CAR T cells in multiple myeloma: lessons learned

The question of whether chimeric antigen receptor (CAR) T cell therapies should be used in earlier lines (after 1-2 prior lines of therapy) in patients with relapsed and/or refractory multiple myeloma remains unanswered. Herein, I argue that the use of surrogate end points that lack a robust correlation with overall survival, as well as suboptimal control arms and use of post-progression therapies, limit the ability to make definitive conclusions on the basis of the available data.