On September 29, 2025 Candel Therapeutics, Inc. (Candel or the Company) (Nasdaq: CADL), a clinical-stage biopharmaceutical company focused on developing multimodal biological immunotherapies to help patients fight cancer, reported subgroup analyses focused on the radiation regimen from the Company’s positive phase 3 clinical trial of CAN-2409 (aglatimagene besadenovec) in patients with intermediate-to-high-risk localized prostate cancer at the 2025 Annual Meeting of the American Society for Radiation Oncology (ASTRO) (Press release, Candel Therapeutics, SEP 29, 2025, View Source [SID1234656327]).
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Current standard-of-care radiation therapy for intermediate-to-high-risk localized prostate cancer has remained largely unchanged, with a significant unmet medical need, as approximately ~30% of patients experience disease recurrence within 10 years.
The Company has previously presented data from a randomized phase 3 clinical trial of CAN-2409 plus valacyclovir vs. placebo added to standard of care radiotherapy with curative intent in patients with localized prostate cancer. The press release is posted on the investor relations section of our website, available here. The randomized, double-blind, placebo-controlled, multicenter phase 3 trial (NCT01436968) enrolled 745 patients with intermediate-to-high-risk localized prostate cancer randomized 2:1 to either CAN-2409 plus valacyclovir in combination with standard of care or standard of care alone, with experimental treatment administered before and during radiation therapy. The trial achieved its primary endpoint with a 30% improvement in disease-free survival (HR 0.7, p=0.0155) and demonstrated a 38% improvement in prostate cancer-specific disease-free survival (HR 0.62, p=0.0046). At two years, pathological complete response rates were 80.4% as compared to 63.6% observed in the control arm (p=0.0015).
This study represents the first potential advancement in localized, non-metastatic prostate cancer in more than 20 years. The Company today released additional information from its subgroup analysis of the phase 3 data showing that CAN-2409’s activity was independent of the radiation modality used in the trial.
Key Highlights from ASTRO 2025 Presentation:
CAN-2409 significantly improved prostate cancer-specific outcomes (HR 0.62; p=0.0046). Effects observed in both moderate hypofractionated EBRT (HR 0.52, CI 0.30 – 0.93, p=0.0236) and conventional EBRT (HR 0.76, CI 0.53 – 1.07, p=0.1131)
Demonstrated safety and compatibility across radiation therapy modalities, with both conventional radiation therapy (~78 Gy in 2 Gy fractions, ~72% of patients) and moderate hypofractionated radiation therapy (60 Gy in 3 Gy fractions, ~25% of patients) showing similar tolerability profiles
Grade ≥ 3 treatment related adverse events were similar in the CAN-2409 plus valacyclovir and control arms with both hypofractionated (1.6% vs. 1.9%) and standard EBRT (1.8% vs. 1.1%), respectively
"These additional analyses suggest that the efficacy of CAN-2409 is independent of the modality of radiation used. Most importantly, the activity of CAN-2409 was maintained with moderate hypofractionated radiation, which is more convenient for patients," said Glen Gejerman, M.D., M.B.A., Co-Director of Urologic Oncology at Hackensack Meridian Health and one of the principal investigators of the study.
Paul Peter Tak, M.D., Ph.D., FMedSci, President and Chief Executive Officer of Candel said, "These new insights presented at ASTRO further support the broad therapeutic potential of CAN-2409 in localized prostate cancer treated with curative intent. Previously, we have shown the benefit of CAN-2409 compared to placebo in patients treated with standard of care radiotherapy, independent of the use of short-term androgen deprivation therapy. The consistency of benefit, across radiation therapy modalities, supports the therapy’s potential as the first major advancement in localized prostate cancer treatment in over 20 years. Our regulatory strategy remains on track with Biologics License Application submission expected in the fourth quarter of 2026."
About CAN-2409
CAN-2409 (aglatimagene besadenovec), Candel’s most advanced multimodal biological immunotherapy candidate, is an investigational, off-the-shelf, replication-defective adenovirus designed to deliver the herpes simplex virus thymidine kinase (HSV-tk) gene to a patient’s tumor. After intratumoral administration, HSV-tk enzyme activity results in conversion of prodrug (valacyclovir) into deoxyribonucleic acid (DNA)-incorporating nucleotide analogs, leading to immunogenic cell death in cells exhibiting DNA damage and proliferating cells, with subsequent release of a variety of tumor (neo)antigens in the tumor microenvironment. At the same time, the adenoviral serotype 5 capsid proteins promote inflammation through the induction of expression of pro-inflammatory cytokines, chemokines, and adhesion molecules. Together, this regimen is designed to induce an individualized and specific CD8+ T cell-mediated response against the injected tumor and uninjected distant metastases for broad anti-tumor activity, based on in situ immunization against a variety of tumor antigens. CAN-2409 has the potential to treat a broad range of solid tumors. Encouraging monotherapy activity as well as combination activity with standard of care radiotherapy, surgery, chemotherapy, and immune checkpoint inhibitors have previously been shown in several preclinical and clinical settings. More than 1,000 patients have been dosed with CAN-2409 in clinical trials with a favorable tolerability profile to date, supporting the potential for combination with standard of care, when indicated.