Table 1.

Studies on Integrin αvβ6 as Imaging Point and Therapeutic Target.

Peptide/drug	Pharmaceutical	Binding materials	Characteristics summary	References
A20FMDV2	[18F]FBA-PEG28-A20FMDV2; [18F]FBA-(PEG28)2-A20FMDV2; [18F]-FBAA20FMDV2-PEG28; [18F]-FBA-PEG28-A20FMDV2-PEG28	18F；PEG 28	PEG increases biological half-life, metabolic stability, and tumor absorption. When compared to just one PEG, the addition of two PEGs inhibited drug clearance. Experiments show that adding one PEG 28 to the N-terminal and one PEG 28 to the C-terminal produces optimal results.	119 , 140
	Ad-3Δ-A20T	Oncolytic adenovirus AdΔΔ	Ad5-3d-a20t retains the replication function of the virus, even in the presence of gemcitabine. It can effectively kill cancer cells, inhibit tumor growth, and weaken the ability of cancer cells to bind with red blood cells and blood factors. It also has a high binding affinity for PDAC.	141
	Ad-3Δ-A20T	125I；oncolytic adenovirus AdΔΔ	The addition of 125I does not necessitate gene modification or significantly reduce viral biological activity. It directly radioactively labels the virus. 125I shows biological distribution, elimination rate, and off-target effect rate of the adenovirus.	135
	PDC SG3299	Tesirine	SG3299 can cure PDAC with an optimal dosage and dosing regimen. The presence of pancreatic stellate cells has no effect on SG3299 cytotoxicity. SG3299 significantly reduces the spherogenesis of PDACPDX cells.	134
Knottins (Cystine forms peptides) 121	99m Tc-SAAC-S02	99mTc	Rapid tumor targeting with renal clearance. High blood and liver uptake and retention rates. Low miss rate.	142
	18F-FP-R01 and 18F-FP-S02	18F	18F-FP-R01 intake was low in non-target tissues and healthy tissues, and moderate in the kidney. 18F-FP-R01 outperforms 18F-FP-S02 in terms of tumor affinity and plasma stability.	122
	R01-MG-IRDye800	IRDye800	Tumor-specific targeting and a high rate of renal clearance. High tumor background ratio and a clear correlation were observed between fluorescence signal and the PDAC histopathology.	126
	18F-FP-R01-MG-F2	18F	Tumor accumulation is faster, higher, and stable. Uptake of 18F-FP-R01-Mg-F2 in retroperitoneal lymph node metastasis was reported. Distant metastases are visible in organs with low physiological intake, such as the lungs and liver. Knottin may be able to meet the need for accurate cancer spread assessment.	143 , 118
	177Lu-DOTA-integrin αvβ6 knottin	177Lu	It is a high-affinity tracer for PDAC with high tumor accumulation and moderate, rapidly declining renal uptake.	96
HK (TP H2009.1)	99m Tc-HHK	99m Tc	With rapid tumor accumulation, the radiotracer showed maximum tumor uptake at 0.5h after injection. The tumor can be seen with high contrast but it has a low uptake rate. It has high sensitivity and accuracy in identifying and localizing small metastatic liver lesions.	123
	Dye-SA-B-HK	IRDye700	Dye-SA-B-HK has a high receptor-binding affinity, indicating that dye-SA-B-HK could be enriched in tumors in large and specific quantities. It can be used as photodynamic therapy (PDT) to necrotize cancer cells and reduce tumor proliferation.	128
	99m Tc-HYNIC-cHK	99m Tc	In vivo, cyclic HK peptide (cHK) had similar biological distribution characteristics to linear HK peptide but significantly improved metabolic stability and rapid tumor accumulation in vivo. The binding affinity of cHK to integrin αvβ6 was slightly lower than compared to that of the HK peptide, which might be attributed to peptide sequence shortening and conformational constraints.	144
Cycratide	68Ga-cycratide	68Ga	It is easy to prepare and has good pharmacokinetic and biological characteristics. Cleared by renal and bladder pathways, the blood and surrounding abdominal organs have a low background, it can be sensitively detected in pancreatic neoplasms, and is internally stable.	125
IsoDGR	99mTc-3PisoDGR	99m Tc	IsoDGR has the ability to target both αvβ6 and α5β1. This strategy avoids the tedious labor and timely preparation. It avoids the interaction of two different targeted molecules. High tumor uptake.	145
αvβ6-BP	[64Cu]Cu DOTA-EB-αvβ6-BP([64Cu]1) and [64Cu]Cu DOTA-IP-αvβ6-BP([ 64Cu] 2)	64Cu；Albumin binding moirty (ABM) (EB、IP)	Rapid tumor uptake, increased circulation time, decreased renal uptake, rapid clearance, and increased tumor accumulation. [64Cu]2 is stable in serum and improves tumor visualization.	146
Avebehexin	Ga-68-avebehexin	68Ga	Polymerization has no effect on the αvβ6 integrin-selective peptide C (FRGDLAFp(NMe)K), and the TRAP-conjugated monomer 68Ga-Avebehexin can achieve highly sensitive PET imaging as well as therapeutic effects. Despite the fact that tumor intake is low, it is still higher than in all other organs, except the kidney.	147
Trivehexin	Ga-68-Trivehexin	68Ga	68Ga-trivehexin showed significant selectivity to integrin αvβ6 over other RGD-binding integrins. With the exception of the kidney, nonspecific uptake is almost completely eliminated. More specific and sensitive metastatic cancer diagnosis.	148