INTRODUCTION
Primary membranous nephropathy (pMN) is a common cause of nephrotic syndrome in adults.[ 1 ] Approximately 30% of patients with pMN can achieve spontaneous remission,[ 2 ] and approximately 30%–40% of patients with persistent nephrotic syndrome progress to end-stage kidney disease (ESKD) in over 10 years.[ 3 , 4 ] pMN is currently a common non-diabetic kidney disease (NDKD), accounting for 45% of NDKD in a retrospective study in Iran[ 5 ] and 19.2% in the study reported by Soni et al .[ 6 ] It strongly predicts NDKD for patients with a brief diabetes history and without diabetic retinopathy, especially when presenting nephrotic proteinuria. Furthermore, patients with NDKD are associated with better renal outcomes than those with diabetic kidney disease.[ 7 , 8 ]
Glucocorticoids plus cyclophosphamide (CTX) are recommended as the standard pMN therapy for patients with a high or very high risk of kidney disease progression by 2021 KDIGO guidelines for managing glomerular diseases.[ 9 , 10 ] However, its application in treating patients with pMN and diabetes is limited by severe adverse effects, such as deteriorating glycemic control, increased risk of cancers, and reproductive toxicity.[ 11 , 12 ]
Most current published literature available are on pMN without diabetes, except for one study from India examining the therapeutic response to immunosuppressive medications in patients with pMN and diabetes.[ 13 ] In 2010, a multicenter randomized controlled trial (RCT) in China revealed that the reduction in urinary protein excretion and the remission rates of patients with pMN were significantly greater in the prednisone plus tacrolimus group than that in the prednisone plus CTX group at the 6th month.[ 14 ] In addition, mycophenolate mofetil had been proven to mitigate proteinuria in some patients with pMN previously resistant to glucocorticoids or cyclosporine treatment.[ 15 ] In 2007, Bao et al .[ 16 ] suggested therapy as an induction regimen for class IV+V lupus nephritis, including prednisone, tacrolimus, and mycophenolate mofetil, with an initial dose of 0.6–0.8 mg/kg/d, 4 mg/d, and 1 g/d, respectively. Their study revealed that the therapy was well tolerated by patients and was better than intravenous CTX for inducing complete class IV+V lupus nephritis remission in patients with minimal adverse effects.[ 16 ] This study provides an important basis for the potential application of combination therapy in pMN due to the similar immune disorder between pMN and IV+V lupus nephritis. Therefore, we have tried to treat patients with pMN and type 2 diabetes mellitus (T2DM) using combination therapy for a few years. The relatively lower doses of prednisone and tacrolimus may mitigate infection and facilitate glycemic control. Therefore, we collected and analyzed the data for this study and compared the efficacy and adverse effects of the combination of glucocorticoids, tacrolimus, and mycophenolate mofetil and conventional therapy of glucocorticoids plus CTX.
MATERIALS AND METHODS
In this retrospective study, all the patients provided written informed consent according to the Declaration of Helsinki before using glucocorticoids and immunosuppressive agents. Xi'an Jiaotong University Health Science Center (Xi'an, China) approved the study and the approval number was No. [2021] 049.
Recruitment criteria
Inclusion criteria were: (1) age 18–80 years; (2) newly diagnosed, biopsy-proven pMN between January 2013 and October 2019; (3) diagnosed T2DM according to the diagnosis and classification criteria of diabetes mellitus established by the American Diabetes Association; (4) not receiving glucocorticoids or any other immunosuppressive agents until the pathological diagnosis was confirmed using light, immunofluorescence, and electron microscopy.
Exclusion criteria were: (1) positive test for HBV, HCV, and HIV; (2) systemic lupus erythematosus or positive antibodies to double-stranded DNA or other autoimmune diseases; (3) malignancy; (4) peptic ulcer; (5) severe or potentially life-threatening infections; (6) previous immunosuppressive therapy, interrupting immunosuppressive therapy, or switching to traditional Chinese therapy on patient's initiative; (7) incomplete clinical data due to lack of follow-up or transfer to other hospitals for treatment; (8) severe heart and lung dysfunction; (9) pregnancy or lactation.
