Treatment When IVIG and Plasma Exchange Fail to Reduce Circulating Autoantibodies in Rapidly Progressive Cerebellar Syndrome with Cell-Surface Antineuronal Antibodies
This protocol applies to patients with paraneoplastic cerebellar degeneration presenting as a rapidly progressive cerebellar syndrome in whom antineuronal antibodies directed against cell-surface antigens have been confirmed, and in whom a prior immunotherapy line did not achieve sufficient reduction of circulating autoantibodies.
Rapidly progressive cerebellar syndrome with detected antineuronal antibodies directed against cell-surface antigens. Identifying whether antibodies target intracellular antigens or cell-surface antigens is essential, as this distinction directly shapes the therapeutic strategy employed.
The preceding treatment involved intravenous immunoglobulins (IVIG) or plasma exchange (PLEX), used alongside corticosteroids — initiated simultaneously in patients with severe symptoms or rapid clinical worsening, or as a second-line step when corticosteroid monotherapy was insufficient.
The defined goal for that line — reduction of circulating autoantibodies — was not achieved. This failure to meet the target is the trigger for escalation to the protocol described here.
- If a specific antibody has been detected, one can distinguish between antibodies directed against intracellular antigens and antibodies directed against cell-surface antigens.
- Concepts targeting B-cells alone are primarily used if antibodies against cell-surface antigens have been detected.
- In case of intended depletion of CD20 positive plasma cells, rituximab is a well-tolerated substance.
- In case of contraindications or adverse effects under therapy with immunosuppressants, monthly administrations of IVIG or performance of PLEX can be considered in the presence of good clinical response.