Regeneron Posts Positive Phase 2 Baloncibart Data In POTS, Setting Up A 2027 Phase 3 Trial

Regeneron has reported positive phase 2 data for baloncibart in postural orthostatic tachycardia syndrome, giving the company a path to start a phase 3 trial in the first half of next year. For a field with no FDA-approved treatments and few active industry-sponsored programs, the result stands out not only because it met the study’s primary endpoint, but because it advances a mechanistically distinct approach in a condition that has remained underdeveloped commercially.

POTS is marked by an abnormally large increase in heart rate when patients stand up from sitting or lying down. Symptoms tied to standing can include palpitations and dizziness, while the condition is also associated with ongoing fatigue, exercise intolerance, cognitive difficulties, gastrointestinal symptoms and chronic pain. Regeneron’s thesis is that blocking NPR1 can ease symptoms by increasing blood volume in circulation.

The Data

The phase 2 Pinnacle trial randomized 82 patients to one of two doses of the anti-NPR1 antibody baloncibart or placebo. At Day 8, patients given a single 450 mg dose had an 11.4 beats per minute lower change in heart rate from lying down to standing than patients on placebo, meeting the trial’s primary endpoint.

The effect narrowed but remained present at Day 29, when the difference versus placebo was 7.4 beats per minute. The 150 mg dose also beat placebo at Day 8, but that benefit faded by Day 29.

Beyond the primary endpoint, Regeneron said symptoms linked to standing improved on the 450 mg dose compared with placebo at Day 29. The higher dose also improved assessments of physical functioning and activities of daily living, while the 150 mg group showed no obvious improvement over placebo on those measures.

Biomarker changes at Day 8 were consistent with the expected effect on blood volume. Average standing systolic blood pressure increased on both doses and rose 8.7 mmHg to a mean of 118.8 mmHg on Day 29 in the 450 mg cohort.

On safety, treatment-emergent adverse events were more common with baloncibart than placebo. They affected 67.9% of patients on the 450 mg dose versus 48.1% of people in the control arm. Regeneron said the adverse events were mostly mild or moderate, and none led patients to stop treatment.

Why It Matters

The main signal from Pinnacle is dose separation. The 450 mg cohort carried the efficacy story across the primary endpoint, Day 29 heart-rate change and multiple symptom-related measures, while the 150 mg cohort did not. That gives Regeneron a clearer development path than a mixed study would have.

George Yancopoulos said on Regeneron’s third-quarter earnings call late last month that the improvements appear to be associated with durable restoration of intravascular volume. If that interpretation holds in a larger study, baloncibart could give Regeneron a way to define the first approved treatment in POTS around a specific physiological mechanism rather than broad symptom management.

Regeneron said POTS affects between 500,000 and several million people in the U.S. Most patients are women, and the condition has historically been underdiagnosed. Argenx and CSL Behring previously ran trials in patients who developed POTS after contracting COVID-19, but neither program is active.

That leaves baloncibart entering phase 3 with relatively little active late-stage industry competition. The commercial opportunity will still depend on whether the phase 2 signal translates into durable benefit in a broader trial, but the development picture is now materially more defined than it was before these data.