  We evaluated the scattering amplitude of neutral scalar particles at one-loop
order in the context of effective field theory of quantum gravity in the
presence of a cosmological constant. Our study suggests that quantum
gravitational corrections induce an asymptotic freedom behavior to the
$\lambda\phi^4$ theory, for a positive cosmological constant. This result hints
that a complete theory of quantum gravity can play an important role to avoid
the issue of triviality in quantum field theory.
