SPS is a rare immune-mediated neurological disorder characterised by muscle rigidity, spasms and high GAD antibodies. Auto-HSCT has previously been used to treat limited numbers of patients.

To describe the UK experience of assessing patients with Stiff Person Syndrome (SPS) for Autologous Haematopoietic Stem Cell Transplantation (Auto-HSCT).

Between 2015-2018, 7 patients with SPS were referred to our institution from the UK and Finland for auto-HSCT. One patient was found to be stable and was declined treatment and six were deemed suitable for autograft. Three patients have been treated. Patient 1 had the Progressive Encephalomyelitis with Rigidity and Myoclonus (PERM) variant of SPS. Patients 2 and 3 had classical SPS. All patients were significantly disabled and had failed multiple immunotherapies including intravenous immunoglobulin (IVIG) and plasmapheresis. They were mobilised with Cyclophosphamide (Cy) 2g/m2 + G-CSF and conditioned with Cy 200mg/kg + ATG followed by auto-HSCT as per EBMT Guidelines. A fourth patient is scheduled for auto-HSCT and two patients are awaiting funding approval. 

Despite their significantly reduced performance status, all 3 patients tolerated the procedure with routine toxicities.  

Patient 1 - post-transplant assessments showed disease ‘stabilisation’ and his anti-GAD titre normalised. His IVIG was discontinued. At 12 months, MR spectroscopy showed significant increase in the NAA/Cr ratio. 

Patient 2 - post-transplant assessments showed marked improvement but her anti-GAD titre remained high. She required no further IVIG dosing.  At 12 months, her neurophysiological assessment showed improvement. 

Patient 3 – post-transplant assessments showed marked improvement and anti-GAD titre normalised. She required no further IVIG dosing.  At 3 months, Her neurophysiological assessment showed marked improvement. 

Auto-HSCT is an effective treatment option in patients with severe SPS.  The best results are seen in patients with the classical phenotype.

Further work is warranted to optimise patient selection and establish the efficacy, long-term safety, and cost-effectiveness of this treatment.