Background
Anti-CD20 antibodies, such as rituximab, are crucial in the therapeutic strategies for nearly all subtypes of B-cell non-Hodgkin’s lymphoma (NHL). However, when these lymphomas become resistant to standard treatments, the prognosis is poor.1 CD47 blockade has emerged as a promising approach, demonstrating synergy with anti-CD20 therapies2 and inhibiting disease dissemination by blocking the CD47-SIRPα axis, which prevents tumour cells from evading macrophage phagocytosis.3 While anti-CD47 monotherapy has shown limited efficacy, combining it with conventional treatments highlights the need for additional cytotoxic mechanisms. Nonetheless, safety concerns have arisen, including potential off-target effects and hematotoxicity.4
To address these issues, we developed CO-005, a humanized bifunctional fusion protein combining two scFvs with an IgG4 Fc. CO-005 induces programmed cancer cell death (PCCD) and enhances tumour cell phagocytosis by inhibiting CD47-SIRPα signalling. It also shows superior hematologic toxicity profiles in vitro compared to benchmark anti-CD47 monoclonal antibodies (mAbs).
Methods
The effects of CO-005 on cancer cells and normal cells were evaluated using Annexin V and 7-AAD staining to assess induction of PCCD. Tumour cell phagocytosis was measured by co-culturing fluorescently labelled murine macrophages with target cell lines.
The binding affinity of CO-005 was analysed using a phycoerythrin-conjugated goat anti-human IgG Fc secondary antibody and flow cytometry. For normal cells, immune-cell phenotyping of PBMCs from healthy donors was performed to assess CO-005 binding, with subpopulations identified using specific antibody markers for each cell type.
The antitumor activity of CO-005 was evaluated in NOD-scid IL2Rnull (NSG) mice bearing subcutaneous lymphoma xenografts. Efficacy and survival outcomes were reported for CO-005 as a monotherapy and in combination with rituximab
Results
In this study, we evaluated the antitumor activity of CO-005 on different NHL cell lines and mouse models. CO-005 demonstrated potent and rapid cell death induction in lymphoma cell lines while exhibiting remarkable specificity for malignant cells while sparing healthy cells. The robust antitumor activity demonstrated by CO-005 and as single agent or in combination with rituximab underscores the significance of their additional PCCD capabilities compared to other anti-CD47 agents.
Conclusions
The dual functionality of CO-005, involving both programmed cancer cell death (PCCD) induction and enhanced tumor cell phagocytosis, presents a novel strategy for treating NHL. This approach effectively tackles previous limitations associated with anti-CD47 therapeutics, particularly their hematotoxcity and limited efficacy against NHL.
References
Plosker GL, Figgitt DP. Rituximab: a review of its use in non-Hodgkin’s lymphoma and chronic lymphocytic leukaemia. Drugs 2003;63(8):803–43. doi: 10.2165/00003495-200363080-00005. PMID: 12662126.
Zhao P, Xie L, Yu L, Wang P. Targeting CD47-SIRPα axis for Hodgkin and non-Hodgkin lymphoma immunotherapy. Genes Dis 2023 Jan 11;11(1):205–217. doi: 10.1016/j.gendis.2022.12.008. PMID: 37588232; PMCID: PMC10425755.
Chao MP, Tang C, Pachynski RK, Chin R, Majeti R, Weissman IL. Extranodal dissemination of non-Hodgkin lymphoma requires CD47 and is inhibited by anti-CD47 antibody therapy. Blood 2011 Nov 3;118(18):4890–901. doi: 10.1182/blood-2011-02-338020. Epub 2011 Aug 9. PMID: 21828138; PMCID: PMC3208297.
Maute R, Xu J, Weissman IL. CD47-SIRPα-targeted therapeutics: status and prospects. Immunooncol Technol 2022 Jan 17;13:100070. doi: 10.1016/j.iotech.2022.100070. PMID: 35754851; PMCID: PMC9216458.
Ethics Approval
The study was conducted under adherence with the Declaration of Helsinki. The blood collection for PBMCs isolation was performed under written informed consent by healthy human donors and it was approved by the Regional Committee for Medical and Health Research Ethics in the South-Eastern Norway Regional Health Authority under REK ID number 635222. Animals were kept under appropriate housing conditions with food and water ad libitum. All animal experiments were approved by the Norwegian Food Safety Authorities under identification number 29016.