The suspension is for four games, and based on what other suspensions of this nature have been, I'd assume it's adderall.
Another one bites the dust I guess, Brandon Bolden was suspended earlier also. He'll be eligible to return for the Texans game. That makes three players currently on the Patriot roster to be suspended for PEDs (Cunningham, Bolden, Talib).
It's a shame because Cunningham was having his best season of his career (leads team in holding penalties), this should throw a wrench into that. He'll be back for the last game of the season, but the Patriots could definitely use him the next four weeks.
With Chandler Jones hurt and his status unclear for the game against Miami, the Patriots are suddenly very thing on the defensive line. The top backups would be Trevor Scott or undrafted rookie Justin Francis. Both are more than capable of filling in, but they won't bring the same production of Jones or Cunningham.