Cytokine Profiles in Acute Promyelocytic Leukemia Patients at Diagnosis and during the Treatment with Acid All-Trans Retinoic and Anthracyclines

INTRODUCTION:

Acute promyelocytic leukemia (APL) cells have been shown to secrete IL-1β, TNFα and IL-6 in vitro and particularly the first one has a relevant role in the APL-associated coagulopathy. All-trans retinoic acid (ATRA) treatment decreased levels of IL-8 and increased of IL-1β and G-CSF secreted in the medium. However, the serial analysis of cytokine levels in the plasma of patients with APL during ATRA treatment has never been performed. Considering the importance of inflammation in the pathogenesis of APL-associated coagulopathy, we have analyzed plasma levels of IL-8, IL-1β, IL-6, IL-10, TNF and IL-12p70 in 19 Brazilian patients with APL treated with ATRA and anthracyclines according to the International Consortium on APL protocol.

METHODS:

We retrospectively analyzed the levels of pro- and anti-inflammatory cytokines in previously frozen plasma samples of 19 APL patients, enrolled in the IC-APL study. Samples were collected at diagnosis (D0) and in the 3^rd (D3) and 7^th (D7) days of treatment with ATRA and anthracyclines. The control group consisted of 11 healthy adult volunteers. IL-8, IL-1β, IL-6, IL-10, TNF and IL-12p70 were measured using cytometric bead array (CBA-Human Inflammatory Cytokine Kit, BD Biosciences) . The results were analyzed using FCAP Array software (BD Biosciences). The cytokine levels were correlated with white blood cell count (WBC) as well as with the frequency of death during induction (early death) and overall survival (OS). Statistical analysis was performed by using either Mann-Whitney (for comparison of two groups) or ANOVA (comparison of three or more groups) test. Fisher's exact test was used to associate cytokine levels and white blood cells (WBC) count. Overall survival analysis was considered from the date of diagnosis to date of death or last contact. Overall survival curves were prepared by the Kaplan-Meier method and compared by the log-rank test. Significance was set at p <0.05.

RESULTS:

IL-1β, IL-10, TNF and IL-12p70 cytokines were not detected in the plasma from all APL patients and healthy controls, except for the presence of low levels of IL-10 in 3 APL patients at D0 (median concentration: 0 pg/mL; range 0 to 4.5 pg/mL). Plasma IL-8 (median 25.9 pg/mL; range 2.6 to 285.5 pg/mL) and IL-6 levels (median 5.0 pg/mL; range 0 to 580.1 pg/mL) at D0 were higher in APL patients compared with healthy controls (undetected in all samples). ATRA significantly decreased IL-8 plasma levels at D7 in 84.2% of APL patients (p<0.005, D0 vs D7) whereas the plasma concentrations of IL-6 did not change with treatment. There were no correlation between the plasma levels of IL-8 and high (WBC > 10⁴) or low (WBC < 10⁴) risk groups of APL patients. Furthermore, IL-8 and IL-6 levels were not associated with early mortality with IL-6 and IL-8 plasma concentrations of 0.8 vs. 6.8 and 5.1 vs. 34.1 in patients who died or not during induction. Moreover, there was no difference in the overall survival in patients with IL-6 levels above or below the median value of the group (p=0.538; 53.2 vs. 75.2 months; 95% confidence interval = 32.9 to 73.5). The same was observed for IL-8 (p=0.59; 61.5 vs. 65.0 months; 95% confidence interval = 45.6 to 77.4).

CONCLUSIONS:

APL patients exhibit increased cytokine plasma levels of the pro-inflammatory cytokines IL-8 and IL-6 but these parameters were not associated with known prognostic factors or with disease outcome.