04 Apr 2021 α-Synuclein immunotherapy is in its infancy, with few trials posting results yet. The first two completed Phase 2s, of Biogen’s cinpanemab and Prothena and Roche’s prasinezumab, were both negative. However, while the cinpanemab study was fully negative, prasinezumab posted positive results on some secondary motor measures. At the 15th International Conference on Alzheimer’s and Parkinson’s Diseases, held virtually March 9–14, Gennaro Pagano of Roche gave researchers a first look at prespecified subgroup analyses from this study, called PASADENA. It turned out that subgroups of participants whose disease progressed fastest benefited more from prasinezumab, with more slowing of motor decline. Pagano believes this is because the signal-to-noise ratio in these subgroups was greater, allowing the small effect of prasinezumab to be discerned more readily in this slow disease.