One aspect of the invention provides methods for treating cancers which are resistant to treatment with a protein tyrosine kinase inhibitor by co-treatment with the protein tyrosine kinase inhibitor and one or more antisense oligomers that reduce the expression of HER3 and/or HER2 and/or EGFR. Another aspect of the invention provides methods for treating cancers by co-treatment with an inhibitor of HER2 and one or more antisense oligomers that reduce the expression of HER3.
