  We present the current status of the analysis of about 1.7 billion K_S K_L
pair events collected at DA{\Phi}NE with the KLOE detector to determine the
branching ratio of K_S -> {\pi}e{\nu} decay and the lepton charge asymmetry.
This sample is ~4 times larger in statistics than the one used in the previous
most precise result, from KLOE as well, allowing us to improve the accuracy on
the measurement and related tests of CPT symmetry and Delta S = Delta Q rule.
