Disclosed herein are methods for treating or inhibiting allograft rejection in a transplant recipient. In some embodiments, the methods include administering to the transplant recipient a first amount of a JAK1/3 inhibitor comprising 5-(2-(4-fluoro-3-methoxy-5-methylphenylamino)-5-methylpyrimidin-4-ylamino)benzo[d]oxazol-2(3H)-one (Compound I) or a prodrug thereof and administering to the transplant recipient a second amount of a non-JAK1/3 inhibitor immunosuppressant, wherein the combined effect of the first amount and the second amount is greater than the effect of the first amount or the second amount individually, wherein the JAK1/3 inhibitor acts in combination with the non-JAK1/3 inhibitor immunosuppressant to inhibit or treat allograft rejection. In some embodiments at least one of the first amount or the second amount is individually a suboptimal dose for inhibiting or treating allograft rejection. In some examples, the combined effect of the first amount and the second amount to inhibit or treat allograft rejection in the transplant recipient is synergistic.
