Effects of Late Toxicities on Outcomes in Long-Term Survivors of Ex-Vivo CD34⁺-Selected Allogeneic Hematopoietic Cell Transplantation

The late adverse events in long-term survivors after myeloablative-conditioned allogeneic hematopoietic cell transplantation (HCT) with ex vivo CD34⁺ cell selection are not well characterized. Using the National Cancer Institute's Common Terminology Criteria for Adverse Events, version 4.0, we assessed all grade ≥3 toxicities from the start of conditioning to the date of death, relapse, or last contact in 131 patients who survived >1 year post-HCT, identifying 285 individual toxicities among 17 organ-based toxicity groups. Pretransplantation absolute lymphocyte count >.5 K/µL and serum albumin >4.0 g/dL were associated with a reduced risk of toxicities, death, and nonrelapse mortality (NRM), whereas serum ferritin >1000 ng/mL was associated with an increased risk of toxicities and NRM after 1 year. An HCT Comorbidity Index (HCT-CI) score ≥3 was associated with an increased risk of all-cause death and NRM, but was not associated with a specific increased toxicity risk after 1 year. Patients who incurred more than the median number of toxicities (n = 7) among all patients within the first year subsequently had an increased risk of hematologic, infectious, and metabolic toxicities, as well as an increased risk of NRM and inferior 4-year overall survival (OS) (67% versus 86%; P = .003) after the 1-year landmark. The development of grade II-IV acute graft-versus-host disease (GVHD) within the first year was associated with incurring >7 toxicities within the first year (P = .016), and also with an increased risk of all-cause death and NRM after 1 year. In multivariate models, cardiovascular, hematologic, hepatic, infectious, metabolic, neurologic, and pulmonary toxicities incurred after 1 year were independently associated with increased risk of death and NRM when adjusting for both HCT-CI and grade II-IV acute GVHD within the first year. One-year survivors of ex vivo CD34⁺ selection had a favorable 4-year OS of 77%, although the development of grade ≥3 toxicities after the first year was associated with poorer outcomes, emphasizing the fundamental importance of improving survivorship efforts that may improve long-term toxicity burden and outcome.