As excitement builds around personalised cancer vaccines, researchers at the Icahn School of Medicine at Mount Sinai have reached a new milestone—showing that their custom-made vaccine, in combination with immune checkpoint inhibitor, is safe and able to spark strong immune responses in people with bladder cancer.

Their phase 1 study, led by Nina Bhardwaj, MD, PhD, and Matthew Galsky, MD, appears in Nature Cancer and adds to growing evidence that personalised vaccines could make existing cancer treatments more safe and effective.

Mount Sinai’s experimental vaccine, called PGV001, is designed to target the unique mutations in each patient’s tumour. Using advanced tumour sequencing and a computational platform developed by Mount Sinai experts, researchers pinpoint which tumour changes—known as neoantigens—are most likely to alert the immune system.

They then create a custom vaccine using lab-made peptides based on these markers. Given with treatments like the immunotherapy drug atezolizumab, PGV001 helps train the body’s defenses to attack cancer cells while leaving healthy cells alone.

"Our findings move the field forward by showing how personalised vaccines like PGV001 can work in bladder cancer," says Dr. Bhardwaj, Ward-Coleman Chair in Cancer Research and Director of Mount Sinai’s Vaccine and Cell Therapy Lab. "We’ve proven these custom vaccines can consistently activate the immune system in powerful, cancer-fighting ways."

 Building on the success of PGV001 in eliciting immune responses across multiple cancer types, the personalised vaccine is now demonstrating encouraging results in bladder cancer and shows potential for broader applications. Motivated by these promising early findings, the Mount Sinai team is working to accelerate the vaccine’s development, expand its accessibility, and test new combinations to help even more patients. This individualised approach offers renewed hope for patients, particularly those whose tumours are resistant to existing therapies.

In the latest trial, 10 patients with bladder cancer received their own personalised version of PGV001, along with  atezolizumab. Each vaccine was carefully crafted to match the patient’s specific tumour mutations and maximize the immune response.

"This study adds to growing evidence that combining personalised vaccines with immunotherapy could help many more patients benefit," says Dr. Galsky, Co-Director of the Center of Excellence for Bladder Cancer and Associate Director for Translational Research at The Tisch Cancer Institute. "It also lays the groundwork for larger trials that are now underway."

Bladder cancer responds well to immune-based treatments, but not everyone benefits equally. According to the American Cancer Society, about 84,870 new cases and 17,420 deaths from bladder cancer are expected in the United States this year.

A collaborative team at Mount Sinai, bringing together experts in immunology, oncology, genetics, and pathology, drove the study. Contributors included Mansi Saxena, PhD, Jonathan Anker MD, PhD, Julia Kodysh, Anna Kaminska, PhD, and more. The National Cancer Institute of the National Institutes of Health, the Cancer Research Institute, the Parker Institute of Cancer Immunotherapy, and industry partners supported this study.

For a list of all contributors and supporters please read the full research report: https://www.nature.com/articles/s43018-025-00966-7

Source: Icahn School of Medicine at Mount Sinai