Early Safety Trial Tests Engineered Adenovirus in Three Pancreatic Cancer Patients

U.S. clinical trial, according to results presented in May 2026. Masato Yamamoto at the University of Minnesota led development of the treatment and presented the findings at the annual meeting of the American Society of Gene and Cell Therapy in Boston, Massachusetts.

The first patient, whose tumor measured 7 centimetres across, received the virus one year before the presentation. The other two patients were treated later, all within the past year as of May 2026. At the time of treatment, the patients’ tumors had not spread beyond the pancreas.

Since then, the tumors have not grown further. All three patients remain alive and have clinically stable disease as of May 2026. The trial is an initial safety study that used one-tenth of the intended eventual dose.

The virus is an adenovirus genetically engineered to replicate only inside tumors and not in healthy tissue. Viral replication is activated by the enzyme cyclooxygenase-2 (COX-2), which is present at much higher levels in cancer cells than in normal cells. After infection, cancer cells burst open and die, releasing more virus that can infect neighboring cancer cells.

The virus was injected directly into the patients’ tumors through a thin tube guided down the throat to the pancreas. The injection tube had an ultrasound probe on the end to allow visualization of the tumors. Yamamoto said the tumors have stopped growing but have not become smaller, possibly due to the low treatment dose.

He expects the tumors may start to shrink as the virus has more time to replicate. He added that as tumor cells break apart, the immune system may recognize and attack the cancer. Yamamoto said the treatment could potentially be effective against metastatic pancreatic cancer if the immune system targets cells that have spread.

Yamamoto and colleagues are planning to combine the viral treatment with checkpoint inhibitor immunotherapies in future trials. Another 15 patients will now be given higher doses of the virus to find the optimum level. Pancreatic cancer patients usually live only around three to six months after diagnosis once the cancer has spread.

Pancreatic tumors have tough, fibrous interiors that block chemotherapy drugs. Pancreatic tumors can hide from the immune system, making immunotherapies ineffective. Adenoviruses have been investigated as potential cancer treatments since the 1950s.

In the 1950s, women with cervical cancer were injected with an unmodified adenovirus in a clinical trial with partial success. T-VEC is the only cancer-killing virus approved by the FDA; it is a genetically modified herpes simplex virus injected into melanoma tumors.

Kai Brown, a pancreatic surgeon at Royal North Shore Hospital in Sydney, said the early signal is interesting but noted that the history of oncology includes promising early signals that vanished in later testing.

He said the trial so far has not included a control group, making it difficult to determine whether the virus works better than other treatments or none at all.