This is a randomized, double-blind, vehicle-controlled, parallel-group comparison study to evaluate the safety and efficacy of Q301 Cream vs. vehicle in adult subjects with moderate to severe AD. Study drug (Q301 Cream or vehicle) will be administered topically twice a day for 8 consecutive weeks.

Inclusion Criteria:

1. Male or female subjects aged 18 or older
2. Subjects with a clinical diagnosis of AD according to the Hanifin and Rajka Criteria by a board certified/eligible dermatologist
3. Subjects with IGA score 3 or 4 corresponding to moderate to severe AD at screening and baseline visits

Exclusion Criteria:

1. Subjects who had topical treatment with corticosteroids within 1 week before randomization
2. Subjects who had systemic treatment with corticosteroids or cyclosporine or other immunosuppressive treatment within 4 weeks before randomization
3. Subjects who had ultraviolet irradiation (including photopheresis) within 4 weeks before screening
4. Subjects who participated in another drug trial within 4 weeks before screening