Candel Therapeutics Inc (NASDAQ:CADL) said Monday that its experimental treatment CAN-2409 significantly extended the time patients lived without their prostate cancer returning, according to results from a large late-stage study presented at the annual meeting of the American Society for Radiation Oncology.
The therapy, also known as aglatimagene besadenovec, was tested in 745 men with intermediate-to-high-risk localized prostate cancer, a group typically treated with radiation therapy but still facing a roughly 30% chance of recurrence within 10 years.
In the Phase 3 study, patients were randomly assigned to receive either CAN-2409 plus the antiviral drug valacyclovir or a placebo alongside standard radiation therapy.
The trial met its main goal, showing a 30% improvement in disease-free survival compared with placebo. Prostate cancer-specific disease-free survival improved by 38%. At the two-year mark, complete response rates were 80% in the CAN-2409 group versus 64% in the control arm.
In new subgroup data released at the meeting, Candel reported that the benefit of CAN-2409 was consistent whether patients received conventional radiation therapy or a shorter-course version known as moderate hypofractionation.
Both approaches showed similar safety results, with severe side effects in less than 2% of patients across treatment groups.
“These additional analyses suggest that the efficacy of CAN-2409 is independent of the modality of radiation used,” said Glen Gejerman, co-director of urologic oncology at Hackensack Meridian Health and one of the study’s principal investigators.
“Most importantly, the activity of CAN-2409 was maintained with moderate hypofractionated radiation, which is more convenient for patients.”
Paul Peter Tak, Candel’s chief executive, said the findings represent “the first major advancement in localized prostate cancer treatment in over 20 years.”
He added that the company expects to submit its application for approval to the U.S. Food and Drug Administration in late 2026.
CAN-2409 is designed as a type of gene therapy delivered directly into the tumour. It uses a modified adenovirus to insert a gene that triggers an immune response when combined with an antiviral drug.
The goal is to kill tumour cells and activate the body’s immune system to recognise and attack cancer.
More than 1,000 patients have received CAN-2409 in clinical studies across several tumour types, including lung and pancreatic cancers, with what the company describes as a favourable safety profile so far.