Single tocilizumab dose effectively suppresses systemic inflammation in COVID-19

A single injection of tocilizumab is enough to weaken systemic inflammation for up to 7 days in patients with the coronavirus disease 2019 (COVID-19), a recent study suggests.

Researchers retrospectively assessed 54 COVID-19 patients (median age 64 years, 33 percent women) who were given either dexamethasone alone (n=25) or in combination with tocilizumab (n=29). Parameters measured included levels of interleukin (IL)-6 and C-reactive protein (CRP), as well as absolute lymphocyte (ALC) and neutrophil counts.

Add-on tocilizumab led to a strong and significant increase in serum IL-6, which jumped from 39 pg/mL at day 0 to 1,031 pg/mL after 7 days (p<0.001). This was accompanied by a drastic reduction in circulating CRP, dropping from 134 mg/L at baseline to 4 mg/L at day 7 (p<0.001).

In contrast, no such changes in IL-6 (p=0.86) and CRP (p=0.36) in the dexamethasone-alone group in the same time frame were noted.

Moreover, between-group comparisons showed that at day 7, IL-6 concentrations were significantly higher in patients treated with tocilizumab and dexamethasone, while CRP levels were suppressed by around 30 times relative to the dexamethasone monotherapy arm. ALC was likewise elevated in the combination treatment group (1.39 vs 0.66 G/L; p<0.01) at day 7.

“Our study strongly suggests that IL-6R blockade with a single dose of tocilizumab is sufficient to blunt systemic inflammation for up to 7 days following administration,” the researchers said. “The observed increase in IL-6 with the concomitant normalization of serum CRP advocates in favour of an effective shut down of the IL-6-IL-6-receptor classic signaling, on which CRP synthesis depends.”