Cancer cells' ability to gain drug resistance makes them smarter than we think. To outsmart these rogue cells, some research groups are working to develop multi-action, multi-target cancer therapies. Molecules for such therapies are like Swiss-army knives that can change their reaction mechanisms depending on the job at hand. 

One recent molecule, made by researchers in France and Israel, is better than the sum of its parts. Made up of two metals — ruthenium and platinum — one half of the new molecule turns into a lethal cancer-killer when irradiated with light, and the other half kills cancerous cells just by gluing itself to them.

Photodynamic therapy is a medical procedure that uses light as a way of treating cancers and other skin diseases. Normally, a drug known as a photosensitizer is used in combination with the light therapy to increase the effectiveness of the treatment. Photosensitizers do this by absorbing lots of light and reacting to help make small molecules that can go on to destroy tumors. 

The new molecule for multi-action therapy works in two ways. The ruthenium center helps the solubility of the drug so it can reach the tumors and acts as a miniature antenna to gather as much light as possible there, much like a traditional photosensitizer. But rather than working alone, it transfers some of this light energy to the platinum half of the molecule, turning the platinum site into a highly efficient chemotherapy drug that can bind very tightly to DNA. By doing this, the platinum half of the molecule only reveals its identity as a highly effective chemotherapy drug when it is already at the site of the tumor, reducing unwanted side-effects and toxicity elsewhere in the body. By teaming up and working together, the ruthenium half of the molecule also helps to boost the anti-cancer activity of the platinum, helping it overcome issues with drug resistance.