Oh yeah, I've pitched plenty of comics that got rejected by publishers! 
Back in around... I dunno, like, '08? I pitched to do Measure for Measure for the Self Made Hero Manga Shakespeare series, which was largely created by young UK-based illustrators.
I imagined it with a Gothic, New-Romantic kind of feel to complement the play's themes of lust, sin and death, and how it's a "problem play" that's kind of a comedy, but veers close to tragedy.
The series is still in print and sold internationally, but the publisher told me when I pitched this, they weren't making them any more. (and to be fair, they never made any more, so it wasn't a lie.)
It's old work, but unlike a lot of my old failed pitches, this one hurts because it actually holds up all right, it was definitely my best work at the time and I'm a massive Shakespeare nerd. I'd have liked to have made this.
Maybe someday I'll make it myself, but I'd have to redesign Angelo, I kinda used his design a bit for Urien in Errant hahahaha!