An experimental vaccine called camupepimut prompted an increased immune response in nearly 99% of vaccinated patients in a phase 2 trial involving people with pancreatic cancer. The results were published in Nature Medicine by researchers associated with the Mayo Clinic in the United States.
The vaccine is designed to train the immune system to recognize seven mutations in the KRAS gene. These mutations are associated with around 90% of cases of pancreatic ductal adenocarcinoma, the most common form of pancreatic cancer. The researchers aimed to determine whether the vaccine could help eliminate cancer cells that might remain after surgery and chemotherapy.
The trial included 144 patients whose KRAS-associated pancreatic cancer had been treated with surgery and chemotherapy. At the start of the study, none had detectable signs of disease. Participants were randomly assigned to receive camupepimut, in a group of 96, or to remain under observation, in a group of 48.
Among those who received the vaccine, nearly 99% developed an increased T-cell response against the KRAS mutations. T cells are white blood cells involved in identifying and fighting abnormal cells. The response was still detectable in 95.5% of vaccinated participants 46 weeks after the study began.
However, the strong immune response did not translate into a statistically significant improvement in disease-free survival. Patients who received the vaccine remained disease-free for an average of 23.8 months, compared with 21.2 months among those under observation. The trial therefore does not establish that camupepimut reduces the risk of cancer returning.
The vaccine uses a fat molecule that binds to albumin, a protein in the blood, to help carry its components to lymph nodes, which play a key role in immune responses. The intended effect is to help immune cells recognize the targeted KRAS mutations and attack cells carrying them.
Researchers also identified possible factors linked to outcomes. Patients without detectable circulating tumor DNA at the beginning of the trial remained disease-free for longer after vaccination than those with detectable fragments. Participants who had not received radiotherapy had higher lymphocyte counts, which appeared to favor the immune response.
Camుపepimut requires further testing. Researchers plan to use the phase 2 findings to refine the vaccine and develop a larger phase 3 trial. The study’s lead author, Mayo Clinic oncologist Ben George, described the immune response as an important sign of the vaccine’s biological effect and a guide for future research.
Sources: Olhar Digital.