Trastuzumab deruxtecan for treating locally advanced, unresectable, or metastatic HER2+ solid tumours

Trastuzumab deruxtecan is in clinical development for treatment of unresectable (unable to be removed with surgery), locally advanced or metastatic (i.e., the cancer has spread to other tissues or organs) HER2+ solid tumours which have not responded to a prior treatment. HER2+ means that, due to a genetic mutation, the cancer cells produce a protein called HER2 in large quantities on their surface, making the tumour grow rapidly. Normally HER2 receptors are involved in controlled cell growth but in some cases, due to genetic mutations, these receptors can become overactive. HER2 overexpression is present in a relatively low percentage of solid tumours, but its presence has been linked with a more aggressive cancer development, a reduced response to generalised anticancer treatments and an increase in mortality. There are currently limited types of cancers with solid tumours that have approved treatments that target the HER2 mutations, indicating that there remains to be an unmet need for targeted therapies in other cancer types.