The official website of Champion RED magazine has announced on Thursday that Saint Seiya's spin-off manga Saint Seiya: Saintia Shou will receive an anime adaptation. The format of the anime has yet to be revealed. More information regarding the new anime will be announced in the February 2017 issue of the magazine, to be released on December 19.

Synopsis
After the defeat of Gemini Saga, the Sanctuary faces a new threat known as Eris, the Goddess of Discord and Chaos, with her minions, the Dryades. In order to combat such threat, a special class of female Saints, known as the Saintias, steps forward in order to protect their patroness, the goddess of justice, wisdom, and hope, Athena, in her present reincarnation, Saori Kido. (Source: Saint Seiya Wiki)

Saint Seiya: Saintia Shou is written by Masami Kurumada with illustrations by Chimaki Kuori, and has been serialized in Champion RED magazine since August 2013. Eight compiled volumes have been published by Akita Shoten, with the 9th volume shipping on December 20, 2016.

Source: Official site

Saint Seiya: Saintia Shou on MAL

Update December 19
The February 2017 issue of Champion RED magazine has announced on Monday that Toei Animation will be producing the anime.

Source: Comic Natalie