These results reveal that the anti-tumor effects of the synthesized oligodeoxynucleotide-based antagonist, HJ901, which competitively binds to TLR7/9, may be associated with the downregulation of the NF-κB and JAK2-STAT3 signaling pathways and provide rationale for treating ABC-DLBCL patients with the MyD88 L265P mutation. Here, STAT3 is linked to diffuse large B-cell lymphoma.