Motivated by the ongoing searches for new physics at the LHC, we explore the low energy consequences of a D-brane inspired SU(4)C×SU(2)L×SU(2)R (4-2-2) model. The Higgs sector consists of an SU(4) adjoint, a pair H+H¯ in (4,1,2)+(4¯,1,2), and a bidoublet field in h(1,2,2). With the SU(4) adjoint, the symmetry breaks to a left-right symmetric SU(3)C×U(1)B−L×SU(2)L×SU(2)R model. A missing partner mechanism protects the SU(2)R Higgs doublets in H, H¯, which subsequently break this latter symmetry at around to 104–106 GeV to the Standard Model. An inverse seesaw mechanism generates masses for the observed neutrinos and also yields a keV sterile neutrino that can play the role of dark matter if its mass lies in the keV range. Other phenomenological implications, including proton decay, are briefly discussed.