at the vanguard (of something)

Having the leading or foremost position of development among others in a trend, movement, industry, etc. The company has long been at the vanguard of computer technology. Every major advancement has come from their labs over the last 50 years. With its aggressive environmental policies, the small country has remained at the vanguard when it comes to combating climate change. No, I didn't like her latest collection either, but she's such a renowned designer that I simply cannot believe she's no longer at the vanguard of fashion.