Single Center Evaluation of Patients with Therapy and Prior-Malignancy Related Acute Lymphoblastic Leukemia and the Use of Hematopoietic Stem Cell Transplants

Background Therapy-related (t-ALL) and previous malignancy-related acute lymphoblastic leukemia (pm-ALL) are a subset of ALL that arise after treatment of prior malignancy. Recent reports indicate that allogeneic hematopoietic stem cell transplantation (HCT) may yield comparable outcomes in t-ALL when compared to pm-ALL, however data remains limited in both diagnostic criteria and highest risk factors for worse prognosis. This single-center analysis aims to shed light on the unique behavior of t-ALL and pm-ALL with and without HCT. Methods and Patient Selection We collected all cases of ALL treated at our institution from 2000 to 2023; acute lymphoblastic lymphoma was excluded. Cases of t-ALL were defined as any ALL diagnosed after exposure to chemotherapy or XRT prior to leukemia diagnosis, whereby pm-ALL had documented prior malignancy, but having only undergone surgery or observation. Results We identified 264 patients diagnosed with ALL who noted previous malignancy, 198 (74%) patients considered to have t-ALL, and 68 (26%) were identified as pm-ALL, demographics of both are included in Table 1. The most common previous malignancies were breast (18%), non-melanoma skin (12%), prostate (10%), and myeloma (9%). HCT was performed in 38 (14%) patients. Therapy for primary malignancy can be seen in Table 1. Average age of patient at diagnosis was 57 years (range, 45-62 years) and 66 years (range 55-73 years) for those who underwent HCT and those who did not, respectively. Rates of proceeding to transplant were roughly similar in t-ALL vs pm-ALL. Five-year overall survival (OS) was comparable between t-ALL and pm-ALL (Figure 1). The 5-year OS in those receiving HCT was 52.5% (range, 34.9-70.1%) and 33.1% [25.6-40.7%] in those who did not (Figure 2A and B). Within t-ALL, those who received prior chemotherapy with or without XRT had a 5-year OS of 45.2% [31.7-58.6%] and 27.5% [13.6-41.4%] respectively (Figure 3). Outcomes when comparing previous malignancy type (solid vs. liquid) were similar. Conclusion In our single-center analysis, t-ALL and pm-ALL fared comparably, and there did not appear to be any distinct predictors of outcomes. Larger, multi-center analyses are needed to better elucidate predictors of prognosis, and to inform selection of patients who may benefit from intensive consolidation such as allogeneic HCT.