• Age ≥ 18 years old.

• Able to understand and provide a signed informed consent that fulfills the relevant Human Research Ethics Committee (HREC) or Independent Ethics Committee (IEC) guidelines.

• Histologically documented CD19- and CD20-positive B-cell NHL (excluding primary CNS lymphoma, CLL, and Burkitt lymphoma) with the following specific criteria:

‣ Have completed ≥ 2 lines of cytotoxic chemotherapy.

⁃ Have received rituximab or another anti-CD20 antibody.

⁃ Have measurable disease by Lugano classification documented within 8 weeks of the time of consent, defined as nodal lesions \> 15 mm in the long axis or extranodal lesions \> 10 mm in long and short axis, or bone marrow involvement that is biopsy proven.

⁃ Have CD19- and CD20-positive disease confirmed on the diagnostic or repeat biopsy specimen. A minimum of 5% CD19 and CD20 positivity by immunohistochemistry or flow cytometry is required.

• Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1.

• Expected survival \> 16 weeks.

• Stated willingness to comply with study procedures.

• Able to attend required study visits and return for adequate followup, as required by this protocol.

• Agreement to practice effective contraception for female participants of childbearing potential and nonsterile males. Female participants of childbearing potential must agree to use effective contraception while on study and for at least 5 months after the last dose of study drug. Nonsterile male participants must agree to use a condom while on study and for up to 5 months after the last dose of study drug. Effective contraception includes surgical sterilization (eg, vasectomy, tubal ligation), two forms of barrier methods (eg, condom, diaphragm), and intrauterine devices (IUDs).