LEXINGTON, Mass.--(BUSINESS WIRE)--Dec. 21, 2005--Cubist Pharmaceuticals, Inc. (Nasdaq: CBST) today provided data from a recently concluded Phase 2 study of HepeX-B(TM) as maintenance therapy to prevent reinfection with hepatitis B in patients with liver transplants. Data from liver transplant patients who were treated with monthly infusions of 20 or 40 mg HepeX-B versus 5000 IU of HBIg showed that patients with either dose of HepeX-B experienced no evidence of viral reinfection. The data also showed fewer and less serious adverse experiences reported in both HepeX-B groups as compared to the HBIg group, although the differences were not statistically significant given the number of patients in the trial. Patients who were treated with HepeX-B as well as HBIg also received concurrent HBV polymerase inhibitor. The Company will be reviewing Phase 2 results with the U.S. Food and Drug Administration (FDA) early in 2006.