Researchers at the National University of Singapore (NUS) have used brief, low-intensity magnetic pulses to turn corrupted immune cells inside breast tumors against the cancer they were protecting. In preclinical tests, four 30-minute sessions completely eliminated tumors in 75 percent of the models, all without a single dose of chemotherapy.
The study, led by Associate Professor Alfredo Franco-Obregón from the NUS Yong Loo Lin School of Medicine and the NUS Institute for Health Innovation & Technology, was published in the journal Smart Medicine on June 4, 2026, and announced by NUS on September 14. It identifies a precise molecular pathway through which pulsed electromagnetic fields (PEMFs) convert tumor-protecting immune cells into cancer killers, an approach that could eventually complement or reduce chemotherapy.
- 75 percent complete eradication: three of four treated animals had no detectable tumor after treatment.
- Four 30-minute sessions: the entire preclinical regimen took two weeks, with no surgery and no drugs.
- A 10-minute trigger: a single brief exposure was enough to flip macrophages from tumor-protecting to tumor-killing in the lab.
- Human safety established: the same device has completed Phase 1 clinical trials with zero adverse events.
How Tumors Corrupt the Immune System
Solid tumors do not grow alone. Cancer cells actively recruit nearby immune cells and corrupt them, building a protective microenvironment that shields the tumor, accelerates its growth, and helps it spread. Among the most prominent recruits are tumor-associated macrophages (TAMs), which can make up as much as half of a tumor’s mass.
Macrophages normally come in two functional states. M1 macrophages are the pro-inflammatory “soldiers” that attack threats and devour diseased cells. M2 macrophages are the anti-inflammatory “medics” that orchestrate tissue repair once a threat is cleared. Cancer cells hijack this system, corrupting most TAMs into the M2 state so that the immune system’s own medics suppress the attack and instead nurture the tumor.
Drugs targeting TAMs have struggled in clinical development. The most advanced strategy, blocking the CSF1R survival receptor, depletes macrophages systemically and has produced severe liver toxicity, earning one such drug a black box warning. Reprogramming M2 macrophages back to the aggressive M1 state has been the more attractive goal, but pharmacological reprogramming agents tend to trigger dangerous whole-body inflammation when given systemically. A localized, physical approach has been the missing piece.
Flipping a Molecular Switch With Magnetic Fields
The NUS team found that piece in pulsed electromagnetic fields: intermittent, low-intensity magnetic pulses (about 3 milliTesla, roughly 50 times Earth’s magnetic field but a thousand times weaker than a standard MRI scanner) applied at 15 Hz. The pulses pass through tissue without generating heat or damaging it.
The mechanism starts with a protein called TRPC1, a calcium channel embedded in the cell membrane that also happens to act as a biological antenna for weak magnetic fields. A brief 10-minute exposure opens these channels, triggering a controlled influx of calcium that activates STING, a central alarm protein of the innate immune system, and its downstream NF-κB inflammatory pathway. The cascade flips macrophages from the M2 “medic” state to the M1 “soldier” state. Blocking TRPC1 or STING abolished the effect entirely, confirming the pathway is essential.
“Rather than shocking the body, the pulses act like a biological tuning fork,” Franco-Obregón told The Straits Times. “When they pass through cells, they interact with specialised microscopic gates on the cell surface called TRPC1 channels, which act as biological antennae for weak magnetic fields. Opening these gates triggers a small, controlled wave of calcium into the cell that activates the mitochondria, the cell’s energy furnace.”
The same stimulus has a very different effect on cancer cells. Because aggressive breast cancers overexpress TRPC1 to fuel their rapid proliferation, the pulses overload their calcium handling and push their mitochondria into metabolic stress, while healthy tissue simply mounts a protective, energizing response. “This excess makes cancer cells uniquely vulnerable to calcium overload and mitochondrial overheating,” said Franco-Obregón.
Four Sessions, Zero Drugs
In the lab, the effect showed up at every scale the team tested. In co-cultures of macrophages and triple-negative breast cancer cells, a single 10-minute pulse exposure raised the macrophage phagocytosis index by 60 percent and selectively depleted cancer cells while leaving the macrophages intact. In 3D tumor spheroids, pulsed exposure reprogrammed macrophages inside the tumor structure and cut the proportion of cancer cells from 50 percent to 35 percent. Healthy muscle cells co-cultured under the same conditions were untouched.
In BALB/c mice bearing aggressive 4T1 triple-negative breast tumors, four 30-minute sessions over two weeks, with no chemotherapy, eradicated tumors completely in three of the four treated animals. Dissection confirmed the tumors had fully resorbed with no residual mass or scarring. The remaining treated animal’s tumor shrank, and analysis of that regressing tumor showed heavy infiltration of M1 macrophages, cytotoxic T cells, and natural killer cells, suggesting the pulses also triggered a broader anti-tumor immune response.
