This is a multicenter, randomized, double-blind, placebo-controlled, parallel-group, flexible-adaptive, group-sequential study (Part A), followed by an open-label LTE period (Part B) to investigate the efficacy, and safety of rilzabrutinib in participants with sickle-cell disease (SCD).
Study details include:
* Study duration: a 52-week double-blind period (Part A), followed by an open-label LTE period (Part B). Double-blind period has two parts, 50% (adult only) until the interim analysis (a proof-concept part analogous to a phase 2b study), and 50% (adult and children) after the interim analysis. Only the participants who complete double-blind treatment period (Part A) are eligible to continue to the LTE period. The duration of the LTE period (Part B) will be from the first-participant-in (FPI)-LTE (Part B) until the last participant who enters the LTE has completed 52 weeks.
* Treatment duration: 52-week double-blind period (Part A); LTE period (Part B) from the (FPI until the last participant who enters the LTE has completed 52 weeks.
* Visit frequency: Week visits based on the Schedule of Assessments.