Preclinical characterization of AMG 330, a CD3/CD33-bispecific T-cell-engaging antibody with potential for treatment of acute myelogenous leukemia.

There is high demand for novel therapeutic options for patients with acute myelogenous leukemia (AML). One possible approach is the bispecific T-cell-engaging (BiTE, a registered trademark of Amgen) antibody AMG 330 with dual specificity for CD3 and the sialic acid-binding lectin CD33 (SIGLEC-3), which is frequently expressed on the surface of AML blasts and leukemic stem cells. AMG 330 binds with low nanomolar affinity to CD33 and CD3ε of both human and cynomolgus monkey origin. Eleven human AML cell lines expressing between 14,400 and 56,700 CD33 molecules per cell were all potently lysed with EC(50) values ranging between 0.4 pmol/L and 3 pmol/L (18-149 pg/mL) by previously resting, AMG 330-redirected T cells. Complete lysis was achieved after 40 hours of incubation. In the presence of AML cells, AMG 330 specifically induced expression of CD69 and CD25 as well as release of IFN-γ, TNF, interleukin (IL)-2, IL-10, and IL-6. Ex vivo, AMG 330 mediated autologous depletion of CD33-positive cells from cynomolgous monkey bone marrow aspirates. Soluble CD33 at concentrations found in bone marrow of patients with AML did not significantly affect activities of AMG 330. Neoexpression of CD33 on newly activated T cells was negligible as it was limited to 6% of T cells in only three out of ten human donors tested. Daily intravenous administration with as low as 0.002 mg/kg AMG 330 significantly prolonged survival of immunodeficient mice adoptively transferred with human MOLM-13 AML cells and human T cells. AMG 330 warrants further development as a potential therapy for AML.

Friedrich M ，Henn A ，Raum T ，Bajtus M ，Matthes K ，Hendrich L ，Wahl J ，Hoffmann P ，Kischel R ，Kvesic M ，Slootstra JW ，Baeuerle PA ，Kufer P ，Rattel B ... -  《-》

T lymphocytes can be effectively recruited for ex vivo and in vivo lysis of AML blasts by a novel CD33/CD3-bispecific BiTE antibody construct.

Aigner M ，Feulner J ，Schaffer S ，Kischel R ，Kufer P ，Schneider K ，Henn A ，Rattel B ，Friedrich M ，Baeuerle PA ，Mackensen A ，Krause SW ... -  《-》

The Broad Anti-AML Activity of the CD33/CD3 BiTE Antibody Construct, AMG 330, Is Impacted by Disease Stage and Risk.

Harrington KH ，Gudgeon CJ ，Laszlo GS ，Newhall KJ ，Sinclair AM ，Frankel SR ，Kischel R ，Chen G ，Walter RB ... -  《PLoS One》

Characterization of CD33/CD3 Tetravalent Bispecific Tandem Diabodies (TandAbs) for the Treatment of Acute Myeloid Leukemia.

Randomized studies with gemtuzumab ozogamicin have validated CD33 as a target for antigen-specific immunotherapy of acute myelogenous leukemia (AML). Here, we investigated the potential of CD33/CD3-directed tandem diabodies (TandAbs) as novel treatment approach for AML. These tetravalent bispecific antibodies provide two binding sites for each antigen to maintain the avidity of a bivalent antibody and have a molecular weight exceeding the renal clearance threshold, thus offering a longer half-life compared to smaller antibody constructs. We constructed a series of TandAbs composed of anti-CD33 and anti-CD3 variable domains of diverse binding affinities and profiled their functional properties in CD33+ human leukemia cell lines, xenograft models, and AML patient samples. Our studies demonstrated that several CD33/CD3 TandAbs could induce potent, dose-dependent cytolysis of CD33+ AML cell lines. This effect was modulated by the effector-to-target cell ratio and strictly required the presence of T cells. Activation and proliferation of T cells and maximal AML cell cytolysis correlated with high avidity to both CD33 and CD3. High-avidity TandAbs were broadly active in primary specimens from patients with newly diagnosed or relapsed/refractory AML in vitro, with cytotoxic properties independent of CD33 receptor density and cytogenetic risk. Tumor growth delay and inhibition were observed in both prophylactic and established HL-60 xenograft models in immunodeficient mice. Our data show high efficacy of CD33/CD3 TandAbs in various preclinical models of human AML. Together, these findings support further study of CD33/CD3 TandAbs as novel immunotherapeutics for patients with AML. Clin Cancer Res; 22(23); 5829-38. ©2016 AACR.

Reusch U ，Harrington KH ，Gudgeon CJ ，Fucek I ，Ellwanger K ，Weichel M ，Knackmuss SH ，Zhukovsky EA ，Fox JA ，Kunkel LA ，Guenot J ，Walter RB ... -  《-》

CD33 target validation and sustained depletion of AML blasts in long-term cultures by the bispecific T-cell-engaging antibody AMG 330.

Krupka C ，Kufer P ，Kischel R ，Zugmaier G ，Bögeholz J ，Köhnke T ，Lichtenegger FS ，Schneider S ，Metzeler KH ，Fiegl M ，Spiekermann K ，Baeuerle PA ，Hiddemann W ，Riethmüller G ，Subklewe M ... -  《-》