Yelamali AR, Chendamarai E, Ritchey JK, Rettig MP, DiPersio JF, Persaud SP (2024) Streptavidin-drug conjugates streamline optimization of antibody-based conditioning for hematopoietic stem cell transplantation. bioRxiv 2024.02.12.579199. doi: 10.1101/2024.02.12.579199 PMID: 38405731

Objective: Use biotinylated CD45.2 antibodies conjugated to Streptavidin to target hematopoietic stem cells (HSCs) for HSC transplantation.

Summary: Hematopoietic stem cell transplantation offers a promising alternative to standard cancer treatments. Using Click Chemistry, different toxic payloads were attached to streptavidin and observed.

Usage: 75 micrograms of CD45.2 delivered to HSCs deriving from B6 mice.

Related Products: Anti-CD45.2-SAP (Cat. #IT-91), Streptavidin-ZAP (Cat. #IT-27)

Zhao Q, Zong H, Zhu P, Su C, Tang W, Chen Z, Jin S (2024) Crosstalk between colorectal CSCs and immune cells in tumorigenesis, and strategies for targeting colorectal CSCs. Exp Hematol Oncol 13(1):6. doi: 10.1186/s40164-024-00474-x PMID: 38254219

Summary: Cancer immunotherapy has become a promising strategy in the treatment of colorectal cancer, and relapse after tumor immunotherapy. Cancer stem cells (CSCs) have the capabilities of self-renewal and differentiation and are also resistant to the traditional therapies of radiotherapy and chemotherapy. The authors review strategies for targeting colorectal CSCs, where one method described uses a biotinylated antibody against EpCAM (clone 3-171) conjugated to saporin via Streptavidin-ZAP (IT-27).

Related Products: Streptavidin-ZAP (Cat. #IT-27)

See Also:

• Lund K et al. The novel EpCAM-targeting monoclonal antibody 3-17I linked to saporin is highly cytotoxic after photochemical internalization in breast, pancreas and colon cancer cell lines. MAbs 6(4):1038-1050, 2014.

Canarutto D, Omer Javed A, Pedrazzani G, Ferrari S, Naldini L (2023) Mobilization-based engraftment of haematopoietic stem cells: a new perspective for chemotherapy-free gene therapy and transplantation. Br Med Bull ldad017. doi: 10.1093/bmb/ldad017 PMID: 37460391

Objective: The authors review alternative chemotherapy-free approaches to niche voidance that could replace conventional regimens and alleviate the morbidity of the procedure.

Summary: In haematopoietic stem cell transplantation (HSCT), haematopoietic stem cells (HSCs) from a healthy donor replace the patient’s. Ex vivo HSC gene therapy (HSC GT) is a form of HSCT in which HSCs are genetically modified before infusion, to generate a progeny of gene-modified cells. In HSCT and HSC-GT, chemotherapy is administered before infusion to free space in the bone marrow niche, which is required for the engraftment of infused cells. One approach reviewed by the authors involves Anti-CD45-SAP. The conjugate was shown to clear the white blood cell compartment. Administration into mice prior to HSCT resulted in comparable haematopoietic reconstitution as total body irradiation, with less side effects (Palchaudhuri R. et al, 2016) and faster T-cell repopulation likely due to sparing radio damage to the thymic stroma (Schiroli G et al., 2017).

Related Products: Anti-CD45.2-SAP (Cat. #IT-91)

See Also:

• Palchaudhuri R et al. Non-genotoxic conditioning for hematopoietic stem cell transplantation using a hematopoietic-cell-specific internalizing immunotoxin. Nat Biotechnol 34:738-745, 2016.
• Schiroli G et al. Preclinical modeling highlights the therapeutic potential of hematopoietic stem cell gene editing for correction of SCID-X1. Sci Transl Med 9(411):eaan0820, 2017.

Kfoury YS, Ji F, Jain E, Mazzola MC, Schiroli G, Papazian A, Mercier FE, Sykes DB, Kiem A, Randolph MA, Abdel-Wahab OI, Calvi LM, Sadreyev R, Scadden DT (2023) The bone marrow stroma in human myelodysplastic syndrome reveals alterations that regulate disease progression. Blood Adv bloodadvances.2022008268. doi: 10.1182/bloodadvances.2022008268 PMID: 37450380

Objective: Evaluate mesenchymal cell molecular features searching for modifications that could impact Myelodysplastic syndrome (MDS) and offer potential therapeutics.

