Relationship between age, conditioning intensity, and outcome after allografting in adults age ≥60 years with AML

Methodological advancements now allow older adults with AML to receive allografts although conflicting data exist regarding relative outcomes across age groups and benefits of different conditioning intensities. We retrospectively analyzed 495 adults aged 60-64 (n = 184), 65-69 (n = 189), or ≥70 (n = 122) allografted for AML in remission at our institution from 2006 to 2023. There were no significant differences in relapse or relapse-free survival (RFS) among the 3 age cohorts after multivariable adjustment. Patients aged ≥70 years had higher non-relapse mortality (NRM) than those aged ≥60-64 (P = 0.022) but their overall survival (OS) was only statistically non-significantly shorter (P = 0.11). There was an important interplay between age, conditioning intensity, and outcomes. Relative to age 60-64, age ≥70 years was associated with a higher risk of relapse (hazard ratio [HR] = 3.47; P = 0.012) and NRM (HR = 3.88; P = 0.001) with reduced intensity conditioning (RIC), leading to shorter RFS (HR = 3.79; P < 0.001) and OS (HR = 3.46; P < 0.001), while no such associations were found with nonmyeloablative (NMA) conditioning. Underlying, patients aged 60-64 and 65-69, but not those aged ≥70, had a significantly lower relapse risk with RIC relative to NMA conditioning, whereas NRM risks increased across all age cohorts. Our findings support allografting for adults ≥70 with AML in remission, especially with NMA conditioning.