Blood Filtering Treatment Shows Promise for Severe Early Preeclampsia in Small Clinical Trial
Key Insights
Cedars-Sinai investigators developed a blood filtering treatment that removes harmful sFlt-1 (search) protein to manage severe early preeclampsia (search), a leading cause of premature birth and maternal death.
The treatment safely extended pregnancies by an average of 10 additional days in 16 women with early preeclampsia (search), potentially doubling the time to delivery after hospitalization.
The extracorporeal apheresis technique reduced blood sFlt-1 (search) levels by 17 percent and slightly decreased blood pressure while allowing continued fetal growth during treatment.
Cedars-Sinai Health Sciences University (search) investigators have developed and successfully tested a new blood filtering treatment for pregnant women with severe early preeclampsia (search), a condition that affects 3 to 8 percent of people who give birth worldwide and represents a leading cause of premature birth as well as maternal and fetal death.
The early-stage international study, published in Nature Medicine, demonstrated that removing a harmful protein from maternal blood can safely extend pregnancy duration, giving babies crucial additional time to develop before birth. In severe early preeclampsia (search) occurring before 34 weeks of pregnancy, physicians frequently must deliver babies prematurely to protect the mother, even though early delivery poses significant risks for the infant.
Targeting the Root Cause
The innovative approach focuses on a protein called soluble Flt-1 (search) (sFlt-1 (search)), which is produced by the placenta and known to damage blood vessels while driving preeclampsia (search) symptoms. In people with preeclampsia, levels of sFlt-1 may reach five times the usual amount for that stage in pregnancy, leading to swelling of certain cells lining kidney blood vessels, high blood pressure, and protein in the urine.
"Our goal was to directly target one of the root causes of preeclampsia (search)," said study co-corresponding author Ravi Thadhani, MD, MPH, executive vice president of Clinical Affairs and chief medical officer for Cedars-Sinai Medical Center. "By lowering sFlt-1 (search), we were able to stabilize patients and extend pregnancy—a meaningful and exciting step forward."
The research team engineered a specialized immune protein that binds to sFlt-1 (search) and incorporated it into a blood-filtering device. Using extracorporeal apheresis—a process similar to kidney dialysis—they filtered maternal blood to remove excess sFlt-1 without affecting other essential blood components.
Clinical Trial Results
The treatment was evaluated in 16 women with early preeclampsia (search). Each treatment session reduced sFlt-1 (search) levels in the women's blood by approximately 17 percent and slightly decreased blood pressure and protein in the urine. The patients' blood pressure improved, their babies continued to grow normally during treatment, and they remained pregnant for an average of 10 additional days—more than double the time seen in untreated patients.
The babies were delivered at a median of 31 weeks, still preterm, but when pregnancies lasted longer, fetal growth continued. One woman developed a severe form of the condition and delivered within two days of admission, while one pregnancy lasted 19 additional days.
"Even a few extra days in the womb can make a meaningful difference in outcomes for premature infants," said co-corresponding study author Ananth Karumanchi, MD, professor of Medicine and director of the Renovascular Research Center at Cedars-Sinai. "We found a way to potentially buy that time safely. Our approach could shift how we manage very early preeclampsia (search)."
Safety Profile and Limitations
The treatment showed a notable safety profile because it removes a harmful factor rather than introducing new drugs, potentially reducing the risk of side effects. However, there were some side effects reported, including false labor, chest discomfort, headaches, and liver enzyme issues, though researchers noted it was difficult to determine whether these were caused by the treatment or by worsening preeclampsia (search).
"Right now, the only way to cure preeclampsia (search) and protect the life and health of the mother is to deliver the baby," said Sarah Kilpatrick, MD, PhD, chair of the Department of Obstetrics and Gynecology at Cedars-Sinai. "That puts very premature infants at high risk. This approach could give clinicians more flexibility in managing these high-risk cases."
Future Research Directions
Despite the positive results from this small study, researchers emphasize that the treatment remains experimental and requires validation in larger clinical trials. The current study's small size cannot fully address all safety concerns, and larger studies with control groups will be needed to measure the treatment's safety and effectiveness comprehensively.
Thomas McElrath, a maternal and fetal medicine specialist at Mass General Brigham (search) and Harvard University, noted that the study could mark innovation in a field that hasn't seen improvements for decades. "No harms stood out to either the mother or the fetus," he said. "That piece is encouraging."
The research builds on previous work by Thadhani and Karumanchi, who helped develop an FDA-approved test based on the ratio of sFlt-1 (search) to placental growth factor (search) that can predict whether women with preeclampsia (search) symptoms will develop a more serious form of the condition.