I got it after several teams and different strategies.
Joe Diamond + Jenny Barnes + Carlyn Fern + Vincent Lee: Healers wont win many adventures, and most of the times it was like heales were wasting my turns... so I discarded this team after some tries.
Kate Winthrop + Aschan pete + Rita Young + Wilson Richards: Good team, I had used in other bosses, but not good enough in Ithaqua campaign.
Leo anderson + Jim Culver + Mandy Thompson: Leo was buying lots of supplies, while Jim and Mandy had abilities to solve difficult adventures. Defeated Ithaqua but without saving Ashley.
Dexter Drake + Bob Jenkins + Monterey Jack + Kate Winthrop: Always had plenty of items to use... I picked the adventures according to success or failure conditions. Noticed I needed a smaller team.
Kate Winthrop + Rita Young + Sister Mary + Joe Diamond: Defeated Ithaqua but without rescuing Ashley... I was convinced about number of investigators was the key, because I got to the final stage of the campaign wit not many items, and I was about to defeat Ithaqua if I had some more clues.
Jenny Barnes + Kate Winthrop:
Had monsters and terror controlled with kate and difficult adventures controlled with Jenny, I had the right number of items because I had a small team and I was able to pick quickly the adventures according to success or failure so I controlled sanity/Stamina risks when entering an adventure and what I was getting when I succeded. Kate was the key since in Alaska I had lots of terror adventures or monster spawning when wining/losing an adventure. Went to Alaska with 24 supplies and when I was 1 elder sign away from entering the final battle I spent some turns buying healing and some clues and common items. started the 3 stages of final battle with Jenny, then Kate and then Jenny again to defeat Ithaqua.