Toxicity of a Modified Peg-Asparaginase-Based SMILE Regimen Is Comparable to L-Asparaginase-Based SMILE in a Non-Asian Population
Authors: Caddell Ryan J , Saeed Hayder , Nelson Rebecca , Isenalumhe Leidy , Chavez Julio , Bello Celeste , Pinilla Ibarz Javier , Sokol Lubomir , Shah Bijal 
Published: November 2019

Abstract
Background:
Asparaginase may improve outcomes in chemotherapy resistant malignancy, especially of lymphoid origin. L-asparaginase (L-ASP) was introduced in 1992 and hence has been incorporated in multiple regimens. An effective regimen including steroid (dexamethasone), methotrexate, ifosfamide, L-asparaginase, and etoposide (SMILE) was developed by the NK-Cell Tumor Study Group as a unique chemotherapeutic regimen to combat chemo-resistant NK-cell neoplasms (Yamaguchi et al. 2008) and later shown to have efficacy in relapsed and refractory lymphoblastic lymphoma (Chang et al. 2014). The pegylated-asparaginase (PEG-ASP) is the only readily available commercial product as the other forms either have limited availability due to shortages (Erwinia asparaginase) or are no longer available in the United States (E-coli asparaginase). We present retrospective data incorporating PEG-ASP into a modified SMILE (mSMILE) regimen. To our knowledge, no prior comparison between the PEG-ASP and L-ASP based SMILE regimen is available in the literature.
Methods:
All adult patients treated with mSMILE for either extranodal NK/T-cell leukemia and lymphoma (ENKTL), T-cell acute lymphoblastic leukemia (T-ALL), T-cell lymphoblastic lymphoma (T-LBL), adult T-cell leukemia/lymphoma (ATLL), or peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS) from 12/1/2009-6/30/2019 at Moffitt Cancer Center were included. PEG-ASP replaced L-ASP in SMILE regimen at a dose of 2500 units/m2/dose IV on Day 8 only (maximum dose of 3750 units). Cycles were repeated every 28 days until disease progression, excessive toxicity, or consolidation with hematopoietic cell transplantion (HCT). Patients received appropriate supportive care with peg-filgrastim or filgrastim (until absolute neutrophil count > 1000/ul x 3Days or >3,000/ul) as well as antimicrobial prophylaxis with acyclovir, ciprofloxacin, and fluconazole once methotrexate cleared and post-chemotherapy. Toxicity assessment was analyzed retrospectively and graded based upon Common Terminology Criteria for Adverse Events (CTCAE) version 5. Toxicity profiles of PEG-ASP-based mSMILE in present study were compared to profiles of L-ASP-based SMILE in the recently published literature (Pokrovsky & Vinnikov Expert Rev Anticancer Ther, 2019).
Results:
A total of 13 patients were treated with mSMILE during the 10-year period (Table 1). Of these patients, the median age was 46 years (range, 19-69), caucasians (46%) and males (70%). Most of the patients were treated for ENKTL (46%). mSMILE was the first line therapy in 3 patients, while the median number of prior therapies was 1 (range 0-3).
Toxicity assessment for mSMILE focused on PEG-ASP-induced toxicity as no patients had any hemorrhagic cystitis, neurotoxicity, or renal dysfunction that could be associated with ifosfamide, methotrexate, or etoposide. mSMILE was comparatively associated with more hematologic toxicity, likely related to inclusion of patients with lymphoblastic leukemia (table 2). Grade 3/4 hepatotoxicity rates are low, possibly owing to inclusion of carnitine prophylaxis (Schulte et al. 2018). Thrombosis was not observed. Hypertriglyceridemia was observed in 15% with no cases of pancreatitis. Hypersensitivity and neurotoxicity were not observed. Of the two patients who discontinued therapy due to toxicity, one was related to grade 3 hypofibrinogenemia and the other grade 4 bleeding. Mortality was attributable to disease progression in all cases, with 0% treatment related mortality. Efficacy is comparable, with ORR 54% (7/13), including 30% (4/13) successfully bridged to HCT.
Conclusion:
In a non-Asian population, modified SMILE regimen with PEG-ASP is a safe alternative to L-ASP-based SMILE regimen. There is increased hematological toxicity, which did not seem to affect chemotherapy delivery.

Disclosures
Chavez: Genentech: Speakers Bureau; Janssen Pharmaceuticals, Inc.: Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees; Kite Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees. Bello:Celgene: Speakers Bureau. Pinilla Ibarz:Sanofi: Speakers Bureau; Bayer: Speakers Bureau; TG Therapeutics: Consultancy; Teva: Consultancy; Janssen: Consultancy, Speakers Bureau; Novartis: Consultancy; Bristol-Myers Squibb: Consultancy; Takeda: Consultancy, Speakers Bureau; Abbvie: Consultancy, Speakers Bureau. Sokol:EUSA: Consultancy. Shah:AstraZeneca: Honoraria; Spectrum/Astrotech: Honoraria; Novartis: Honoraria; Celgene/Juno: Honoraria; Kite/Gilead: Honoraria; Incyte: Research Funding; Jazz Pharmaceuticals: Research Funding; Pharmacyclics: Honoraria; Adaptive Biotechnologies: Honoraria.