SonoThera, a South San Francisco biotech working on nonviral genetic medicines delivered through therapeutic ultrasound, has closed an oversubscribed $125 million Series B financing round. The capital will fund the company's first human clinical trials. Co-founder and CEO Kenneth Greenberg, Ph.D., has built the company around a simple premise: most diseases that could benefit from gene therapy are currently unreachable by the tools that exist today.
The problem starts with delivery. Most gene therapies rely on viral vectors, which are modified viruses used to carry therapeutic genes into cells. These vectors work, but they come with significant limitations. They can only carry payloads up to a certain size, they tend to provoke immune responses in the body, and once a patient has been treated, the same vector generally cannot be used again safely.
For Duchenne muscular dystrophy, those limitations are particularly consequential. The full-length dystrophin gene, which is what DMD patients need, is too large for most viral vectors to carry. DMD affects approximately one in 6,000 live male births and causes progressive muscle weakness, loss of mobility, and eventually respiratory and cardiac failure. Many patients have no access to effective treatment. Broader interest in nonviral alternatives is growing: the global non-viral gene delivery technologies market was valued at around $4.18 billion in 2025 and is projected to reach approximately $13.38 billion by 2035, expanding at a compound annual rate of 12.34%.
Vida Ventures led the $125 million Series B, joined by a group of new and returning investors.
Viral delivery has been the standard in gene therapy for decades, and it has produced approved treatments. But those systems have real constraints: they were not built for repeated use, and the size limits on what they can carry narrow the range of diseases they can address. Nonviral platforms trade some of that natural cellular efficiency for greater flexibility, and in theory, the ability to treat patients more than once.
SonoThera uses ultrasound, a technology already standard in hospitals, as its delivery mechanism. Its RIPPLE platform directs genetic payloads into specific tissues using sound energy. The companion technology, PORE, handles the engineering of those payloads and supports DNA, RNA, gene editing, and gene silencing approaches.
"We at Vida have a long history of investing in and developing genetic medicines, some of which are now used to treat patients across the globe. We believe SonoThera, with its RIPPLE™ delivery and PORE™ payload engineering technologies, has the potential to unlock opportunities in diseases with significant unmet need that have been previously inaccessible to other genetic medicine approaches." — Rajul Jain, M.D., Managing Director at Vida Ventures
The bulk of the funding will go toward moving SonoThera's two lead programs into clinical trials. The DMD program aims to deliver full-length dystrophin, a payload too large for conventional viral vectors. That makes it a meaningful test of whether SonoThera's platform can address conditions that other approaches have been unable to reach. The second program targets autosomal dominant polycystic kidney disease, a genetic disorder that affects the kidneys and has few disease-modifying treatment options.
The company also plans to expand its pipeline into additional organ systems and scale its platform technologies. Preclinical work has shown targeted delivery and gene expression in skeletal muscle, heart, liver, kidney, adipose tissue, and brain. RNA-based payloads for gene silencing have also been tested successfully in preclinical studies. SonoThera expects to begin its first clinical trial in DMD in 2027.
"We are grateful to have the support of this exceptional group of new and existing investors who share our vision of expanding the potential of genetic medicines. We believe our technology has the potential to expand the range of diseases addressable by genetic medicines while enabling more precise, durable, safer, and repeatable therapies for patients." — Kenneth Greenberg, Ph.D., Co-Founder and CEO of SonoThera
The two core technologies sit at the center of everything SonoThera is developing. RIPPLE is the delivery system, using ultrasound energy to guide genetic material into targeted tissue. PORE manages the design and engineering of the payloads themselves, covering a range of genetic medicine formats including DNA, RNA, gene editing tools, and gene silencing agents.
One practical aspect of the platform is its compatibility with existing hospital equipment. SonoThera's approach uses FDA-cleared diagnostic ultrasound systems and commercially approved ultrasound contrast agents, substances already cleared for diagnostic use. The company says the procedure can be performed on an outpatient basis in roughly one hour or less. SonoThera is headquartered in South San Francisco, California.
Vida Ventures led the Series B. New investors joining the round include ARK Invest, CureDuchenne Ventures, Leaps by Bayer, Otsuka Pharmaceutical, SymBiosis, UCB Ventures SA, and Vivo Capital. Rajul Jain of Vida Ventures and Rakhshita Dhar of Leaps by Bayer have joined SonoThera's Board of Directors.
Returning investors include ARCH Venture Partners, Alexandria Venture Investments, Duquesne Family Office, Illumina Ventures, Johnson and Johnson Innovation through JJDC, Medical Excellence Capital, RA Capital, and Vertex Ventures HC. SonoThera previously closed a $60.75 million Series A in December 2022, also led by ARCH Venture Partners.
"SonoThera has made impressive progress since its founding and continues to demonstrate the potential of its approach to genetic medicine. The team has built a strong foundation, generated compelling preclinical data, and assembled an outstanding group of investors and partners." — Steven Gillis, Ph.D., Managing Director at ARCH Venture Partners
