaches to prostate-specific membrane antigen, or PSMA, a protein that is found on the membrane of more than 90 percent of all prostate cancers. It also is found on the blood vessels of most solid tumors and could provide a way to cut off the tumor blood supply, Low [Philip Low, the Ralph C. Corley Distinguished Professor of Biochemistry at Purdue] said.
“A lot of new drugs are being designed to destroy the vasculature of solid tumors, and, if they could be linked to this new targeting molecule, we could have a two-pronged attack for prostate cancer,” he said. “We could not only kill the prostate cancer cells directly, we could also destroy the vasculature that feeds the tumors.”
There also is potential for the targeting molecule to be used to attack the vasculature of solid tumors of other types of cancers, Low said.
The team’s animal study data shows an ability to eliminate human prostate cancer cells in mice with no evidence of collateral toxicity in normal tissue.
Sumith Kularatne, a graduate student in Purdue’s chemistry department and first author of both papers, compared the targeting molecule to a homing device.
“The molecule acts like a homing device for prostate cancer,” he said. “PSMA, which is found only on prostate cancer cells and tumor blood vessels, acts as the homing signal that the molecule targets. The molecule and its cargo go only to cancerous tissue, leaving healthy tissue unharmed.”
Once the molecule reaches the PSMA protein, it binds to it. The molecule is designed with a specific shape that fits with the protein like a key to a lock, Kularatne said. The molecule and its cargo are then carried inside the cell with the protein as it goes through its normal cycle.
A clinical trial of the radioimaging application is expected to begin at the Indiana University Medical Center in the fall through a collaboration between the Purdue Cancer Center and the Indiana University Melvin and Bren Simon Cancer Center with additional support from Endocyte Inc.
A radioimaging agent linked to the targeting molecule will be injected into prostate cancer patients and pictures will be taken using a special camera that detects radioactivity. The pictures show where the cancer is present to help doctors determine if it has metastasized, or spread, to any other areas of the body. It also will help doctors decide on the best course of treatment, Low said.