Treatment of Adult T-ALL with a Pediatric Asparaginase-Intensive Protocol Results in Survival Benefit When Compared to Other Adult Based Protocols
Authors: Al-Khabori Murtadha K. , Minden Mark , Gupta Vikas , Schimmer Aaron D. , Schuh Andre C. , Yee Karen WL , Xu Wei , Brandwein Joseph M. 
Published: April 2020

Abstract
T cell acute lymphoblastic leukemia (T-ALL) accounts for 14–22% of adult ALL. No prospective comparisons between different chemotherapy protocols have been done. Since 2000 a modified DFCI protocol (Silverman et al, Blood2001;97:121–1218) has been used as standard treatment for all newly diagnosed patients with T-ALL at Princess Margaret Hospital (PMH). This protocol includes a remission induction phase, a CNS prophylaxis phase with intrathecal chemotherapy and 12 Gy cranial irradiation, a 30-week intensification phase including weekly asparaginase, and a 72-week maintenance phase. We compared outcomes using this regimen to previous results for all newly diagnosed T-ALL from 1990 – 2000 at PMH using the standard institutional protocol in use at the time. Between 1990–2000, 44 patients (Group 1) were treated with a variety of protocols, including 9203ALL PMH protocol (11 patients), L10 (2 pts), Protocol C (7 pts), HyperCVAD (15 pts) and ECOG E2993 (9 pts). From 2000–2007, 33 T-ALL patients were treated with modified DFCI protocol (Group 2). The median age for all patients was 31 years (range 14–69 years). There was no significant difference between the two groups with respect to age at diagnosis, presenting WBC (median or percent &gt; 100 ×109/L), CSF positivity, or cytogenetics. More patients from Group 1 underwent allogeneic stem cell transplantation (BMT) in CR-1 (54%) as compared to those in Group 2 (54% vs. 14%, P = 0.001), primarily due to a change in BMT policy in 2002. The median follow up was 23 months (range 1–161 months) for the entire group and 53 months (range 14–161 months) for the surviving patients. Sixty-nine patients (90%) achieved complete remission, and 37 patients have relapsed. The CR rates were not significantly different between the two groups. The 3-year failure-free survival (FFS) was significantly higher in Group 2 (DFCI protocol) as compared with Group 1 (other protocols) (89% vs. 27%, P = 0.0001). Multivariate analysis using Cox proportional hazard model showed only the treatment regimen received (DFCI vs. others) to have a statistically significant impact on FFS (P = 0.0001). The 3-year overall survival (OS) was significantly higher in the DFCI group compared to the group receiving the other protocols (81% vs. 45%, P = 0.0006). On multivariate analysis, only the treatment regimen received (P=0.001) and the CSF status (P=0.014) had a significant impact on OS; BMT did not have a significant impact on OS. When patients were censored at the time of transplant, the FFS and OS analyses still showed statistically significant benefit for patients treated on DFCI protocol (P = 0.0001 and 0.03, respectively). In summary, treatment outcomes have markedly improved from 2000 onward as compared to the previous decade. Although improvements in supportive care and reduced use of allogeneic BMT may have been factors, it is likely that the institution of the DFCI pediatric protocol was the primary factor in the improved outcome. These results support the use of such pediatric asparaginase-intensive pediatric protocols for adult T-ALL.