The Role of Genetic Polymorphisms ofTPMTandNUDT15Genes in Adult Patients with Ph-Negative Acute Lymphoblastic Leukemia in Russia
Authors: Kotova Ekaterina S. , Gavrilina Olga A. , Yakutik Igor A , Sudarikov Andrey B. , Parovichnikova Elena N. , Troitskaya Vera V. , Sokolov Andrey N. , Isinova Galina A. , Zarubina Ksenija I. , Savchenko Valeriy G. 
Published: November 2020

Context: TPMTandNUDT15polymorphisms are involved in the toxicity and therapeutic efficacy of thiopurine drugs (6-mercaptopurine (6-MP)). The frequencies of polymorphisms of these genes are different across diverse populations. The role ofTPMTandNUDT15genes in adult patients (pts) with Ph-negative acute lymphoblastic leukemia (ALL) in Russia is still unclear.
Objective:Evaluation of frequency and significance ofTPMTandNUDT15polymorphisms in the cohort of adult Ph-negative ALL pts treated by the RALL-2016 protocol.
Design and Patients:Since April 2017 till July 2020 56 adult Ph-negative ALL patients treated by RALL-2016 protocol were included in the research ofTPMTandNUDT15polymorphisms. Median age was 32 у (range, 18-54), m/f: 39 (70%) / 17 (30%). B-ALL/LBL were diagnosed in 26 (46,4%) pts, T-ALL- in 26 (46,4%) and MPAL- in 4 (7,2%). Genomic DNA was extracted from peripheral blood samples of given pts. Genetic polymorphisms inNUDT15(*2, *3)and TPMT(*2, *3A, *3B, *3C)genes were detected using the allele-specific RT-PCR. The dose of 6-MP was calculated only for 54 pts from 56 (one of these pts stopped the therapy and another received the 1 st phase of induction by RALL-2016 without 6-MP). According to the RALL-2016 protocol 6-MP dose correction imply: if the level leukocytes&lt;2,0*109/l, thrombocytes &lt;100*109/l pts got 50% from the required dose. The therapy of 6-MP was stopped, if the level leukocytes &lt;1,0*109/l, thrombocytes &lt;50*109/l. On the 2 induction therapy by the protocol, the doses of 6-MP were calculated only for 47 pts with CR. The group of pts who didn't have remission on the 36 day by the protocol took the drug without corrections.
Results:From 54 pts CR rate was 87 % (n=47) and resistance - 13% (n=7). One patient died in CR. The frequency ofTPMTandNUDT15polymorphisms in study group was 17,8 % (n=10): 6 (23%) of 26 pts with B-ALL, 3 (11,5 %) of 26 pts -T-ALL and 1 (25%) of 4 pts - MPAL. In our cohort these polymorphisms were found significantly more frequently in pts with B-ALL (p&lt;0.001). These polymorphisms were detected in 8 (80%) men and 2 (20%) women (p=0.432). All detected polymorphisms were presented as heterozygous variants:NUDT15*3was in 2 (20%) pts,TPMT*2-1(10%),TPMT*3A-6 (60%),TPMT*3C-1 (10%). The doses of 6-MP in 5 pts withTPMTandNUDT15and 42 pts withWTwere 54% (27-89%) vs 71% (25-100%), respectively. Statistics analysis didn't show correlation between the 6-MP toxicity (difference of the fact dose of 6-MP therapy) and the polymorphisms in our cohort (fig.1). The frequency of resistance cases didn't different in cohort with/withoutTPMTandNUDT15polymorphisms in 3 (37, 5%) from 8 pts and 4 (10, 5%) from 42 pts, respectively. Only 1 patient with heterozygousTPMT*2died in CR due to toxicity and infection. Two-years overall survival (OS) in pts with the genetic polymorphisms was worse 75 % than in pts without them - 83,6% (p=0,67) (fig.2).
Conclusions:In our study the frequency ofTPMTandNUDT15polymorphisms in adult pts with Ph-negative ALL was 17,8%. The statistical analysis showed that polymorphisms of these genes were detected more frequently in pts with В-ALL. Only one patient withTPMT*2had significant toxicity on the therapy of 6-MP and died in CR. However, we don't know whether this is due to deficient 6-MP metabolism. We didn't find a correlation between the 6-MP toxicity and the polymorphisms in our pts. There is a tendency that OS within 2-years in pts withoutTPMTandNUDT15polymorphisms is better than in the group of pts with them. But our cohorts are small and require further study.
Keywords:acute lymphoblastic leukemia, toxicity, 6-mercaptopurine,TPMT,NUDT15

Disclosures
No relevant conflicts of interest to declare.