Medication regimens
The low-dose multitarget regimen consisted of glucocorticoids, tacrolimus, and mycophenolate mofetil. The dose of daily oral prednisone was 10 mg/d (or an initial dose of 8 mg/d methylprednisolone). The tacrolimus dose started at 0.05 mg/kg/d twice daily at 12-hour intervals and was titrated in the first month to maintain a blood trough concentration of 5–10 ng/mL. The dosage of mycophenolate mofetil was initiated at 1 g/d twice daily at 12-hour intervals. The initial doses of prednisone (or methylprednisolone), tacrolimus, and mycophenolate mofetil in the low-dose multitarget regimen were maintained for six months and then tapered gradually according to the patient's remission progress. The CTX regimen consisted of glucocorticoids and CTX. CTX was intravenously administered monthly for two consecutive days at approximately 0.8–1.0 g/month for six months, followed by 0.8–1.0 g every three months (accumulated dosage was 6–9 g). Daily oral prednisone or methylprednisolone was started at 1.0 mg/kg/d or 0.8 mg/kg/d, respectively, for eight weeks, tapered gradually to 20 mg/d, maintained for a month, and then individually tapered according to proteinuria levels.
The hypoglycemic agents and detailed dietary guidance were provided for glucose control. In addition, all the patients received supportive care, including angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) to decrease the excretion of urinary protein and control blood pressure, aspirin for prophylactic anticoagulant therapy when serum albumin was < 20 g/L or there was thrombosis risk, and statins for hyperlipidemia.
Efficacy and safety assessments
The primary endpoint of this study was the percentage of patients achieving complete or partial remission. Complete remission was defined as urinary protein excretion < 300 mg/24h maintained for over one week, serum albumin > 35 g/L, and normal serum creatinine. Conversely, partial remission was defined as urinary protein excretion < 3500 mg/24h, ≥ 50% reduction in baseline levels maintained for over a week, improved or normalized serum albumin level, and stable serum creatinine.
The secondary endpoint was decreased urinary protein excretion. Safety assessments included infections, worsened diabetes, leucopenia, gastrointestinal hemorrhage, and other clinical manifestations.[ 17 ]
Sample size calculation
The sample size was calculated using the following formula:
In the above formula, n, Z, α, β, p1 , and p2 represent the sample size, normal distribution, type I error rate, type II error rate, and the remission rates of both groups, respectively. 1 +p2 )/2; α = 0.05; β = 0.2. According to the study of Bhadauria et al .[ 13 ] , p1 and p2 were 63% and 18%, respectively. Therefore, the minimum required sample size was 13 in each group.
Statistical analysis
Statistical analyses were performed using SPSS 18.0 software (SPSS Inc, Chicago, USA). The data of normal or approximately normal distribution were represented by the mean ± standard deviation. The Student's t -test compared the differences in quantitative parameters between groups, and the Chi-square and Fisher's exact tests compared differences in qualitative results. Changes in clinical parameters from baseline levels in each group were evaluated using the paired-samples t -test, and the Benjamini-Hochberg (BH) method was used to correct multiple comparisons. The remission rates were analyzed using the Kaplan-Meier curve, and the Log-rank test was used to compare both curves. Adverse events were tabulated using descriptive statistics. A P -value < 0.05 was considered significant.
RESULTS
Baseline characteristics of the patients
Twenty-eight of the 67 patients diagnosed with pMN and T2DM were included in this study, with 14 patients in each group [Figure 1 ]. The patient's choice of treatment regimen depended on their reproductive needs, economic status, and blood glucose control. The patients were followed up until June 2021. The baseline characteristics of both groups were shown in Table 1 . The age expressed as mean ± standard deviation was 54.36 ± 8.60 years. Diabetic retinopathy and hypertension were observed in 4 and 16 cases, respectively. No significant difference was observed in fasting blood glucose (FBG), glycated hemoglobin (HbA1c), estimated glomerular filtration rate (eGFR), serum creatinine (Scr), and urine protein excretion between both groups at baseline.
Figure 1:: Enrollment of patients and treatment assignments. CTX, cyclophosphamide; pMN, primary membranous nephropathy; T2MD, type 2 diabetes mellitus.
