Design and Evaluation of (68)Ga-Labeled Peptide-Based PET Probes for Noninvasive Imaging of ROR1 Expression in Tumor Models.
PET imaging just got a shot in the arm from peptide research. A team out of Xiamen University and several partner labs has engineered a new batch of gallium-68 labeled peptides designed to target ROR1 — a receptor that’s overexpressed in several tumor types. ROR1 isn’t just another biomarker. It’s showing up in multiple cancers and increasingly used to guide staging and therapy choices. Figuring out how to see it in living systems is a big deal for translational research.
J Med Chem
by Yang T, An Q, Lin S et al.
“Design and Evaluation of (68)Ga-Labeled Peptide-Based PET Probes for Noninvasive Imaging of ROR1 Expression in Tumor Models. Yang T(1), An Q(1), Lin S(1), Sun J(1), Wang Y(1), Chen H(1), Liao Z(1), Zhang Q(1), Wang H(1), Yang G(2), Hong L(3), Li Y(4), Yi H(5), Huang G(1), Liu H(1), Guo Z(1)(3)(4). Author information: (1)State Key Laboratory of Vaccines for Infectious Diseases, Xiang An Biomedicine Laboratory, National Innovation Platform for Industry-Education Integration in Vaccine Research, Fujian Engineering Research Center of Molecular Theranostic Technology, Center for Molecular Imaging and Translational Medicine, School of Public Health, Xiamen University, Xiamen, Fujian 361102, China. (2)Department of Nuclear Medicine, The Affiliated Hospital of Qingdao University, Qingdao 266000, China. (3)Zhangzhou Affiliated Hospital of Fujian Medical University, Zhangzhou 363000, China. (4)Department of Nuclear Medicine & Minnan PET Center, The First Affiliated Hospital of Xiamen University, Xiamen 361003, China. (5)Department of Nuclear Medicine, Zhejiang Cancer Hospital, Hangzhou Zhejiang 310022, China. The receptor tyrosine kinase-like orphan receptor 1 (ROR1) is aberrantly overexpressed in multiple malignancies and has emerged as a clinically relevant biomarker for tumor staging and therapeutic decision-making. Here, we developed a series of PR7-derived ROR1-targeted radiotracers, including linear and cyclic analogues, and systematically evaluated their specificity in vitro and in vivo. All radiotracers showed high stability in saline and fetal bovine serum for at least 90 min and rapid tumor accumulation within 30 min post-injection in MC38 tumor-bearing mice. Among them, [68Ga]Ga-LP4 achieved favorable tumor targeting and tumor-to-nontumor ratios in PET imaging with predominant renal clearance. Notably, compared with [18F]AlF-NP1 reported in our previous study, [68Ga]Ga-LP4, which incorporates N-methylation and carboxyl amidation, demonstrated improved in vivo metabolic stability. Collectively, these findings identify [68Ga]Ga-LP4 as a promising ROR1-targeted imaging probe and highlight useful peptide optimization strategies.”
Here’s what the researchers did: They built several PR7-derived peptides, tweaked them for linear or cyclic structure, slapped on a gallium-68 label, then ran the probes through the gauntlet in both test tubes and mouse models. The results? All these radiotracers stayed rock-solid for at least 90 minutes in saline and serum. More importantly, they homed in on tumors fast — within 30 minutes of injection in mice.
Key takeaway: The standout was [68Ga]Ga-LP4. This version, modified with N-methylation and carboxyl amidation, didn’t just stick to tumors — it also showed better metabolic stability than older analogs like [18F]AlF-NP1. Clean PET images, high tumor-to-background ratios, and it clears through the kidneys. No messy buildup.
Why does this matter for peptide researchers?
New peptide probe design strategies (N-methylation, amidation) are working in vivo
ROR1 is a hot target for both imaging and potential intervention
Rapid, selective tumor imaging means faster, more accurate research
If you’re working on radiolabeled peptides or tumor imaging, this approach is worth a close look. More on the science behind these developments is indexed at the peptide research index. This is the kind of progress that keeps the peptide research field moving forward.
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