**Study on Rilzabrutinib for Sickle-cell Disease** This study is testing a medicine called rilzabrutinib for people aged 10 to 65 with sickle-cell disease (SCD). SCD is a condition that affects red blood cells, making them sickle-shaped and causing pain and other problems. The study is divided into two parts: 1. **Double-blind Period (Part A):** Lasts for 52 weeks, where neither the doctors nor the patients know who gets rilzabrutinib or a placebo (a fake treatment). 2. **Open-label LTE Period (Part B):** After Part A, everyone gets rilzabrutinib for another 52 weeks. **Key Points:** - **Study Length:** 104 weeks total, split into two parts. - **Visits:** Participants need to attend visits regularly as per the schedule. - **Eligibility:** Participants must have had 2 to 10 pain episodes in the last year, with stable treatment if on certain SCD medications. Some people can't join, like those with certain infections or who have had cancer recently. This study is important for understanding how safe and effective rilzabrutinib is for SCD.