A Novel Recombinant Anti-CD22 Immunokinase Delivers Proapoptotic Activity of Death-Associated Protein Kinase (DAPK) and Mediates Cytotoxicity in Neoplastic B Cells

Mol Cancer Ther. 2016 May;15(5):971-84. doi: 10.1158/1535-7163.MCT-15-0685. Epub 2016 Jan 29.


The serine/threonine death-associated protein kinases (DAPK) provide pro-death signals in response to (oncogenic) cellular stresses. Lost DAPK expression due to (epi)genetic silencing is found in a broad spectrum of cancers. Within B-cell lymphomas, deficiency of the prototypic family member DAPK1 represents a predisposing or early tumorigenic lesion and high-frequency promoter methylation marks more aggressive diseases. On the basis of protein studies and meta-analyzed gene expression profiling data, we show here that within the low-level context of B-lymphocytic DAPK, particularly CLL cells have lost DAPK1 expression. To target this potential vulnerability, we conceptualized B-cell-specific cytotoxic reconstitution of the DAPK1 tumor suppressor in the format of an immunokinase. After rounds of selections for its most potent cytolytic moiety and optimal ligand part, a DK1KD-SGIII fusion protein containing a constitutive DAPK1 mutant, DK1KD, linked to the scFv SGIII against the B-cell-exclusive endocytic glyco-receptor CD22 was created. Its high purity and large-scale recombinant production provided a stable, selectively binding, and efficiently internalizing construct with preserved robust catalytic activity. DK1KD-SGIII specifically and efficiently killed CD22-positive cells of lymphoma lines and primary CLL samples, sparing healthy donor- or CLL patient-derived non-B cells. The mode of cell death was predominantly PARP-mediated and caspase-dependent conventional apoptosis as well as triggering of an autophagic program. The notoriously high apoptotic threshold of CLL could be overcome by DK1KD-SGIII in vitro also in cases with poor prognostic features, such as therapy resistance. The manufacturing feasibility of the novel CD22-targeting DAPK immunokinase and its selective antileukemic efficiency encourage intensified studies towards specific clinical application. Mol Cancer Ther; 15(5); 971-84. ©2016 AACR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / administration & dosage*
  • Apoptosis / drug effects*
  • Cell Line, Tumor
  • Death-Associated Protein Kinases / antagonists & inhibitors
  • Death-Associated Protein Kinases / chemistry
  • Death-Associated Protein Kinases / genetics
  • Death-Associated Protein Kinases / metabolism*
  • Gene Expression Profiling
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Leukemia, Lymphocytic, Chronic, B-Cell / genetics
  • Leukemia, Lymphocytic, Chronic, B-Cell / metabolism*
  • Leukemia, Lymphocytic, Chronic, B-Cell / pathology
  • Lymphoma, B-Cell / genetics
  • Lymphoma, B-Cell / metabolism*
  • Lymphoma, B-Cell / pathology
  • Multigene Family
  • Mutation
  • Phosphorylation
  • Protein Interaction Domains and Motifs / genetics
  • Recombinant Fusion Proteins / administration & dosage*
  • Sialic Acid Binding Ig-like Lectin 2 / antagonists & inhibitors*
  • Single-Chain Antibodies / administration & dosage


  • Antineoplastic Agents
  • Recombinant Fusion Proteins
  • Sialic Acid Binding Ig-like Lectin 2
  • Single-Chain Antibodies
  • Death-Associated Protein Kinases