Generic Name

Truxima

Mechanism

• Targeted binding: Recognizes the CD20 antigen on B‑cell surfaces.
• Enhanced cytotoxicity: Glycoengineering increases affinity for FcγRIIIa receptors, amplifying antibody‑dependent cellular cytotoxicity (ADCC).
• Direct induction of apoptosis: Type‑II antibodies initiate non‑membrane‑lytic apoptosis pathways via direct cell‑surface interactions.
• Complement‑dependent cytotoxicity (CDC): Truxima also activates the complement cascade, although CDC is less prominent than ADCC in its activity profile.

Pharmacokinetics

*Note:* Renal/hepatic impairment does not markedly alter pharmacokinetics; dose adjustment is not required.

Indications

• Follicular lymphoma (FL): First‑line monotherapy or in combination with bendamustine (Br‑Truxima).
• Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL): Front‑line therapy with obinutuzumab + chlorambucil, or in relapsed disease.
• B‑cell non‑Hodgkin lymphoma (NHL): As part of induction regimens for other subtypes.

Contraindications

• Contraindications:
• Known hypersensitivity to obinutuzumab, murine protein, or any excipient.
• Active uncontrolled tuberculosis or serious infections.
• Warnings:
• Infusion reactions (fever, chills, rash, hypotension).
• Infections (bacterial, viral, fungal) – heightened risk due to B‑cell depletion.
• Neutropenia/labile blood counts – may predispose to opportunistic infections.
• Re‑infusion reactions – mild, manageable with premedication; severe reactions are rare.

Dosing

1. Induction phase (Cycle 1):
• 100 mg IV over 90 min (Day 1).
• 900 mg IV over 120 min (Day 8).

2. Continuation phase (Cycles 2–4):
• 900 mg IV over 120 min (once a week).

3. Maintenance (post‑Cycle 4):
• 900 mg IV every 2 weeks for up to 12 months.

*Infusion precautions:*
• Premedicate with antihistamine (e.g., diphenhydramine) and acetaminophen; steroids optional for high‑risk patients.
• Start at 1 % of the total dose (1 mg / 90 min) and gradually increase if tolerated.

Adverse Effects

Monitoring

• Baseline: CBC with differential, liver/renal panels, electrolytes, hepatitis serology, TB screening.
• During therapy:
• CBC pre‑infusion → assess neutropenia, anemia, thrombocytopenia.
• Monitor for signs of infection (fever, elevated CRP).
• Check for infusion reactions: vitals, oxygen saturation.
• Re‑check hepatitis B status after 6 months if HBsAg‑negative but anti‑HBc‑positive.

*Post‑treatment:*
• Repeat CBC and LFTs every 4–6 weeks; adjust supportive care accordingly.

Clinical Pearls

• Infusion pacing is key: Start at 1 mg over 90 min, double every 30 min while symptoms remain mild; this reduces the severity of infusion reactions and often eliminates the need for steroids.
• Premedication on subsequent infusions: A single dose of 100 mg IV diphenhydramine and 500 mg oral acetaminophen is usually sufficient; steroids are reserved for patients with prior severe reactions.
• Use with caution in patients with impaired humoral immunity: Consider prophylactic antibiotics or antiviral agents (e.g., valganciclovir for CMV) in high‑risk individuals.
• Dose‑based on B‑cell count? No; standard fixed dosing applies regardless of tumor burden.
• Drug interactions: No significant CYP interactions; however, avoid crowding with rituximab or other anti‑CD20 antibodies concurrently unless protocol‑specified.
• Br‑Truxima synergy: Adding bendamustine to Truxima improves progression‑free survival in FL but increases cytopenias; monitor CBC closely every cycle.
• Follow‑up after therapy: Long‑term B‑cell depletion can last >6 months; schedule serologic immunoglobulin assessment and vaccinate for pneumococcus/Haemophilus influenzae after recovery of IgG levels.

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• Reference‑friendly keywords: Truxima, obinutuzumab, CD20, antibody‑dependent cellular cytotoxicity, infusion reaction, follicular lymphoma, chronic lymphocytic leukemia, bendamustine, cytopenia, monitoring.