Los Angeles -- A novel theranostic
approach that targets RET -- a newly identified biomarker for neuroendocrine
prostate cancer enables high-contrast PET imaging and effective, safe
treatment for this highly aggressive malignancy. Because this disease is often
poorly visualized with prostate-specific membrane antigen (PSMA)-based imaging,
the RET approach offers an important alternative when conventional molecular
imaging and PSMA-directed therapies are unsuitable. This research was presented
at the Society of Nuclear Medicine and Molecular Imaging 2026 Annual Meeting.
Neuroendocrine prostate cancer is an aggressive, treatment-resistant
subtype that frequently develops as an evolution of castration-resistant
prostate cancer. It often expresses low levels of PSMA or is PSMA negative. Consequently,
the disease is difficult to detect with current PSMA-based imaging, leading to
less effective treatment.
"Patients with neuroendocrine prostate cancer face a major challenge
because this cancer can hide from PSMA-based scans and therapies," said Yongxiang Tang, associate professor and deputy
director in the Department of Nuclear Medicine at Xiangya
Hospital at Central South University, in Changsha, Hunan, China. "In our
study, we aimed to identify a neuroendocrine prostate cancer biomarker and
develop a theranostic pair for PET imaging and
radioligand therapy."
Based on previous studies, researchers identified RET as a candidate
surface marker, and RET expression was validated by immunohistochemistry in 134
human prostate specimens. Upon selecting RET-L7 as a binding peptide, 68Ga-DOTA-RET-L7
PET/CT and 177Lu-DOTA-RET-L7 therapy were evaluated in RET-positive and
RET-negative xenografts, and blocking, biodistribution, survival, and toxicity
studies were conducted.
68Ga-DOTA-RET-L7 demonstrated high, specific uptake in
RET-positive tumors versus RET-negative tumors, with strong self-blockade and
rapid blood clearance. A single dose of 177Lu-DOTA-RET-L7 produced
dose-dependent survival benefit without significant hematologic or organ
toxicity.
"RET is a clinically relevant neuroendocrine prostate cancer-selective
surface target," said Tang. "This preclinical work supports translation of the
RET-targeted theranostic approach for PSMA-negative
prostate cancer."
The research continues to move forward as first-in-human
imaging is currently being conducted as part of an investigator-initiated
clinical study. Broader patient access will require additional safety and dosimetry
evaluation, larger clinical validation, and regulatory approvals.