Since the first successful kidney transplantation in 1954, immunosuppressive regimens for kidney transplantation have evolved considerably, with the advent of cyclosporine A (CsA) in the late 1970s and morte-macrolate (primaquine, MMF) in the mid-1990s becoming two major leaps in the history of organ transplantation therapy, and immunosuppressive agents such as anti-CD25 antibodies, tacrolimus (Tac) and rapamycin (Rapa) further enriching immunosuppressive regimens. Immunosuppressive regimens such as anti-CD25 antibodies, Tac and Rapamycin have further enriched the choice of immunosuppressive regimens. From the statistics of immunosuppressive regimens for kidney transplant patients at discharge in the United States, calcium phosphatase inhibitors (CNI) combined with MMF are still the mainstream, with Tac+MMF accounting for about 76% and other regimens such as Tac+Rapa, CsA+Rapa, and Rapa+MMF using less than 10%. Despite the increasing choice of regimens and a significant increase in the 1-year survival rate of first-time cadaveric kidney transplantation, half of the graft survival time has remained stagnant at about 8-10 years, indicating that slowing the occurrence and progression of chronic graft nephropathy (CAN) and improving the long-term survival of the transplanted kidney are still urgent challenges for the organ transplantation community to break through. The causes of CAN are complex and include immune and non-immune factors such as donor quality, HLA mapping, delayed graft rework (DGF), acute rejection due to inadequate immunosuppression, CNI nephrotoxicity due to oversuppression, and BK virus infection. MMF combined with CNI dose reduction or withdrawal has been closely monitored. The results of CAESAR showed that CNI withdrawal resulted in a significantly higher incidence of acute rejection (25% vs 38%, p<0.05) and no significant improvement in renal function 1 year after withdrawal, suggesting that a CNI-free regimen is not a reasonable way to reduce CAN. The SYMPHONY study published in the New England Journal of Medicine at the end of last year gave a new direction when a randomized controlled study analyzed the effect of MMF 2g/d in combination with different immunosuppressive agents on renal function and showed that the GFR levels at 1 year after transplantation were significantly higher in the low-dose Tac+MMF 2g/d regimen than in the conventional or low-dose CsA or low-dose Rapa combined with MMF regimens. It also had a significantly lower incidence of acute rejection than all other groups, while the effects of low-dose CsA and conventional dose CsA were similar, suggesting that low-dose CNI combined with MMF may be a better option for improving long-term graft survival. The SYMPHONY study has many commonalities with the results of two previous studies. One is the creeping creatinine study published in 2005, in which 143 kidney transplant patients with creeping creatinine elevation were randomized to discontinue CsA and add MMF or continue with CsA, and the follow-up results showed a significant improvement in the trend of creatinine elevation after switching to MMF compared to continuing with CsA. The second is the TRANCEPT study on the long-term effects of conversion to MMF-based immunosuppressive regimens on renal function in patients with CNI-based immunosuppressive regimens more than 6 months after transplantation. Regression analysis of changes in glomerular filtration (GFR) in more than 1700 renal transplant patients showed that the slope of the change curve of GFR after conversion to MMF changed from negative to positive, suggesting that renal function The data after 2 years of conversion to MMF showed that more than 50% of the patients had significant improvement in renal function, and the improvement was even greater in those who added MMF early after transplantation, while those who added MMF more than 5 years after transplantation could also obtain improvement in the decreasing trend of GFR. The overall incidence of acute rejection after conversion to MMF was only 2.5%, and 2.4% in patients who experienced hyperalgesia and CNI reduction/withdrawal. Combining the SYMPHONY, creeping creatinine and TRANCEPT studies, it can be seen that MMF combined with low-dose Tac is superior to other regimens in preserving transplanted kidney function, which is consistent with the trend of immunosuppressive regimens used in recent years; MMF-based CNI minimization regimens may be a reasonable treatment strategy for patients with persistent declining renal function.