key Inclusion Criteria:  Completed study drug treatment in the parent study (VX20-445-111 Part B, NCT04537793), or had study drug interruption(s) in the parent study, but did not permanently discontinue study drug, and completed study visits up to the last scheduled visit of the Treatment Period of the parent study  Key Exclusion Criteria:  History of study drug intolerance in the parent study History of poor compliance with ELX/TEZ/IVA and/or procedures in the parent study  Other protocol defined Inclusion/Exclusion criteria may apply