# Single Chelator-Minibody Conjugate for PET and Therapy Radionuclides

> **NIH NIH R43** · LUMIPHORE, INC. · 2021 · $251,985

## Abstract

Abstract
The overall goal of this SBIR is to develop an innovative theranostic agent for imaging and
treatment of cancer, by combining PET imaging and targeted radionuclide therapy (TRT) agents
via a single chelator-minibody conjugate precursor.
The novel theranostic agent described here employs a chelator, Lumi804, that can quickly and
stably chelate the most widely used positron emitter for antibodies (Zr-89) and the most widely
used therapeutic beta-emitting radionuclide (Lu-177), and an alpha emitting isotope (Th-227)
currently undergoing clinical evaluation in multiple phase I efficacy trials. To our knowledge,
there are no chelator-antibody or chelator-minibody conjugates that are in human trials or used
clinically that can be labeled with both Zr-89 (PET imaging) and Lu-177 (TRT) quickly at room
temperature.
Small molecule peptide analogues based on a dipeptide urea motif such as F-18-PSMA-1007 or
Ga-68-PSMA-11 have recently improved imaging of prostate cancer, and analogues such as
Lu-177-PSMA-617 and Ac-225-PSMA-617 are showing significant efficacy in patients. However,
patients treated with Lu-177-PSMA-617 often recur, and salvage therapy with Ac-225-PSMA-
617, while effective, is limited due to salivary gland toxicity. Use of radiolabeled antibodies has
been shown to avoid salivary gland localization, but can lead to bone marrow suppression due
to the longer biological half-life of antibodies. The Zr-89-DFO-IAB2M minibody has been
evaluated in Phase I clinical study and found to display low salivary gland localization while
exhibiting a biological half-life that is much shorter than the corresponding Zr-89-DFO-J591
antibody conjugate. The proposed research in this SBIR Phase I project will develop the
synthesis and evaluate the performance of a novel Zr-89, Lu-177, and Th-227 labeled anti-
prostate specific membrane antigen (PSMA) intact minibody construct, leveraging a single
chelator suitable for all three radiometals, for lesion detection, treatment, and monitoring patient
response to radionuclide therapy. These studies will enable the development in Phase II of the
first theranostic agent to target positron, beta particle, and alpha particle radiation to PSMA
expressing tumors.

## Key facts

- **NIH application ID:** 10325851
- **Project number:** 1R43CA265652-01
- **Recipient organization:** LUMIPHORE, INC.
- **Principal Investigator:** Darren Magda
- **Activity code:** R43 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $251,985
- **Award type:** 1
- **Project period:** 2021-09-23 → 2023-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10325851

## Citation

> US National Institutes of Health, RePORTER application 10325851, Single Chelator-Minibody Conjugate for PET and Therapy Radionuclides (1R43CA265652-01). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10325851. Licensed CC0.

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