**Study Overview:** This clinical trial is testing a new medicine called **rilzabrutinib** for people with sickle-cell disease (SCD). It's divided into two parts: a **52-week double-blind period** where neither patients nor doctors know who gets the medicine or a placebo (a fake treatment), and an open-label LTE (Long-Term Extension) period where everyone gets the actual medicine. **Key Points:** - **Length of Study:** Part A lasts 52 weeks, and Part B continues until all participants complete another 52 weeks. - **Visits Needed:** Participants will have scheduled visits regularly throughout the study period. - **Eligibility:** Must have SCD, experienced 2-10 acute pain episodes in the past year, and meet other health criteria. Participants must not have certain health conditions like cancer or active infections. The study aims to see if rilzabrutinib is safe and effective. Participants should discuss the potential benefits and risks with their doctor.