A study to find a suitable dose of ASP8731 and check for medical problems at each dose in healthy adults

ASP8731 is a potential new treatment for people with sickle cell disease. Before ASP8731 is available as a treatment, the researchers need to understand how it is processed by and acts upon the body. They do this to find a suitable dose and to check for potential medical problems from the treatment. This type of study usually includes healthy adults but can include people with the relevant condition.

The main aim of this study is to learn if healthy adults have any medical problems after taking different doses of ASP8731.

This study will be in 2 parts.

In Part 1, different small groups of people will take lower to higher doses of ASP8731 or a placebo. In this study a placebo looks like ASP8731 but will not have any medicine in it. This is done to find suitable doses of ASP8731 and work out how often it should be taken. Some of this information will be used in Part 2 of the study. The first group will take the lowest dose of ASP8731 or the placebo. A medical expert panel will check the results from this group and decide which ASP8731 dose the next group can take. The panel will do this for each group until all groups have taken ASP8731 or until a suitable dose of ASP8731 has been reached.

In Part 1, people will visit the study clinic 4 times. The first visit is to check if they can take part. People will be asked about their medical history, have a physical exam, and their vital signs checked (pulse rate, temperature, and blood pressure). Also, they will have an ECG to check their heart rhythm and have some blood samples taken for laboratory tests. For women this will include a pregnancy test.

At the second visit, people will stay in the study clinic for a few days. In most groups, people will be picked to take either ASP8731 or the placebo by chance alone. They will fast before taking ASP8731 or the placebo. 1 group will take ASP8731 with food. No-one in that group will take the placebo. After taking ASP8731 or the placebo (or just ASP8731 with food), people in all groups will give blood and urine samples during the next 3 days. Also, they will be checked for any medical problems during their clinic stay.

People will return to the study clinic for a 2 follow-up visits – at about 8 and 30 days after they last took ASP8731 or the placebo. At these visits people will be asked if they have any medical problems. They will have a physical exam, have their vital signs checked (pulse rate, temperature, and blood pressure), and have some blood samples taken for laboratory tests. For women, this will include another pregnancy test.

In Part 2, other different small groups of people will take lower to higher doses of ASP8731 or a placebo. How often it is taken will be worked out from Part 1.The first group will take the lowest dose of ASP8731 or the placebo each day over several days. A medical expert panel will check the results from this group and decide which ASP8731 dose the next group can take. The panel will do this for each group until all groups have taken ASP8731.

In Part 2, people will visit the study clinic 5 times. The first visit is to check if they can take part. People will be asked about their medical history, have a physical exam, and their vital signs checked. Also, they will have an ECG and have some blood samples taken for laboratory tests. For women this will include a pregnancy test.

At the second visit, people will stay in the study clinic for several days. In all groups, people will be picked to take either ASP8731 or the placebo by chance alone. After taking ASP8731 or the placebo, people in all groups will give blood samples throughout their stay. They will give urine samples during the last few days of their stay. Also, they will be checked for any medical problems during their clinic stay. After discharge, people will return to the clinic 4 days later for a third visit. At this visit, they will have some blood samples taken for laboratory tests. Also, they will have their vital signs checked and will be asked if they have any medical problems.

People will return to the study clinic for a 2 follow-up visits - at about 15 and 30 days after they last took ASP8731 or the placebo. At these visits people will be asked if they have any medical problems. They will have a physical exam and have their vital signs checked. They will also have an ECG and have some blood samples taken for laboratory tests. For women, this will include another pregnancy test.

No other visits are planned during this study.