Excision BioTherapeutics
Corporate brand
UnclaimedExcision BioTherapeutics was a San Francisco-based biopharmaceutical company developing CRISPR–Cas9 gene therapy approaches for HIV infection.
Last updated August 25, 2026
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Overview
Excision BioTherapeutics was a biopharmaceutical company based in San Francisco, California, whose research focused on using gene editing to address HIV infection. Its development program centered on EBT-101, an investigational therapy designed to use CRISPR–Cas9 molecular editing technology against HIV-1 genetic material. The program originated in academic research conducted by the laboratory of Kamel Khalili, a professor at Temple University, before being developed by Excision as a potential therapeutic approach. EBT-101 was positioned as an attempt to address a fundamental limitation of existing HIV treatment. Antiretroviral therapy can suppress viral replication, but it does not normally eliminate latent HIV reservoirs embedded in the genomes of infected cells. Excision’s approach sought to excise HIV genetic material from infected cells, with the broader objective of creating a functional cure or durable remission rather than relying indefinitely on daily suppressive medication. Because latent virus can persist in cellular reservoirs and because gene-editing delivery must reach relevant infected cells, the approach involved substantial scientific and clinical uncertainty. In July 2023, the United States Food and Drug Administration granted EBT-101 fast-track designation. This designation was intended to facilitate development and regulatory interaction for a therapy addressing a serious condition, but it did not constitute approval or establish clinical effectiveness. In October 2023, early-stage clinical findings involving three people were reported as showing no major safety problems. These preliminary observations were limited by the very small number of participants and the early stage of investigation. By March 2024, reports indicated that EBT-101 did not maintain HIV viral suppression when administered alone at the initial dose tested. One participant may have experienced a delay in viral rebound, but the result did not demonstrate durable suppression or a cure. A possible explanation discussed in connection with the findings was that the therapy did not reach every cell containing latent HIV. A long-term follow-up study of adults with HIV-1 who had received EBT-101 was also initiated to monitor durability and safety over time. The available reference material identifies EBT-101 as Excision BioTherapeutics’ single investigational therapy and does not establish an approved product portfolio, commercial revenue, public listing, current ownership, or current operating status. Accordingly, the company is best documented as an early-stage gene-therapy developer whose principal program produced important preliminary safety information but had not demonstrated durable HIV viral suppression at the initial tested dose.
History
Excision BioTherapeutics developed from research into gene editing as a possible means of addressing HIV infection at the level of viral DNA. The scientific foundation for its principal program was associated with the laboratory of Kamel Khalili at Temple University. Rather than treating HIV only by blocking viral replication, the research sought to remove or disable HIV genetic material in infected cells using CRISPR–Cas9 technology. The company’s publicly described development portfolio was concentrated in EBT-101, an investigational therapy intended for HIV-1 infection. The therapeutic concept was particularly ambitious because conventional antiretroviral medicines generally suppress active replication without eliminating latent reservoirs. These reservoirs can remain in infected cells and can produce renewed viremia if treatment is stopped. A gene-editing therapy would therefore need to reach a sufficiently broad set of infected cells and edit the relevant viral sequences without causing unacceptable off-target effects or other safety problems. EBT-101 entered early human investigation as a candidate therapy rather than an approved medicine. In July 2023, the FDA granted the program fast-track designation. The designation reflected the seriousness of HIV infection and the potential importance of a new therapeutic approach, but it was a regulatory-development measure rather than marketing authorization. Initial findings reported in October 2023 involved three people. The treatment appeared to be safe in that limited early assessment, with no major side effects reported. The size and stage of the study meant that the findings could not establish efficacy, long-term safety, or the ability to eliminate HIV reservoirs. Further information reported in March 2024 provided a more difficult efficacy picture. EBT-101 did not maintain HIV viral suppression when administered alone at the initial dose tested. One participant appeared to have delayed viral rebound, which suggested a possible biological effect but did not demonstrate durable remission. A possible explanation was that the therapy failed to reach all cells containing latent HIV, a central delivery challenge for any reservoir-targeting strategy. A long-term follow-up study of adults with HIV-1 who received EBT-101 was also started. Such follow-up is relevant both to gene-therapy safety and to the durability of any effects on viral replication. The available material does not document an approved product, commercial launch, financial results, public-market listing, later pipeline expansion, or a confirmed current operating status for the company. Excision BioTherapeutics is therefore best characterized on the available evidence as a biotechnology developer whose central clinical program remained investigational and had not achieved durable viral suppression at the initial tested dose.
- 2024
Initial dose fails to maintain viral suppression
[1]EBT-101 did not maintain HIV viral suppression when used alone at the initial dose tested, although delayed viral rebound was observed in one participant.
- 2024
Long-term follow-up initiated
[1]A long-term follow-up study of adults with HIV-1 who had received EBT-101 was started to monitor longer-term outcomes.
- 2023
FDA grants fast-track designation to EBT-101
[1]The FDA granted fast-track designation to Excision BioTherapeutics’ investigational EBT-101 therapy for HIV infection.
- 2023
Early clinical safety findings reported
[1]An early-stage study involving three participants reported that EBT-101 appeared to be safe, with no major side effects observed in the preliminary assessment.
Products and positioning
An early-stage biotechnology developer focused on gene-editing therapies intended to address HIV infection and latent viral reservoirs.
Investigational CRISPR–Cas9 gene therapy
EBT-101
EBT-101 was Excision BioTherapeutics’ principal and publicly described investigational therapy. It used CRISPR–Cas9 gene-editing technology in an effort to target HIV-1 genetic material in infected cells, including material associated with latent viral reservoirs. The program was intended to explore a route toward durable HIV remission or a functional cure rather than continuous viral suppression alone. Early findings suggested no major safety problems in three participants, but the initial tested dose did not maintain viral suppression when the therapy was used alone.
Brand decisions
2023
Advance EBT-101 through an expedited regulatory pathwayStrategyBackground
Excision BioTherapeutics was developing EBT-101 as a gene-editing approach for HIV infection, a serious disease in which existing medicines generally suppress replication without removing latent viral reservoirs.
Action taken
The company pursued development of EBT-101 under FDA fast-track designation.
Aftermath
Early safety findings were reported, but subsequent information indicated that the initial tested dose did not maintain viral suppression when used alone.
Recent events
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