No sooner do I develop a new interest in graphic novels, then I learn that a graphic novel company publishing YA no less has ceased publication. Why a US alternative to manga failed in The Guardian suggests the problem was that "the quality wasn't actually very high." He singles out The Plain Janes by Cecil Castellucci, Minx's first novel, as an example.
The Comics Reporter has a more sophisticated account of Minx's demise. The author, Tom Spurgeon does say, "...it could simply be the books just weren't doing it for their intended audience. They were books you could convince yourself might be successful, not books that you were stunned to find out weren't." (The intended audience, by the way, was teenage girls.) But he also quotes a former inventory manager at Borders as saying the bookstores didn't shelf the books in the right place and that DC didn't ask them to. I'm not a hundred percent clear on where the right place was, though, and why a bookstore needed to be told by a publisher where to shelf books.
Link from Blog of a Bookslut.