P698: BOSUTINIB DOSE OPTIMIZATION IN THE SECOND-LINE TREATMENT OF ELDERLY CML PATIENTS: EXTENDED 3-YEAR FOLLOW-UP AND FINAL RESULTS OF THE BEST STUDY. (23rd June 2022) - Castagnetti, F.; Bocchia, M.; Abruzzese, E.; Capodanno, I.; Bonifacio, M.; Rege Cambrin, G.; Crugnola, M.; Binotto, G.; Elena, C.; Lucchesi, A.; Bergamaschi, M.; Albano, F.; et al.