title: Targeted ex vivo reduction of CD64-positive monocytes in chronic myelomonocytic leukemia and acute myelomonocytic leukemia using human granzyme B-based cytolytic fusion proteins.
abstract: CMML (chronic myelomonocytic leukemia) belongs to the group of myeloid neoplasms known as myelodysplastic and myeloproliferative diseases. In some patients with a history of CMML, the disease transforms to acute myelomonocytic leukemia (AMML). There are no specific treatment options for patients suffering from CMML except for supportive care and DNA methyltransferase inhibitors in patients with advanced disease. New treatment strategies are urgently required, so we have investigated the use of immunotherapeutic directed cytolytic fusion proteins (CFPs), which are chimeric proteins comprising a selective domain and a toxic component (preferably of human origin to avoid immunogenicity). The human serine protease granzyme B is a prominent candidate for tumor immunotherapy because it is expressed in cytotoxic T lymphocytes and natural killer cells. Here, we report the use of CD64 as a novel target for specific CMML and AMML therapy, and correlate CD64 expression with typical surface markers representing these diseases. We demonstrate that CD64-specific human CFPs kill CMML and AMML cells ex vivo, and that the mutant granzyme B protein R201K is more cytotoxic than the wild-type enzyme in the presence of the granzyme B inhibitor PI9. Besides, the human CFP based on the granzyme B mutant was also able to kill AMML or CMML probes resistant to Pseudomonas exotoxin A.
authors: Department of Experimental Medicine and Immunotherapy, Institute for Biomedical Engineering, University Hospital RWTH Aachen, Aachen, Germany; Department of Pharmaceutical Product Development, Fraunhofer IME, Aachen, Germany.
authors: Sonja
authors: S
authors: Schiffer
authors: Reinhard
authors: R
authors: Rosinke
authors: Edgar
authors: E
authors: Jost
authors: Grit
authors: G
authors: Hehmann-Titt
authors: Michael
authors: M
authors: Huhn
authors: Georg
authors: G
authors: Melmer
authors: Stefan
authors: S
authors: Barth
authors: Theo
authors: T
authors: Thepen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004355:Drug Stability; D005260:Female; D053804:Granzymes / Q000008:administration & dosage*; D018922:HL-60 Cells; D006801:Humans; D000922:Immunotoxins / Q000008:administration & dosage / Q000097:blood / Q000276:immunology / Q000493:pharmacokinetics; D015479:Leukemia, Myelomonocytic, Acute / Q000188:drug therapy* / Q000276:immunology; D015477:Leukemia, Myelomonocytic, Chronic / Q000188:drug therapy* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D017452:Receptors, IgG / Q000096:biosynthesis / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000097:blood / Q000276:immunology / Q000493:pharmacokinetics; D057127:Single-Chain Antibodies / Q000008:administration & dosage / Q000276:immunology / Q000493:pharmacokinetics
chemical_list: D000922:Immunotoxins; D017452:Receptors, IgG; D011993:Recombinant Fusion Proteins; D057127:Single-Chain Antibodies; D053804:Granzymes
keywords: immunotoxin; leukemia; serpin B9; therapy-resistance