Pediatric relapsed/refractory ALK-positive anaplastic large cell lymphoma treatment and outcomes in the targeted-drug era.

Abstract: Treatment options for patients with relapsed or refractory (R/R) anaplastic large cell lymphoma (ALCL) have increased in the era of targeted therapies such as brentuximab vedotin (BV) and anaplastic lymphoma kinase (ALK) inhibitors. However, there is no standard treatment and published data evaluating their use are limited. The goal of this retrospective study was to describe current real-world treatment and outcomes of pediatric, adolescent, and young adult patients with R/R ALK-positive ALCL. We conducted a retrospective, multi-institutional study identifying 81 patients with R/R ALK-positive ALCL aged ≤21 years at initial diagnosis treated between 2011 and 2022 across 18 institutions. Median time from diagnosis to relapse was 8.9 months (range, 2.6-131.9). Initial reinduction regimens included ALK-inhibitor monotherapy (n = 37, 46%), BV monotherapy (n = 19, 23%), chemotherapy without targeted therapy (n = 12, 15%), chemotherapy with targeted therapy (n = 9, 11%), or vinblastine monotherapy (n = 4, 5%), with 83% of patients achieving a complete response to initial reinduction regimen. Fifty-eight patients received a hematopoietic stem cell transplant (HSCT), 11 autologous and 48 allogeneic, with 1 receiving both. Duration of treatment for patients receiving BV or the ALK-inhibitor crizotinib (CZ) varied widely (BV, 1-11 years; CZ, 2-10 years). Five-year event-free survival was 63% (95% confidence interval [CI], 53-75) and 5-year overall survival was 91% (95% CI, 84-98). This is, to our knowledge, the largest collection of patients with R/R ALK-positive ALCL treated in the era of targeted therapy. Patients achieved excellent responses to ALK-inhibitor or BV monotherapy, but questions remain about duration of therapy and role of HSCT.