Randomized Controlled Clinical Trial of Allogeneic Mesenchymal Stromal Cell Infusion in Diabetic Kidney Disease

Introduction

Diabetic kidney disease (DKD) is the leading cause of kidney failure globally.¹ It is initiated by hyperglycemia, which activates diverse pathways that drive progressive kidney injury.² Despite recent pharmacological breakthroughs, the risk of DKD progression persists, because of poor adherence to multidrug regimens and/or pathophysiological complexity, underscoring the need for multitargeted treatment strategies.³ Mesenchymal stromal cells (MSCs) may address this need through the release or induction of paracrine mediators, which modulate multiple renal injury mechanisms.^4,5 Recently, we reported safety and preliminary efficacy outcomes following a single i.v. infusion of 80 ×10⁶ bone marrow–derived, anti-CD362-selected, allogeneic MSCs (ORBCEL-M) in adults with type 2 diabetes mellitus and progressive DKD participating in cohort 1 of the multicenter, randomized, placebo-controlled, phase 1b/2a NEPHSTROM trial.⁶

Herein, we report on the results of the second dose cohort (ORBCEL-M 160 × 10⁶ cells or placebo) of the NEPHSTROM trial and exploratory analyses of the combined data from the two cohorts.

Results

Participants

Sixteen patients were screened for cohort 2, of whom 13 were randomized to receive ORBCEL-M (n = 10) or placebo (n = 3) (Supplementary Figure S1); all completed the study. Baseline characteristics are shown in Supplementary Table S1.

Primary Outcome

All participants received the full infusion of ORBCEL-M or placebo. No infusion-related adverse events (AEs) occurred. Throughout the follow-up, 1 serious AE occurred in 1 ORBCEL-M recipient. This consisted of an acute kidney injury episode, which was deemed treatment-unrelated, and resolved without sequelae. There were 46 nonserious AEs, 32 in 9 ORBCEL-M recipients and 14 in 3 placebo recipients. All were considered treatment-unrelated. One new cancer, a malignant melanoma, was diagnosed in an ORBCEL-M recipient (Supplementary Table S2).

Secondary Outcomes

Kidney Function

The mean changes in measured glomerular filtration rate (GFR) and in estimated GFR (eGFR) (Chronic Kidney Disease–Epidemiology Collaboration or Modification of Diet in Renal Disease equations) at 6-, 12- and 18-months follow-up were not different in ORBCEL-M compared with placebo recipients (Table 1). Similarly, differences in the median annual rates of measured GFR and eGFR decline did not reach statistical significance (Table 1). Albuminuria did not differ between the groups throughout follow-up (Supplementary Table S3).

Table 1.

Measured GFR and estimated GFR at baseline, 6 months, 12 months and 18 months, and annual rate of renal function decline from baseline to 18-month follow-up in participants receiving ORBCEL-M or placebo in the second dose cohort of the NEPHSTROM trial

	ORBCEL-M	Difference vs. baseline	Placebo	Difference vs. baseline	P-value
mGFR
Baselinea	38.90 ± 9.54		38.30 ± 15.02
6 moa	33.80 ± 9.26	−5.14 (−11.69 to 0.77)	35.26 ± 14.40	−9.98 (−11.13 to −8.82)	0.278b
12 moa	33.48 ± 8.56	−5.42 (−11.38 to −0.28)	31.21 ± 11.64	−7.09 (−11.27 to −0.37)	0.490b
18 moa	31.93 ± 9.65	−6.96 (−13.85 to 3.22)	29.32 ± 12.38	−8.98 (−14.30 to −2.00)	0.578b
Annual slopec	−5.8 [−7.3 to −2.6]		−8.1 [−10.6 to −1.2]		0.565d
eGFR (CKD-EPI)
Baselinea	37.83 ± 11.35		37.13 ± 6.97
6 moa	34.00 ± 9.05	−4.92 (−12.51 to −0.21)	32.66 ± 6.74	−4.46 (−10.63 to −0.32)	0.997b
12 moa	33.38 ± 9.71	−4.44 (−10.21 to 5.99)	31.57 ± 7.47	−5.56 (−12.53 to −1.43)	0.676b
18 moa	32.10 ± 8.51	−5.72 (−12.84 to −0.06)	27.18 ± 7.18	−9.94 (−16.09 to −6.33)	0.072b
Annual slopec	−2.5 [−6.1 to −1.5]		−4.5 [−10.0 to −4.0]		0.294d
eGFR (MDRD)
Baselinea	38.01 ± 10.54		36.73 ± 8.04
6 moa	34.58 ± 8.59	−4.60 (−11.14 to −0.08)	32.45 ± 7.17	−4.28 (−10.22 to −0.28)	0.916b
12 moa	33.92 ± 9.21	−4.10 (−9.89 to 6.12)	31.48 ± 7.86	−5.25 (−12.09 to −1.22)	0.634b
18 moa	32.74 ± 8.15	−5.27 (−11.30 to 0.20)	27.35 ± 7.57	−9.39 (−15.51 to −5.67)	0.067b
Annual slopec	−2.3 [−5.9 to −1.4]		−4.2 [−9.7 to −3.6]		0.294d

