RecruitingPhase 1Drug trialA Study of LY4152199 in Participants With Previously Treated B-cell Malignancies (BAF_FRontier-1 )The purpose of this study is to find the best dose of the drug and measure the safety and efficacy of LY4152199 in participants with previously treated B-cell malignancies. Participants will have the option to continue taking LY4152199 until the study ends.