Abstract: The present invention relates to a method of identifying a subject being susceptible to a co-treatment with an histone deacetylase 10 (HDAC10)-inhibitor, said subject being in need of and/or being treated with cancer therapy against a cancer, comprising the steps of a) determining the amount of an HDAC10 gene product and/or an autophagy-related gene 4D (ATG4D) product in a cancer sample from said subject, b) comparing the amount of said HDAC10 gene product as determined in step a) with a reference amount for said HDAC10 gene product and/or the amount of ATG4D product as determined in step a) with a reference amount for said ATG4D product, and c) identifying a subject being susceptible to co-treatment with an HDAC10-inhibitor.