CKD-EPI, Chronic Kidney Disease Epidemiology Collaboration; eGFR, estimated GFR; MDRD, Modification of Diet in Renal Disease; mGFR, measured GFR; Q1, first quartile; Q3, third quartile.

mGFR and eGFR values are reported as mean ± SD. Annual slopes from baseline to 18-months follow-up are reported as median [Q1–Q3]. Difference vs. baseline is reported as mean (range, min–max).

^aml/min per 1.73 m².

^bBy analysis of covariance adjusted for baseline value. ORBCEL-M vs. Placebo, as difference vs. baseline.

^cml/min/1.73 m² /yr.

^dWilcoxon rank sum ORBCEL-M vs. placebo.

Metabolic Parameters and Blood Pressure

There were no clinically meaningful changes or between-group differences in glycemic parameters, lipid profile, C-reactive protein, or blood pressure throughout follow-up (Supplementary Table S3).

Immunological and Inflammatory Parameters

At 3 months postinfusion, 1 ORBCEL-M and 1 placebo recipient developed, respectively, anti- human leukocyte antigen (HLA) class I and class II antibodies, which persisted until study end without associated AEs. Serum concentrations of proinflammatory biomarkers showed no significant changes or between-group differences throughout follow-up, except for increased serum sVCAM-1 over time in ORBCEL-M recipients (Supplementary Figure S2).

Combined Cohort 1 and 2 Analyses

The combined ORBCEL-M and placebo groups had similar baseline characteristics (Supplementary Table S4). The mean changes in measured GFR at 6, 12, and 18 months and the rate of decline of measured GFR during follow-up did not differ between ORBCEL-M and placebo groups (Supplementary Table S5). However, the mean changes in eGFR (Chronic Kidney Disease–Epidemiology Collaboration or Modification of Diet in Renal Disease equations) at 12 and 18 months were smaller and the rates of eGFR decline during follow-up were slower in the ORBCEL-M group (Supplementary Table S5, Figure 1).

Figure 1.

Time course of kidney function during the study period in the analysis of the combined data from the first and second ORBCEL-M dose or placebo cohorts. Estimated glomerular filtration rate (eGFR) calculated by Chronic Kidney Disease–Epidemiology Collaboration equation during the 18-month follow-up in participants randomized to (a) ORBCEL-M or (b) placebo in the combined cohort. Individual patient estimated glomerular filtration rate values are shown across time as grey lines, with corresponding randomization group median [interquartile range] indicated by blue (ORBCEL-M) and red (placebo) bars and shaded across time. ∗P < 0.05, ∗∗P < 0.01 between ORBCEL-M and placebo group (analysis of covariance adjusted for baseline values).

Longitudinal peripheral blood mononuclear cell profiling showed no changes or between-group differences in the proportions of CD4⁺ T cells, regulatory T cells and memory regulatory T cells (Supplementary Figure S3). The proportions of classical and intermediate monocytes were similar between the groups throughout follow-up. However, proportions of nonclassical monocytes remained stable following ORBCEL-M but increasing following placebo. The between-group differences were significant at 1 and 12 months (Supplementary Figure S3).

Serum concentrations of proinflammatory biomarkers did not differ between groups throughout follow-up, except for serum neutrophil gelatinase-associated lipocalin, which was significantly lower with ORBCEL-M than in placebo at 18 months (Supplementary Figure S4).

