Attempting to wipe out cancer can at times seem like a cruel, high-stakes game of Whack-a-Mole. Recurrence is common, and while treated tumors may disappear, new ones often appear in different parts of the body. But two new studies published today in the journal Nature may have found a better way: personalized vaccines that could kick the disease out for good.

Current forms of cancer treatment can be quite effective in knocking tumors out, but they can’t keep them from coming back. That’s partly because cancer is not one disease but many, each with its own unique combination of genetic mutations and accompanying antigens (immune-triggering molecules), and standardized treatments can’t reach them all.

But what if we could create targeted treatments for each combination? Two small clinical trials of skin cancer vaccines have attempted just that.

For the first study, researchers created a vaccine that targets specific antigens, alerting the body to their presence so it can fight back. Of the six people who were given the vaccine, four were still cancer-free after 25 months. While the remaining two people did have melanoma, their tumors were responsive to treatment and eventually completely disappeared.

The second study used patients’ RNA to create customized vaccines that targeted antigens called neo-epitopes. The scientists administered the vaccine to 13 people. Of those 13, eight were tumor-free 23 months later, and one person was declared tumor-free after the vaccination and regular treatment. Most importantly, the vaccine had done what it set out to do: all 13 participants had shown an immune response. Their bodies learned what to do to get rid of the cancer.

While these results are impressive, both studies were quite small. We’ll need more studies and larger clinical trials before we can say for sure that the vaccines work, and we’ll need to test them in other forms of cancer. But as first steps go, these are promising indeed.