Most of the MRD-negative patients who relapsed did so within the first 6 months, an observation that led investigators to consider whether factors exist that could predict better outcomes.
In a multivariate analysis, they found three variables associated with disease free survival: higher LDH prior to lymphodepletion (hazard ratio, 1.39), along with higher platelet count prior to lymphodepletion and incorporation of fludarabine into the regimen, with hazard ratios of 0.65 and 0.34, respectively.
Using those three characteristics, investigators grouped patients as “good risk” if they had normal LDH, platelet count at or above 100 prior to lymphodepletion that included fludarabine. The 24-month disease-free survival for good-risk patients was 78%, and overall survival was 86%.
The role of allogeneic HSCT after ALL patients achieved MRD-negative complete remission with CAR T-cell therapy was one of the “major questions in the field,” Dr. Hay said.