RMD looks before leaping into MoAb probe market

Radiation Monitoring Devices is in no rush to get a product tomarket. The firm manufactures and supplies custom radiation-detectingprobes to researchers for applications such as monoclonal antibody-guidedsurgery and diagnosis. The devices are similar to those underdevelopment by Neoprobe and Care Wise Medical Products (SCAN 2/24/93and 12/04/91).

Unlike these companies, however, RMD is content to let thetargeted tracer market sort itself out before jumping in witha commercial product, according to vice president Jacob Paster.

RMD, of Watertown, MA, is a privately held company formed 20years ago as a spin-off from technology firm Tyco Laboratories.The company's claim to fame is the manufacture of radiation-detectioncrystals made from cadmium telluride. Cadmium telluride's highatomic number enables the manufacture of small detectors thatare easily built into hand-held probes, according to Paster.

During probe-guided surgery and diagnosis, a patient is injectedwith an imaging agent like a radiolabeled monoclonal antibody,which seeks and binds to cancerous tissue. When a surgeon appliesthe probe to tissue believed to be cancerous, a control unit attachedto the probe emits an audible signal if any radioactivity is detected.Surgeons are thus able to remove cancers that might have beenmissed if they were relying on sight and touch to find tumors.

Neoprobe and Care Wise are the main competitors in the radiation-detectingprobe market. Care Wise's C-Trak device works with technetium-99m,indium-111 and iodine-131, and the company has been marketingthe unit for the past several years.

Neoprobe intends to market as a package its radioimmunoguidedsurgery (RIGS) system and the monoclonal antibody it is designedto detect. The monoclonal is CC49, licensed from Dow Chemical,and labeled with iodine-125. While Neoprobe has Food and DrugAdministration marketing clearance for its probe, the companyis awaiting FDA approval for the monoclonal antibody, which isin phase three clinical trials for colorectal cancer.

Unlike Neoprobe, Care Wise does not plan to market a monoclonalin conjunction with its probes, according to president and CEORobin A. Wise.

THE PROBLEM WITH NEOPROBE'S APPROACH is that it could tie a companyto a single monoclonal antibody that might become obsolete oncea new technology comes along, according to Paster. For example,companies that spent millions developing monoclonal antibodiesare shifting to peptide-based targeting imaging agents becauseof their greater utility and cost-effectiveness (SCAN 10/6/93).

"It was never clear to us that there was (a monoclonalantibody) that was so outstanding that clearly it was going tobe something you could point to and say, `That's it, there's whereyou should direct your efforts. No matter what happens, that'sgoing to be a success,'" Paster said.

RMD has avoided putting all its antibodies in one basket bymanufacturing probes that detect a variety of radioisotopes usedin a range of clinical applications. RMD builds probes to thespecifications of researchers, and the company's clients includeinvestigators for both medical imaging vendors and governmentagencies.

Some of RMD's intraoperative surgery probes include a Tc-99m-measuringprobe to locate a type of benign bone cancer called osteoid osteoma.RMD's monoclonal antibody probes include devices for use in detectingIn-111- and Tc-99m-labeled monoclonal antibodies for colorectalcancer. RMD also makes a surgical probe using a cesium iodidescintillation crystal coupled to a photomultiplier tube for usein detecting Tc-99m.

Other probes have been designed for detecting thrombosis andmeasuring xenon-133 washout from organs.

RMD isn't averse to entering the commercial market if one ofits products does show promise, according to Paster. It is nowin discussions with an unnamed company about marketing its technology.

"At such time as there are protocols that are approvedwhere one requires a truly optimized probe for an application,we will then seek to have our probes approved for general use,"Paster said.

Whatever course RMD takes, the company believes its experiencein manufacturing probes will enable it to focus on the radiopharmaceuticalthat will finally fulfill the promise of targeted imaging.

"We have a great number of probes out, and what we getis feedback from investigators," Paster said. "We aredoing what we do best, which is building probe technology andresponding to investigators' needs. Hopefully, we will have enoughinsight over time to be able to narrow down the field and focuson where we think the commercial opportunity is going to be."