Predictive Biomarkers For Cytokine Release Syndrome (CRS) by CAR T-Cells & Immune Cell Engagers

Cytokine Release Syndrome

Cytokine Release Syndrome (CRS) is a supraphysiological response following any immune therapy that results in the activation or engagement of endogenous or infused T cells and or other immune effector cells. Symptoms can be progressive, must include fever at the onset, and may include hypotension, capillary leak, hypoxia, and end-organ dysfunction. 

Classification/Stages of CRS 

Grade 1 CRS: 

Grade 1 CRS is defined as fever (> 38 degrees celsius) with or without constitutional symptoms of CRS include myalgia, arthralgia, and malaise with the coincidence of fever. 

Grade 2 CRS: 

Grade 2 CRS is defined as fever (>38 degrees celsius) with hypotension not requiring vasopressin and or hypoxia requiring the use of a low-flow nasal canula or blow-by.

Grade 3 CRS:

Grade 3 CRS is defined as fever (>38 degrees celsius)  with hypotension requiring 1 vasopressor with or without vasopressin and hypoxia requiring high flow nasal cannula (>64 min), face mask, non-breather mask not attributable to any other cause. 

Grade 4 CRS: 

Grade 4 CRS is defined as fever (> 38-degree celsius) with hypotension requiring multiple vasopressors (excluding vasopressin) and or hypoxia requiring positive pressure not attributable to any other cause. As CRS progresses capillary leak often leads to pulmonary edema, impairment of ventilation in addition to oxygen.

Grade 5 CRS: 

By convention, grade 5 CRS is defined as death due to CRS with another cause is not the principal factor leading to this outcome.

Biomarkers Measured To Monitor Cytokine Release Syndrome

  • C-reactive protein
  • Ferritin
  • GM-CSF
  • Granzyme B
  • Intracellular Cell Adhesion Molecule 1 (ICAM-1)
  • Interleukin 2
  • Interleukin 6
  • Interleukin 5
  • Interleukin 8
  • Interleukin 10
  • Interleukin 13
  • Interleukin 18
  • Interleukin 2 receptor alpha
  • Interferon-gamma
  • Macrophage Inflammatory Protein 1-alpha
  • Serum Amyloid A1 
  • Tumor Necrosis Factor-alpha
  • Fas L

Differential Cytokine Levels in CAR-T Cell Treatment


Higher baseline markers in subject with CRS: CRP, Ferritin, intracellular adhesion molecule 1 (ICAM), IL-6, Macrophage inflammatory protein 1 alpha, serum amyloid A1 and tumor necrosis factor alpha were observed.

CRS associated soluble biomarkers included: ICAM-1, IL-2, IL-6, IL-8, INF-Y, MIP1 alpha, TGFb3, TNF-alpha, 


In subjects treated with Abcema, compared to subjects with no cytokine release syndrome, levels of following immune-related biomarkers were significantly elevated in subjects with any grade of CRS 

Within the first day after infusion: GM-CSF, INF-Y, IL-10, IL-12, IL-2, IL-6& IL-8

At Cmax: CRP, Granzyme B, IL-8, IL-12R alpha, IL-5, MIP-beta, TNF & TNFSF6 (Fas L)



After infusion, 17 key analyte were increased except TNF-alpha & VCAM. The median time to peak for all key analytes ranged from 4 to 8 days, the majority of the key analytes returned near to baseline levels except 6 analytes (CXCL10, ferritin, INF-Y, IL-6, IL-8, IL-15)

Of 17 key analytes, the median peak serum levels of the following 9 analytes with Grade 3 or higher CRS were higher (Normal Wilcoxon rank sum p values less than/equal to 0.05) than in subjects with Grade 2, Grade 1, or no CRS: Ferritin, Granzyme B, IL-2 alpha, IL-6, IL-8, IL-10, IL-15, Perforin, TNF-alpha)


After infusion of KTE-C19 levels of most of the 13 biomarkers increased to peak levels within the first 14 days post-infusion, and then returned to baseline within 28 days. More than 50% of subjects had a greater than two-fold increase at a peak from baseline. 

CRP, Granzyme B, INF-Y, IL-1RA, IL-2Raplha, IL-6, IL-10, 1L-15