IFNB1 and secondary progressive multiple sclerosis: Sixty‐nine SPMS patients who received aHSCT were compared to 217 patients treated with anti‐inflammatory DMTs (beta interferons, azathioprine, glatiramer acetate, mitoxantrone, fingolimod, natalizumab, methotrexate, teriflunomide, cyclophosphamide, dimethyl fumarate and alemtuzumab).