Can Lutetium-177 (Lu-177) infusion cause an increase in eosinophil count?

Lutetium-177 (Lu-177) Infusion and Eosinophil Count

Yes, Lutetium-177 (Lu-177) infusion can potentially cause a rise in eosinophil count, though it is not among the most commonly reported hematological toxicities associated with this treatment.

Hematological Effects of Lu-177 Therapy

Lu-177 therapy is known to cause several hematological toxicities, with the primary impact typically seen in:

• Platelets: Recovery usually occurs by 12-14 days post-infusion 1
• Lymphocytes: Begin recovery within 4-7 days after infusion 1
• Neutrophils: Most significant impact occurring around 10-11 days post-infusion with recovery approximately 6-14 days after infusion 1

Common Hematological Toxicities

The VISION trial, which led to FDA approval of Lu-177-PSMA-617 for prostate cancer, reported:

• Higher incidence of grade ≥3 adverse events in the Lu-177 group compared to control, particularly 2:
  • Anemia
  • Thrombocytopenia
  • Lymphopenia
  • Fatigue

According to Praxis Medical Insights, the degree of hematological toxicity varies, with 1:

• Grade 3/4 neutropenia: ~1% of patients
• Grade 3/4 thrombocytopenia: ~2% of patients
• Grade 3/4 lymphopenia: ~9% of patients

Eosinophils and Lu-177 Therapy

While eosinophilia is not specifically highlighted in the major clinical guidelines for Lu-177 therapy, it's important to note that:

1. Radiopharmaceuticals can trigger various immune responses
2. Changes in eosinophil counts may occur as part of the overall hematological impact
3. Individual patient factors may influence the specific hematological response

Monitoring Recommendations

For patients receiving Lu-177 therapy, the following monitoring is recommended:

• Complete blood count monitoring weekly starting 2 weeks after administration until recovery from cytopenias 1
• For significant cytopenias, more frequent monitoring may be required 1
• Continued blood count monitoring every 2-4 weeks after treatment 1
• Long-term follow-up with blood tests every 8-12 weeks for the first 12 months 1

Management of Hematological Toxicities

If hematological abnormalities including eosinophilia are detected:

• Growth factor support may be administered to treat neutropenia 1
• Transfusions may be considered for significant thrombocytopenia or anemia 1
• Dose modifications may be necessary for subsequent treatment cycles

Clinical Implications

When evaluating eosinophilia in patients receiving Lu-177 therapy:

• Consider the timing in relation to Lu-177 administration
• Evaluate for other potential causes of eosinophilia
• Monitor for any associated symptoms
• Document the pattern and resolution of eosinophil elevation

Conclusion

While the primary hematological toxicities associated with Lu-177 therapy are typically thrombocytopenia, lymphopenia, and neutropenia, changes in eosinophil counts can occur. Regular monitoring of complete blood counts is essential for patients receiving Lu-177 therapy to detect and manage any hematological abnormalities, including potential eosinophilia.