Increases in Serum CYFRA21-1 Concentration during Successful Treatment with Crizotinib

Case series Patient: — Final Diagnosis: — Symptoms: — Medication: — Clinical Procedure: — Specialty: — OBJECTIVE: Unexpected drug reaction BACKGROUND: Increases in tumor marker concentrations usually suggest disease progression. CASES REPORT: We here describe on 3 patients with non-small cell lung cancer whose serum concentrations of CYFRA21-1 increased in spite of successful treatment with crizotinib. Discontinuation of crizotinib resulted in a rapid decrease in serum CYFRA21-1 concentrations in all cases. In 1 patient with progressive disease, in spite of increasing the dose of crizotinib, CYFRA21-1 concentrations decreased. CONCLUSIONS: Crizotinib can induce increases in CYFRA21-1 concentration without disease progression. Pulmonologists and oncologists should be aware of this novel phenomenon, and focus on interpretation of CYFRA21-1 concentrations in monitoring tumor response to crizotinib treatment.