DuPont brings Definity in-house through acquisition of ImaRx

ImaRx ‘s non-Definity business to the continue in new firm, ImaRx LLC

Du Pont Pharmaceuticals moved to solidify its commitment to Definity ultrasound contrast agent earlier this month. The North Billerica, MA-based company has acquired the outstanding shares of its ultrasound contrast development partner ImaRx Pharmaceuticals. The deal brings all activity associated with Definity under the control of Du Pont. Financial terms were not disclosed.

In 1995, Du Pont, then known as Du Pont Merck, and Tucson, AZ-based ImaRx inked a deal for development and marketing of Definity, then known as MRX-115 Aerosomes (SCAN 12/13/95). Under that agreement, Du Pont held the rights to manufacture, market, and sell Definity in North America, Latin America, and Europe.

As Definity has moved closer to commercialization, it became clear to Du Pont executives that it would make sense for the company to craft an even stronger commitment to Definity by purchasing the product, the worldwide marketing rights, and the patent estate associated with it, according to William DeLorbe, executive vice president of Du Pont Pharmaceuticals’ medical imaging division. The way to do that was to acquire ImaRx Pharmaceutical.

“(The acquisition) really demonstrates our commitment to the ultrasound contrast field,” he said. “All of our efforts are now going to be focused on moving Definity forward and coming up with a strong presence in the marketplace.”

With this deal, Du Pont has also acquired some backup research compounds ImaRx has in the pipeline for ultrasound contrast imaging, DeLorbe said. ImaRx’s Asian marketing partner for Definity, Japanese firm Yamanouchi Pharmaceutical, will now provide milestone payments and royalties to Du Pont. Definity is known in Asia as YM454.

Du Pont and ImaRx have worked closely in their efforts to bring Definity to market. In December 1998, Du Pont submitted a new drug application to the Food and Drug Administration for Definity, seeking approval for its use in heart, liver, and kidney imaging. The company has submitted applications for regulatory approval in Canada and Europe as well.

Du Pont and ImaRx have also waged legal battles together over Definity, participating in patent challenges and legal action against Molecular Biosystems of San Diego and its marketing partner Mallinckrodt (SCAN 5/13/98 and 5/26/99).

Although no ImaRx spokesperson was available for comment, indications are that the company, now known as ImaRx LLC, will continue to move forward with its other products. All of the employees at ImaRx Pharmaceuticals will now be part of ImaRx LLC. Dr. Evan Unger will retain the ImaRx Pharmaceutical name and intellectual property rights to develop targeted drug and gene delivery technology, according to Du Pont.

In addition to the Definity agent developed as part of its relationship with Du Pont, ImaRx has developed a gastrointestinal ultrasound agent. SonoRx, which reduces shadowing artifacts by absorbing and displacing gas in the bowel, was licensed to Bracco, and is unaffected by the Du Pont acquisition.

In other areas, the FDA in 1997 approved an ImaRx-developed MRI oral contrast agent for imaging the gastrointestinal tract. This agent, called LumenHance and based on manganese chloride, was also licensed to Bracco.

Of course, the radiology side of the business is just one facet of ImaRx, which was founded in 1991. Among its various other projects are pharmaceutical delivery systems for therapeutic agents, cosmetics, sunscreens, and gene therapy.

In the imaging pipeline are MRI agents that use manganese, like LumenHance, or gadolinium. These prospective products are in early stages of development for eventual use as MR blood pool enhancers.

Nanogels, composed of manganese using colloidal particles or suspensions, is being developed as an MR agent for imaging the liver. The technology promises to allow a relatively low dose of the rare earth metal and greater organ enhancement. Because the manganese is administered in a biocompatible form, toxicity is not likely. Further back in the pipeline are memsomes, a liver agent designed for MR and based on lipophilic paramagnetic complexes associated into liposomes; and block copolymers for use as liver and blood pool agents in MR.

ImaRx is also adapting microbubble technology to develop new products. Particularly remarkable among these is TomoRx, an oral agent that may enhance both CT and MR images. TomoRx, which is based on a suspension of stable gas microbubbles, produces a stabilized dispersion of gas in the GI tract, thereby lowering density on CT and making the bowel black on MR. The dispersion of gas also distends the intestinal lumen and makes the contrast more uniform throughout the entire GI tract. The product is being positioned to compete with barium contrast.