The potency of typical MPN mutations, including JAK2V617F or CALR exon 9 mutations, for cancer vaccination therapy as a specific anti-cancer immunotherapy approach was pushed forward by findings of Holmström et al. who could identify a spontaneous T-cell response against a PD-L1-derived epitope in MPN patients [169,170,171]. Here, CALR is linked to myeloproliferative disorder.