Administration of Carfilzomib (Kyprolis) After Filgrastim (Zarxio)
Carfilzomib (Kyprolis) should not be administered less than 24 hours after a Filgrastim (Zarxio) injection, as growth factors should not be administered within 24 hours of chemotherapy. 1
Timing Recommendations for Growth Factors and Chemotherapy
The National Comprehensive Cancer Network (NCCN) guidelines provide clear recommendations regarding the timing of growth factors like filgrastim (Zarxio) in relation to chemotherapy:
- Filgrastim should be started 24-72 hours after completion of chemotherapy 1
- Administration of growth factors on the same day as chemotherapy is not recommended 1
- The inverse relationship also applies - chemotherapy should not be administered within 24 hours of growth factor administration
Rationale for Timing Separation
This timing recommendation is based on the mechanism of action of growth factors and their potential interactions with cell-cycle specific chemotherapeutic agents:
- Growth factors stimulate proliferation of myeloid progenitor cells
- Administering chemotherapy (like carfilzomib) too soon after growth factor administration could potentially:
- Increase toxicity to rapidly dividing cells stimulated by the growth factor
- Reduce the efficacy of the growth factor in preventing neutropenia
- Increase risk of adverse events
Specific Considerations for Carfilzomib
Carfilzomib (Kyprolis) is a proteasome inhibitor with known potential for serious adverse effects:
- Pulmonary toxicity has been reported with carfilzomib use 2
- Proper timing between growth factors and carfilzomib administration is particularly important to minimize risk of adverse events
Alternative Approaches
If treatment timing is critical and cannot be delayed, consider these options:
- Wait at least 24 hours after filgrastim administration before giving carfilzomib
- If treatment must be given sooner, consult with a hematologist/oncologist about potential risks
- Consider whether pegfilgrastim might be a better option for future cycles, as it requires only one administration per chemotherapy cycle 1
Monitoring Recommendations
If carfilzomib must be given less than 24 hours after filgrastim (which is not recommended):
- Monitor closely for signs of increased toxicity
- Watch for respiratory symptoms, as pulmonary toxicity is a known risk with carfilzomib 2
- Monitor complete blood counts to assess neutrophil response
Conclusion
Following the established guidelines for timing between growth factors and chemotherapy administration is essential for both safety and efficacy. The 24-hour minimum interval between filgrastim administration and subsequent chemotherapy (including carfilzomib) should be maintained whenever possible to optimize treatment outcomes and minimize adverse events.