Monitoring Asparaginase Activity in 21 Patients with Extranodal NK/T-Cell Lymphoma Shows a Very High Proportion of Asparaginase Inactivation

Abstract Introduction Extranodal NK/T-cell lymphoma (ENKTL) is a rare disease; in Western countries it represents less than 1% of all Non-Hodgkin lymphoma. When localized, ENKTL is associated with a good prognosis. In contrast, patients (pts) with a disseminated disease still have a dismal outcome despite the use of asparaginase (ASPA) containing regimens that have significantly improved the prognosis of this lymphoma. Production of neutralizing anti-ASPA antibodies leading to inactivation of the enzyme can reduce its activity. Inactivation of ASPA activity is correlated with a worse prognosis in acute lymphoblastic leukemia (ALL). Monitoring of ASPA activity is therefore recommended in ALL pts with 100 IU/L as threshold value of serum enzymatic activity considered to be sufficient for complete depletion of l-asparagine in serum. However, ASPA monitoring is not routinely performed in pts with ENKTL, despite the frequent use of ASPA-containing regimens. The main objective of this study was to determine the proportion of pts with an insufficient ASPA activity corresponding to production of neutralizing anti-ASPA antibodies, risk of allergic reaction and inefficacy of the drug. Methods Adult pts with histologically confirmed ENKTL who received an ASPA-containing regimen between 2014 and 2018 and had a monitoring of ASPA activity were included. ASPA activity measurement was usually performed with a quantitive enzyme assay 48 hours after the last ASPA injection of each cycle for native forms of ASPA and 14 days after injection of the pegylated form. Activity below 100 UI/L was considered as insufficient. ASPA activity was correlated with pts outcome. The choice of initial form of ASPA and reasons to switch between two forms of ASPA were also analyzed. Results From 2014 to 2018, a total of 21 pts received an ASPA-containing regimen and were monitored for ASPA activity. Median age was 53 years with 14 men and 7 women. More than half of these pts had a stage IV disease (n=11/21), 6 were in stage I and 4 in stage II. Fifteen pts were in first line and 6 pts were in relapse. Pts have received either native e-coli L-asparaginase (Kidrolase®: KID) (n= 13 in the treatment-naïve group, n=2 in the relapsing group) or a pegylated form of e-coli- L-asparaginase (Oncaspar®: ONC) (n=2 in the treatment-naïve group, n=4 in the relapsing group). Most of the pts received ASPA (8 injections at each cycle for native forms and 1 injection for the pegylated form) associated with gemcitabine, methotrexate and dexamethasone, plus oxaliplatine for disseminated diseases. Six pts had optimal ASPA activity, 3/6 had localized disease: 2 had persistent RC and 1 relapsed, 3/6 had a disseminated disease: 2 progressed during treatment and 1 relapsed. Fifteen pts displayed low ASPA activity, 12/15 pts with a KID containing regimen after 1 cycle (n=10) or 3 cycles (n=2) and 3/6 pts with an ONC containing regimen after the first cycle (n=2) or the second (n=1). Among these 3 pts, 2 have been previously treated with KID that could induce an immunization against ONC. Ten pts received a second form of asparaginase: Erwinia asparaginase (Erwiniase®: ERW) in 9 pts and ONC in 1 pt. In 9/10 cases, this switch was justified by detection of low ASPA activity. Measurement of enzymatic activity in these 9 pts showed satisfactory levels in 2/5 pts treated with ERW and monitored for ASPA activity and in the pt receiving ONC, 4/6 pts with a localized form and 1/3 with a disseminated form are in persistent RC. Six pts with low ASPA activity including one case with a localized form and 5 cases with a disseminated disease, did not receive another form of ASPA, they all progressed or relapsed. Conclusion More than 2/3 of pts had sub-optimal ASPA activity after 1 to 3 cycles of ASPA containing regimens. This finding is probably due to the development of anti-ASPA inhibitory antibodies and may explain the poor outcome of pts with a disseminated disease despite the remarkable efficacy of ASPA in this disease. Although the series reported here is small and heterogeneous, our results still suggest a better outcome in pts with good ASPA activity or in case of switch between ASPA molecules in the context of low activity. ASPA activity monitoring should be recommended in pts with ENKTL, to avoid allergic reaction and ineffective treatment by switching ASPA molecules. Pegylated forms of ASPA, or encapsulated in red cells may, be less immunogenic, should be used in the first line setting instead of native forms. Table. Table. Disclosures Bachy: Celgene: Consultancy; Janssen: Honoraria; Gilead Sciences: Honoraria; Takeda: Research Funding; Sandoz: Consultancy; Amgen: Honoraria; Roche: Research Funding.