Intensified Conditioning Regimen With High-Dose-Etoposide for Allo-HSCT for Adult Acute Lymphoblastic Leukemia

Overview

Evolving paradigms in the treatment of adult ALL include the application of intense pediatric regimens to the treatment of adolescents and young adults (AYA) and the optimization of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in the cure of patients. The Cancer and Leukemia Group B (CALGB) and the Children's Cancer Group (CCG) first asked whether AYA between the ages of 16 and 20 fared differently whether they were treated on pediatric protocols. The results of this study demonstrated that although the complete remission rates were identical for the AYAs treated on the CALGB and CCG trials, the AYAs had a 63% event-free survival (EFS) and 67% OS at 7 years on the CCG trials compared with 34% and 46%, respectively, on the CALGB trials. High relapse and transplantation-related-mortality still remains great challenge for HSCT of adult ALL, which both range between 25% and 30%. Recently, risk-adapted indication and optimization of conditioning regimen are highlighted, which aiming to reduce TRM and relapse rate, respectively.City of Hope National Medical Center studied the substitution of etoposide (VP-16) for CY in the treatment of ALL patients receiving HCT. The result suggested that etoposide and TBI are associated with a decreased relapse rate following transplantation for ALL, compared with those receiving CY and TBI. Japanese and Germany reports pronounced the advantage of VP-16 in intensified regimen for adult ALL. On the same time, the investigators previous researches have confirmed the effect and safety of FA-intensified conditioning regimen on relapse and refractary leukemia. Based on mentioned above, the investigators speculate that VP-16-intensified conditioning regimen could improve the outcome for adult ALL. The potential mechanism will be attributed to reduce MRD and promote GVL effect via providing enough time-window for immuno-reconstitution by high-dose preparative regimen.

In the first decade of the new millennium, multiple studies have begun to change our thinking about the treatment of adults with acute lymphoblastic leukemia (ALL). In pediatric patients cure rates in the range of 80% to 90% are now attainable. While adult patients with ALL now have a 90% complete remission (CR) with modern chemotherapy, most patients will relapse, and leukemia-free survival with 3 to 7 years of follow-up in large series is only in the range of 30% to 40%. The poor outcome of chemotherapy in adults with ALL as compared to children relates to multiple factors, including poor tolerance of intensive courses of chemotherapy and a higher incidence of poor prognostic subtypes of ALL such as Philadelphia chromosome-positive ALL and a lower incidence of favorable subtypes such as the t (12; 21). Evolving paradigms in the treatment of adult ALL include the application of intense pediatric regimens to the treatment of adolescents and young adults (AYA) and the optimization of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in the cure of patients. Adult regimens are typically less intense than pediatric regimens. The Cancer and Leukemia Group B (CALGB) and the Children's Cancer Group (CCG) first asked whether AYA between the ages of 16 and 20 fared differently whether they were treated on pediatric protocols. The results of this study demonstrated that although the complete remission rates were identical for the AYAs treated on the CALGB and CCG trials, the AYAs had a 63% event-free survival (EFS) and 67% OS at 7 years on the CCG trials compared with 34% and 46%, respectively, on the CALGB trials. These results have prompted new studies where pediatric ALL regimens have been adapted to the treatment of younger adults. With short follow-up, GRAALL-2003 reports suggest EFS and OS outcomes in the range of 60%. This improved outcome was more pronounced in the standard-risk patients with a donor who had an OS at 5 years of 69%. On the same time, our previous researches have confirmed the effect and safety of FA-intensified conditioning regimen on relapse and refractary leukemia. Based on mentioned above, we speculate that VP-16-intensified conditioning regimen could improve the outcome for adult ALL. The potential mechanism will be attributed to reduce MRD and promote GVL effect via providing enough time-window for immuno-reconstitution by high-dose preparative regimen.