Originally, wasn't that antenna tuned for 100.7. Only after what had been WCOP-FM (now WZLX) moved (first, I believe, to the John Hancock building and then to WHERE...
100.7 WZLX ended up on the Pru.
More recently, a (religious, IIRC) outfit had applied to site a 91.7 noncomm there. Obviously, Pat Montheath was not happy and I don't think a CP was ever issued. Now, with WAVM having been granted an increase in power on 91.7, I believe the Lexington 91.7 is a dead issue.
It was Monteith's finally parterning with Maynard H.S. (after years of pending a competing application in Stow, MA that would have completely knocked them off the air) resulting in the granted 500w CP for WAVM, which will time-share programming content with WUMB, that effectively shut out the religious application for Lexington.
Combining the community support for their local high school station with her desire to put more repeaters on the air (even if a time-shared one) and therefore get its power increase CP finally granted (which the H.S. had failed to do on their own for many years while it remained a vulnerable Class D) turned out to be the only effective way to stave off the religious applicants from the frequency in the area.
I may have heard that it will be built once local NIMBY issues regarding a new tower are resolved.