Discussion

The results for cohort 2 of the NEPHSTROM trial support the safety and tolerability of a single i.v delivery of 160 × 10⁶ ORBCEL-M cells in patients with type 2 diabetes mellitus and progressive DKD through 18 months of follow-up. The only serious AE was an acute kidney injury episode in 1 ORBCEL-M recipient. This event occurred 9 months after cell infusion during a transient acute illness associated with fever, diarrhea, and vomiting and was followed by recovery of eGFR to baseline (Chronic Kidney Disease–Epidemiology Collaboration eGFRs before, during, and after the acute kidney injury were 21.7, 13.9, and 28.3 ml/min per 1.73 m², respectively). In this context, and given the limited persistence of infused MSCs, the event was considered not to be caused by ORBCEL-M. In another ORBCEL-M recipient, a malignant melanoma was diagnosed 4 months postinfusion. Concerns exist that cultured MSCs could transform and induce tumors after administration; however, such an event has never been reported with human MSC-based therapies.^7,8 In addition, MSC infusions have not, to date, been associated with increased risk of developing malignancy, even in immunosuppressed patients.^8,9 Nonetheless, the fact that 1 ORBCEL-M recipient in cohort 1 died due to a malignancy (myeloma) and a second died of cardiovascular disease during follow-up highlights the need for continued caution and vigilance regarding the long-term safety of MSCs and other disease-modulating cell therapies.⁶

Only 1 ORBCEL-M recipient in cohort 2 developed anti-HLA class I (multiple HLA-B allotypes) antibodies, detectable at stable and intermediate titers from 3 months postinfusion. Notably, 1 placebo recipient developed de novo anti-HLA class II (DQ7,8,9) antibodies at intermediate to high titers from 3 months postinfusion. Medical records review for this previously nonsensitized participant did not identify sensitizing events such as blood transfusion or vaccination, which could explain anti-HLA antibody formation. This finding emphasizes the need for stricter monitoring of potentially sensitizing events in future trials of allogeneic MSCs as well as the challenge of definitively ascribing the development of de novo anti-HLA antibodies to allogeneic MSCs.

The renal functional measures during follow-up of cohort 2 did not differ between ORBCEL-M and placebo recipients. However, the analysis of combined eGFR results for both cohorts strengthens the preliminary evidence that a single infusion of ORBCEL-M at an approximate dose range of 1 to 2 × 10⁶ cells/kg may favorably modulate the rate of progression of established DKD. Combined immune profiling data strengthen our observation that circulating numbers of proinflammatory monocytes may be stabilized following ORBCEL-M infusion. Nonetheless, no clear conclusion can be drawn regarding efficacy because the trial was statistically underpowered for this outcome and observed differences in renal functional trends may have been influenced by baseline differences in risk factors.

Other limitations of the trial must be acknowledged. First, premature trial termination because of the COVID-19 pandemic resulted in incomplete patient recruitment into cohort 2. Second, the generalizability of the results is limited. Specifically, despite robust screening of potentially eligible patients at 3 trial sites, all randomized cohort 1 and 2 participants were males with insulin-treated type 2 diabetes mellitus. Thus, it will be essential for future trials of ORBCEL-M to enroll patients that more broadly represent the prevalent DKD population.

In conclusion, no new safety signals emerged in cohort 2 following a single i.v. infusion of 160 × 10⁶ ORBCEL-M cells, although definitive safety conclusions are precluded by the small sample size and the occurrence of malignancies in both cohorts. These findings extend to a higher dosing regimen our previous observation of low potential for ORBCEL-M to sensitize against allo-HLA.⁶ Combined longitudinal data from both cohorts strengthen the preliminary evidence that ORBCEL-M infusion in the range of 80 to 160 × 10⁶ cells may slow the rate of eGFR decline and stabilize circulating proinflammatory monocytes. Ultimately, the outcome of the NEPHSTROM trial supports the pursuit of a larger, randomized controlled trial of ORBCEL-M infusions in adults experiencing progressive DKD despite maximally tolerated standard-of-care therapy.

Appendix

List of members of the NEPHSTROM Trial Consortium

Coordinating Centre

Mario Negri Institute for Pharmacological Research IRCCS, Clinical Research Centre for Rare Diseases Aldo e Cele Daccò, Ranica (Bergamo, Italy); Research Coordinator: Giuseppe Remuzzi (Bergamo, Italy), Trial coordinator: Norberto Perico, Nadia Rubis, Federica Casiraghi (Bergamo, Italy).

