Soufflé Therapeutics closed a $135 million Series B as its first RNA drug entered an early-stage human study, moving the company’s targeted-delivery platform into clinical testing. Juvia Group led the round, which Soufflé said will support clinical work on three lead programs and additional preclinical research.
Soufflé’s REMEDY system identifies receptors that pull molecules into selected cells, then designs antibodies or other binders to carry gene-silencing oligonucleotides through them. Lead candidate SFL-0821 pairs a muscle-targeting antibody with small interfering RNA designed to suppress DUX4 in skeletal muscle. The company says its target disease, facioscapulohumeral muscular dystrophy, has no approved disease-modifying treatment.
The second program targets the PLN gene in heart muscle cells for heart failure with reduced ejection fraction, while the target of a third muscle and metabolic program remains undisclosed. The broader platform already has a pharmaceutical partnership: Bayer signed a global licensing collaboration in January to develop a heart-targeted RNA therapy for a rare form of dilated cardiomyopathy, with financial terms undisclosed.
The round follows a $200 million Series A disclosed when Soufflé emerged publicly in October 2025, Fierce Biotech reported. New Series B investors include TCG Crossover Management, BB Biotech, Fidelity Management & Research and Balyasny Asset Management; existing backers including Amgen Ventures, ARCH Venture Partners, Bessemer Venture Partners and Leaps by Bayer also participated.
A public trial tracker mirroring ClinicalTrials.gov shows the SFL-0821 study switched to recruiting on September 29, two weeks before the financing announcement. The randomized, placebo-controlled Phase 1/2 study aims to enroll 90 adults in Australia and New Zealand and lists March 2028 as its estimated primary-completion date.