This sounds promising

Virus “harnessed to kill cancers”

The virus lacks a gene viruses normally use to disguise themselves so they can sneak into the cell unnoticed.

Normal cells can recognise they are under attack by the modified virus and commit suicide to prevent it from replicating and infecting other cells.

Cancer cells are programmed differently and resist suicide at all costs.

This “selfishness” on the cancer’s behalf allows the engineered virus to replicate within the cancer cells and spread through the tumour tissue.