Centers Including Patients

Azienda Socio Sanitaria Territoriale Ospedale Papa Giovanni XXIII, Bergamo Italy (Giuseppe Remuzzi, Piero Ruggenenti, Stefano Rota, Laura Cappelletti, Valentina Portalupi, Eliana Gotti, Elena Perticucci, Grazia Natali, Alessandro Rambaldi, Giuseppe Gritti, Anna Maria Barbui, Silvia Ferrari, Silvia Mariani, Gianmaria Borleri); University of Galway Ireland (Matthew Griffin, Veronica McInerney, Tomás Griffin, Michelle Hennessy, Sarah Cormican, Nathan Devaney, Cassandra Phan, Amy Hanson, Sara Martyn, Joy Buckley, Sean Naughton, Julie Woods, Caroline Kelly, Amjad Hayat); Queen Elizabeth Hospital Birmingham, Birmingham UK (Paul Cockwell, Dimitrios Chanouzas, Lesley Fifer, Kulli Kuningas, Natalie Walmsley-Allen, Amisha Desai, Lucy Atchinson, Sinead White, Vijayan Suresh, Katie Kirkham, Fiona Evans).

Data Monitoring Safety Board

Dr Mark Little (Professor of Nephrology and Consultant Nephrologist, Trinity College Dublin / Tallaght and Beaumont Hospitals, Ireland). Prof. Piergiorgio Messa (Full professor of Nephrology – Università degli Studi di Milano, Italy). Christina Yap (PhD CStat, Professor of Clinical Trials Biostatistics, the Institute of Cancer Research, Sutton, UK).

Centralized Activities

Regulatory activities, Monitoring and Pharmacovigilance: Laboratory of Pharmacovigilance and Monitoring for Clinical Investigations, Bergamo Italy (Nadia Rubis, Alessandro Villa, Olimpia Diadei, Paola Boccardo, Bergamo Italy with the collaboration of Lesley Fifer Birmingham UK and Veronica McInerney, Oleksii Noreiko, Galway Ireland); Database and Data Validation: Unit of Clinical Web Design and Development, Bergamo Italy (Davide Martinetti); Randomization: Laboratory of Biostatistics, Bergamo Italy (Giovanni Antonio Giuliano); Data Analysis: Laboratory of Biostatistics, Bergamo Italy (Annalisa Perna, Tobia Peracchi); GFR measurement: Laboratory of Clinical Chemistry, Bergamo Italy (Daniela Cugini, Fabiola Carrara, Silvia Ferrari, Nadia Stucchi); anti-HLA measurement: N. I. Histocompatibility and Immunogenetics Laboratory, Belfast UK (A. Peter Maxwell, Bernadette Magee); Immune profile: Laboratory of Immunology of Organ Transplantation, Bergamo Italy (Federica Casiraghi, Marta Todeschini, Marilena Mister); Inflammatory Mediator Profile: Laboratory of M. Griffin, Galway Ireland (Matthew Griffin, Nahidul Islam, Tomás Griffin); Cell production and management: Orbsen Therapeutics Ltd, Galway Ireland (Stephen Elliman, Lisa O’Flynn, Yuka Shimizu, Galway Ireland), Leiden University Medical Center, Leiden Netherlands (Willem Fibbe, Helene Roelofs, Esther Steeneveld, Brigitte Wieles), Centro di Terapia Cellulare “Gilberto Lanzani” ASST-PG23 Bergamo, Italy (Martino Introna, Josée Golay, Olga Pedrini, Chiara Capelli), NHS Blood and Transplant, Liverpool UK (Jon Smythe, Eric Austen, Helen Murray, Vivien Hanson, Jenny Chan), Centre for Cell Manufacturing Ireland, Galway Ireland (Andrew Finnerty, Aoife Duffy, Miriam Holohan, Janusz Krawczyk, Matthew Duggan, Lauren Connolly), Galway Blood and Tissue Establishment, University Hospital Galway, Ireland (Amjad Hyatt, Janusz Krawczyk, Margaret Tarpey, Sean Naughton, Joy Buckley), Terumo BCT Europe NV, Zaventem Belgium (Layka Abbasi Asbagh, Brent Rice, Stefano Baila); EU H2020 project leader: University of Galway, Galway Ireland (Timothy O’Brien, Grace Davey, Michael Creane); EU H2020 project management: Pintail Ltd, Ireland (Ciaran Clissmann, Mark Sweetnam).