Summary: MDS is a heterogenous group of diseases affecting hematopoietic stem cells and are curable only by stem cell transplantation. Animal models of MDS indicate that changes in specific mesenchymal progenitor subsets in the BM can induce or select for abnormal hematopoietic cells. The authors identified that osteopontin (SPP1) is overexpressed in human bone marrow mesenchymal cells. SPP1 expression in comparable mesenchymal stromal cell populations plays protective roles in disease progression in an MDS mouse model.

Usage: Streptavidin-ZAP was combined with biotinylated CD117 (cKit) Ab in a 1:1 molar ratio. Mice were dosed with the conjugate at 3 mg/kg. The authors used the antibody-drug conjugate as a conditioning strategy that spares the non-hematopoietic microenvironment in the BM from genotoxic injury. This approach has been shown to deplete host hematopoietic stem cells with minimal toxicity effectively.

Related Products: Streptavidin-ZAP (Cat. #IT-27)

Konturek-Ciesla A, Dhapola P, Zhang Q, Säwén P, Wan H, Karlsson G, Bryder D (2023) Temporal multimodal single-cell profiling of native hematopoiesis illuminates altered differentiation trajectories with age. Cell Rep 42(4):112304. doi: 10.1016/j.celrep.2023.112304 PMID: 36961818

Objective: Using single-cell transcriptome and epitope profiling to study hematopoiesis and the effects from aging.

Summary: The contribution from Hematopoietic stem cells (HSCs) to mature blood cells decline with age. The authors used transcriptome and epitope profiling to reconstruct early hematopoiesis and assessed HSC-specific lineage tracing. Their analysis identified previously uncharacterized cell populations which included multipotent progenitor cells (MPP) Ly-1 and Ly-II. Flt3 is a marker indicative of early differentiation found on MPP cells and was targeted for elimination via an antibody to Flt3 combined with Streptavidin-ZAP. This cell depletion provided evidence for the lack of self-renewal of Ly-1 and Ly-II cells in a transplantation setting and suggests that they need to be continuously replenished by upstream HSPCs.

Usage: Biotinylated anti-CD135 (clone A2F10) was combined with Streptavidin-ZAP at a 1:1 molar ratio, diluted in PBS to 0.2 mg/ml and injected into mice at 3 mg/kg.

Related Products: Streptavidin-ZAP (Cat. #IT-27)

Chan YY, Ho PY, Swartzrock L, Rayburn M, Nofal R, Thongthip S, Weinberg KI, Czechowicz A (2023) Non-genotoxic restoration of the hematolymphoid system in fanconi anemia. Transplant Cell Ther 29(3):164.e1-164.e9. doi: 10.1016/j.jtct.2022.08.015 PMID: 35995393

Objective: Evaluate the efficacy of different CD117 mAb agents and immunosuppression on hematopoietic stem cell (HSC) depletion, and their ability to safely establish therapeutic donor hematopoiesis post-HSCT in Fancomi Anemia (FA) disease models.

Summary: Patients with FA are particularly sensitive to genotoxic agents in the treatment of blood and immune diseases. By targeting the disease through use of a CD117 antibody conjugate to an antagonist agent, some of the sensitivities of Fancomi anemia can be circumvented compared to traditional therapeutics. The results demonstrated the efficacy of several different non-genotoxic monoclonal antibody-based conditioning strategies in Fancomi anemia.

Usage: Biotinylated CD117 mAb mixed with Streptavidin-ZAP (Anti-CD117-SAP) and was administered on Day 0. Anti-CD117-SAP was diluted with sterile PBS and administered at 1.5 mg/kg via i.v. injection.

Related Products: Streptavidin-ZAP (Cat. #IT-27), Anti-CD117-SAP (Cat. #IT-83)

Van Hentenryck M, Li Z, Murphy PM, Czechowicz A (2022) Antibody-based preparative regimens for cell, tissue and organ transplantation. (eds. 162). OBM Transplantation 6(3):162. doi: 10.21926/obm.transplant.2203162

Objective: Provide a review of progress in the use of antibodies to support cell and tissue transplantation with a particular focus on induction of donor-specific tolerance for solid organ transplantation.

Summary: Antibody-based conditioning to prepare the recipient is a promising approach towards achieving transplant tolerance in both hematopoietic and solid organ transplant settings.

Usage: To enhance HSC depletion while avoiding bystander toxicity (neutropenia, lymphopenia, and thrombocytopenia) caused by CD45-radioimmunotherapy, Palchaudhuri et al. developed a saporin-based CD45 (CD45-SAP) immunotoxin using a biotinylated antibody and Streptavidin-ZAP.

Related Products: Streptavidin-ZAP (Cat. #IT-27)

See Also:

• Palchaudhuri R Featured Article: Targeted depletion of hematopoietic stem cells promises safer transplantation. Targeting Trends 17(3), 2016.
• Palchaudhuri R et al. Non-genotoxic conditioning for hematopoietic stem cell transplantation using a hematopoietic-cell-specific internalizing immunotoxin. Nat Biotechnol 34:738-745, 2016.

