Stem cell research offers yet another breakthrough with the latest success of an engineered cancer-killing cell, according to the BBC.

The experiments on mice by Harvard Medical School scientists showed cells genetically engineered to produce and secrete toxins that target and kill brain tumors.

The next step will be to test on humans and get FDA approval.

The team of scientists has developed this method in order to attack tumors that remain in the brain after a main tumor is removed.

The stem cells are placed at the site encapsulated in a biodegradable gel, which solves prior issues in recent clinical trial that aimed to deliver purified cancer-killing toxins, the Harvard University team said in a statement.

This is achieved by the toxins entering the cancer cells, disrupting the cell's ability to make proteins, and within days, the cell starts to die.

This method has been pursued for some time, and only in the 1990s was the first breakthrough seen in being able to target cancer cells.

In prior trials for solid tumors, the healthy cells were affected or engineered cells were also affected by the toxins.

"Cancer-killing toxins have been used with great success in a variety of blood cancers, but they don't work as well in solid tumors because the cancers aren't as accessible and the toxins have a short half-life," team lead Khalid Shah said. "A few years ago we recognized that stem cells could be used to continuously deliver these therapeutic toxins to tumors in the brain, but first we needed to genetically engineer stem cells that could resist being killed themselves by the toxins."

Experts told BBC this signals a new wave and revolution in cancer therapy.

Chris Mason, professor of regenerative medicine at University College London, said, "It shows you can attack solid tumors by putting mini pharmacies inside the patient, which deliver the toxic payload direct to the tumor."

The hope is for this type of therapy to be ready for human use in the next five years.