Integrin α_vβ₃ is overexpressed in various tumor cells and angiogenesis. To date, no drug has been proven to target it for therapy. A first-in-human study was designed to investigate the safety, pharmacokinetics, and dosimetry of ¹⁷⁷Lu-AB-3PRGD2, a novel integrin α_vβ₃-targeting radionuclide drug with an albumin-binding motif to optimize the pharmacokinetics. Ten patients (3 men, 7 women; aged 45 ± 16 years) with integrin α_vβ₃-avid tumors were recruited to accept ¹⁷⁷Lu-AB-3PRGD2 injection in a dosage of 1.57 ± 0.08 GBq (42.32 ± 2.11 mCi), followed by serial scans to obtain its dynamic distribution in the body. Safety tests were performed before and every 2 weeks after the treatment for 6–8 weeks. No adverse event over grade 3 was observed. ¹⁷⁷Lu-AB-3PRGD2 was excreted mainly through the urinary system, with intense radioactivity in the kidneys and bladder. Moderate distribution was found in the liver, spleen, and intestines. The estimated blood half-life was 2.85 ± 2.17 h. The whole-body effective dose was 0.251 ± 0.047 mSv/MBq. The absorbed doses were 0.157 ± 0.032 mGy/MBq in red bone marrow and 0.684 ± 0.132 mGy/MBq in kidneys. This first-in-human study of ¹⁷⁷Lu-AB-3PRGD2 treatment indicates its promising potential for targeted radionuclide therapy of integrin α_vβ₃-avid tumors. It merits further studies in more patients with escalating doses and multiple treatment courses.

Inhibiting glutamine metabolism has been proposed as a potential treatment strategy for improving non-alcoholic steatohepatitis (NASH). However, effective methods for assessing dynamic metabolic responses during interventions targeting glutaminolysis have not yet emerged. Here, we developed a positron emission tomography (PET) imaging platform using L-[5-¹¹C]glutamine ([¹¹C]Gln) and evaluated its efficacy in NASH mice undergoing metabolic therapy with bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide (BPTES), a glutaminase 1 (GLS1) inhibitor that intervenes in the first and rate-limiting step of glutaminolysis. PET imaging with [¹¹C]Gln effectively delineated the pharmacokinetics of L-glutamine, capturing its temporal-spatial pattern of action within the body. Furthermore, [¹¹C]Gln PET imaging revealed a significant increase in hepatic uptake in methionine and choline deficient (MCD)-fed NASH mice, whereas systemic therapeutic interventions with BPTES reduced the hepatic avidity of [¹¹C]Gln in MCD-fed mice. This reduction in [¹¹C]Gln uptake correlated with a decrease in GLS1 burden and improvements in liver damage, indicating the efficacy of BPTES in mitigating NASH-related metabolic abnormalities. These results suggest that [¹¹C]Gln PET imaging can serve as a noninvasive diagnostic platform for whole-body, real-time tracking of responses of glutaminolysis to GLS1 manipulation in NASH, and it may be a valuable tool for the clinical management of patients with NASH undergoing glutaminolysis-based metabolic therapy.

Peptide-based radiopharmaceuticals targeting integrin α5β1 show promise for precise tumor diagnosis and treatment. However, current peptide-based radioligands that target α5β1 demonstrate inadequate in vivo performance owing to limited tumor retention. The use of PEGylation to enhance the tumor retention of radiopharmaceuticals by prolonging blood circulation time poses a risk of increased blood toxicity. Therefore, a PEGylation strategy that boosts tumor retention while minimizing blood circulation time is urgently needed. Here, we developed a PEGylation-enabled peptide multidisplay platform (PEGibody) for PR_b, an α5β1 targeting peptide. PEGibody generation involved PEGylation and self-assembly. [⁶⁴Cu]QM-2303 PEGibodies displayed spherical nanoparticles ranging from 100 to 200 nm in diameter. Compared with non-PEGylated radioligands, [⁶⁴Cu]QM-2303 demonstrated enhanced tumor retention time due to increased binding affinity and stability. Importantly, the biodistribution analysis confirmed rapid clearance of [⁶⁴Cu]QM-2303 from the bloodstream. Administration of a single dose of [¹⁷⁷Lu]QM-2303 led to robust antitumor efficacy. Furthermore, [⁶⁴Cu]/[¹⁷⁷Lu]QM-2303 exhibited low hematological and organ toxicity in both healthy and tumor-bearing mice. Therefore, this study presents a PEGibody-based radiotheranostic approach that enhances tumor retention time and provides long-lasting antitumor effects without prolonging blood circulation lifetime. The PEGibody-based radiopharmaceutical [⁶⁴Cu]/[¹⁷⁷Lu]QM-2303 shows great potential for positron emission tomography imaging-guided targeted radionuclide therapy for α5β1-overexpressing tumors.