A Study to Evaluate the Effects of ASP5502 in Healthy Adults and Adults With Primary Sjögren's Syndrome

Primary Sjögren's syndrome (pSS) is a condition when the body's immune system attacks glands that produce fluids, such as the tear and saliva glands. This leads to dry eyes and a dry mouth. However, other symptoms may occur such as fatigue, joint pain, and skin problems. These symptoms can be severe. Symptoms can be treated but there is an unmet need to treat the actual condition. In this study, ASP5502 is being given to humans for the first time. The people taking part are healthy adults or adults with pSS. The main aims of the study are to check the safety of ASP5502 and how people tolerate ASP5502. This study will be in 3 parts. In Part 1, healthy men and women will take tablets of ASP5502 or a placebo just once. In this study, the placebo looks like the ASP5502 tablet but doesn't have any medicine in it. Different small groups of people will take a lower to a higher dose of ASP5502 or a placebo. This will happen one group after another. One small group will take tablets of ASP5502 or placebo with and without food. This is to find out if food affects how the body processes ASP5502. After their dose, people will stay in the medical center for a few nights. This is to have blood tests, electrocardiograms (ECGs) to check heart health, and other safety checks, and to report any medical problems. One of these checks is to have their heart continuously tracked during the first night. This is called telemetry. People who take tablets of ASP5502 or placebo with and without food will stay in the medical center for a few extra nights. In Part 2, healthy men and women will take tablets of ASP5502 or a placebo. They will do this once a day for 2 weeks (14 days). Different small groups of people will take a lower to a higher dose of ASP5502 or a placebo. This will happen one group after another. After taking ASP5502 or the placebo, people will stay in the medical center for a few nights. This is to have blood tests, ECGs to check heart health, and other safety checks, and to report any medical problems. Telemetry will also be done continuously during the first night. In Part 3, men and women with pSS will take tablets of ASP5502. They will do this once a day for 4 weeks (28 days). Different small groups of people will take a lower to a higher dose of ASP5502. This will either happen for one group after another, or just for 1 group. The number of groups and the doses taken will be worked out from the results from Part 1 and Part 2 of this study. People will stay in the medical center for a couple of nights. This will happen for their first dose, then again after about 2 weeks and 4 weeks of treatment. As in Parts 1 and 2, this is to have blood tests, ECGs to check heart health, and other safety checks, and to report any medical problems. In all parts of the study, people will return to the medical center about 1 week after their final blood sample is taken, for health check. People in parts 2 and 3 will also receive a telephone call safety check about 4 weeks after their last dose of ASP5502.