Etavopivat is a new medicine being tested for treating blood disorders like sickle cell disease and thalassaemia. These disorders affect haemoglobin, which is a protein that carries oxygen in our blood. This study checks how safe and effective Etavopivat is over a long time. The study could last up to 264 weeks, but might finish sooner if the medicine gets approved in a participant's country.

• Participation requires ongoing involvement in a related parent study and having experienced benefits from Etavopivat.
• The study won't accept participants with other disorders that could risk their health or those who have stopped Etavopivat treatment permanently.
• Participants cannot use certain other medications during the study, like haemoglobin S inhibitors or selectin antagonists.