As exemplified herein by (Rap)2-E1-(Rap)2, comprising four copies of Rap linked to the AD2-fused CH3 termini of hRS7 IgG (denoted as E1), and by (Rap)2-E1*-(Rap)2, comprising four copies of Rap linked to the AD2-fused CK termini of hRS7 IgG (denoted as E1*), these DNL-based immunoRNases could offer a distinct advantage over their recombinantly-produced fusion counterparts, such as Rap(Q)-hRS7, in improved potency against targeted cancer cells in vitro and tumor xenografts in vivo. The gene discussed is LRPAP1; the disease is cancer.