Low Dose Mosunetuzumab for the Treatment of Patients With Indolent B-Cell Lymphoma

The film gives the main points. The full list below is copied from the registry; the study team makes the final decision.

• Age18 Years to no maximum
• SexAll
• Healthy volunteersNo

You may be able to join if

• 18 years or older at time of signing informed consent
• Capable of understanding and providing written informed consent
• Histologically confirmed indolent B-cell non-Hodgkin lymphoma with no prior therapy for lymphoma. (Prior peptide-based therapeutic vaccines are allowed.) Eligible histologies include:
• Follicular lymphoma (grade 1-2 or 3A)
• Marginal zone lymphoma
• Ann Arbor stage II-IV disease
• No prior therapy for lymphoma
• Have low-tumor burden disease, defined by Groupe D'Etude des Lymphomes Folliculaires (GELF) criteria:
• Nodal or extranodal tumor mass < 7 cm
• Involvement of less than 3 nodal sites with a diameter > 3 cm
• No systemic or B symptoms
• No splenomegaly > 16 cm by imaging
• No local risk of vital organ compression
• No pleural or peritoneal serous effusions
• No leukemic phase (> 5,0000/ uL circulating lymphocytes)
• No significant cytopenias defined as platelets < 100,000/uL, hemoglobin < 10 g/dL, or absolute neutrophil count (ANC) < 1500/ uL
• Have measurable nodal disease, including at least 1 disease site measuring at least 1.5 cm in longest dimension on CT or fludeoxyglucose F-18 (FDG)-PET, or a FDG-avid extranodal measurable site measuring at least 1.0 cm in longest dimension. Measurable disease also includes spleen size more than 13 cm in vertical length
• Eastern Cooperative Oncology Group (ECOG) performance status of 0-2
• Creatinine clearance ≥ 50 mL/min calculated by Cockcroft-Gault equation
• Total bilirubin ≤ 1.5 x the upper limit of normal (ULN), except in patients with Gilbert's syndrome who may have a total bilirubin up to ≤ 3 x ULN
• Aspartate aminotransferase (AST) ≤ 3 x the ULN
• Alanine aminotransferase (ALT) ≤ 3 x the ULN
• Gamma glutamyl transferase (GGT) ≤ 3 x the ULN
• Negative serum or urine pregnancy test within 7 days of initiating mosunetuzumab for women of childbearing potential, defined as those who have not been surgically sterilized or who have not been free of menses for at least 1 year
• Fertile male and woman of childbearing potential must agree to use highly effective contraceptive methods from start of treatment to at least 3 months after the last dose of mosunetuzumab

You cannot join if

• History of severe allergic reaction to monoclonal antibody therapy
• History of a second primary malignancy that could affect compliance with the protocol or interpretation of results except with permission of the principal investigator. Malignancies treated curatively or at low-risk of progressing at the judgment of the principal investigator (PI) may be included
• Known active and uncontrolled bacterial, viral, fungal, mycobacterial, or other infection at study enrollment
• Infection with human immunodeficiency virus (unless viral load is undetectable and CD4 count ≥ 200)
• Positive test results for chronic hepatitis B infection (defined as positive hepatitis B surface antigen [HbBsAg] serology):
• Patients with occult or prior hepatitis B infection (defined as positive total hepatitis B core antibody and negative HBsAg) may be included if hepatitis B virus (HBV) deoxyribonucleic acid (DNA) is undetectable at the time of screening. These patients must be willing to undergo monthly DNA testing and appropriate antiviral therapy as indicated by institutional standards
• Autoimmune disease requiring active therapy
• History of hemophagocytic lymphohistiocytosis (HLH) or macrophage activation syndrome (MAS)
• Evidence of significant concurrent disease or medical condition that could interfere with the conduct of the study, or put the patient at significant risk including, but not limited to, significant cardiovascular disease (e.g., New York Heart Association class III or IV cardiac disease, unstable arrhythmias, or unstable angina) or pulmonary disease (including obstructive pulmonary disease and history of bronchospasm)
• Ongoing systemic corticosteroid treatment, with the exception of corticosteroid use for other (non-tumor and non-immunosuppressive) indications up to a maximum of 10 mg/day of prednisone or equivalent
• Prior use of any monoclonal antibody within 4 weeks before the first mosunetuzumab administration
• Prior solid organ transplantation
• Pregnant or breast-feeding women, or intending to become pregnant during the study or within 3 months of the last dose of mosunetuzumab

This is how the treatment is meant to work. Whether it helps, and how safe it is, is what this trial is testing.

mosunetuzumab-axgb. A bispecific, humanized monoclonal antibody with potential antineoplastic activity. Mosunetuzumab contains two antigen-recognition sites: one for human CD3, a T-cell surface antigen, and one for human CD20, a tumor-associated antigen (TAA) that is exclusively expressed on B cells during most stages of B-cell development and is often overexpressed in B-cell malignancies. Upon administration, mosunetuzumab binds to both T cells and CD20-expressing tumor B cells; this cross-links T cells to tumor cells, and may result in a potent cytotoxic T-lymphocyte (CTL) response against CD20-expressing tumor B cells. NCI Drug Dictionary

Treatments listed in the registry

• Biospecimen Collection (Procedure): Undergo blood, oral, and/or rectal sample collection
• Computed Tomography (Procedure): Undergo PET/CT or CT
• Magnetic Resonance Imaging (Procedure): Undergo MRI
• Mosunetuzumab (Biological): Given IV
• Positron Emission Tomography (Procedure): Undergo PET/CT
• Questionnaire Administration (Other): Ancillary studies

Na · Single Group · masking: None

As the registry describes them. Requirements to join, such as a tissue sample, are in the eligibility list above even when on-study procedures are optional. Ask the study team which steps apply to you.

• blood samples: Part of the study plan
• CT scans: Part of the study plan; some time points described as optional
• MRI: Part of the study plan; some time points described as optional
• PET scans: Part of the study plan
• questionnaires: Part of the study plan

Main goals

• Overall response (OR) (Up to week 13)

Other goals

• Incidence of adverse events (AE's)
• Incidence of grade 3 or greater cytokine release syndrome (CRS)
• Incidence of Immune Effector Cell Associated Neurotoxicity syndrome
• Progression free survival (PFS)
• Duration of response
• Time to next lymphoma treatment
• Time to cytotoxic treatment

Planned enrollment: 20 (estimated).

• Fred Hutch/University of Washington Cancer Consortium, Seattle, Washington

Site status as of Oct 30, 2026. Check the live record before contacting a site.

• ClinicalTrials.gov NCT06442475
• NCI Drug Dictionary: C129691

Registry record reviewed as fetched Oct 30, 2026, last updated by the sponsor Aug 26, 2026. Public record; not medical advice.