Rexahn Adds Drug Conjugate Platform To Its Oncology Offerings

The Rockville, Md.-based biotech hopes to bring more value to shareholders through a slew of polymer-conjugated cancer drugs that it will add to its pipeline while it continues moving its three lead cancer compounds forward.

Rexahn Pharmaceuticals Inc. is hoping to de-risk its oncology pipeline by adding a new technology platform to the mix that builds on currently marketed chemotherapies. The Maryland biotech has licensed the technology from the University of Maryland, Baltimore.

The Nano-Polymer-Drug Conjugate Systems (NPDCS) platform coats a currently marketed chemotherapy agent in a polymer carrier with a signaling moiety attached that directs the drug to the tumor. Rexahn CEO Peter Suzdak explained in an interview that this targeted action prevents excess drug from entering the circulatory system and floating freely in the bloodstream, thus minimizing adverse effects and potentially increasing the potency of the drug due to the higher concentration of the chemotherapy agent in the tumor.

The terms of the deal, announced July 17, were not disclosed. The initial funding for the deal came from the Maryland Industrial Partnership award, a program that facilitates relationships between industry and academia.

Rexahn already has determined its first drug candidate from the platform, RX-21101, a polymer conjugated form of docetaxel. The common chemotherapy agent is available as a generic, but is sold under the brand name Taxotere by Sanofi. Taxotere is used in the treatment of breast, prostate, ovarian and non-small cell lung cancer and has annual sales over $3 billion. Yet, Taxotere has a high incidence of adverse events, including nausea, vomiting, anemia, fever and hair loss. Rexahn hopes to improve on this profile.

“So, it’s potentially a win-win situation; having something that has increased efficacy and a lower potential for adverse events,” said Suzdak. “With this type of platform, the company would have the capability of generating a number of different development candidates for a number of the anti-cancer compounds that are currently in the market.”

Suzdak said that the compounds differ from other drug conjugates because they are based on compounds that are proven to work and not entirely new chemical entities. “A lot of the other technologies are novel technologies and obviously have a lot of risk associated with them – normal risk that would be associated with a new chemical entity,” said Suzdak. “What is unique about what we are doing from a risk perspective is that it is much lower risk.”

Suzdak added that the company would be open to partnering or out-licensing some of the compounds developed using the technology as a line extension for the initial compounds. “If we out-license some of these, it would be a revenue source for the company that would help to offset at least some of the costs of the clinical development we are doing with our three main programs,” he added.

De-risking Its Pipeline

Rexahn recently has streamlined its operations, dropping development of several programs in central nervous system disorders and concentrating all of its efforts on oncology. The new direction was prompted by Suzdak taking over as CEO in February when the former CEO and founder Chang Ahn chose to move to the position of chief scientific officer (Also see "Rexahn Looks For Breakthrough Year With Three Clinical Candidates" - Pink Sheet, 15 Feb, 2010.).

The company’s pipeline now includes Archexin, a first-in-class Akt inhibitor, which was granted orphan drug status from the FDA for five types of cancer: pancreatic, ovarian and stomach cancer, renal cell carcinoma and glioblastoma. The drug was shown to be safe and tolerable in a Phase I study and has completed a small Phase IIa study in advanced pancreatic patients. Patients in the single-arm, open-label trial were given Archexin with the current standard of care, gemcitabine (Eli Lilly & Co.'s Gemzar). The therapy was shown to extend median survival by 9.1 months.

Rexahn also has two compounds in Phase I – RX-3117 and supinoxin (also known as RX-5902). RX-3117, which is partnered with Teva Pharmaceutical Industries Ltd., inhibits DNA and RNA synthesis and induces apoptotic cell death by a mechanism distinct from other DNA synthesis inhibitors. Preclinical studies have shown it be effective in inhibiting the growth of solid tumors in several types of cancer.

In 2012, Teva conducted a Phase I study in Europe and announced earlier this month that it has filed for an IND in the U.S. Phase I studies in the U.S. are expected to begin later this year. Teva originally signed its agreement with Rexahn in 2009 and currently owns a 6.3% stake in the biotech [See Deal].

Supinoxin is an orally administered inhibitor of phosphorylated p68, which is found only in cancer cells. A Phase I clinical trial in cancer patients with solid tumors is expected to begin in the third quarter.

The company recently shelved an erectile dysfunction drug called zoraxel and the depression drug serdaxin. Suzdak said the company would has made it known that it would like to license these compounds out to any interested parties, but that Rexahn will not devote any further time or money to the drugs.

Jessica Merrill contributed reporting to this story.