Griffin JM, Healy FM, Dahal LN, Floisand Y, Woolley JF (2022) Worked to the bone: antibody-based conditioning as the future of transplant biology. J Hematol Oncol 15(1):65. doi: 10.1186/s13045-022-01284-6

Objective: To analyze the current status of antibody-based drugs in pre-transplant conditioning regimens and assess their potential in the future of transplant biology.

Summary: This review article suggests that antibody-based conditioning regimens may be the next big advancement in hematopoietic stem cell transplantation.

Related Products: Anti-CD117-SAP (Cat. #IT-83)

See Also:

• Palchaudhuri R et al. Non-genotoxic conditioning for hematopoietic stem cell transplantation using a hematopoietic-cell-specific internalizing immunotoxin. Nat Biotechnol 34:738-745, 2016.
• Castiello MC et al. Efficacy and safety of anti-CD45-saporin as conditioning agent for RAG deficiency. J Allergy Clin Immunol 147(1):309-320.e6, 2021.
• Czechowicz A et al. Selective hematopoietic stem cell ablation using CD117-antibody-drug-conjugates enables safe and effective transplantation with immunity preservation. Nat Commun 10:617, 2019.
• Li Z et al. Hematopoietic chimerism and donor-specific skin allograft tolerance after non-genotoxic CD117 antibody-drug-conjugate conditioning in MHC-mismatched allotransplantation. Nat Commun 10:616, 2019.

Saha A, Hyzy S, Lamothe T, Hammond K, Clark N, Lanieri L, Bhattarai P, Palchaudhuri R, Gillard GO, Proctor J, Riddle MJ, Panoskaltsis-Mortari A, MacMillan ML, Wagner JE, Kiem HP, Olson LM, Blazar BR (2022) A CD45-targeted antibody-drug conjugate successfully conditions for allogeneic hematopoietic stem cell transplantation in mice. Blood 139(11):1743-1759. doi: 10.1182/blood.2021012366 PMID: 34986233

Objective: To investigate the effectiveness of a CD45-targeted antibody-drug conjugate (ADC) in conditioning for allogeneic hematopoietic stem cell transplantation (HSCT) in mice.

Summary: In this study, researchers evaluated a novel CD45-targeted antibody-drug conjugate as a conditioning regimen for allogeneic hematopoietic stem cell transplantation in mice. The results demonstrated successful conditioning, highlighting the potential of this approach for improving the outcomes of allogeneic HSCT in the future.

Related Products: Anti-CD117-SAP (Cat. #IT-83)

See Also:

• Palchaudhuri R et al. Non-genotoxic conditioning for hematopoietic stem cell transplantation using a hematopoietic-cell-specific internalizing immunotoxin. Nat Biotechnol 34:738-745, 2016.
• Czechowicz A et al. Selective hematopoietic stem cell ablation using CD117-antibody-drug-conjugates enables safe and effective transplantation with immunity preservation. Nat Commun 10:617, 2019.
• Li Z et al. Hematopoietic chimerism and donor-specific skin allograft tolerance after non-genotoxic CD117 antibody-drug-conjugate conditioning in MHC-mismatched allotransplantation. Nat Commun 10:616, 2019.
• Gao C et al. Nongenotoxic antibody-drug conjugate conditioning enables safe and effective platelet gene therapy of hemophilia A mice. Blood Adv 3(18):2700-2711, 2019.
• Castiello MC et al. Efficacy and safety of anti-CD45-saporin as conditioning agent for RAG deficiency. J Allergy Clin Immunol 147(1):309-320.e6, 2021.

Charlesworth CT, Hsu I, Wilkinson AC, Nakauchi H (2022) Immunological barriers to haematopoietic stem cell gene therapy. Nat Rev Immunol 1-15. doi: 10.1038/s41577-022-00698-0

Objective: This review article attempts to encourage more research to address the immunological barriers to haematopoietic stem cell based gene therapies.

Summary: The authors lay out the history and clinical trials of hematopoietic stem cell gene therapy and then discuss the challenges of both innate immunity and adaptive immunity.

Usage: This review mentions a publication that used Anti-CD117-SAP to ablate hematopoietic stem cells.

Related Products: Anti-CD117-SAP (Cat. #IT-83)

See Also:

• Czechowicz A et al. Selective hematopoietic stem cell ablation using CD117-antibody-drug-conjugates enables safe and effective transplantation with immunity preservation. Nat Commun 10:617, 2019.