Rampart Bioscience was working on a platform to deliver gene therapies without the need for viral vectors.
Rampart Bioscience has reportedly ended its quest to develop DNA-based therapies that don’t use viral vectors for delivery.
The closure, broken by Endpoints News on Thursday after speaking with two former employees, appears to have officially happened last week, though no public announcements were made. Rampart also quietly downsized twice last year, one source added. Rampart’s website is no longer responsive and its LinkedIn page has been taken down.
BioSpace has reached out to CEO Louis Breton and other employees for confirmation.
Rampart emerged from stealth in October 2023 with $85 million in series A funds—money that buffed its $40 million seed capital, according to a press announcement at the time. The startup was formed around a proprietary platform called HALO, which the company claimed could sidestep the drawbacks of using viruses to get gene therapies into a cell.
Currently, the dominant way of delivering genetic medicines is by packaging them into a viral vector, which then injects the therapeutic payload into the cell. While this gets the job done, it also comes with unwanted, sometimes severe and fatal, side effects.
Such toxicities took center stage last year when Sarepta Therapeutics’ Duchenne muscular dystrophy therapy Elevidys was linked to two patient deaths. In March 2025, the biotech reported that one patient on the gene therapy died after developing severe acute liver failure. Another mortality came to light in June.
Rampart sought to overcome these problems, but it never really publicly explained how. The company had been largely tight-lipped about its technology and operation, revealing only that its assets “contain novel structural elements that drive nuclear trafficking and retention while avoiding immune responses,” Jefferey Bartlett, co-founder and chief innovation and technical officer, said in the company’s October 2023 announcement of its series A raise.
Rampart made it into BioSpace’s NextGen Class of 2025, a list of the most highly anticipated up-and-coming biotechs. The company was intending to use its HALO approach to treat hypophosphatasia, a rare genetic disorder disrupting bone mineralization, but this program never reached the clinic.
