When Maria Reyes checked into The Mount Sinai Hospital for CAR-T cell therapy to treat her multiple myeloma, she wore a small device on her wrist that did far more than count her steps. Behind the scenes, a sensor was quietly tracking her temperature, heart rate, breathing and movement around the clock — watching for the earliest whisper of a dangerous complication before she might even feel unwell.
That whisper, it turns out, often arrives seven hours before clinicians using standard monitoring methods would catch it. In a pilot study published in JCI Insight, researchers at the Icahn School of Medicine at Mount Sinai demonstrated that wearable devices could detect cytokine release syndrome — a common and sometimes life-threatening inflammatory reaction to CAR-T therapy — dramatically earlier than traditional hospital assessments.
The finding carries weighty implications for the roughly 35,000 Americans diagnosed with multiple myeloma each year, a blood cancer that forms in plasma cells and can cause bone pain, kidney damage and recurrent infections. CAR-T therapy, which engineers a patient's own immune cells to hunt and destroy cancer, has been transformative for patients whose disease has returned or stopped responding to other treatments. But because of CRS risk, most patients require extended hospital stays or intensive inpatient monitoring after infusion — a barrier that limits where and how broadly this therapy can be offered.
The Mount Sinai team enrolled 30 patients receiving CAR-T therapy, equipping them with wearable sensors that continuously monitored skin and underarm temperature, heart rate, oxygen saturation, breathing rate and motion. Among the 25 evaluable participants, the system identified 18 of 20 CRS episodes, flagging signs of toxicity a median of seven hours before nurses using conventional methods would notice. The researchers also found that changes in a cytokine called interferon gamma closely tracked the temperature shifts detected by the wearables — a discovery that could sharpen future prediction models.
"Continuous monitoring gave us a clearer picture of how cytokine release syndrome develops in real time," said co-corresponding author Adriana Rossi, MD, associate professor of medicine at Icahn Mount Sinai. "Earlier detection could allow clinicians to intervene sooner, potentially reducing complications and improving the patient experience."
The team's ambition extends beyond the hospital walls. Senior corresponding author Samir Parekh, MD, envisions a future where wearables make CAR-T therapy safe enough to deliver in outpatient clinics or even at home. "If validated in larger studies, this approach could help expand access to CAR-T therapy by supporting safer outpatient treatment models and reducing the need for prolonged hospitalization," he said.
Co-author Alessandro Laganà, PhD, whose work bridges genomics and wearable data, described the study as a proof of concept for smarter monitoring systems that could eventually personalize care for each patient. "Our long-term goal is to develop smarter monitoring systems that help clinicians predict toxicity earlier, personalize care and improve outcomes for patients receiving advanced cancer therapies," he said.
The researchers caution that the study was small and conducted at a single center, and larger, multicenter trials will be needed before wearables become standard practice. But the early results suggest that the quiet hum of a wrist-worn sensor may one day give patients like Reyes something that no amount of bedside observation could: a head start against the storm.