Orthopedic toxicities among adolescents and young adults treated in DFCI ALL Consortium Trials.

Adolescent and young adult patients with acute lymphoblastic leukemia (ALL) have superior outcomes when treated on pediatric regimens. Pediatric ALL regimens rely heavily on corticosteroids and asparaginase and are known to increase the risk of osteonecrosis (ON) and fractures in children, particularly adolescents. Orthopedic toxicity among young adults treated on pediatric-inspired regimens is not well described. Here, we report the symptomatic orthopedic toxicities of patients aged 15 to 50 years treated on sequential Dana-Farber Cancer Institute ALL Consortium protocols. Among 367 patients with a median age of 23 years (range, 15-50 years; 68% aged <30 years), 60 patients were diagnosed with ON (5-year cumulative incidence, 17%; 95% confidence interval [CI], 13-22), and 40 patients experienced fracture (5-year cumulative incidence, 12%; 95% CI, 8-15). Patients aged <30 years were significantly more likely to be diagnosed with ON (5-year cumulative incidence, 21% vs 8%; P = .004). Patients treated more recently on pegaspargase-based protocols were significantly more likely to be diagnosed with ON compared with those treated on earlier trials with native Escherichia coli asparaginase (5-year cumulative incidence, 24% vs 5%; P < .001). Of the 54 ON events for which adequate information was available, surgery was performed in 25 (46%). Patients with ON had superior overall survival (OS) compared with those without (multivariable OS hazard ratio, 0.15; 95% CI, 0.05-0.46; P = .001; ON included as a time-varying exposure). Increased rates of orthopedic toxicity in late-generation protocols may be driven by the pharmacokinetic drug interaction between pegaspargase and dexamethasone, leading to higher dexamethasone exposure.