Horror High (1974) LE 333 Mediabook B - Blu-ray Region B

Vernon is an inconspicuous nerd who, due to his special intelligence and his inconspicuous appearance, is a pawn in his fellow students' nasty pranks and physical altercations. A true genius in biology, he secretly experiments with a drug that causes animals to grow unnaturally. When he administers the serum to his own guinea pig, it mutates into a monster that then attacks the caretaker's cat. The caretaker is not at all happy that his beloved house cat has been eaten and wants to see justice done. He forces Vernon to drink the concoction, which has devastating consequences. From then on, a monster stalks the campus and primarily tears to pieces those who once made Vernon's life hell.