AI-generated research brief — verify at source
Aglatimagene Plus Radiotherapy Significantly Improves Disease-Free Survival in Localised Prostate Cancer
Adding intraprostatic aglatimagene besadenovec plus valacyclovir to standard external beam radiotherapy reduced the risk of disease recurrence by approximately 30% compared with placebo in men with intermediate or high-risk localised prostate cancer, with median disease-free survival not yet reached in the treatment arm versus 86.1 months in the control arm (HR 0.70, 95% CI 0.52–0.94; p=0.016). This phase 3 result supports a meaningful clinical benefit with a safety profile comparable to that of radiotherapy alone.
What Was Studied
The trial investigated whether adding aglatimagene besadenovec (CAN-2409), an intraprostatic gene therapy, together with its prodrug valacyclovir, to standard-of-care external beam radiation therapy (EBRT) could improve disease-free survival in men with intermediate or high-risk localised prostate cancer. The rationale was based on earlier evidence suggesting synergy between aglatimagene and radiation, as well as immune-mediated cytotoxic activity in this tumour type — a combination that could address the roughly 30% recurrence rate observed in this population following radiotherapy with curative intent.
How It Was Studied
This was a phase 3, multicentre, randomised, double-blind, placebo-controlled trial enrolling 745 adult men (aged ≥18 years) with intermediate or high-risk localised prostate cancer who were planning to undergo EBRT and had an Eastern Cooperative Oncology Group performance score of 0–2. The trial was conducted across 51 medical centres in the United States and Puerto Rico, spanning both community and institutional or military settings. Participants were randomly assigned 2:1 to receive either three courses of intraprostatic aglatimagene plus valacyclovir (n=496) or placebo plus valacyclovir (n=249), both in addition to standard EBRT. Enrolment took place between February 2012 and September 2021, with a median follow-up of 50.3 months (IQR 35.2–63.3).
What Was Observed
- Disease-free survival was significantly prolonged in the aglatimagene group: median DFS was not reached (95% CI 121.78 months to not reached) versus 86.1 months in the placebo group, representing approximately 30% lower risk of disease recurrence or death (HR 0.70, 95% CI 0.52–0.94; p=0.016). The upper confidence bound indicates this benefit is unlikely to be explained by chance, though the true magnitude of effect remains somewhat uncertain given the treatment arm’s DFS endpoint has not yet been reached.
- Serious adverse events were similar between groups, occurring in 6% of patients in the aglatimagene arm and 7% in the placebo arm. Treatment-related serious adverse events were also comparable at 2% in each group, with acute kidney injury being the most frequently reported treatment-related serious event in both arms.
- Grade 3 or worse treatment-emergent adverse events (TEAEs) occurred at low and similar rates — 8% in the aglatimagene group versus 7% in the placebo group — indicating that the addition of aglatimagene did not meaningfully increase clinically significant toxicity relative to placebo. No treatment-related deaths were reported in either arm.
Why This Matters
Approximately 30% of men with localised prostate cancer undergoing radiotherapy with curative intent experience disease recurrence, which carries substantial morbidity from both progression and the toxicity of subsequent salvage therapies. This trial demonstrates that an intraprostatic gene therapy–prodrug strategy can be layered onto standard radiotherapy to meaningfully reduce recurrence risk without amplifying the adverse event burden. The result suggests that immune-mediated and radiation-synergistic mechanisms of aglatimagene may offer a new therapeutic approach for intermediate- and high-risk disease.
How to Read This Result
This large, well-controlled phase 3 trial provides credible evidence of a disease-free survival benefit for aglatimagene added to radiotherapy, though a median follow-up of only 50.3 months — with the treatment arm’s median DFS not yet reached — means the full magnitude of long-term benefit and overall survival impact remain to be characterised in continued follow-up.
Limitations
The abstract does not explicitly report study limitations.