Breakthrough Boosts Tamoxifen Effectiveness for Younger Breast Cancer Patients
STUTTGART, Germany – October 16, 2025 – A novel approach combining the standard breast cancer drug tamoxifen with a supplement of (Z)-endoxifen is showing promise in improving treatment outcomes for premenopausal women with early-stage, hormone-dependent breast cancer, researchers announced today. The findings address a long-standing challenge: the reduced effectiveness of tamoxifen in patients who don’t adequately metabolize the drug.
Tamoxifen relies on conversion within the body to it’s active form, endoxifen. Some women, particularly younger patients, have limited capacity for this conversion, diminishing the drug’s impact. While postmenopausal women have choice treatment options like aromatase inhibitors, these are not suitable for premenopausal individuals.
A study published in clinical Cancer Research involved 235 patients who received either tamoxifen alone or tamoxifen plus (Z)-endoxifen,based on their metabolic capacity. Results demonstrated that the combination therapy achieved blood drug concentrations comparable to those seen in patients with normal tamoxifen metabolism.Side effects were reported as mild and similar across both groups.
“With this approach, we offer the first effective solution to a long-standing problem: the insufficient affect of tamoxifen in a important proportion of patients,” said Dr. Matthias Schwab, leader of the study at the Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology.
A mid-phase clinical trial of (Z)-endoxifen in premenopausal women with newly diagnosed, early-stage hormone-sensitive breast cancer is currently underway in the United States, sponsored by Atossa Therapeutics (ACTS.O). The company anticipates filing for Food and Drug Administration approval in 2026.
Pill-Sized Bioprinters Show potential for Gastrointestinal Repair
Researchers are also developing a pill-sized “bioprinter” capable of delivering tissue-repairing bio-ink directly to injuries within the gastrointestinal tract, such as ulcers and hemorrhages.
The Magnetic Endoluminal Deposition System (MEDS) functions like a pen, using a spring-loaded tip and external magnetic guidance to deposit a biological ink at the injury site. A near-infrared laser beam, safely penetrating tissue, triggers the release of the bio-ink. The capsule can then be retrieved orally using magnetic control.
Initial testing in rabbits has shown the cell-laden bio-ink maintains structural integrity for over 16 days. Researchers, led by Sanjay Manoharan at the École Polytechnique Fédérale de Lausanne (Switzerland), plan to expand testing to injured blood vessels and abdominal wall tissue.
“In our controlled laboratory experiments, our cell-laden bioink retained its structural integrity for more than 16 days,” Manoharan stated. The bio-ink can also be combined with drugs or cells to enhance tissue repair and protect ulcers from gastric acids.
