A new “Trojan horse” weight-loss drug sneaks extra metabolic power into cells and delivers striking results in mice.
Researchers at Helmholtz Munich have developed a new drug strategy that could improve treatment for obesity and type 2 diabetes. Led by metabolism scientist Prof Timo D. Müller, the team created a hybrid molecule that uses the GLP-1/GIP signaling pathway as a kind of gateway into cells. Once inside, the molecule delivers an additional metabolic compound directly to targeted cells.
In experiments involving mice, the treatment reduced food intake, produced greater weight loss, and improved blood-glucose levels compared with existing reference therapies. The findings were reported in the journal Nature.
Building on GLP-1 and GIP Therapies
Current incretin-based treatments, which mimic the body’s natural satiety and blood sugar signals (GLP-1/GIP), have already transformed obesity and type 2 diabetes care. Even so, scientists continue searching for ways to make these medications more effective.
One possible strategy is adding drugs that improve insulin sensitivity, helping glucose move from the bloodstream into tissues more efficiently. The problem is that many of these compounds spread throughout the body rather than targeting specific cells, which can increase unwanted side effects.
“Our guiding question was: how can we enhance incretin activity without creating a second, systemically active source of side effects?” says study leader Timo D. Müller, Director of the Institute for Diabetes and Obesity (IDO) at Helmholtz Munich, Professor at the Ludwig Maximilian University of Munich (LMU) and researcher at the German Center for Diabetes Research (DZD).
Hybrid Molecule Delivers Drug Cargo Into Cells
To address this challenge, the researchers designed what they call an “address label with cargo.” They chemically linked a known incretin-based compound with another drug called lanifibranor, which is classified as a pan-PPAR agonist.
The incretin portion attaches to GLP-1 or GIP receptors on the cell surface, allowing the hybrid molecule to enter the cell. Once inside, the second component activates PPARs, which act as genetic “switches” involved in regulating fat and sugar metabolism. The goal is to concentrate these added metabolic effects specifically in GLP-1R/GIPR- expressing cells instead of throughout the entire body.
“Trojan Horse” Drug Targets Five Pathways
The new molecule acts on five different drug targets simultaneously. It activates two receptors on the cell surface (GLP-1R and GIPR) while also engaging three PPAR “switches” inside the cell nucleus.
Müller compares the process to a “Trojan horse”: the incretin component opens the door to the cell, while the “cargo” only becomes active after entering.
“A major advantage is the amount,” says Müller. “Because the second component is not administered separately and systemically, but ‘travels along’ with the incretin part, it can be used at a dose that is orders of magnitude lower.”
According to the researchers, this targeted delivery may increase effectiveness without increasing side effects caused by widespread exposure throughout the body.
Weight Loss and Blood Sugar Improvements in Mice
The hybrid therapy produced strong results in mice with diet-induced obesity. “The animals ate less and lost more weight than under a GLP-1/GIP co-agonist without cargo,” says Dr Daniela Liskiewicz, group leader at IDO and co-first author together with Dr Aaron Novikoff. “In the head-to-head comparisons shown, the effect was in part even stronger than with a GLP-1-only drug.”
The findings suggest the combination does more than simply add another mechanism. Instead, it appears to strengthen incretin activity itself, at least in animal studies.
Signs of Better Metabolic Health
The treatment’s effects extended beyond body weight. Researchers observed improved blood-glucose control and signs that insulin function became more effective. In simple terms, insulin appeared better able to move glucose from the blood into tissues, while the liver released less glucose into circulation.
The team also reported that gastrointestinal side effects were similar to those seen with existing incretin therapies. In the measures examined, they did not observe signs of fluid retention or anemia, two concerns linked to the added drug component.
Human Studies Still Needed
The mouse data also hinted at possible benefits for heart and liver health. However, the scientists emphasize that this remains a preclinical study, and it is still unclear whether the same results will occur in humans. One reason for caution is that the GIP receptor functions differently in mice and people.
“We see a principle with strong effects in the animal model – now the task is to optimize the approach for humans and move it towards the clinic,” says Müller. He adds that advancing the therapy toward clinical use will require support from industry partners.
Reference: “GLP-1R–GIPR–PPARα/γ/δ quintuple agonism corrects obesity and diabetes in mice” by Daniela Liskiewicz, Aaron Novikoff, Ahmed Khalil, Seun Akindehin, Jonathan E. Campbell, Pietra Candela, Russell L. Castelino, Callum Coupland, Maxime Culot, W. Scott Dodson, Jonathan D. Douros, Hannes Embring, Annette Feuchtinger, Brian Finan, Cristina Garcia-Caceres, Xiao-Bing Gao, Fabien Gosselet, Gerald Grandl, Robert M. Gutgesell, Daniel T. Haas, Martin Jastroch, Ezgi Karaoglu, Pamela Kakimoto, Anna Cristina Kaltenbach, Michaela Keuper, Christine M. Kusminski, Danielle C. Leander, Arkadiusz Liskiewicz, Xue Liu, Gandhari Maity-Kumar, Sara Martinez Martinez, Stephanie A. Mowery, Ruben Nogueiras, Marshall Paisley, Diego Perez-Tilve, Patricia S. S. Petersen, Paul T. Pfluger, Sneha Prakash, Sabine Steffens, Alberto Cebrian-Serrano, Monica Tost, Jordan Wean, Christian Weber, Junichi Yoshida, Zachary Gerhart-Hines, Tamas L. Horvath, Philipp E. Scherer, Randy J. Seeley, Richard D. DiMarchi, Matthias H. Tschöp, Natalie Krahmer, Patrick J. Knerr and Timo D. Müller, 29 April 2026, Nature.
DOI: 10.1038/s41586-026-10427-5
Prof. Timo D. Müller is Director of the Institute for Diabetes and Obesity (IDO) at Helmholtz Munich, Professor at the Ludwig Maximilian University of Munich (LMU), and researcher at the German Center for Diabetes Research (DZD).
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