• Age ≥18 years

• Provided written informed consent

• Histologically confirmed B-cell malignancy, including CLL/SLL, WM, MCL, MZL, or FL

• Patients with SLL, MCL, MZL, and FL: at least 1 radiographically measurable lesion

• Failed or are intolerant to ≥2 prior lines of systemic therapy

• ECOG Performance Status 0 to 2

• Adequate hematologic status (ie, absolute neutrophil count ≥0.75 × 10⁹/L, platelet count ≥50 × 10⁹/L, hemoglobin ≥8 g/dL) not requiring transfusion support or growth factors

• Adequate hepatic function

• Adequate renal function

• Ability to swallow tablets and comply with study requirements for the duration of study participation

• Male and female patients of reproductive potential: Willing to observe conventional and effective birth control methods

• Male patients: agree not to donate sperm during and for 6 months after the study

• Dose Expansion Cohort 3 patients: prior treatment with pirtobrutinib (Jaypirca) for an approved indication