Taking Better Aim at Tumors

(DGIwire) – When it comes to treating cancer, chemotherapy and immunotherapy have proven to be powerful within certain limits. Take immunotherapy: Despite its great promise, it doesn’t help every patient to which it is given—and its track record of success is uneven among different cancers. So notes Douglas J. Swirsky, President and CEO of Rexahn Pharmaceuticals, in a recent article in Western Pennsylvania Healthcare News.

“With an eye toward boosting the effectiveness of both chemotherapy and immunotherapy, some research is focusing on specific compounds that are not only active against the toughest cancers but are also highly selective,” Swirsky notes. “This means that they have the ability to destroy cancer cells while leaving healthy cells intact.”

Rexahn is studying its proprietary compound RX-3117 in pancreatic cancer and advanced bladder cancer, and another compound, RX-5902, in triple negative breast cancer. The company believes there is a strong possibility that these compounds—administered alone or in tandem with either chemotherapy or immunotherapy—can do a better job of knocking these cancers out.

 Broadly, RX-3117—which has been granted orphan drug designation—can bind with an activation enzyme found mainly in cancer cells. Once activated, this compound travels into a cancer cell’s nucleus where it is incorporated into the DNA and RNA, resulting in the cell’s death. This approach differs from traditional chemotherapy, which non-selectively kills both cancer cells and normal healthy tissue in the body. Studies to date indicated that in addition to killing cancer cells while leaving healthy cells intact, RX-3117 has shown few severe adverse events and allows oral dosing. It may also be able to work in tandem with existing therapies and facilitate a spectrum of anticancer activity.

RX-3117 is being evaluated in combination with a chemotherapeutic drug in patients with metastatic pancreatic cancer. Preliminary data from the first 24 patients in the study show that RX-3117 is safe and well-tolerated. One patient experienced a complete response after six months of therapy; eight patients exhibited a partial response; and a further 13 patients had stable disease. The overall response rate was 38 percent and the disease stabilization rate at eight weeks was 92 percent.

Meanwhile, RX-5902 binds to a key protein that is also found primarily in tumor cells and only in very small amounts in normal tissue. By doing so, RX-5902 turns off cancer genes, resulting in a decrease in cancer cell growth and metastases, and an increase in the body’s immune system’s ability to fight cancer. Preliminary data from a triple negative breast cancer study in patients whose cancer had progressed after multiple prior treatments showed encouraging clinical responses, with two patients showing stable disease for longer than 200 days. Notably, one subject—a 78-year-old woman with malignant neoplasm of the right breast who had progressed on all of her previous therapies—showed an overall tumor reduction of more than 18 percent.

“‘Small and selective’ could turn out to be the traits that mark the next step in the treatment of a slew of traditionally hard-to-treat cancers,” adds Swirsky.