CAN-2409 improved disease-free survival by 30% versus placebo in a 745-patient Phase 3 trial in intermediate-to-high-risk localized prostate cancer (HR 0.70; p=0.0155), with a 38% improvement in prostate cancer–specific disease-free survival (HR 0.62; p=0.0046). At two years, pathological complete response was 80.4% versus 63.6% (p=0.0015). In subgroup analyses presented at ASTRO 2025, benefit was observed across radiation strategies: moderate hypofractionated EBRT showed a stronger signal (HR 0.52; 95% CI 0.30–0.93; p=0.0236), while conventional EBRT trended favorably (HR 0.76; 95% CI 0.53–1.07; p=0.1131). Grade ≥3 treatment-related adverse events were low and comparable to control with both hypofractionated (1.6% vs. 1.9%) and conventional EBRT (1.8% vs. 1.1%).
The core update is that CAN-2409’s efficacy and tolerability appear independent of radiation modality, an operationally important nuance as centers continue to migrate toward moderate hypofractionation. The randomized, double-blind, placebo-controlled study (2:1 randomization) administered the intratumoral adenoviral HSV-tk vector with oral valacyclovir before and during radiotherapy; roughly 72% received conventional fractionation and 25% received moderate hypofractionation. Coupled with prior analyses indicating consistency irrespective of short-term androgen deprivation therapy, the ASTRO readout supports positioning CAN-2409 as an add-on to standard radiotherapy across common practice patterns.
Strategically, the modality-agnostic signal is the de-risking Candel needed for broad adoption claims. Radiation oncology is optimizing toward fewer visits and resource-efficient schedules; any adjunct that only fits one fractionation approach risks fragmentation and slower uptake. Demonstrating compatibility with hypofractionation addresses a leading barrier to integration and aligns with payer and health-system pressure for shorter, lower-burden regimens. It also differentiates the program from escalation strategies that rely on prolonged systemic intensification, by staking a claim in a local–regional, procedure-integrated immunotherapy pathway that may be simpler to operationalize at scale if handling and workflow are standardized.
For sites, the implication is a cross-disciplinary workflow between urology and radiation oncology to perform intraprostatic injections aligned to planning and early treatment visits, with vector receipt, storage, and biosafety procedures embedded in hospital pharmacy operations. The low rate of high-grade adverse events and comparable tolerability across fractionations are favorable for clinic throughput, but centers will still need training on injection technique, scheduling logistics, and documentation to satisfy risk management and, ultimately, REMS or postmarketing commitments if required. For sponsors and CROs, the heterogeneity of radiation practice is less of a confounder now, reducing design complexity for registries and Phase 4 studies aimed at real-world effectiveness, quality of life, and health resource utilization in community settings.
Attention now turns to durability and regulatory posture. A Biologics License Application is targeted for Q4 2026, which suggests additional follow-up, CMC scale-up, and potentially further analyses of metastasis-free survival, prostate cancer–specific survival, and functional outcomes will be important to firm up the dossier. FDA’s receptivity to disease-free survival and prostate cancer–specific endpoints in this setting will shape the review path, even with expedited designations in place. Watch for longer-term readouts that clarify the magnitude of benefit in conventional fractionation, standardized guidance on administration and site requirements, and evidence that the workflow can be replicated outside academic centers. Manufacturing reliability for an intratumoral viral therapy, label scope relative to ADT use and radiation regimen, and payer assessments of incremental benefit versus added procedural complexity are the practical risks to monitor.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
