The present invention relates to compounds binding to calreticulin which selectively inhibit growth of CALR mutant cells and/or exhibit selective cytotoxicity towards CALR mutant cells, to pharmaceutical compositions comprising such compounds as well as to their use in treating diseases or conditions caused by or associated with a mutation of CALR, in particular myeloid malignancies, such as myeloproliferative neoplasms or myelodysplasia syndrome. The present invention also relates to screening assays allowing the identification of such compounds.