Scientific discoveries are often the result of hard work mixed in with a bit of luck. A recent discovery at Stanford University is a perfect example. In a chance observation, researchers saw destructive cancer cells transform into harmless immune cells right before their eyes. The finding is remarkable and may potentially lead to a new, more effective form of leukemia treatment.

During routine laboratory observation of cancer cell cultures of the most common type of acute lymphoblastic leukemia, known as precursor B cell ALL or B-ALL, Dr. Ravi Majeti, senior author of the paper, observed a difference: The normally aggressive cancer cells were transforming to harmless immune system cells, called macrophages.

Macrophages are not your ordinary white blood cell. As part of the immune system they work to seek out foreign invaders and destroy them. The macrophages engulf foreign material, including cancer cells, forever ridding them from the body, iflscience reported.

The cancer cells in the culture were being treated in the hopes of helping them survive, so the researchers were not prepared for their extreme transformation. Although at first perplexed by what might cause the otherwise deadly cells to suddenly become harmless, lead researcher Majeti remembered a study on mice cancer cells he read years ago that might offer an explanation.

In the mouse study, the same type of cancer cells became macrophages when exposed to certain transcription factors (proteins that bind to DNA sequences). After a few more experiments, Majeti and his team confirmed that the same reaction was causing the transformation in the human cancer cells.

Not only are macrophages harmless to the body, but they also aid in the destruction of cancer. Majeti and his team believe that these specific macrophages, which began their life as cancer cells, may be even more effective than ordinary macrophages.

“Because the macrophage cells came from the cancer cells, they will already carry with them the chemical signals that will identify the cancer cells, making an immune attack against the cancer more likely,” Majeti explained in a press release.

The finding alone isn’t about to transform cancer as we know it, but it has the potential to lead to more effective treatments. The transformation works on B cell lymphoblastic leukemia, a form of cancer which is particularly aggressive and often has poor outcomes. This type of cancer is most common among children under 5 and kills around 1,450 individuals in the U.S. each year.

The next step for the Stanford team is to see if they can find a drug that will bring about the same reaction. Thankfully, there are already a few drugs out there that work in a similar, although not exact same, manner for which the team can mirror their drug developments after.

Source: Majeti R, McClellan JS, Dove C, et al. Reprogramming of primary human Philadelphia chromosome-positive B cell acute lymphoblastic leukemia cells into nonleukemic macrophage. PNAS. 2015.