Pharmacodynamic biomarkers for anti-IL6R therapy in COVID-19


High IL-6 levels are associated with greater COVID-19 severity and IL-6 receptor (IL-6R)  blockade by tocilizumab has been used globally for the treatment of over 1 million people with severe COVID-19. Despite the widespread use, the reporting of efficacy results has been mixed, and a full molecular understanding of the therapeutic benefit remains unclear. In the COVACRA phase III clinical trial for tocilizumab, 452 patients were given tocilizumab or placebo, but the primary endpoints of the study (improved clinical status and reduced mortality at day 28) were not met. There was, however, a reduction in the median time to hospital discharge for drug v placebo. A study by scientists from Genentech took advantage of the unique opportunity represented by these trial samples to carry out a post hoc analysis to evaluate the mechanism of action for IL-6R blockade with tocilizumab in patients with COVID-19 and determine the basis for its benefit on improved time to clinical recovery. A combination of Olink® Explore 1536 and RNAseq was used for multiomic characterization of patients given tocilizumab or placebo, looking for markers related to disease severity, clinical outcomes and drug response pharmacodynamics (PD).

Samples were taken at baseline and up to 60 days after dosing, with Olink used to measure 266 tocilizumab-treated patients and 122 placebos and bulk RNAseq used to measure transcriptomics in similar numbers of patients. The investigation had two aspects, 1) identify baseline markers associated with disease severity & clinical outcomes (including time to recovery) 2) a longitudinal analysis of the PD effect of tocilizumab based on changes in the markers identified in stage 1.


In the first stage analysis, 230 proteins had higher levels and 21 had lower serum levels in patients with severe vs. moderate COVID-19, with  inflammation (JAK/STAT & TNF signaling), myeloid dysregulation and organ injury implicated as major pathways involved. Furthermore, 246 proteins were associated with both increased likelihood of clinical failure and lower likelihood of hospital discharge. These prognostic markers included proteins related to inflammation, myeloid cells, vascular domains (coagulation, complement, angiogenesis) and proteins specific to the heart and lung. RNAseq indicated that lymphopenia and myeloid dysregulation were features of severe COVID-19 and that elevated expression of antiviral pathway genes was evident in the first 10 days following symptom onset.

Proteomic PD analysis was carried out using samples taken at baseline and at 3 and 7 days after treatment. Many proteins showed a significantly greater change in treatment v placebo patients, with 44 at day 3 and 7 respectively. As expected from previous studies, tocilizumab induced a temporary spike in IL6 and IL6R , which was also confirmed by ELISA. Of the proteins associated with severity, 28 proteins (CALCA, GPR37, FCRL5, TNC, CCL23, CCL20, MMP8, CD79B, OLR1, VSIG4, OSM, EFNA1, SPP1, AZU1, MZB1, CALB1, IGFBP4, IPCEF1, MNDA, PFKFB2, RASSF2, NCF2, PLA2G2A, LBP, IGSF3, IL5RA, SPINK1, and CHI3L1) showed a significantly greater reduction and 5 proteins (AGR2, CXCL8, CXCL9, KRT18, and IL6) had a greater increase in response to tocilizumab compared to placebo by day 3 or 7. By day 28, there were significant reductions in most severity-associated proteins in most patients, indicating clinical recovery for both treatment arms.

Overall, the proteomic analysis confirmed a pharmacodynamic effect for tocilizumab and identified novel PD biomarkers. Transcriptomic analysis revealed that tocilizumab treatment leads to faster resolution of lymphopenia and myeloid dysregulation associated with severe COVID-19, indicating greater anti-inflammatory activity relative to placebo and potentially leading to faster recovery in patients hospitalized with COVID-19. The pathways revealed to be elevated by the multiomic approach in patients who did not recover may indicate potential new therapeutic targets for COVID-19.



Shivram H, Hackney JA, Rosenberger CM, et al. Transcriptomic and proteomic assessment of tocilizumab response in a randomized controlled trial of patients hospitalized with COVID-19. (2023) iScience, DOI: 10.1016/j.isci.2023.107597

The present study identified prognostic biomarkers for COVID-19 disease progression, confirmed the pharmacologic activity and identified novel pharmacodynamic biomarkers for tocilizumab in patients with COVID-19, uncovered the potential mechanism of action of tocilizumab in patients hospitalized with COVID-19, and revealed pathways elevated in patients who did not recover that may be targets for new COVID-19 therapeutics

Shivram et al. (2023)

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