Background/Purpose : Tocilizumab (TCZ) is a monoclonal anti-IL-6 receptor antibody, and is very effective in controlling RA activity.  However we had noticed that the change in leukocyte number after the administration of TCZ is different from that of TNF-inhibitor, and the change in leukocyte number by TCZ is rapid occurring within few days of administration.  We analyzed retrospectively the relationship between the change in leukocyte number at 4 week and disease activity evaluated by DAS28-ESR at 24 weeks.

Methods : Subjects were 50 patients with RA (male/ female = 10/40, mean age 56.7 +/- 12.7 years-old).  The mean doses +/- SD of PSL (n = 35), MTX (n = 45), SSZ (n = 7), and bucillamine (n = 4)were 4.5 +/- 1.9 mg/day, 7.4 +/- 2.4 mg/week, 1000 +/- 0 mg/day, and 163 +/- 48 mg/day, respectively, at the introduction of TCZ.  Patients were administrated with 8 mg/kg of TCZ every 4 weeks, and blood test and physical examination were done at the time of TCZ administration.  Of the 50 patients, 19 were biologics naïve.

Results : The mean DAS28-ESR at week 0 and 24 were 4.72 and 2.22, respectively, and the difference was statistically significant.  Thirty-one out of 50 patients reached DAS28-ESR remission at 24 weeks.  The changes of leukocyte number after administration of TCZ are summarized as follows; total leukocyte number: decrease, neutrophil number: decrease, % of neutrophil: decrease, eosinophil number: no changes, % of eosinophil: increase as a result of the decrease in total leukocyte number.  The changes of leukocyte number occurred at 4 weeks and did not change thereafter until 24 weeks.  The change of DAS28-ESR, on the other hand,occurred gradually and reached plateau at 16 weeks.  The decrease of the number of total leukocyte and neutrophil at 4 weeks significantly correlated with the decrease of DAS28-ESR at 24 weeks.  The increase of % of eosinophil at the sum of 4 and 8 weeks significantly correlated with the decrease of DAS28-ESR at 24 weeks.  Positive predictive values (PPV) for DAS28-ESR remission at 24 weeks were 76 %, 77 %, and 75 %, respectively, when total leukocyte and neutrophil count decreased by more than 1000 at 4 weeks, and when % of eosinophil increased by 0.5 % at 4 weeks, respectively.

Conclusion : The administration of TCZ induced significant changes of leukocyte count at 4 weeks, which is a good predictor of reaching DAS28-ESR remission at 24 weeks. 

Authors have no COI.

---

« Back to 2014 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/decrease-in-the-number-of-peripheral-leukocytes-and-neutrophils-and-increase-of-the-percentage-of-eosinophils-at-4-week-predict-the-das28-esr-remission-at-24-weeks-after-administration-of-tocilizumab/