All 14 participants of a recent experimental drug trial saw their colorectal cancer disappear, researchers revealed in a new study published Sunday in the New England Journal of Medicine.

The results are astonishing, and while researchers cautioned that they need to be replicated in other trials, this is still leaving patients and health care providers hopeful. “I don’t think anyone has seen this before, where every single patient has had the tumor disappear,” Andrea Cercek, an oncologist at Memorial Sloan Kettering Cancer Center in New York and lead author of the study, told The Washington Post.

The patients had all been recently diagnosed with early stage rectal cancer, had mismatch-repair deficiency, and had not yet received any treatment. As part of the trial, they were given nine doses of a drug called intravenous dostarlimab, which is designed to block a specific cancer cell protein. The participants did not report any major complications from the drug, and six months later, their scans, biopsies, and physical exams showed no signs of cancer. “All 14 patients? The odds are exceedingly low and really unheard of in oncology,” Cercek told the Post.

The study’s sample size was diverse in age, race, and ethnicity, but very small, and the participants will still have to be under observation for several years to make sure the tumors do not return or have metastasized in other parts of their bodies. Researchers are buoyed by the trial results, and want to see this lead to new treatments for other cancers. “I feel a universal feeling of gratitude, but also hope for others,” trial participant Sascha Roth told the Post. “Hope for all cancers.”