In the Standard Model Extension (SME) for neutral kaons, CPT violation manifests to lowest order only in the mixing parameter delta (e.g. vanish at first order in the decay amplitudes), and exhibits a dependence on the 4-momentum of the kaon.
The analysis of the data of the KLOE experiment already yielded the most precise measurement of the CPT violating parameters in the quark sector of the minimal SME. A re-analysis of the same data in addition with the analysis of the data collected by the KLOE-2 experiment could yield the first measurement of the new violation parameters in the much less restrictive context of the non-minimal SME incorporating the Standard Model of particle physics and General Relativity.