The treated figure at week two reflects the single surviving tumor; the other three animals had no detectable tumor signal at all. The team also demonstrated that the killing required direct contact between macrophages and cancer cells, ruling out a simple toxin effect, and that the reprogramming worked in both directions: pulsed cancer cells began releasing inflammatory signals that selectively attracted M1 macrophages, breaking the tumor’s ability to recruit corrupted helpers.
How It Compares With Tumor-Treating Fields
Electric and electromagnetic fields are not new to oncology. Tumor Treating Fields, marketed by Novocure as Optune, is an FDA-approved therapy for glioblastoma (since 2015), mesothelioma (2019), and non-small cell lung cancer (October 2024). In the pivotal LUNAR lung cancer trial, the device extended median overall survival from 9.9 to 13.2 months, and to roughly 18.5 months in patients receiving immunotherapy alongside it.
The NUS approach differs on nearly every dimension. TTFields uses alternating electric fields at 100 to 300 kHz, delivered through adhesive arrays worn on the skin for at least 18 hours a day; they work by physically disrupting cancer cell division. The NUS device uses pulsed magnetic fields at 15 Hz, delivered contactlessly in short sessions, and works through ion channel signaling and immune reprogramming rather than mitotic interference. Its Phase 1 trial reported no skin irritation or other adverse events, a meaningful quality-of-life contrast with Optune’s array-related dermatitis, which affects a majority of wearers.
This is also not the kind of “magnet therapy” sold in wellness bracelets. The treatment relies on precise pulse parameters and a verified molecular pathway, works only in conjunction with the immune system’s own cells, and remains an investigational therapy available, for now, exclusively through clinical trials.
Reprogramming Instead of Destroying
The conceptual leap of the study is replacing depletion with reprogramming. Instead of wiping out macrophages, which tumors quickly replace with new corrupted recruits, the magnetic pulses convert the existing tumor-promoting population into attackers and simultaneously make the cancer cells more visible to the immune system. The study’s first author, PhD researcher Viresh Krishnan Sukumar, and colleagues mapped the full signaling cascade in the open-access Smart Medicine paper, work that also builds on the team’s earlier finding that magnetic pulses boost doxorubicin uptake into breast cancer cells, effectively halving the dose needed for the same effect.
That earlier result shapes the clinical roadmap. The goal is not necessarily to eliminate chemotherapy outright, but to pair the device with reduced drug doses. “PEMF exposure halved the effective dosage required for drugs like doxorubicin to suppress cancer cells,” Franco-Obregón said. “Rather than projecting an unrealistic leap to 100 per cent eradication, our clinical objective is to maximise efficacy while slashing toxicity.”
Because tumor-associated macrophages are found in nearly all solid tumors, the team believes the approach could extend beyond breast cancer to colorectal, lung, ovarian, and prostate cancers, and potentially synergize with immunotherapy drugs such as checkpoint inhibitors. The approach mirrors a broader research trend toward reprogramming rather than replacing immune cells, and Franco-Obregón’s own earlier work on how magnetic fields stimulate muscle growth laid the groundwork for understanding how cells sense magnetic fields at all.
From Mouse Models to Patient Trials
The device behind the study, built in Franco-Obregón’s BICEPS lab and patented through the NUS spin-off QuantumTx, has already cleared its first human hurdle: a Phase 1 safety trial in breast cancer patients (NCT06332508) completed without a single adverse safety event. The team is now seeking clinical and funding partners for Phase 2 efficacy trials, which Franco-Obregón estimates will run two to three years.
The urgency is real. Global breast cancer cases are projected to rise from 2.3 million in 2023 to more than 3.5 million by 2050, with annual deaths climbing from 764,000 to nearly 1.4 million. Any therapy that reduces chemotherapy exposure while maintaining efficacy would matter enormously at that scale, particularly in lower-income countries where the burden is growing fastest.
The caveats matter too. The headline 75 percent eradication rate comes from just four animals, and the complete mechanism has so far been confirmed only in cell cultures, spheroids, and mice. Human efficacy is entirely unproven until Phase 2 reads out. Franco-Obregón himself frames the therapy as investigational, something that should “complement, not replace, proven medical care,” and notes that standard hospital adoption, if trials succeed, would still be years away.
Still, the study does something unusual: it offers a complete, verifiable explanation for why a magnetic field would shrink a tumor at all. In a field crowded with bold claims and thin mechanisms, that may prove as valuable as the result itself.
