P352. Unblinded Results from a dose-escalating placebo-controlled study with allogeneic bone marrow-derived mesenchymal stem cells for the treatment of refractory perianal fistulas in patients with Crohn's disease

Abstract Background and Aims The long-term safety and efficacy of allogeneic bone marrow-derived mesenchymal stromal cell [bmMSC] therapy in perianal Crohn’s disease [CD] fistulas is unknown. We aimed to provide a 4-year clinical evaluation of allogeneic bmMSC treatment of perianal CD fistulas. Methods A double-blind dose-finding study for local bmMSC therapy in 21 patients with refractory perianal fistulising Crohn’s disease was performed at the Leiden University Medical Center in 2012–2014. All patients treated with bmMSCs [1 x 107 bmMSCs cohort 1, n = 5; 3 × 107 bmMSCs cohort 2, n = 5; 9 × 107 bmMSCs cohort 3, n = 5] were invited for a 4-year evaluation. Clinical events were registered, fistula closure was evaluated, and anti-human leukocyte antigen [HLA] antibodies were assessed. Patients were also asked to undergo a pelvic magnetic resonance imaging [MRI] and rectoscopy. Results Thirteen out of 15 patients [87%] treated with bmMSCs were available for long-term follow-up. Two non-MSC related malignancies were observed. No serious adverse events thought to be related to bmMSC therapy were found. In cohort 2 [n = 4], all fistulas were closed 4 years after bmMSC therapy. In cohort 1 [n = 4] 63%, and in cohort 3 [n = 5] 43%, of the fistulas were closed, respectively. In none of the patients anti-HLA antibodies could be detected 24 weeks and 4 years after therapy. Pelvic MRI showed significantly smaller fistula tracts after 4 years. Conclusions Allogeneic bmMSC therapy for CD-associated perianal fistulas is also in the long-term a safe therapy. In bmMSC-treated patients, fistulas with closure at Week 24 were still closed after 4 years.

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AB0370 SAFETY OF CS20AT04, A HAPLOIDENTICAL ALLOGENEIC BONE MARROW-DERIVED MESENCHYMAL STEM CELLS, IN A PHASE 1 STUDY IN LUPUS NEPHRITIS

Annals of the Rheumatic Diseases ◽

10.1136/annrheumdis-2020-eular.3287 ◽

2020 ◽

Vol 79 (Suppl 1) ◽

pp. 1485.2-1485

Author(s):

C. B. Choi ◽

T. Y. Lee ◽

K. S. Kim ◽

S. C. Bae

Keyword(s):

Stem Cells ◽

Bone Marrow ◽

Mesenchymal Stem Cells ◽

Lupus Nephritis ◽

Dose Escalation ◽

Phase 1 ◽

Allogeneic Bone Marrow ◽

Additional Patient ◽

Allogeneic Bone ◽

Dose Limiting Toxicity

Background:Mesenchymal stem cells are known to have immunomodulatory properties and may potentially have therapeutic effect in lupus nephritis. Mesenchymal stem cells form a haploidentical donor are an attractive cell sourceObjectives:CS20AT04, a haploidentical allogeneic bone marrow-derived mesenchymal stem cell, was evaluated in patients with lupus nephritis for safety and tolerability.Methods:This was a single-arm phase 1 dose-escalation trial of CS20AT04 in adult patients with lupus nephritis (NCT03174587). A 3 + 3 design was used for dose escalation. The starting dose was 2.0 x 106 cells/kg and was escalated to 3.0 x 106 cells/kg if there no dose-limiting toxicity. The primary objective was to determine the maximum tolerated dose and evaluate the safety and tolerability at 28 days after the infusion.Results:Seven patients were enrolled in the study. Patients received CS20AT04 through intravenous infusion. The initial dose of 2.0 x 106 cells/kg was administered for the first 3 patients without any dose limiting toxicity. There was 1 patient who were not administered the full 2.0 x 106 cells/kg dose due to technical error during infusion. The patient did not show dose limiting toxicity, but 1 additional patient was enrolled to have 3 patients who received the full 2.0 x 106 cells/kg dose before escalating to the next level dose. The dose of 3.0 x 106 cells/kg was administered for the next 3 patients without any dose limiting toxicity. Three adverse events were reported (1 diarrhea, 1 toothache, and 1 arthralgia) and they were all NCI-CTC grade I events.Conclusion:CS20AT04 was well tolerated in single dose up to 3.0 x 106 cells/kg in patients with lupus nephritis.Acknowledgments:This research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI15C0778).Disclosure of Interests:Chan-Bum Choi: None declared, Tae Yong Lee Shareholder of: Corestem Inc, Employee of: Corestem Inc, Kyung Suk Kim Shareholder of: Corestem Inc, Employee of: Corestem Inc, Sang-Cheol Bae: None declared

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