HLA class I in acute promyelocytic leukemia (APL): possible correlation with clinical outcome

The majority of patients with acute promyelocytic leukemia (APL) possess ei ther a bcr1 or a bcr3 type fusion between PML and RAR alpha genes. The junc tion sequences may possibly be a target for immune response and influence s usceptibility to the disease. In this case, HLA class I allele frequencies would be different between bcr1 and bcr3 patients, To test this hypothesis, we typed 102 APL patients for HLA-A, -B and -Cw alleles. The A*1, A*30, B* 51, B*41, Cw*0602, and Cw*1701 alleles showed a different distribution betw een bcr1 and bcr3 patients, but in no case was this statistically significa nt after correction for the number of comparisons or was confirmed in an in dependent panel. Moreover, no difference was detected between bcr1 and bcr3 when HLA alleles were grouped according to their peptide binding specifici ties. Comparing HLA frequencies, clinical features at diagnosis and clinica l outcome of the 64 patients homogeneously treated with all-trans retinoic acid and idarubicin (AIDA protocol) we observed a statistically significant association between HLA-B*13 and risk of relapse by univariate and multiva riate regression analysis. Should this finding be confirmed in larger futur e studies, this observation would be of outmost importance in identifying p atients at high risk of relapse in which more aggressive consolidation ther apies should be used.