A novel prostate-specific membrane antigen (PSMA)-targeted radioligand, [177Lu]Lu-M3-12, outperformed the clinically established [177Lu]Lu-PSMA-617 in preclinical prostate cancer models, according to a peer-reviewed study published in EJNMMI Research. The work compared the two lutetium-177-labeled compounds head-to-head in cell and mouse experiments, reporting higher PSMA binding affinity, greater tumor uptake, and a better tumor-to-kidney ratio for the new agent.
PSMA-targeted radioligand therapy delivers radiation directly to prostate cancer cells that express the PSMA protein. [177Lu]Lu-PSMA-617 has shown clinical success in metastatic castration-resistant prostate cancer, but the authors note that heterogeneous responses and toxicities remain a challenge. M3-12 was designed with a linear, hydrophilic amide/urea-based linker conjugated to a DOTA chelator, a chemistry intended to improve how the compound behaves in the body.
In the study, [177Lu]Lu-M3-12 was prepared and characterized with a radiochemical purity of 97.5%. The researchers then assessed in vitro ADME properties and PSMA binding affinity, and measured cellular uptake and internalization in LNCaP prostate cancer cells. M3-12 inhibited PSMA with an IC50 of 2.24 nanomolar, compared with 4.07 nanomolar for PSMA-617, and showed superior cellular binding affinity, while the two compounds had comparable ADME profiles.
The pharmacokinetic comparison was carried out in mice bearing LNCaP tumors, using biodistribution measurements, SPECT/CT imaging, and therapeutic efficacy testing for both radioligands. At 24 hours after injection, [177Lu]Lu-M3-12 achieved significantly higher tumor uptake than [177Lu]Lu-PSMA-617, at 44.69 versus 24.09 percent injected dose per gram (P = 0.0043).
Kidney uptake is a critical safety consideration for PSMA-targeted radioligands, because the kidneys are a dose-limiting organ in this therapy class. In the mouse model, [177Lu]Lu-M3-12 showed a 2.73-fold higher tumor-to-kidney ratio than the comparator, a difference the authors attribute to the hydrophilic linker design and one they highlight as having potential to reduce dose-limiting nephrotoxicity.
Therapeutic testing showed dose-dependent antitumor efficacy. At the high dose of 29.6 megabecquerels, [177Lu]Lu-M3-12 produced pronounced tumor control in the LNCaP mouse model without significant toxicity, according to the reported results.
The authors conclude that [177Lu]Lu-M3-12 exhibited significantly higher PSMA binding affinity and tumor cell uptake than [177Lu]Lu-PSMA-617, while demonstrating dose-dependent antitumor efficacy and favorable safety profiles in these preclinical models. They link the improved tumor-to-kidney ratio to the unique hydrophilic linker design.
Importantly, all of these findings come from preclinical models rather than human trials. The authors themselves caution that larger studies are warranted to validate the results and to rigorously compare the efficacy of [177Lu]Lu-M3-12 with that of [177Lu]Lu-PSMA-617 in clinical settings. The findings support further preclinical development of the compound, but any benefit for patients with prostate cancer remains to be demonstrated.
Subject of Research: Preclinical evaluation of a novel PSMA-targeted radioligand for prostate cancer
Article Title: Preclinical evaluation of [177Lu]Lu-M3-12: a novel PSMA-targeted radioligand with enhanced antitumor efficacy in prostate cancer
Article References: Yang, M., Li, P., Huang, Q., Kong, X., & Cheng, G. (2026). Preclinical evaluation of [177Lu]Lu-M3-12: a novel PSMA-targeted radioligand with enhanced antitumor efficacy in prostate cancer. EJNMMI Research. https://doi.org/10.1186/s13550-026-01523-8
Image Credits: AI Generated
DOI: 10.1186/s13550-026-01523-8
Keywords: PSMA, radioligand therapy, lutetium-177, prostate cancer, preclinical study, LNCaP, tumor uptake, DOTA chelator, SPECT/CT, nephrotoxicity, Preclinical, evaluation
News Source: Nathaniel Bowman. (October 29, 2026). New PSMA-Targeted Radioligand Shows Stronger Tumor Uptake Than Lu-PSMA-617 in Mice. Scienmag.
