  Using the approach based on conformal symmetry we calculate the three-loop
(NNLO) contribution to the evolution equation for flavor-nonsinglet leading
twist operators in the $\overline{\text{MS}}$ scheme. The explicit expression
for the three-loop kernel is derived for the corresponding light-ray operator
in coordinate space. The expansion in local operators is performed and explicit
results are given for the matrix of the anomalous dimensions for the operators
up to seven covariant derivatives. The results are directly applicable to the
renormalization of the pion light-cone distribution amplitude and
flavor-nonsinglet generalized parton distributions.
