Human microtubule‐associated protein tau mediates targeted killing of CD30⁺ lymphoma cells in vitro and inhibits tumour growth in vivo

Abstract

SummaryHodgkin lymphoma (HL) and systemic anaplastic large cell lymphoma (sALCL) are rare lymphoproliferative cancer types. Although most HL patients can be cured by chemo-and radio-therapy, 4-50% of patients relapse and have a poor prognosis. The need for improved therapeutic options for patients with relapsed or refractory disease has been addressed by CD30-specific antibody-based immunotherapeutics. However, available CD30-specific monoclonal antibodies (mAbs), antibody drug conjugates (ADCs) or chimeric immunotoxins suffer from the requirement of a functional host immunity, undesirable immune reactions or heterogeneity and instability, respectively. Here, we present a new fusion protein comprised of the CD30-specific antibody single-chain fragment Ki4(scFv) and the human pro-apoptotic effector protein, microtubule-associated protein tau (MAPT). Ki4(scFv)-MAP selectively induced apoptosis in rapidly proliferating L540cy, L428, and Karpas 299 cells in a dose-dependent manner. Tubulin polymerization assays confirmed that Ki4(scFv)-MAP stabilizes microtubules, suggesting a mechanism for its pro-apoptotic action. Dosefinding experiments proved that Ki4(scFv)-MAP is well tolerated in mice compared to the previously reported Ki4(scFv)-ETA'. Ki4(scFv)-MAP significantly inhibited growth of subcutaneous L540cy xenograft tumours in mice. Our data present a novel approach for the treatment of CD30 + lymphomas, combining the binding specificity of a target-specific antibody fragment with the selective cytotoxicity of MAPT towards proliferating lymphoma cells.

CD64-directed microtubule associated protein tau kills leukemic blastsex vivo

“…We previously reported the identification of a novel cytolytic effector protein known as microtubule-associated protein tau (MAP) which promotes the assembly of the mitotic spindle [18–20]. MAP binds to microtubules via microtubule-binding repeats and enhances the stability of microtubule polymers [21–23].…”

“…The modified MAP protein kills proliferating EGFR + cancer cells, EpCAM + carcinoma cells, AChR + rhabdomyosarcoma cells and CD30 + lymphoma cells when fused to appropriate targeting components [18–20, 25]. Most recently, the CD64-targeting construct H22(scFv)-MAP was shown to eliminate pro-inflammatory M1 macrophages but not the anti-inflammatory M2 population following intradermal administration to the chronically inflamed skin of transgenic mice expressing human CD64 [26].…”

Phage display-based generation of novel internalizing antibody fragments for immunotoxin-based treatment of acute myeloid leukemia

“…22 This could be avoided by replacing the cytotoxic component with human proapoptotic proteins, such as granzyme B/M, angiogenin, DAPK2 and Tau, to form fully human constructs. [22][23][24][25][26] Using the Tomlinson phage display library J, we isolated a series of novel scFv antibodies that show specific binding activity against unknown surface antigens on AML-derived Kasumi-1 cells. EMI404 and EMI405 showed potent binding activity against human primary AML cells.…”

Phage display-based on-slide selection of tumor-specific antibodies on formalin-fixed paraffin-embedded human tissue biopsies

“…ETA is a potent toxin but it originates from a prokaryotic source and therefore triggers an undesirable immune response if administrated repeatedly [48]. This unwanted side effect can be avoided by using modified forms of ETA lacking the B-cell and T-cell epitopes [49][50][51] or by replacing the bacterial component with a human pro-apoptotic protein such as Tau [52], DAPK2 [53], granzyme B [54] or granzyme M [55].…”