Biomarkers measuring the activity of Toll-like receptor ligands in clinical development programs

Methods Mol Biol. 2009;517:415-40. doi: 10.1007/978-1-59745-541-1_25.


Efforts to develop therapeutic approaches based on stimulation of Toll-like receptor (TLR) pathways have increased in recent years (Nat Med 13:552-559). The effectiveness of TLR agonists is currently being tested in diseases such as cancer, asthma, allergic rhinitis, and viral infections (J Clin Invest 117: 1184-1194; Blood 105: 489-495; Proc Am Thorac Soc 4:289-294; N Engl J Med 355:1445-1455; Am J Respir Crit Care Med 174:15-20). For a successful clinical trial program, it is important to know whether the therapeutic agent under development is both pharmacologically active and activating the intended pathway in humans. A biomarker reflecting this in an accurate and sensitive manner greatly facilitates dose/regimen-finding and is a "must-have." In this chapter, we describe a polymerase chain reaction (PCR)-based method that quantifies gene expression levels indicative of TLR-stimulation in human samples. We focus on genes specifically induced in an IFN-alpha-dependent manner, as this pathway is activated after stimulation of both TLR-7 and TLR-9. We demonstrate that IFN-alpha-inducible gene expression levels can be successfully applied in a clinical trial setting as a marker of drug activity in a variety of human samples, including peripheral blood mononuclear cells (PBMC), cells derived from the airways, as well as cells from induced-sputum.

MeSH terms

  • Biomarkers / analysis*
  • Biomarkers / blood
  • Clinical Trials as Topic
  • DNA, Complementary / genetics
  • DNA, Complementary / isolation & purification
  • Gene Expression Regulation*
  • Humans
  • Ligands*
  • RNA, Messenger / genetics
  • RNA, Messenger / isolation & purification
  • Toll-Like Receptors / metabolism*


  • Biomarkers
  • DNA, Complementary
  • Ligands
  • RNA, Messenger
  • Toll-Like Receptors