Omniscan inventor sees parallels inMRI and ultrasound contrast results

Sonus explores targeted ultrasound media

Clinical trials for ultrasound contrast agents are showing resultssimilar to those of early studies conducted for MRI agents, accordingto Dr. Steven Quay, founder of ultrasound contrast developer SonusPharmaceuticals of Bothell, WA. In many early clinical trialsfor the company's products, the use of ultrasound contrast mediais changing a physician's diagnosis, Quay said.

Quay developed Omniscan while with Salutar, which licensedthe agent to Sterling Winthrop. Salutar was purchased by HafslundNycomed in 1989 (SCAN 4/12/89). Nycomed bought Sterling's diagnosticimaging business last year (SCAN 6/13/94).

After leaving Salutar, Quay formed Sonus to develop ultrasoundcontrast media. The company's lead product is EchoGen, an intravascularultrasound agent for echocardiography and perfusion studies thatis based on a phase-shift colloid technology developed by Quay(SCAN 5/5/93).

EchoGen has completed phase-two clinical trials. The studiesindicate that there should be a broad range of applications forultrasound contrast media, Quay said. Quay made a presentationon ultrasound contrast agents at the Hambrecht & Quist LifeSciences Conference in San Francisco last month.

In the U.S., Molecular Biosystems' Albunex is the only ultrasoundcontrast agent with regulatory approval (SCAN 8/31/94). Albunexis indicated for enhancing opacification of the heart's left ventricleand is sold in North and South America by Mallinckrodt Medicaland in Europe by Hafslund Nycomed.

In addition to EchoGen's cardiology applications, Sonus ishoping the product will have utility in radiological applications.Physicians surveyed in EchoGen trials said ultrasound contrastimproved or assisted a diagnosis in 76% of studies, accordingto Quay. When EchoGen was used as part of a baseline ultrasoundexam, it reduced the need for follow-up studies by modalitiessuch as MRI or CT in 47% of cases, according to physicians surveyed.The results are similar to those reached in early work on Omniscanand indicate that ultrasound contrast could enjoy the same levelof clinical acceptance and usage experienced by MRI agents, Quaysaid.

A fundamental difference between ultrasound and MRI contrastis pricing, however. Due to the lower cost of ultrasound exams,ultrasound contrast will not be able to command the prices ofMRI agents. Sonus hopes to overcome this obstacle by demonstratingthe clinical value that contrast adds to an exam.

"We are very sensitive to the price of the product andthe price of the scan, but we are trying to look at what the patientis like before they do the imaging process, and what we know aboutthem afterwards," Quay said.

Despite pricing issues, Sonus estimates that there is a $2billion global market for ultrasound contrast agents, and thecompany has been lining up marketing partners around the world.Sonus recently signed an agreement with Guerbet of France forclinical development, regulatory registration and commercializationof EchoGen in Europe. Sonus will receive milestone payments, fundingfor development of EchoGen and manufacturing and royalty paymentsfor European sales. The agreement complements a deal with DaiichiPharmaceutical for Japanese sales of EchoGen (SCAN 9/14/94). Sonusdoes not yet have a U.S. marketing partner for EchoGen, althoughAbbott Laboratories has agreed to manufacture the agent.

In addition to EchoGen, Sonus is conducting early researchon compounds that target pathology such as tumors or infections.By placing these compounds on the surface of its microbubble colloids,Sonus may be able to develop ultrasound agents that can home inon disease.

The compounds are carbohydrate moieties that are attractedto receptors such as selectins on the surface of endothelial cells.Selectins are produced by endothelial cells near infections, infarctsor tumors as a way of attracting white blood cells to fight thepathology. Sonus hopes to have a product in human clinical trialsin about two years, Quay said.