Disclosure

PC reports advisory or leadership role: Past President and Trustee UK Kidney Association; other interests or relationships: Boehringer Ingelheim (nonremunerated research collaboration), AstraZeneca (clinical development program and advisory board), and Vifor (advisory board). SJE is an employee of and equity holder in Orbsen Therapeutics. He was not involved in recruitment or follow-up of participants enrolled in the trial, or in the collection, analysis, and interpretation of the data presented herein; SJE also reports research funding: Orbsen Therapeutics; Patents or Royalties: Orbsen Therapeutics; and Speakers Bureau: Orbsen Therapeutics. WEF reports consultancy: Boost Pharma, Glycostem Therapeutics (iDMC), and Starfish Innovations; and advisory or leadership role: Starfish Innovations. MDG reports honoraria from the American Society of Nephrology, Hebei Medical University in China, Novo Nordisk, and Théa Pharma Ltd. in Ireland, as well as advisory roles as an Editorial Board member for the journals Frontiers in Pharmacology and Transplantation and an Associate Editor for JASN, Mayo Clinic Proceedings, and American Journal of Transplantation; MDG also reports research funding: Orbsen Therapeutics Ltd.; honoraria: American Society of Nephrology and National Institutes of Health (NIDDK). TPG reports consultancy: AbbVie, AstraZeneca, Dexcom, Eli Lilly, Abbott, and Novo Nordisk; research funding: Hardiman Scholarship from the College of Medicine, Nursing and Health Science at the National University of Ireland in Galway, a bursary from the Irish Endocrine Society/Royal College of Physicians of Ireland, and a grant from the European Commission Horizon 2020 Collaborative Health Project NEPHSTROM (grant number 634086); honoraria: AbbVie, AstraZeneca, Dexcom, Eli Lilly, and Novo Nordisk; advisory or leadership role: Irish Diabetes Technology Network (no fee), Diabetes Ireland Research Alliance (no fee), Board Member of Diabetes Ireland (no fee); Speakers Bureau: Dexcom, Eli Lilly, and Novo Nordisk; and other interests or relationships: Member of Diabetes UK, Irish Endocrine Society, ADA, EASD, TPG and spouse have pensions that are invested by pension providers. TPG and spouse are not aware of the stocks purchased by these pension providers but could include pharmaceutical company stocks. TPG collaborated with RANDOX Teronta and was a subinvestigator for studies conducted by Medtronic and Abbott. TO’B is a director and equity holder in Orbsen Therapeutics. He was not involved in recruitment or follow-up of participants enrolled in the trial, or in the collection, analysis, and interpretation of the data presented herein. TO’B also reports employer: University of Galway; consultancy: AstraZeneca and Novo Nordisk; and advisory or leadership role: Board member of Orbsen Therapeutics. GR reports consultancy: consulting fees: Alexion Pharmaceuticals, AstraZeneca Pharmaceuticals, Otsuka, Silence Therapeutics and Janssen Research & Development LLC; and advisory or leadership role: member of numerous Editorial Boards of Scientific Medical Journals. JS reports other interests or relationships: JACIE Inspector. MT reports employer: Recordati S.p.A. (spouse). All the other authors declared no competing interests.

Supplementary Material

Supplementary File (PDF)

Supplementary Methods. Supplementary References. Figure S1. Study flow chart. Supplementary Figure S2. Inflammatory mediators in the second ORBCEL-M dose/placebo cohort recruited into the NEPHSTROM trial. Figure S3. Frequency of peripheral blood CD4⁺ T cells, Tregs and monocyte subpopulations during the study period in the analysis of combined data from the first and second ORBCEL-M dose/placebo cohorts. Figure S4. Inflammatory mediators in the analysis of the combined data from the first and second ORBCEL-M dose/placebo cohorts. Table S1. Participant baseline, demographic, clinical and laboratory characteristics in the second dose cohort of the NEPHSTROM trial. Table S2. Summary of adverse events in the second dose cohort of the NEPHSTROM trial. Table S3. Time course of urinary albumin-to-creatinine ratio, metabolic parameters, blood pressure, and heart rate during the 18-month follow-up in participants receiving ORBCEL-M or placebo in the second dose cohort of the NEPHSTROM trial. Table S4. Participant baseline, demographic, clinical, and laboratory characteristics by treatment groups combined across the first and second ORBCEL-M/placebo cohorts. Table S5. Measured GFR and estimated GFR at baseline, 6 months, 12 months, and 18 months, and annual rate of kidney function decline from baseline to 18-month follow-up in participants receiving ORBCEL-M or placebo in the analysis of the combined data from the first and second ORBCEL-M dose/placebo cohorts. Consort Checklist.