This is a collaboration with the Central Laser Facility to study anti-cancer drugs such as Combretastatin A4 (CA4). This drug has a naturally occurring structural configuration - known as cis isomer (cis-CA4) - that is particularly useful for attacking cancer cells. However, due to the significant level of toxicity of this cis isomer, in cancer treatments is more convenient to use a different structural configuration of Combretastatin A4: the considerably less toxic trans isomer analogue to cis-CA4, which is known as trans-CA4. The diminished toxicity of the trans-CA4 allows for it to be placed in areas affected by cancer cells and then be transformed into the cis-CA4 isomer. This transformation is achieved by photo-excitating the trans-CA4 analogue using tissue penetrating radiation that is usually in the red or near-infrared region of the spectra. We employ computational techniques based on Time-dependent Density Functional Theory (TDDFT) methods to study this photo-excitation phenomenon, and our aim is to find out a Combretastatin drug candidate with a maximised efficiency for local cancer therapy.