The owners of a decades-old property in the heart of Warner Center are preparing to redevelop the site. Cornerstone Real Estate Advisors is said to be investigating the redevelopment of 6464 Canoga Ave. at the corner of Victory Boulevard. The redevelopment is still many months, if not years, away, but it is also probably long overdue. Since the 1960s, the site has housed a 60,000-square-foot low-rise office building that now appears almost shabby in comparison to the buildings that have grown up in the surrounding area. Cornerstone, which has owned the property for about seven or eight years, first leased the building to Syncor International Inc., a medical imaging company that was acquired by Cardinal Health Inc. in 2003. Since the acquisition, Cardinal has either laid off or relocated most of the employees that were once employed in the building. But attempts to sublease the property were only somewhat successful, in all likelihood because of the age of the property, which was rehabbed following the Northridge Earthquake. But the Cardinal lease expires this year, leading the owners to reconsider uses for the real estate, sources said. Officials at Cornerstone were traveling and unavailable for comment. Cornerstone, based in Hartford Conn., has a portfolio that spans just about every sector of real estate. But with the property entitled for office development and the current low vacancy rates in that sector, a redevelopment that maintains the office use but expands and improves the property would be most likely. The vacancy rate for office properties in the San Fernando Valley was just 5.6 percent as of the first quarter of 2007, according to data from Grubb & Ellis. In the West Valley, the vacancy rate was 7.6 percent for the same period, but the higher rate in the submarket is largely due to a single building, Trillium, which is quickly leasing up. In all likelihood, Cornerstone will demolish the existing building and reconstruct a larger building, although the size of the new property is yet to be determined. Cornerstone, which provides real estate equity investment services for its parent, Massachusetts Mutual Life Insurance Co., had more than $7.2 billion of property under management as of 2006, according to its Web site. The company has another Warner Center property, and most of its western region holdings are located in other parts of Los Angeles, Orange, San Bernardino and Riverside counties as well as other Western states. Warner Center has been a hotbed of redevelopment activity in recent years, with much of the effort focused on multifamily housing. With the Cardinal lease due to expire, it is also possible that another buyer will step up to acquire the site, but no discussions are believed to be taking place currently.