NPS Pharmaceuticals, Inc. reported encouraging preliminary results from a two-year rat carcinogenicity study of Preos, its full-length human parathyroid hormone (PTH) drug candidate being developed for the treatment of osteoporosis. Based upon these findings the company believes it has identified a non-carcinogenic dose of Preos, and confirmed the positive effects of Preos on bone seen in other animal studies and in human clinical trials.

The preliminary study data are summarized below. NPS recently completed a pivotal Phase III clinical trial with Preos and plans to submit a New Drug Application (NDA) to the US Food and Drug Administration next year for clearance to market Preos.

The two-year rat carcinogenicity study was initiated as a component of a standard toxicology package for submission with the Preos NDA. Bone cancer (osteosarcoma) was observed in similar studies of teriparatide, an N-terminal fragment of PTH. Although the complete toxicological, pathological, and histopathological data from the Preos rat study are still being compiled, an analysis of the available data indicates that:

1) There was no difference in the incidence of osteosarcoma seen in the low-dose and control arms of the study;

2) A dose-related increase in the incidence of osteosarcoma occurred in the mid- and high-dose arms of the study, but at rates that appear to be lower than those observed in published carcinogenicity studies using teriparatide; and,

3) The bone-building effects of Preos, as measured by increases in bone mineral density, bone mineral content, and bone size has been confirmed.

Dr. Hunter Jackson, NPS chairman and CEO said: "We are pleased with the results of this study, which include the observation of a non-carcinogenic dose. While we do not yet have all the data necessary to perform a complete statistical analysis of the study, we believe, based on previously documented background incidence of osteosarcomas in Fischer 344 rats, and the similar survival profile of the low-dose and control groups in this study, that our data are consistent with a non-carcinogenic level at the study's low dose. This dose in rats represents approximately four times the exposure we are testing and will propose for human clinical use.

"There also appears to be a lower frequency of bone lesions in this study versus those in similar teriparatide studies. This result may be due to the activation of a unique set of receptors that responds to the C-terminus of PTH, which is present in Preos, but not in teriparatide. We are continuing to explore this difference in receptor activation as a potential explanation for pharmacological differences between Preos and teriparatide. At the same time, we are compiling and look forward to reporting our Phase III results and to submitting our NDA to the FDA next year."