Therapy - immunomodulation - Part IIFriday, September 30, 2005, 15:30 - 17:00
Autologous T cell therapy in multiple sclerosis: an open-label safety and dose-range studyB. Loftus, M. Montgomery, J. Williams (The Woodlands, USA)
Objective: To evaluate the safety of a trivalent autologous T cell therapy (TCT) (Tovaxin™) and the effective dose to deplete myelin peptide-reactive T cells (MRTCs) in Multiple Sclerosis. Background: MRTCs play a critical role in the pathogenesis of MS. Previous TCT pilot studies used a monovalent formulation of attenuated MRTCs to deplete myelin basic protein (MBP) reactive T cells. Because several myelin antigens are described as potential autoantigens for MS, depletion of MRTCs using a trivalent formulation (TF) may have enhanced therapeutic effects.
Design/Methods: Patients with relapsing remitting- or secondary progressive-MS intolerant of or having failed current therapy donated blood from which T cells reactive to two peptides each of three proteins [MBP, proteolipid protein (PLP) and myelin oligodendrocyte glycoprotein (MOG)] were expanded ex vivo and prepared as a TF of CD4+ and CD8+ MRTCs. The MRTCs were attenuated by Cesium137 irradiation prior to patients receiving subcutaneous injections of either 6-9 million cells (dose 1) or 30-45 million cells (dose 2) at weeks 0, 4, 12 and 20. MRTC frequencies were performed at baseline and weeks 5, 13, 21, 28 and 52. Patients were evaluated for changes in Expanded Disability Status Scale (EDSS), Multiple Sclerosis Impact Scale (MSIS) and exacerbations.
Results: MRTCs in the peripheral blood were depleted in a dose dependent manner and analyses showed reductions in all 3 types of MRTCs at all follow-up visits. All patients in the dose 2 group had a 100% reduction in MRTC counts at the week 5 follow-up visit. Percentage reductions were greater in the dose 2 group than in the dose 1 group at every follow-up visit. Correlation between the reduction in overall MRTC frequencies and the physical component of the MSIS (p=0.0086) was strong. There was a trend to improved EDSS (p=0.0561). One exacerbation was observed in the dose 1 group. The treatment appears to be safe and well tolerated with minimal adverse events and no dose-limiting toxicities.
Conclusion: MRTCs in patients with MS can be depleted by Tovaxin treatment. MSIS and EDSS clinical measures are improved and the treatment appears safe and well tolerated. A Phase IIb double-blind placebo-controlled trial to study the effects of Tovaxin in treatment of early relapsing MS patients is being planned.