Candel prostate therapy shows 30% DFS gain in Lancet Oncology

Candel Therapeutics has announced the peer-reviewed publication in The Lancet Oncology of pivotal Phase 3 data for aglatimagene besadenovec (CAN-2409), a multimodal biological immunotherapy being developed for intermediate- to high-risk localised prostate cancer. The trial — a randomised, double-blind, placebo-controlled study enrolling 745 patients — met its primary endpoint, demonstrating a statistically significant 30% improvement in disease-free survival (DFS) compared with placebo, both arms also receiving standard-of-care radiotherapy and valacyclovir (hazard ratio 0.70; 95% CI 0.52–0.94; p=0.016).

Secondary and exploratory analyses added further weight to the primary result. The trial showed a 38% improvement in prostate cancer-specific DFS — defined as recurrence or cancer-related death — with a hazard ratio of 0.62 (95% CI 0.44–0.87; p=0.0046). A post-hoc blinded biopsy review conducted two years after radiotherapy found that 80% of patients in the aglatimagene arm had negative biopsies, versus 63% in the placebo group (p=0.0018). The safety profile was described as generally favourable, with the most common treatment-related adverse events — chills, flu-like symptoms, fatigue, pyrexia, increased urinary frequency, and nausea — rated Grade 1–2 and self-limiting.

Extended follow-up and regulatory path

Data presented at the American Urological Association 2026 Annual Meeting extended the picture further: at a median follow-up of 58 months (as of March 2026), the improvement in prostate cancer-specific DFS reached 39%, with favourable trends across time to biochemical failure, time to metastasis, and time to salvage therapy. Candel said it intends to use these published data to underpin a Biologics Licence Application submission to the US Food and Drug Administration in the fourth quarter of 2026. The programme has already received FDA Fast Track and Regenerative Medicine Advanced Therapy designations for localised prostate cancer.

Garrett Nichols, Chief Medical Officer at Candel, said the biopsy findings were "particularly meaningful because biopsy findings after radiotherapy have previously been shown to predict later biochemical failure and metastasis with longer follow-up."

Market context and competitive landscape

Localised prostate cancer is a large and commercially significant indication, yet the treatment landscape for intermediate- to high-risk patients undergoing radiotherapy has seen limited systemic innovation in recent years. Current standard-of-care approaches combine external beam radiotherapy or brachytherapy with androgen deprivation therapy for higher-risk patients; adding an immunotherapy layer that does not substantially worsen tolerability is a meaningful differentiator, if the DFS benefit proves durable.

Aglatimagene's mechanism — intratumoral delivery of the herpes simplex virus thymidine kinase gene, converting valacyclovir into a local cytotoxic agent and triggering immunogenic cell death — sits apart from checkpoint inhibitors, which have so far shown limited activity in localised, non-metastatic prostate cancer. The adenoviral vector is off-the-shelf, a logistical advantage over autologous cell therapies in a primary-care oncology setting. The primary risk for investors remains whether the DFS benefit observed at median follow-up of around five years will translate into overall survival gains as the trial matures — a data point that will likely determine the commercial reception of any approved product. Candel's parallel Phase 2a programmes in non-small cell lung cancer and pancreatic ductal adenocarcinoma also carry the aglatimagene platform into indications where unmet need is acute and competitive intensity is high.