Should elranatamab be held in a multiple myeloma patient with neutropenia and recent UTI?

Management of Neutropenia in Multiple Myeloma Patient on Elranatamab

Elranatamab should not be held today for this patient with WBC of 2.9 and ANC of 1.46 who had a UTI on 8/4/25. The patient's current neutrophil count is above the threshold requiring dose interruption.

Assessment of Current Neutropenia Status

• The patient has a WBC of 2.9 and ANC of 1.46 × 10^9/L, which represents mild neutropenia (ANC 1.0-1.5 × 10^9/L)
• The patient has a history of UTI diagnosed on 8/4/25 (recent infection)
• The patient is currently receiving elranatamab for multiple myeloma

Decision Algorithm for Elranatamab Continuation

Neutrophil Count Thresholds:

• According to consensus recommendations for bispecific antibody therapy in multiple myeloma 1, treatment should be held for severe neutropenia (ANC < 0.5 × 10^9/L)
• For grade 3-4 neutropenia (ANC < 500/mm³), causative medications should be held until ANC ≥ 1000/mm³ 2
• The patient's current ANC of 1.46 × 10^9/L is above these thresholds

Infection Considerations:

• The patient had a UTI on 8/4/25, which is a recent infection
• For patients with active infections, bispecific antibody therapy may need to be temporarily discontinued until infection resolution 1
• However, the UTI was diagnosed several days ago, and without information suggesting ongoing active infection, treatment can continue

Management Recommendations

1. Continue elranatamab at the current dose since ANC is > 1.0 × 10^9/L

2. Monitor for infection signs/symptoms:

   • Fever (≥38.0°C)
   • Worsening urinary symptoms
   • New onset of other infectious symptoms

3. Laboratory monitoring:

   • Complete blood counts should be checked weekly during the first 4-6 weeks of treatment 2
   • More frequent monitoring may be warranted given the recent UTI

4. Consider antibiotic prophylaxis:

   • Anti-bacterial prophylaxis should be considered for patients with prolonged neutropenia (>2 weeks) and ANC < 0.5 × 10^9/L 2
   • The current ANC of 1.46 × 10^9/L does not warrant prophylactic antibiotics

Important Considerations for Bispecific Antibody Therapy

• Neutropenia is a common adverse event with elranatamab, occurring in 48.8% of patients (grade 3-4 in 48.8%) in the MagnetisMM-3 trial 3
• Infections are also common with elranatamab (69.9% any grade, 39.8% grade 3-4) 3
• Regular monitoring is essential as cytopenias may develop at any time during treatment 2

Potential Pitfalls to Avoid

1. Unnecessary treatment interruptions: Holding elranatamab when ANC is > 1.0 × 10^9/L may compromise treatment efficacy without providing clinical benefit

2. Inadequate monitoring: Despite continuing treatment, close monitoring of blood counts remains essential

3. Overlooking infection signs: Recent UTI history warrants vigilance for recurrent or persistent infection

4. Inappropriate antibiotic use: Prophylactic antibiotics are not indicated for mild neutropenia (ANC > 1.0 × 10^9/L) unless there are additional risk factors

In conclusion, based on the current neutrophil count of 1.46 × 10^9/L, which is above the threshold requiring dose interruption, elranatamab treatment should be continued with appropriate monitoring for infection and neutropenia.