By Mary Welch
Diatide Inc. reported mixed — but mostly positive — results from a Phase III study of P829, its imaging agent to detect lung cancer, and expects to file a new drug application (NDA) with the FDA in the middle of this year.
Findings from the trial support an NDA for imaging malignant tumors, but not localizing them, said Richard Dean, president and CEO of Londonderry, N.H.-based Diatide. Still, he said, the small-molecule, synthetic peptide combined with technetium-99m makes the diagnostic procedure easier after an X-ray or computed tomography scan.
"The next step is usually a biopsy," Dean said. "There is no good way to detect whether it's malignant or not without an invasive procedure. With P829, that is no longer the case."
The multicenter lung cancer trial consisted of two clinical studies with 112 patients in one and 114 in the other. The primary endpoint was the agreement of the P829 blinded read, relative to the histopathologic diagnosis for the tumor under evaluation.
Injected P829 peptide attaches itself to the somatostatin receptor on the tumor. After about a two-hour wait, the patient is scanned with a gamma camera, which can pick up the gamma signal emitted by the technetium.
"If a bright light goes off, it means it's cancer," Dean said.
The test required an agreement rate of 80 percent, which would be judged significant if the lower confidence interval was above 70 percent. The agreement rate for malignancy was 76.8 percent in the first study and 81 percent in the second. Those results compare favorably with other nuclear medicine studies in oncology, the company said.
Another part of the test measured whether P829 could identify a malignancy on a regional basis. Due to the complexity of the lung anatomy, and the "hot spot" nature of P829's detection of malignancy, the results did not support precise regional localization of the mass, Dean said.
"Our wording [for the FDA] will be that we will pursue an 'indication for imaging of malignant tumors in the lung,'" said Dean. "It won't have the word 'localization,' but we don't think that's a problem. It's not significant. The big hit is determining whether cancer is there or not."
Diatide will not pursue neuroendocrine or melanoma indications for P829, but will focus attention on larger lung-cancer opportunity instead.
If all goes well, P829 will be available to hospital and outpatient centers by early 2000. The company has not settled on a marketing name for the product.
"We're looking into that right now. We need something else," said Dean. Diatide's collaborator, Oslo, Norway-based Nycomed AS, will market P829 in Europe and will copromote it with Diatide in the U.S.
With the successful completion of Phase III trials, Diatide gets a $2 million milestone payment from Nycomed and another $2 million with the NDA filing. The original 1995 deal called for a $10 million equity placement by Nycomed in Diatide and $2 million per year for research and development grants, as well as other milestone payments.
So far, the deal has been worth more than $15 million to Diatide.
"This will be our second NDA filing in the last two years and provides us with — depending on approval — two products to market," Dean said. The company has received an approvable letter from the FDA on AcuTect, a small-peptide targeting agent coupled with technetium, designed to show when deep blood clots require surgery or may be treated with medication. (See BioWorld Today, Feb. 24, 1998, p. 1.)
Diatide's stock (NASDAQ:DITI) closed Monday at $9.625, down $0.25. *