IgA-Mediated Killing of Tumor Cells by Neutrophils Is Enhanced by CD47-SIRPα Checkpoint Inhibition.

Therapeutic monoclonal antibodies (mAb), directed toward either tumor antigens or inhibitory checkpoints on immune cells, are effective in cancer therapy. Increasing evidence suggests that the therapeutic efficacy of these tumor antigen-targeting mAbs is mediated-at least partially-by myeloid effector cells, which are controlled by the innate immune-checkpoint interaction between CD47 and SIRPα. We and others have previously demonstrated that inhibiting CD47-SIRPα interactions can substantially potentiate antibody-dependent cellular phagocytosis and cytotoxicity of tumor cells by IgG antibodies both in vivo and in vitro IgA antibodies are superior in killing cancer cells by neutrophils compared with IgG antibodies with the same variable regions, but the impact of CD47-SIRPα on IgA-mediated killing has not been investigated. Here, we show that checkpoint inhibition of CD47-SIRPα interactions further enhances destruction of IgA antibody-opsonized cancer cells by human neutrophils. This was shown for multiple tumor types and IgA antibodies against different antigens, i.e., HER2/neu and EGFR. Consequently, combining IgA antibodies against HER2/neu or EGFR with SIRPα inhibition proved to be effective in eradicating cancer cells in vivo In a syngeneic in vivo model, the eradication of cancer cells was predominantly mediated by granulocytes, which were actively recruited to the tumor site by SIRPα blockade. We conclude that IgA-mediated tumor cell destruction can be further enhanced by CD47-SIRPα checkpoint inhibition. These findings provide a basis for targeting CD47-SIRPα interactions in combination with IgA therapeutic antibodies to improve their potential clinical efficacy in tumor patients.

Treffers LW ，Ten Broeke T ，Rösner T ，Jansen JHM ，van Houdt M ，Kahle S ，Schornagel K ，Verkuijlen PJJH ，Prins JM ，Franke K ，Kuijpers TW ，van den Berg TK ，Valerius T ，Leusen JHW ，Matlung HL ... -  《-》

Targeting the myeloid checkpoint receptor SIRPα potentiates innate and adaptive immune responses to promote anti-tumor activity.

Kuo TC ，Chen A ，Harrabi O ，Sockolosky JT ，Zhang A ，Sangalang E ，Doyle LV ，Kauder SE ，Fontaine D ，Bollini S ，Han B ，Fu YX ，Sim J ，Pons J ，Wan HI ... -  《Journal of Hematology & Oncology》

Functional characterization of the selective pan-allele anti-SIRPα antibody ADU-1805 that blocks the SIRPα-CD47 innate immune checkpoint.

Voets E ，Paradé M ，Lutje Hulsik D ，Spijkers S ，Janssen W ，Rens J ，Reinieren-Beeren I ，van den Tillaart G ，van Duijnhoven S ，Driessen L ，Habraken M ，van Zandvoort P ，Kreijtz J ，Vink P ，van Elsas A ，van Eenennaam H ... -  《Journal for ImmunoTherapy of Cancer》

Enhancing IgA-mediated neutrophil cytotoxicity against neuroblastoma by CD47 blockade.

Approximately half of the neuroblastoma patients develop high-risk neuroblastoma. Current treatment involves a multimodal strategy, including immunotherapy with dinutuximab (IgG ch14.18) targeting GD2. Despite achieving promising results, the recurrence rate remains high and poor survival persists. The therapeutic efficacy of dinutuximab is compromised by suboptimal activation of neutrophils and severe neuropathic pain, partially induced by complement activation. To enhance neutrophil cytotoxicity, IgG ch14.18 was converted to the IgA isotype, resulting in potent neutrophil-mediated antibody-dependent cell-mediated cytotoxicity (ADCC), without complement activation. However, myeloid checkpoint molecules hamper neutrophil cytotoxicity, for example through CD47 that is overexpressed on neuroblastomas and orchestrates an immunosuppressive environment upon ligation to signal regulatory protein alpha (SIRPα) expressed on neutrophils. In this study, we combined IgA therapy with CD47 blockade. In vitro killing assays showed enhanced IgA-mediated ADCC by neutrophils targeting neuroblastoma cell lines and organoids in comparison to IgG. Notably, when combined with CD47 blockade, both IgG and IgA therapy were enhanced, though the combination with IgA resulted in the greatest improvement of ADCC. Furthermore, in a neuroblastoma xenograft model, we systemically blocked CD47 with a SIRPα fusion protein containing an ablated IgG1 Fc, and compared IgA therapy to IgG therapy. Only IgA therapy combined with CD47 blockade increased neutrophil influx to the tumor microenvironment. Moreover, the IgA combination strategy hampered tumor outgrowth most effectively and prolonged tumor-specific survival. These promising results highlight the potential to enhance immunotherapy efficacy against high-risk neuroblastoma through improved neutrophil cytotoxicity by combining IgA therapy with CD47 blockade.

Chan C ，Stip M ，Nederend M ，Jansen M ，Passchier E ，van den Ham F ，Wienke J ，van Tetering G ，Leusen J ... -  《-》

Modulation of CD47-SIRPα innate immune checkpoint axis with Fc-function detuned anti-CD47 therapeutic antibody.

Cluster of differentiation 47 (CD47) is a transmembrane protein ubiquitously expressed on human cells but overexpressed on many different tumor cells. The interaction of CD47 with signal-regulatory protein alpha (SIRPα) triggers a "don't eat me" signal to the macrophage, inhibiting phagocytosis. Thus, overexpression of CD47 enables tumor cells to escape from immune surveillance via the blockade of phagocytic mechanisms. We report here the development and characterization of CC-90002, a humanized anti-CD47 antibody. CC-90002 is unique among previously reported anti-CD47 bivalent antibodies that it does not promote hemagglutination while maintaining high-affinity binding to CD47 and inhibition of the CD47-SIRPα interaction. Studies in a panel of hematological cancer cell lines showed concentration-dependent CC-90002-mediated phagocytosis in acute lymphoblastic leukemia, acute myeloid leukemia (AML), lenalidomide-resistant multiple myeloma (MM) cell lines and AML cells from patients. In vivo studies with MM cell line-derived xenograft models established in immunodeficient mice demonstrated significant dose-dependent antitumor activity of CC-90002. Treatment with CC-90002 significantly prolonged survival in an HL-60-disseminated AML model. Mechanistic studies confirmed the binding of CC-90002 to tumor cells and concomitant recruitment of F4-80 positive macrophages into the tumor and an increase in expression of select chemokines and cytokines of murine origin. Furthermore, the role of macrophages in the CC-90002-mediated antitumor activity was demonstrated by transient depletion of macrophages with liposome-clodronate treatment. In non-human primates, CC-90002 displayed acceptable pharmacokinetic properties and a favorable toxicity profile. These data demonstrate the potential activity of CC-90002 across hematological malignancies and provided basis for clinical studies CC-90002-ST-001 (NCT02367196) and CC-90002-AML-001 (NCT02641002).

Narla RK ，Modi H ，Bauer D ，Abbasian M ，Leisten J ，Piccotti JR ，Kopytek S ，Eckelman BP ，Deveraux Q ，Timmer J ，Zhu D ，Wong L ，Escoubet L ，Raymon HK ，Hariharan K ... -  《-》