Researchers at the National University of Singapore said they used pulsed electromagnetic fields, or PEMFs, to reprogram tumour-associated macrophages in breast cancer. The university said the immune cells, which usually support tumour growth, were shifted into a state that attacks and destroys cancer cells. The study was led by Associate Professor Alfredo Franco-Obregón of the NUS Department of Surgery at the Yong Loo Lin School of Medicine and the NUS Institute for Health Innovation & Technology. It was published in Smart Medicine on 4 June 2026.

PEMF therapy delivers short bursts of low-intensity magnetic pulses to targeted areas, the university said. In preclinical models, the NUS team found that four 30-minute sessions eliminated tumours in 75 per cent of the models without chemotherapy, according to the university. The work follows earlier findings by the same group that brief PEMF exposure increased breast cancer cells' uptake of doxorubicin, a chemotherapy drug, the university said. It also said breast cancer cases are projected to rise from 2.3 million in 2023 to more than 3.5 million by 2050, with annual deaths may nearly double from 764,000 to nearly 1.4 million. Treatment faces challenges including tumour heterogeneity, drug resistance and treatment-related toxicities, and approaches targeting TAMs have faced off-target effects, it said.

The study described how breast cancer cells recruit nearby immune cells and push most tumour-associated macrophages into an M2 state. M1 macrophages are pro-inflammatory and attack threats such as bacteria and viruses, while M2 macrophages are anti-inflammatory and support wound healing and tissue repair, the university said. Cancer cells corrupt most TAMs into the M2 state, suppressing immune attacks and helping the tumour grow and spread. The researchers linked the reprogramming to a protein called TRPC1, which regulates the M1 state and lets cells sense magnetic fields. A 10-minute PEMF exposure activated TRPC1 on M2-like TAMs, triggering a signalling cascade that converted them to the M1 state, the study found. The activated cells then target cancer cells and leave healthy tissue alone, and the magnetic signal also disrupted communication between TAMs and cancer cells, according to the university.

Assoc Prof Franco-Obregón said the team identified the molecular switch and signalling pathway that allows TAM reprogramming. He said the reprogrammed immune cells actively hunt and consume cancer cells, destroying the tumour. He said the non-invasive and targeted nature of PEMF therapy could provide patients with an alternative treatment that has fewer side effects.

The same PEMF device used in the study has completed Phase 1 clinical trials and was found to be safe in humans, Assoc Prof Franco-Obregón said. The team is seeking partners for Phase 2 efficacy trials to evaluate how well the PEMF treatment works in patients and to advance its development toward clinical use. He said the group will evaluate whether PEMF immunotherapy can work with chemotherapy, following earlier work on doxorubicin uptake. Because the reprogrammed immune cells are commonly found in most solid tumours, he said the team is optimistic the therapy could be a complementary treatment for other cancers beyond breast cancer.