• Subjects provided written informed consent to participate. For minor subjects, both minor's assent and parental consent will be required.

• Male and female subjects with a confirmed diagnosis of EPP or XLP based on medical history.

• Subjects aged 12 years to 75 years, inclusive, at Screening.

• Subjects are willing and able to travel to the study sites for all scheduled visits.

• In the Investigator's opinion, subject can understand the nature of the study and any risks involved in participation, and willing to cooperate and comply with the protocol restrictions and requirements (including travel and receiving direct sunlight exposure as much as possible).

• Female subjects who are non-lactating and have a negative urine pregnancy test at baseline visit prior to receiving the first dose of study drug.

• Female subjects of childbearing potential and male subjects with partner of child-bearing potential currently using/willing to use 2 effective methods of contraception.

⁃ Additional screening criteria check may apply for qualification.