A gene therapy targeting herpes simplex virus enters Phase 3 clinical trials before 2029.

Question

Six frontier AI models put this at 9% by 26 Sept 2029. Full reasoning from every model.

WillHappen.ai · Accepted Answer

9% — the median of 6 frontier models, resolving by 2029-09-26.

Answer

Gemini (Google): 8% — Gene editing for latent HSV is still at preclinical or early Phase 1 stages, leaving too little time to reach Phase 3 by 2029. Leading programs like Fred Hutch/BDgene are only navigating early human safety trials, which typically require 4-6 years to reach Phase 3. FDA oversight for in vivo meganucleases or CRISPR in nervous tissue demands extensive long-term follow-up before approving pivotal trials. Fast-track designation following flawless early Phase 1/2 shedding and safety data by late 2027 would push odds toward 25%.

Answer

Claude (Anthropic): 8% — Success hinges on whether any HSV gene-editing candidate clears Phase 1/2 fast enough to reach Phase 3 by 2029. Current HSV gene therapy candidates (e.g., Tune, ContraFect-adjacent, academic CRISPR/meganuclease programs) are still preclinical or early Phase 1, far from Phase 3… Typical drug development timelines require 3-5+ years from Phase 1 start to Phase 3 entry, and no HSV gene therapy has even begun human dosing at scale yet. A surprise accelerated approval pathway or breakthrough therapy designation for an in-human trial already underway would be the main thing that could change this.

Answer

GPT (OpenAI): 9% — The decisive issue is whether any HSV editor can show durable reservoir clearance and acceptable systemic delivery safety in humans by 2028. No in-vivo HSV gene-editing program has yet established human efficacy; moving from preclinical work to Phase 3 in three years is rare. Sponsors would need IND clearance, Phase 1/2 safety and antiviral-effect data, then a large trial launch before September 2029. My view would rise sharply if a named candidate enters Phase 1 by 2027 with systemic delivery and validated latent-reservoir endpoints.

Answer

Grok (xAI): 14% — No HSV in-vivo gene therapy is yet in humans; 3 years is too short to reach P3. A sponsor must already be in/near P2 by ~2027 with a clean safety/efficacy signal on latent HSV, which none have. Gene-editing antivirals (HIV CRISPR, etc.) typically need 5–8 yrs from first-in-human to P3; HSV is earlier and harder to endpoint. A 2027 P2 start plus breakthrough data would raise this sharply; otherwise the clock runs out.

Answer

DeepSeek (DeepSeek): 12% — No HSV gene therapy has cleared Phase 1/2, and a Phase 3 start needs a sponsor with a late-stage candidate already in the clinic. As of late 2026 the leading HSV gene-editing programs (Fred Hutch/Excision BioTherapeutics-style approaches) remain preclinical or early Phase 1, with no efficacy… A Phase 3 start requires an FDA-agreed pivotal design plus Phase 2 efficacy data, a sequence that typically takes 4-6 years from first-in-human dosing. Base rate for any gene therapy jumping from preclinical to Phase 3 within ~3 years is very low; HSV's latent reservoir in sensory ganglia makes potency endpoints…

Answer

Qwen (Alibaba): 4% — No HSV gene therapy has even entered Phase 1; jumping to Phase 3 in under 3 years is implausible given regulatory timelines. As of mid-2026, no HSV-targeting gene therapy has a publicly registered Phase 1 trial on ClinicalTrials.gov; candidates remain preclinical. Phase 1→2→3 progression typically requires 4-7 years minimum even with expedited pathways, and no candidate has cleared the first gate. A development that would change my mind: a company like Excision BioTherapeutics or similar announcing an IND clearance for HSV gene editing in 2026-2027.

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