Reston, Virginia (June 27, 2025)
The SNMMI Mars Shot Research Fund is pleased to announce that Mark A.
Sellmyer, MD, PhD, assistant professor in the Department of Radiology,
Biochemistry and Biophysics at the University of Pennsylvania, in Philadelphia has
been selected as the recipient of a $100,000 innovator’s grant from the 2025
Mars Shot Fund. Sellmyer’s Mars Shot grant was awarded based on his proposal, “Transforming
antibody-based imaging and therapy using a tetrazine-knock-out (TKO) approach.”
The SNMMI Mars Shot innovator’s grants focus on highly innovative research
initiatives designed to advance precision and personalized healthcare through
diagnostic and therapeutic nuclear medicine. This award was presented to Sellmyer
at the SNMMI 2025 Annual Meeting in New Orleans, Louisiana.
Full-length antibodies have had a remarkable
impact on cancer therapy due to key advantages including their high target
specificity. As a companion imaging and diagnostic tool, however, their large
molecular weight can result in slow blood clearance. This often leads to
delayed, suboptimal results for PET imaging and can cause critical toxicities
for radioimmunotherapy.
“To be
clinically applicable, it is crucial that radioimmunoconjugates remain in the
blood and interstitial space for just enough time to accumulate in target
tissues; ideally, they then would be rapidly excreted from the body to minimize
damage to healthy organs,” Sellmyer said. “Our research will address this
challenge by engineering an approach for diagnostic and therapeutic
radioimmunoconjugates that will enable rapid clearance of off-target
radioactivity after achieving specific accumulation in target tissues.”
In
this study, Sellmyer and colleagues will investigate a click-chemistry approach,
termed tetrazine knock-out (TKO), for the removal of unnecessary radiation from
circulation and non-target organs. First, precursor and radiosynthetic routes
for theranostic, radiolabelled antibodies for TKO will be developed. Next, the
researchers will characterize the parameters of these radioimmunoconjugates for
optimal target to background signal for PET imaging in rodent hematologic
malignancy models. Finally, they will test the parameters of TKO-based
radioimmunoconjugates for therapeutic effect in vivo.
“By conducting
experiments with these tracers, we aim to establish the versatility and
applicability of our method for different basic research and clinical scenarios
including diagnostic imaging and therapy which will be transferable to other
internalizing antibodies,” noted Sellmyer.
Sellmyer
co-founded and directs the Penn Center for Translational Chemical Biology and directs
the PET Center, a university core in the Department of Radiology, which aims to
bring new radiopharmaceuticals into clinical practice. He has developed several
small-molecule technologies ranging from chemical tools for basic biology
applications through imaging probes that are being applied in human patients.
His past research has focused on development of protein regulatory systems,
imaging and chemical control of gene/cell therapies, and biologic
radiopharmaceutical imaging and theranostics.
Sellmyer holds a bachelor of science in
chemistry from Massachusetts Institute of Technology in Cambridge,
Massachusetts, and medical and doctoral degrees from Stanford University in
Stanford, California.
Established in 2023, the
SNMMI Mars Shot Research Fund is a forward-looking glimpse into the future of nuclear medicine. It provides resources that translate visionary
nuclear medicine imaging, radiopharmaceutical therapy, and data science
research or projects into tools or treatments that will help improve the lives
of patients. The
Mars Shot Research Fund acknowledges and appreciates the generous contributions
from all our donors in support of the Mars Shot Innovator’s Grants.
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About the Society of Nuclear Medicine and Molecular Imaging
The Society of Nuclear
Medicine and Molecular Imaging (SNMMI) is an international scientific and
medical organization dedicated to advancing nuclear medicine, molecular
imaging, and theranostics—precision medicine that allows diagnosis and
treatment to be tailored to individual patients in order to achieve the best
possible outcomes. For more information, visit snmmi.org.