bb2121 is defined as autologous T lymphocytes (T cells) transduced ex vivo with anti-BCMA02 CAR lentiviral vector encoding the chimeric antigen receptor (CAR) targeted to human BCMA suspended in cryopreservative solution. bb2121 is administered in subjects 1 time (or retreated if retreatment criteria are met) in parent clinical study. No investigational treatment will be administered in this study.