cutoff marks depend on many factors like the number of students who took the exam, level of the exam and number of seats available among others. Therefore, it isn’t correct to speculate the cutoff marks. However, I can provide you with the last year data which will give you some idea of the cut off marks required.

Firstly, the seat reservation policy of St John's Medical College, Bangalore does not include OBC category, you can check the seat reservation and cut off rank in the table given below-

Hope it helps!