Table 2.

PD markers for all FDA-licensed monoclonal antibody types.

Therapeutic Protein Class	PD Marker	Receptor Binding Test
Anti-CD20 antibodies (e.g., Rituximab) [75]	CD20+ B-cell counts, immunoglobulin levels	CD20 binding assay
Anti-IgE therapies (e.g., Omalizumab) [76]	Serum-free IgE levels, basophil activation	IgE binding assay
Anti-IL-5 therapies (e.g., Mepolizumab, Reslizumab) [77]	Blood eosinophil count, asthma exacerbation rates	IL-5 receptor binding assay
Anti-PD-1 antibodies (e.g., Nivolumab, Pembrolizumab) [78]	Tumor responses, immune cell activation	PD-1 binding assay
Anti-VEGF agents (e.g., Bevacizumab, Aflibercept) [79]	Tumor response, normalization of tumor vasculature	VEGF binding assay
Bruton’s tyrosine kinase (BTK) inhibitors (e.g., Ibrutinib) [80]	B-cell counts, lymph node size, BTK phosphorylation	BTK binding assay
BTK inhibitors (e.g., Ibrutinib) [81]	B-cell counts, lymph node size, BTK phosphorylation	BTK binding assay
CD20-directed therapies (e.g., Rituximab) [82]	B-cell counts, tumor response in B-cell malignancies	CD20 binding assay
CD3-directed therapies (e.g., Blinatumomab) [83]	T-cell counts, tumor response in B-ALL	CD3 binding assay
CD38-directed therapies (e.g., Daratumumab) [84]	Plasma cell counts in multiple myeloma, immunoglobulin levels	CD38 binding assay
Coagulation factors (e.g., Factor VIII, Factor IX) [85]	Clotting times, bleeding episodes	N/A (Functional activity assays used)
Complement C5 inhibitors (e.g., Eculizumab) [86]	Hemolysis markers, renal function in aHUS	Complement C5 binding assay
CTLA-4 inhibitors (e.g., Ipilimumab) [87]	Tumor response in melanoma, immune cell activation	CTLA-4 binding assay
EGFR inhibitors (e.g., Cetuximab, Panitumumab) [88]	Tumor response, skin rash, EGFR phosphorylation levels	EGFR binding assay
Factor IX products (e.g., BeneFIX) [89]	Control and prevention of bleeding episodes in Hemophilia B	Factor IX binding assays
Factor VIII products (e.g., Advate) [90]	Control and prevention of bleeding episodes in Hemophilia A	Factor VIII binding assays
Factor Xa inhibitors (e.g., Andexanet alfa) [91]	Bleeding control, clotting times	Factor Xa binding assay
HER2/neu-directed therapies (e.g., Trastuzumab) [92]	Tumor response, cardiac monitoring, HER2 phosphorylation	HER2/neu binding assay
IL-1 inhibitors (e.g., Anakinra, Canakinumab) [93]	Inflammatory markers, clinical scores	IL-1 receptor binding assay
IL-1 inhibitors (e.g., Anakinra) [94]	Symptom relief in RA, systemic JIA; inflammatory markers	IL-1 receptor binding assay
IL-12/23 inhibitors (e.g., Ustekinumab) [95]	Cytokine levels (IL-12, IL-23), PASI score in psoriasis	IL-12/IL-23 p40 subunit binding assay
IL-17 inhibitors (e.g., Secukinumab, Ixekizumab) [96]	PASI score in psoriasis, inflammatory markers in spondylitis	IL-17 receptor binding assay
IL-23 inhibitors (e.g., Guselkumab) [97]	PASI score in psoriasis	IL-23 receptor binding assay
IL-5 inhibitors (e.g., Mepolizumab) [98]	Eosinophil counts, symptom control in severe asthma	IL-5 receptor binding assay
IL-6 inhibitors (e.g., Tocilizumab) [99]	CRP, IL-6 serum levels, clinical scores in diseases like RA	IL-6R binding assay
JAK inhibitors (e.g., Tofacitinib, Baricitinib) [98]	Inflammatory markers, clinical scores	JAK protein binding assay (biochemical assay)
mTOR inhibitors (e.g., Everolimus) [99]	Tumor response, organ transplant graft survival	mTOR binding assay
PCSK9 inhibitors (e.g., Evolocumab, Alirocumab) [100]	Serum LDL cholesterol levels	PCSK9 binding assay
PD-1 inhibitors (e.g., Pembrolizumab) [101]	Tumor response in various cancers	PD-1 receptor binding assay
PD-L1 inhibitors (e.g., Atezolizumab) [102]	Tumor responses, immune cell activation	PD-L1 binding assay
SGLT2 inhibitors (e.g., Dapagliflozin, Empagliflozin) [103]	Blood glucose levels, HbA1c levels	SGLT2 receptor binding assay
Soluble guanylate cyclase (sGC) stimulators [104]	Plasma cyclic GMP levels, vasodilatory responses	sGC binding assay
TNF-α inhibitors (e.g., Infliximab, Adalimumab) [105]	Inflammatory markers (CRP, ESR), clinical scores in diseases like RA	TNF-α binding assay