Regulatory cell therapy in kidney transplantation (The ONE Study): a harmonised design and analysis of seven non-randomised, single-arm, phase 1/2A trials

BACKGROUND

Use of cell-based medicinal products (CBMPs) represents a state-of-the-art approach for reducing general immunosuppression in organ transplantation. We tested multiple regulatory CBMPs in kidney transplant trials to establish the safety of regulatory CBMPs when combined with reduced immunosuppressive treatment.

METHODS

The ONE Study consisted of seven investigator-led, single-arm trials done internationally at eight hospitals in France, Germany, Italy, the UK, and the USA (60 week follow-up). Included patients were living-donor kidney transplant recipients aged 18 years and older. The reference group trial (RGT) was a standard-of-care group given basiliximab, tapered steroids, mycophenolate mofetil, and tacrolimus. Six non-randomised phase 1/2A cell therapy group (CTG) trials were pooled and analysed, in which patients received one of six CBMPs containing regulatory T cells, dendritic cells, or macrophages; patient selection and immunosuppression mirrored the RGT, except basiliximab induction was substituted with CBMPs and mycophenolate mofetil tapering was allowed. None of the trials were randomised and none of the individuals involved were masked. The primary endpoint was biopsy-confirmed acute rejection (BCAR) within 60 weeks after transplantation; adverse event coding was centralised. The RTG and CTG trials are registered with ClinicalTrials.gov, NCT01656135, NCT02252055, NCT02085629, NCT02244801, NCT02371434, NCT02129881, and NCT02091232.

FINDINGS

The seven trials took place between Dec 11, 2012, and Nov 14, 2018. Of 782 patients assessed for eligibility, 130 (17%) patients were enrolled and 104 were treated and included in the analysis. The 66 patients who were treated in the RGT were 73% male and had a median age of 47 years. The 38 patients who were treated across six CTG trials were 71% male and had a median age of 45 years. Standard-of-care immunosuppression in the recipients in the RGT resulted in a 12% BCAR rate (expected range 3·2-18·0). The overall BCAR rate for the six parallel CTG trials was 16%. 15 (40%) patients given CBMPs were successfully weaned from mycophenolate mofetil and maintained on tacrolimus monotherapy. Combined adverse event data and BCAR episodes from all six CTG trials revealed no safety concerns when compared with the RGT. Fewer episodes of infections were registered in CTG trials versus the RGT.

INTERPRETATION

Regulatory cell therapy is achievable and safe in living-donor kidney transplant recipients, and is associated with fewer infectious complications, but similar rejection rates in the first year. Therefore, immune cell therapy is a potentially useful therapeutic approach in recipients of kidney transplant to minimise the burden of general immunosuppression.

FUNDING

The 7th EU Framework Programme.

ViaKrome Fixable Viability Dyes: A new approach to dead cell discrimination for intracellular multicolor flow cytometry application

The ability to stain live cells with a viability dye and preserve that staining pattern after fixation is critical for intracellular immunophenotyping by flow cytometry. Excluding dead cells from the data allows cleaner separation and identification of cell populations. All commercially available viability dyes are based on NHS ester activated functional groups crosslinking with primary amines on proteins. These functional groups are susceptible to hydrolysis, necessitating the use of non-aqueous solvents, and additional reagent handling steps to protection from water vapor, such as aliquoting the stock solution and reducing freeze-thaw cycles. Here, we propose a new thiol reactive fluorescent dye that covalently binds free thiols present on cellular proteins at a neutral pH. Live cells, impermeable to the FVD, will be weakly stained by the covalent binding of proteins express on the cell surface while dead cells whose membranes have lost structural integrity, will be strongly stained by the covalent binding of intracellular and membrane expressed proteins.

Contrary to current dyes, the ViaKrome dyes are soluble in aqueous solution and do not require DMSO for re-suspension. Hence, we show that the stability of dye ensure robust and reproducible experimental data.

To further increase the ease of use, this new thiol based chemistry is available in a range of dyes excited by the common lasers used in flow cytometry. This choice provides flexibility for multicolor panel design. The compatibility of the ViaKrome dyes, i.e ViaKrome 405, ViaKrome 561, ViaKrome 638 and ViaKrome 808 will be presented in different workflow set-up such as 18-colors immunphenotyping panels and functional assays using PBMCs and whole blood.

An 8-color panel for detection of human blood dendritic cells by flow cytometry (P3014)

Dendritic cells (DCs) are antigen presenting cells capable of presenting antigen and priming a T cell response. They form a heterogeneous group of cells based on phenotype, location and function. In human blood, DCs represent less than 1% of white blood cells, and can be separated into 2 main cell subsets, namely the myeloid DCs (mDCs) and the plasmacytoid DCs (pDCs). Among the mDCs, 3 distinct cell subsets are identified: CD1c+mDCs, CD141+mDCs and CD16+mDCs. In blood, the frequency of DCs is affected in certain pathological conditions such as HIV, diabetes, asthma, chronic viral hepatitis, and graft-versus-host-disease. Thus, the detection and enumeration of different blood DC subsets is important to understand immune regulation in pathological conditions and to guide specific patient treatments. Due to the lack of specific markers for DC definition, the combination of several markers is required to allow their identification. Based on current knowledge in human DC biology, we have evaluated the expression and association of several DC markers to design an optimized 8-color panel for flow cytometry which allows for the detection of all DCs subsets in whole blood samples or peripheral blood mononuclear cells (PBMCs). This panel (CD1c/HLADR/Lineage/CD11c/CD16/Clec9A/CD123/CD45) provides an easy and robust assay to study the role of DCs in healthy donors and patient samples.