PRESS RELEASE: Nuvelo Re-Initiates SONOMA-3 Trial of Alfimeprase in Patients With Catheter Occlusion

Nuvelo Re-Initiates SONOMA-3 Trial of Alfimeprase in Patients With Catheter Occlusion

SAN CARLOS, Calif., Aug. 22 -- Nuvelo, Inc. today announced enrollment of the first patient in the SONOMA-3 (Speedy Opening of Non-functional and Occluded catheters with Mini-dose Alfimeprase-3) trial evaluating lead product candidate, alfimeprase, for the treatment of central venous catheter occlusion (CO).

This open-label, single-arm trial will evaluate the safety and efficacy of a single 10 milligram dose of alfimeprase with a concentration of 5 milligrams per milliliter in up to 100 patients with occluded central venous catheters.

Data from a previous Phase 3 trial in the CO program, SONOMA-2, showed that alfimeprase restored catheter function in patients with occluded catheters within 15 minutes with a p-value of 0.022. It did not however, meet the more stringent p-value required for a single pivotal trial, less than 0.00125.

"Analysis of data from our previous Phase 3 SONOMA study provided further evidence that alfimeprase is an active thrombolytic which has the potential to dissolve clots quickly and rapidly restore catheter function, however, the dose and concentration we used did not generate results in line with the target product profile we believe necessary for commercial success in this market," said Michael Levy, M.D., executive vice president of research and development for Nuvelo. "Preclinical experiments have provided evidence that increasing the concentration can result in marked improvement in thrombolytic activity. Accordingly, we are resuming development of alfimeprase in CO to evaluate the potential of a single, higher, more concentrated dose and expect data from this trial in 2008."

About Catheter Occlusion

Delivery of chemotherapy, nutritional support, antibiotics and blood products, as well as the frequent withdrawal of blood samples for laboratory testing, are often facilitated via central venous catheters. Approximately five million catheters are placed in patients in the United States each year, with as many as 25 percent becoming occluded. When a catheter becomes occluded, the goal is to restore flow in a prompt and cost-effective manner with minimal risk to the patient. As these catheters are primarily inserted in patients receiving life-saving medications such as chemotherapy, it is critical to restore flow through the catheter as soon as possible. In the case of thrombotic occlusions, treatment with thrombolytic drugs represents a less-invasive and more cost-effective alternative to replacement.

About Alfimeprase

Alfimeprase is a recombinant direct acting fibrinolytic (rDAF) that has the potential to rapidly dissolve blood clots through a unique mechanism of action -- it directly degrades fibrin, a protein that provides the scaffolding for blood clots. In addition, alfimeprase's thrombolytic activity appears to be localized to the site of delivery because it is rapidly inactivated by alpha-2 macroglobulin, a naturally occurring protein in the blood, as it moves away from the site of delivery and into the general blood circulation.

In addition to catheter occlusion, alfimeprase is also being evaluated as a potential treatment for acute ischemic stroke and is in preclinical studies for acute peripheral arterial occlusion.

About Nuvelo

Nuvelo, Inc. is dedicated to improving the lives of patients through the discovery, development and commercialization of novel drugs for acute cardiovascular and cancer therapy. Nuvelo's development pipeline includes alfimeprase, a direct-acting fibrinolytic for the treatment of thrombotic-related disorders including acute ischemic stroke and catheter occlusion and preclinical candidates NU206 for the potential treatment of chemotherapy/radiation therapy-induced mucositis and inflammatory bowel disease and NU172, a direct thrombin inhibitor for use as a short-acting anticoagulant during medical or surgical procedures. In addition, Nuvelo expects to leverage its expertise in cancer antibody discovery to further expand its pipeline and create additional partnering and licensing opportunities.

Information about Nuvelo is available at our website at http://www.nuvelo.com or by phoning 650-517-8000.

This press release contains "forward-looking statements" regarding the timing and progress of Nuvelo's clinical programs, including the timing of the availability of data from Nuvelo's Phase 3 alfimeprase trials, the potential improvement or benefit that current and future clinical trial programs may demonstrate, and our anticipated revenues, operating expenses and net cash used in operations, which statements are hereby identified as "forward-looking statements" for purposes of the safe harbor provided by the Private Securities Litigation Reform Act of 1995. Such statements are based on our management's current expectations and involve risks and uncertainties. Actual results and performance could differ materially from those projected in the forward-looking statements as a result of many factors, including, without limitation, uncertainties relating to drug discovery; clinical development processes; enrollment rates for patients in our clinical trials; changes in relationships with strategic partners and dependence upon strategic partners for the performance of critical activities under collaborative agreements; the impact of competitive products and technological changes; and uncertainties relating to our ability to obtain funding. These and other factors are identified and described in more detail in Nuvelo filings with the SEC, including without limitation Nuvelo's Quarterly Report on Form 10-Q for the quarter ended June 30, 2007 and subsequent filings. We disclaim any intent or obligation to update these forward-looking statements.