We propose a tunable plasmonic semiconductor laser that exploits loss perturbation as a tuning mechanism. A metal oxide semiconductor (MOS) capacitive structure is added on top of an edge-emitting Fabry-Perot (FP) diode laser, such that a hybrid plasmonic TM mode that overlaps partly with the MOS capacitor and the semiconductor gain region is supported as the lasing mode. We also propose the use of a layer of conductive oxide, e.g., indium tin oxide (ITO), as the semiconductor of the MOS structure, because the epsilon near zero (ENZ) condition can be attained therein under accumulation, thereby producing a very large change in the effective index of the hybrid plasmonic TM mode. The change in the imaginary part of the effective index is used to tune the lasing wavelength - exploiting loss perturbation to achieve laser tuning is paradigm-shifting. The laser proposed operates at telecom wavelengths, requiring an electrical forward bias to pump the active layer, and a gate voltage to drive the MOS tuning capacitor. Simulations yield a tuning range of over 7 nm in the O-band for a 100 μm long FP laser cavity.