When Lt. Colonel John Sheppard's team visited the Hoffans, they were at first shown around the city, until the leader of the Hoffans informed them about the cure against the Wraith feeding they were working on. The Atlantis expedition decided to help them and with the help of Dr. Carson Beckett they were able to complete the cure and tested it on the Wraith which the Atlantis expedition had captured earlier.
It was discovered, however, that not only did the vaccine kill the Wraith who fed on a person using the substance, but that it also only worked on 50% of the people who were using it, while the other half died. Nevertheless, the Hoffans decided to use it despite AR-1's warnings that the Wraith won't let them live with such a cure. Appalled by the society's ruthlessness, AR-1 left. (SGA: "Poisoning the Well")
It later turned out that the Atlantis expedition was right since the Wraith destroyed the entire Hoffan population after they found out about the vaccine. Micheal Kenmore stole the information about the Hoffan drug from the archives and began using it in his own war against the Wraith, before he was eventually stopped by the Atlantis expedition. (SGA: "The Kindred, Part 1")