The present invention provides methods for increasing the sensitivity of a tumour to immunotherapy, chemotherapy or radiotherapy by administering an effective amount of an oligonucleotide that inhibits the binding of miR-27a, or a variant thereof, to its target mRNA. Oligonucleotides used in the invention are typically in the form of a blockmirs used as an adjunctive therapy to inhibit tumour growth, normalise and/or improve function of tumour vasculature, and/or promote immune cell infiltration of tumours.