- An experimental vaccine developed by Astellas Pharma Inc. and its biotech partner Vical Inc. failed to protect hematopoietic stem cell transplant recipients from cytomegalovirus (CMV) in a Phase 3 study, setting back the companies' hopes for the candidate.
- "We are disappointed that the results did not demonstrate a significant improvement in overall survival and reduction in CMV end-organ disease," said Bernhardt Zeiher, president of development at Astellas, in a Jan. 22 statement.
- Astellas made no mention of whether further work on the vaccine would be halted, but the trial miss follows a 2016 Phase 2 failure of the vaccine in kidney transplant patients who received an organ for CMV-seropositive donors.
Astellas and Vical joined forces in 2011 to develop the vaccine, called ASP0113. Since then, Vical has relied on the partnership for much of its revenue, providing R&D and supply services to the Japanese pharma.
All told, roughly 90% of Vical's revenue from 2014 to the present has come from payments by Astellas related to license fees or development of ASP0113.
The recent setback in Phase 3 leaves the vaccine's future uncertain. After the 2016 miss in kidney transplant patients, Astellas informed Vical it would discontinue further development in solid organ transplant indications.
Now, topline results disclosed by the companies reveal the vaccine didn't prove beneficial in stem cell transplant recipients either.
Astellas enrolled 514 patients into the Phase 3 study, which was designed to measure overall mortality and CMV end-organ disease through the first year following transplant. While the vaccine was well tolerated, data showed patients receiving treatment were no better protected than placebo.
CMV is a type of herpes virus that commonly infects adults in the U.S. Typically, the body's immune system holds the virus in check, but is unable to clear latent infections. This can become a problem for individuals whose immune system is compromised or otherwise dysfunctional.
Other companies are targeting the virus, too. Merck & Co., for example, recently received U.S. approval for Prevymis (letermovir), an oral tablet indicated for prevention of CMV infection in adult patients seropositive for the virus who receive a hematopoietic stem cell transplant.