Diatide Awarded Eleventh Patent for Cancer Diagnosis and Therapy Technology.

LONDONDERRY, N.H.--(BW HealthWire)--Feb. 18, 1999--Diatide, Inc. (Nasdaq:DITI) announced today that it has been awarded its eleventh patent for its cancer diagnosis and therapy technology platform. U.S. Pat. No. 5,871,711 covers proprietary peptides that bind to somatostatin receptors concentrated on certain tumors. The peptides claimed in this patent may be used with or without radioactive labels to yield clinically useful pharmaceuticals for highly specific imaging and treatment of certain cancers.

"This patent is a valuable addition to our intellectual property estate in cancer targeting technology, an asset that is enabling us to aggressively develop diagnostic agents and therapeutics for specific tumor types," said Richard T. Dean, Ph.D., President and CEO of Diatide. "By strengthening our market exclusivity in this area, we believe we are building value for shareholders and prospective corporate partners while pursuing a substantial unmet medical need for safer, more effective anticancer agents."

U.S. Pat. No. 5,871,711, "Radioactively Labeled Somatostatin-Derived Peptides for Imaging and Therapeutic Uses", joins a group of five related Diatide patents: U.S. Pat. Nos. 5,716,596; 5,814,298; 5,820,845; 5,833,942; and 5,843,401. The group claims the Company's somatostatin receptor-binding peptides that are cyclized through a single sulfur atom (cyclizing thioethers). Diatide's cyclizing thioether technology yields stable somatostatin analogs that can be labeled with technetium-99m and other nuclides. The patent awarded today claims compositions, manufacturing, and use of somatostatin analogs for cancer diagnostic and therapeutic purposes.

Somatostatin receptors targeted by Diatide's Techtide(R) (diagnostic) and Theratide(TM) (therapeutic) peptides are believed to be concentrated on the cells of some tumors. Diatide's somatostatin analog patent estate also includes U.S. Pat. Nos. 5,225,180 and 5,405,597, which claim compositions and methods for direct labeling of peptides capable of forming a disulfide bond; U.S. Pat. No. 5,783,170, which claims cyclic somatostatin analogs that do not contain sulfur atoms in the cyclic portion of the molecule; and U.S. Pat. No. 5,620,675, which claims a broad class of linear somatostatin analogs. In addition, Diatide holds U.S. Pat. No. 5,849,261 which claims peptides specific for vasoactive intestinal peptide receptors believed to be expressed in other cancers. The Company also has filed patent applications for other cancer-related peptides.

"Diatide has synthesized several hundred cancer-related peptides, an accomplishment that may eventually allow the Company to develop pharmaceuticals that target a wide array of receptor subtypes found on many tumor cell types," Dean said. "This capability has substantial favorable implications for our long-term business development prospects and product pipeline."

Diatide is a specialty pharmaceutical company developing a novel line of disease-specific diagnostic and therapeutic agents - Techtides(R) and Theratides(TM) - as pharmaceuticals with commercial and medical promise. Diatide has applied its proprietary technologies in the areas of peptide engineering and radiolabeling chemistry to produce a number of small molecules that bind with high affinity and specificity to targets on diseased tissue and to which a radioisotope can be attached for imaging or therapeutic purposes.

To date, the Company has received 39 U. S. patents and has licensed rights to seven more. On December 16, 1998, the Company received an approvable letter from the FDA for its New Drug Application (NDA) for NeoTect(TM), for the scintigraphic imaging of suspected malignant tumors in the lung. On September 15, 1998, Diatide announced receipt of marketing approval from the FDA for AcuTect(TM), for the scintigraphic imaging of acute deep vein thrombosis (blood clots) in the lower extremities. For these two products, Diatide has a marketing and sales collaboration with U.K.- headquartered Nycomed Amersham plc, the world's leading diagnostic imaging company and one of the largest research-based biotechnology suppliers to global markets.

Diatide is based in New Hampshire, where it conducts most of its research and development activities with a staff of over 80 full-time employees, including 15 Ph.D.s and two MDs on its research staff. More information on the Company can be obtained from its web site, http://www.diatide.com.

This press release contains forward-looking statements that involve a number of risks and uncertainties. For this purpose, any statements contained herein that are not statements of historical fact may be deemed to be forward-looking statements. Without limiting the foregoing, the words "believes," "anticipates," "plans," "expects," "intends," and similar expressions are intended to identify forward-looking statements. Important factors that could cause actual results to differ materially from those indicated by such forward-looking statements are set forth under the caption "Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations - Certain Factors That May Affect Future Results" ("Certain Factors") in the Company's Annual Report on Form 10-K for the year ended December 31, 1997 which is on file with the Securities and Exchange Commission. These Certain Factors are incorporated herein by reference. As more fully described in the Certain Factors, the Company's potential products (other than AcuTect(TM)) are all still in development. There can be no assurance that the Company's potential products will demonstrate the safety, efficacy, and cost attributes currently expected by the Company. There can be no assurance that the claims allowed under the Company's issued patents will be broad enough to protect the Company's technology; that any patents issued to the Company will be sustained if challenged in court proceedings, or otherwise; or, that third parties will not develop products or processes that do not infringe any valid patents held by the Company. There can be no assurance as to when the FDA will complete its review of the NDA for NeoTect(TM) (P829); and, there can be no assurance that the Company will receive regulatory approvals to commence or continue clinical trials of product candidates, or to market any products, including NeoTect(TM); and, there can be no assurance that AcuTect(TM), NeoTect(TM) , or the Company's other potential products will be commercially successful, or accepted by the medical community or third-party payors, or that technologies, patents and proposed products of other companies will not render the Company's products obsolete or noncompetitive.