- Both male and female subjects should agree to use highly effective contraception if the risk of conception exists. (Note: The effects of the trial drug on the developing human fetus are unknown; thus, women of childbearing potential and men able to father a child must agree to use 2 highly effective contraception, defined as methods with a failure rate of less than 1 % per year.) Highly effective contraception is required throughout the study and for at least 120 days after Avelumab treatment.