GameRant ran an article a while back entitled 9 Best Vampire Manga With No Anime Adaptations. As you'd imagine, it focuses on nine vampire manga which haven't yet been adapted into anime, and Cirque Du Freak is one of the nine (listed at #2).

There was exploratory talk between my agent and Japanese publishers, many years ago, of possibly adapting Cirque Du Freak into an anime. My publishers were keen to push the project further, but unfortunately the movie rights were under option in the USA, and the studio there didn't want any competition, so the talks didn't lead anywhere. It's not beyond the realms of possibility that it could happen one day in the future, but I'd say it's fairly unlikely.

As the writer of the article notes, there was a "competition" of sorts to choose the adpating artist for the manga. Several artists were invited to draw a sample chapter (it might even have been a few chapters - if I recall correctly, the works sent to me were fairly long) and they were sent to me to judge. The standard was incredibly high, but my favourite by a long way was the one submitted by a very young, inexperience artist called Takahiro Arai. It wasn't as polished as most of the other pieces, but I was immediately captivated by his story-telling. Even though the text wasn't in English, I could follow the action seamlessly, and the story moved in a way that the other pieces didn't. He was my pick, and the publishers went with my decision, and the rest is freaky history!!!

You can check out the full GameRant list here: https://gamerant.com/9-best-vampire-manga-with-no-anime-adaptations/#bloody-kiss