CDKN2A/p16INK4a DELETION IS NOT A POOR PROGNOSTIC FACTOR IN ADULT ACUTE LYMPHOBLASTIC LEUKEMIA PATIENTS TREATED ACCORDING TO PROTOCOL RALL-2009

Introduction. CDKN2A deletion is a frequent cytogenetic abnormality in acute lymphoblastic leukemia (ALL), ranging from 18 to 46 %, associating with Т-cell ALL, high WBC counts, splenomegaly, lymphadenopathy. In pediatric group of patient’s CDKN2A deletion was associated with poor event-free survival. The prognostic impact of CDKN2A deletion in adult ALL patients appear controversial. The aim of this study was to evaluate the prognostic impact of the CDKN2A deletion in adult patients with acute lymphoblastic leukemia, which were treated by RALL-2009. Materials and methods. We present the results of the CDKN2A deletion in 110 adult patients with newly diagnosed Ph-negative (Ph‒) ALL, which were treated by RALL-2009 (NCT01193933) since June 2009 till September 2016. Patients characteristics: the median age was 26 years (range 15–54), 65 (59 %) of the 110 patients had a B-precursor phenotype, 42 (38 %) had a T-cell phenotype, 3 (2.7 %) patients – biphenotypical ALL. Interphase fluorescence in situ hybridization (FISH) was performed for detection CDKN2A deletion, MLL, с-MYC rearrangement, TP53 deletion, t (1;19) (q23; p13.3)/TCF3-PBX1, t (12;21) (p13.2; q22.1)/ETV6-RUNX1 and iAMP21. The median follow-up was 31 months (0.5 to 80 months). Results. The prevalence of the CDKN2A deletion in all studied population was 24.3 % (27 cases). Our study demonstrated that CDKN2A deletion had no significant association with age, sex and blast cells immunophenotype. The analysis for T-ALL has detected that CDKN2A deletion was strongly associated with high WBC count (the median is 86 × 109/L; p = 0.006) and with high lactate dehydrogenase level (the median is 3062 IU; p = 0.0004). But in BCP-ALL cases similar correlation was not found. CDKN2A deletion didn’t have statistically significant impact on outcome of patients. OS for patients with BCP-ALL with and without deletion was 85 and 76 % (p = 0.35); DFS was 92 and 65 % (p = 0.07), respectively. OS for T-ALL patients with and without deletion was 90 and 80 % (p = 0.63); DFS was 100 and 82 % (p = 0.24), respectively. Conclusion: CDKN2A deletion is not adverse prognostic factor in adult ALL patients treated according to protocol RALL-2009.