Irradiation with mixed helium and carbon ion beams is emerging as a promising approach to treat- ment monitoring in ion beam therapy. In this scenario, the carbon ions are used to irradiate the tumor, whereas the specific energy loss of the helium ions downstream of the patient serves as range probe. This talk presents the ongoing research on generating and accelerating such a mixed beam at the MedAustron accelerator facility in Wiener Neustadt, focusing on the developments that allowed for the delivery of a mixed 4He2+ and 12C6+ beam for the first time using a sequential injection scheme into the MedAustron synchrotron.