FDA awards Regenerative Medicine Advanced Therapy Designation to CAN-2409 for prostate cancer

The FDA has granted a Regenerative Medicine Advanced Therapy (RMAT) Designation to aglatimagene besadenovec (CAN-2409), an investigational off-the-shelf, replication-defective adenovirus for newly diagnosed intermediate- to high-risk localized prostate cancer, Candel Therapeutics announced in a news release.¹

Topline results from the phase 3 PrTK03 trial were shared in December 2024.

The therapeutic was previously awarded a Fast Track Designation for the same indication.

According to the company, “CAN-2409 is an investigational, off-the-shelf, replication-defective adenovirus that delivers the herpes simplex virus thymidine kinase (HSV-tk) gene to tumor cells.” The immunotherapy is designed to work in combination with valacyclovir (prodrug) to induce immunogenic cell death of tumor cells.

The RMAT designation is intended to expedite the development and review process for regenerative medicines that demonstrate promising preliminary data. With this designation, the development process for CAN-2409 can benefit from intensive FDA guidance, as well as the potential for expedited review and opportunities for rolling or priority review.

“Receiving the FDA’s RMAT designation underscores the critical unmet need in patients with early, localized prostate cancer and validates the promising clinical activity observed with CAN-2409. This designation further supports the design of our phase 3 study, including the [disease-free survival] DFS primary end point agreed upon with the FDA during the [Special Protocol Assessment] negotiation,” said Paul Peter Tak, MD, PhD, FMedSci, president and CEO of Candel Therapeutics, in the news release from the company.¹

Data on CAN-2409

Candel Therapeutics shared topline results from the phase 3 PrTK03 trial (NCT01436968) in December 2024. Overall, the trial met its primary end point by demonstrating that the addition of CAN-2409 to radiation therapy significantly improved DFS vs radiation alone in patients with localized prostate cancer.

Patients who received the combination of CAN-2409 and radiation therapy demonstrated a 30% reduction in the risk of prostate cancer recurrence or death due to any cause at 54 months compared with those who received radiation alone (HR, 0.7; P = .0155). This finding was consistent in both patients receiving short-term androgen deprivation therapy (ADT) and in those not receiving ADT.

CAN-2409 also demonstrated a 38% reduction in the risk of prostate cancer-specific survival vs placebo (HR, 0.62; P = .0046) in a secondary analysis, the company reported.

Further, 67.1% of patients in the combination arm vs 58.6% of patients in the radiation alone arm achieved a prostate-specific antigen (PSA) nadir, defined as less than 0.2 ng/mL (P = .0164) Pathological complete responses per 2-year post-treatment biopsies were achieved in 80.4% of patients who received CAN-2409 plus radiation vs 63.6% of patients who received radiation alone (P = .0015).

No new safety signals were identified at the time of data report. Treatment-related adverse events (TRAEs) were generally mild to moderate and self-limited. The most common TRAEs were flu-like symptoms, fever, and chills.

In total, the study enrolled 745 patients with intermediate- to high-risk localized prostate cancer across 73 clinical trial sites in the US and Puerto Rico. To be eligible for enrollment, patients needed to have intermediate- or high-risk disease per National Comprehensive Cancer Center criteria, a plan to undergo standard EBRT for the prostate only, and an ECOG performance score of 0 to 2.³

Those included in the study were randomly assigned 2:1 to receive the combination of CAN-2409 plus valacyclovir plus external beam radiation therapy (EBRT; n = 496) or to placebo plus EBRT (n = 249). All patients had the option to receive short-term (less than 6 months) ADT. The median follow-up time for patients was 50.3 months.

The primary end point was DFS. Secondary end points included prostate cancer-specific survival, PSA nadir, quality of life measures, and safety.

Results from the phase 3 PrTK03 trial will be shared at the upcoming American Society of Clinical Oncology meeting in Chicago, Illinois.

Tak added in the news release, “We look forward to collaborating with the FDA to pursue an expeditious approval of CAN-2409 once we submit our BLA—currently anticipated at the end of 2026. Our aim is to introduce a new treatment option for patients at the early stages of prostate cancer, a disease that has seen minimal innovation over the past 2 decades. We expect the RMAT designation to facilitate the BLA filing process and bring us closer to achieve this objective.”

REFERENCES

1. Candel Therapeutics receives FDA Regenerative Medicine Advanced Therapy Designation for CAN-2409 for the treatment of prostate cancer. News release. Candel Therapeutics. May 28, 2025. Accessed May 29, 2025. https://ir.candeltx.com/news-releases/news-release-details/candel-therapeutics-receives-fda-regenerative-medicine-advanced

2. Candel Therapeutics announces CAN-2409 achieved primary endpoint in phase 3 prostate cancer trial, showing significantly improved disease-free survival. News release. Candel Therapeutics. December 11, 2024. Accessed May 29, 2025. https://ir.candeltx.com/news-releases/news-release-details/candel-therapeutics-announces-can-2409-achieved-primary-endpoint

3. Phase 3 study of ProstAtak immunotherapy with standard radiation therapy for localized prostate cancer (PrTK03). ClinicalTrials.gov. Last updated June 21, 2024. Accessed May 29, 2025. https://clinicaltrials.gov/study/NCT01436968