mosunetuzumab: clinical use

Prescribing considerations

• Administration must be supervised by a clinician experienced in systemic anticancer therapy, with support available for severe CRS and ICANS.
• Ensure adequate hydration and protocol-directed premedication; assess tumour burden, renal function and tumour lysis risk.
• Review active, chronic or recurrent infection and consider appropriate antimicrobial prophylaxis.
• Provide and explain the patient card, including delayed presentation of CRS or neurological toxicity.
• Record product name and batch number for biological traceability.

Contraindications and cautions

• Formal contraindication: hypersensitivity to mosunetuzumab or any excipient.
• Do not administer in the presence of active infection; this is a warning rather than a listed formal contraindication.
• Use particular caution with significant cardiac, pulmonary or renal disease, recurrent infection, substantial prior immunosuppression or bulky disease near airways or vital organs.

Monitoring

• Clinical observations for CRS during and after infusion, with assessment for infection or sepsis as alternative causes.
• Neurological status for ICANS, which may occur with, after or without CRS.
• Full blood count for neutropenia, anaemia and thrombocytopenia.
• Electrolytes, uric acid and renal function for tumour lysis syndrome; liver enzymes are also relevant.
• Signs of infection, tumour flare and atypical or prolonged inflammation suggesting haemophagocytic lymphohistiocytosis.

Clinical pharmacology

A humanised, full-length anti-CD20/CD3 IgG1 bispecific antibody. Simultaneous binding creates an immune synapse between a cytotoxic T cell and a CD20-positive B cell, activating perforin- and granzyme-mediated B-cell lysis. Like other protein therapeutics, it is expected to undergo catabolic degradation to peptides and amino acids.

Formulation and product differences

• Available vial presentations contain the same concentration of clear, colourless concentrate but different total quantities.
• The concentrate is preservative-free, single-use and requires aseptic dilution before intravenous infusion.
• Use a dedicated infusion line; do not administer as an intravenous push or bolus and do not use an in-line filter.

Solution for infusion

Route: Intravenous

Strengths: 1 mg, 30 mg