Vaccines are emerging as a transformative approach in cancer treatment, offering new hope for patients with traditionally difficult-to-treat malignancies. From FDA-approved options to novel candidates in clinical development, cancer vaccines are demonstrating significant potential to prevent recurrence, target micrometastatic disease, and improve outcomes across multiple tumor types.
"Vaccines are truly coming to the forefront of cancer treatment," said Shubham Pant, MD, MBBS, professor in the Department of Gastrointestinal Medical Oncology at The University of Texas MD Anderson Cancer Center. "What I am interested in is looking at vaccines in earlier settings. For example, in early-stage pancreatic cancer, even after resection and adjuvant treatment, patients still have a high chance of disease recurrence."
FDA-Approved Cancer Vaccines Setting the Foundation
Several cancer vaccines have already secured FDA approval and established their place in treatment paradigms. BCG, an attenuated strain of Mycobacterium bovis originally developed as a tuberculosis vaccine, became the first FDA-approved immunotherapy in 1990 for non-muscle-invasive bladder cancer (NMIBC) and remains a standard of care.
For patients with NMIBC who progress after BCG treatment, nadofaragene firadenovec-vncg (Adstiladrin) received FDA approval in December 2022 as the first adenoviral vector-based gene therapy. The phase 3 CS-003 trial demonstrated a complete response rate of 51% with a median duration of response of 9.7 months.
"Nadofaragene firadenovec has an intravesical application," explained Neal D. Shore, MD, FACS, medical director of the Carolina Urologic Research Center. "This therapy combines interferon alfa-2b with an adenoviral component. It's a viral gene vector therapy, and ultimately, the mechanism of action is to stimulate the patient's interferon production, which makes it an effective apoptotic agent against urothelial carcinoma."
Other FDA-approved cancer vaccines include sipuleucel-T (Provenge), approved in 2010 for metastatic castration-resistant prostate cancer, and talimogene laherparepvec (T-VEC; Imlygic), an oncolytic virus-based vaccine approved in 2015 for unresectable melanoma lesions.
Novel Vaccines Showing Promise in Clinical Development
Several innovative cancer vaccines are advancing through clinical trials with encouraging results:
ELI-002: Targeting KRAS Mutations
The KRAS-targeted vaccine ELI-002 is being evaluated in the phase 1 AMPLIFY-201 trial for patients with pancreatic ductal adenocarcinoma (PDAC) or colorectal cancer (CRC) with KRAS G12D and G12R mutations who underwent successful surgical resection.
Results showed that patients who received the 2-peptide formulation of ELI-002 experienced a median overall survival of 28.9 months and a median relapse-free survival of 16.3 months. A 7-peptide formulation targeting additional KRAS mutations is now being examined in the phase 2 AMPLIFY-7P study.
"They could work well for a majority of patients with pancreatic cancer because most of these patients have high-risk disease by definition," noted Dr. Pant. "When we can kill the micrometastatic disease, that's where we can have the maximum impact because we're moving towards curing these patients, which might not have been achievable before."
Aglatimagene Besadenovec (CAN-2409): Viral Vector Approach
Aglatimagene besadenovec is an off-the-shelf, replication-defective adenovirus delivering the herpes simplex virus thymidine kinase gene to induce an individualized immune response. The phase 3 PrTK03 study in patients with newly diagnosed intermediate- to high-risk localized prostate cancer met its primary endpoint of disease-free survival.
At a median follow-up of 50.3 months, patients who received aglatimagene besadenovec experienced a 30% reduction in the risk of disease recurrence or death compared with standard of care (HR, 0.70; P=.0155). The 2-year pathological complete response rates were 80.4% versus 63.6% (P=.0015).
"There hasn't been any new treatment or significant change in the standard of care for localized, nonmetastatic prostate cancer for over 20 years," said Glen Gejerman, MD, MBA, codirector of Urologic Oncology at Hackensack Meridian Health. "If approved, CAN-2409 could transform the treatment paradigm, offering patients with localized disease an effective option that may significantly reduce the risk of disease recurrence."
Aglatimagene besadenovec is also showing promise in non-small cell lung cancer (NSCLC) and pancreatic cancer. In the phase 2 LuTK02 trial, patients with advanced NSCLC who had an inadequate response to immune checkpoint inhibitor treatment achieved a median overall survival of 24.5 months. In pancreatic cancer, the final analysis of the PaTK02 study showed a median overall survival of 31.4 months compared with 12.5 months for standard of care alone.
The FDA has granted fast track designation to aglatimagene besadenovec for both NSCLC and pancreatic cancer.
mRNA-4157 (V940): Personalized mRNA Approach
mRNA-4157 represents a cutting-edge approach as an individualized neoantigen therapy containing synthetic mRNA coding for up to 34 neoantigens, designed based on a patient's unique tumor mutational signature.
In the phase 2 KEYNOTE-942 trial, patients with resected stage IIIB to IV cutaneous melanoma who received mRNA-4157 in combination with pembrolizumab achieved significantly improved relapse-free survival compared to pembrolizumab alone (HR, 0.510; P=.019). The 30-month relapse-free survival rates were 74.8% versus 55.6%.
Based on these promising results, Merck and Moderna have initiated multiple phase 3 trials, including INTerpath-009 evaluating mRNA-4157 plus pembrolizumab as adjuvant therapy in patients with resectable NSCLC who did not achieve a pathological complete response with neoadjuvant pembrolizumab plus chemotherapy.
Future Directions and Clinical Impact
Cancer vaccines are poised to transform treatment paradigms across multiple tumor types, particularly in early-stage and high-risk disease settings where preventing recurrence is crucial.
"The future of cancer vaccines looks incredibly promising," said Dr. Gejerman. "We're witnessing an expansion of therapeutic approaches across multiple platforms, with growing evidence supporting their efficacy. We're seeing a lot of exciting advancements within neoantigen vaccines that target unique tumor mutations, creative viral vector approaches, and novel combination strategies."
The combination of cancer vaccines with other immunotherapies, such as checkpoint inhibitors, appears particularly promising for enhancing efficacy and overcoming resistance mechanisms. As these approaches continue to advance through clinical development, they may offer new hope for patients with previously limited treatment options.
For patients with high-risk disease, cancer vaccines could potentially increase cure rates by eliminating micrometastatic disease that might otherwise lead to recurrence. This approach represents a paradigm shift from treating established disease to preventing its return, potentially transforming outcomes across multiple cancer types.
