Plays a prominent role in transplantation and autoimmunity
C4d has the potential as a biomarker for the detection of patients at risk for the consequences of antibody-mediated disease. The development of new therapeutics that block complement activation makes C4d a promising biomarker with the potential to identify and monitor patients who may benefit from these drugs.
Stable marker associated with transplant rejection
C4d has been used for a long time as a histological biomarker for complement activity and is recognized for its stability and strong association with antibody mediated rejection (AMR) of grafts. C4d in plasma is now increasingly identified as a biomarker for complement activation and as a tool to predict and monitoring flares in for example SLE, Systemic sclerosis and ANCA–associated vasculitis. Several studies are ongoing to evaluate and study plasma C4d as biomarker in a wide area of clinical situations.
Useful biomarker within the cancer area
C4d has also been evaluated as a useful biomarker within the cancer area. Studies indicate that C4d may be of both diagnostic and prognostic value in different types of lung cancer. C4d adds diagnostic value to the evaluation of indeterminate lung nodules allowing patient stratification. In malignant pleural mesothelioma, C4d levels have been shown to correlate with tumor load and chemotherapeutic response.