Myogen ( MYOG) said it has signed an agreement that will enable British drug giant GlaxoSmithKline ( GSK) to market the company's top prospect outside the U.S. The drug, still in late-stage clinical testing, is called ambrisentan. The medication is aimed at treating pulmonary arterial hypertension, or PAH, which causes high pressure in the artery that carries blood from the heart to the small arteries in the lungs. PAH can lead to heart failure. Myogen has no commercial products, but the pact provides it with some upfront money as well as the overseas marketing clout of GlaxoSmithKline. In addition, GlaxoSmithKline has licensed to Myogen the U.S. marketing rights for Flolan, an older PAH drug. The British drugmaker gets a piece of the action for ambrisentan, a promising compound in a crowded field of treatments and experimental drugs. Myogen's announcement Monday of its deal with GlaxoSmithKline coincided with the release of its fourth-quarter and full-year financial data. For all of 2005, Myogen lost $63 million, or $1.68 a share, on R&D revenue of $7 million. For 2004, it lost $57.7 million, or $2 a share, on revenue of $6.6 million. The company said the GlaxoSmithKline deal and other development activities make it difficult to offer precise guidance for 2006. "However, we believe our cash, cash equivalents and investments, together with expected licensing proceeds, will be sufficient to fund operations until at least the end of 2007," the company said. "The Flolan distribution agreement is expected to underwrite the development of our own commercial organization and marketing and field-selling expertise in PAH, well in advance of the potential launch of ambrisentan," said J. William Freytag, president and CEO of Myogen, in a prepared statement. "We believe this strategic development will accelerate our understanding of customer needs, reimbursement opportunities and market dynamics in general."