Bayer HealthCare Pharmaceuticals Inc. and Onyx Pharmaceuticals Inc announced on Thursday that they have begun a Phase 3 test of the drug Nexavar to boost the effectiveness of two cancer treatments.

The trial, called STORM, will enroll around 1,100 patients with hepatocellular carcinoma, or primary liver cancer. They will be administered either two 400-milligram Nexavar tablets per day, or a placebo, for up to four years and observed to determine the use of the Nexavar as an adjuvant treatment.

Nexavar was discovered and is being co-developed by Emeryville-based Onyx and Bayer. It is one of Bayer’s most promising new drugs. Sorafenib, the main component in Nexavar, belongs to a new class of cancer treatments known as kinase inhibitors, which deactivate the enzyme that trigger tumor cell growth or cell division. The drug is designed to suppress tumor growth rather than destroying existing cancer cells.

The company says that it expects this drug to generate combined annual sales of billions of dollars.