A Phase 3, randomized, 2-arm, open-label, multicenter, stratified study of soquelitinib versus physician's choice standard of care (SOC) treatment (selected single agents) in participants with relapsed/refractory (R/R) peripheral T-cell lymphoma not otherwise specified (PTCL-NOS), follicular helper T-cell lymphomas (FHTCLs), or systemic anaplastic large-cell lymphoma (sALCL).