Table 1 -
Baseline characteristics of the patients
Characteristics
Low-dose multitarget group (n = 14)
CTX group (n = 14)
P -value
Male/female, n
10/4
6/8
0.252
Kidney biopsy age, years
56.43 ± 10.50
52.29±5.85
0.209
Duration of diabetes mellitus
32.9 ± 14.9
36.2 ± 12.6
0.536
Diabetic retinopathy, n (%)
3 (21.4)
1 (7.1)
0.596
Hypoglycemic agents, n
Acarboses
3
6
Metformin
3
0
Insulin
5
3
Repaglinide
1
0
0.157
Insulin + Metformin
1
0
Insulin + Metformin + Acarbose
0
1
Diet management
1
4
Hypertension, n (%)
10 (71.4)
6 (42.8)
0.500
Histology grading of pMN, n
Stage I
5
3
Stage II
9
10
0.460
Stage III
0
1
FBG, mmol/L
6.32 ± 1.87
5.84 ± 1.10
0.418
HbA1c, %
7.00 ± 0.96
6.40 ± 1.12
0.156
WBC, ×109 /L
6.38 ± 2.00
7.43 ± 3.06
0.291
RBC, ×1012 /L
4.53 ± 0.49
4.44 ± 0.63
0.671
Hb, g/L
137.28 ± 14.63
134.50 ± 18.16
0.659
PLT, ×109 /L
214.35 ± 47.90
246.07 ± 88.11
0.247
Urine protein excretion, mg/24h
9289.34 ± 3560.63
7266.66 ± 3272.15
0.130
BUN, mmol/L
5.19 ± 1.26
5.38 ± 2.64
0.814
Scr, μmol/L
70.92 ± 28.03
71.87 ± 31.07
0.933
eGFR, mL/min·1.73m2
100.48 ± 25.59
103.29 ± 36.42
0.815
UA, μmol/L
334.38 ± 50.04
315.27 ± 113.37
0.573
STP, g/L
46.24 ± 4.91
49.46 ± 8.02
0.214
SAlb, g/L
24.11 ± 3.51
26.21 ± 5.27
0.226
TC, mmol/L
7.63 ± 2.60
7.21 ± 1.74
0.618
TG, mmol/L
2.84 ± 1.53
3.31 ± 1.70
0.459
FBG: fasting blood glucose, HbA1c: glycated hemoglobin, BUN: blood urea nitrogen, Scr: serum creatinine, eGFR: estimated glomerular filtration rate, UA: uric acid, STP: total serum protein, SAlb: serum albumin, TC: total cholesterol, TG: total triglyceride, WBC: white blood cell, RBC: red blood cell, Hb: hemoglobin, PLT: platelet, pMN: primary membranous nephropathy, CTX: cyclophosphamide. Categorical variables are presented as the number of patients (percentage). Continuous variables are presented as mean ± standard deviation.
Efficacy of treatment regimens
The urine protein excretion significantly decreased in both groups during the treatment period. It significantly decreased from 9289.34 ± 3560.63 mg/24h to 4488.85 ± 2064.72 mg/24h in the second month, 2346.57 ± 1472.52 mg/24h in the sixth month, and 1814.73 ± 2278.05 mg/24h in the twelfth month, respectively (P − BH Table 2 ]. In the CTX group, the excretion of urinary protein decreased from 7266.66 ± 3272.15 mg/24h to 5603.33 ± 4024.69 mg/24h in the second month (P − BH P − BH P − BH Table 2 ].
Table 2 -
Clinical parameters during the follow-up
Characteristics
Baseline
2 months
6 months
12 months
Low-dose multitarget group (n = 14)
CTX group (n = 14)
Low-dose multitarget group (n = 14)
CTX group (n = 14)
Low-dose multitarget group (n = 14)
CTX group (n = 14)
Low-dose multitarget group (n = 14)
CTX group (n = 14)
Urine protein Excretion, mg/24h
9289.34 ± 3560.63
7266.66 ± 3272.15
4488.85 ± 2064.72a
5603.33 ± 4024.69
2346.57 ± 1472.52b
3605.04 ± 3117.32b
1814.73 ± 2278.05c
2428.19 ± 2157.69c
BUN, mmol/L
5.19 ± 1.26
5.38 ± 2.64
6.33 ± 1.40
6.38 ± 1.87
6.97 ± 2.19b
5.76 ± 1.11
7.58 ± 2.90
6.24 ± 1.65
Scr, μmol/L
70.92 ± 28.03
71.87 ± 31.07
73.51 ± 23.62
65.19 ± 23.07
79.68 ± 38.52
66.44 ± 22.16
77.89 ± 31.19
64.60 ± 15.92
eGFR, mL/min·1.73m2
100.48 ± 25.59
103.29 ± 36.42
100.55 ± 31.71
107.58 ± 29.83
97.38 ± 39.53
106.29 ± 22.10
98.07 ± 37.42
105.50 ± 22.101
UA, μmol/L
334.38 ± 50.04
315.27 ± 113.37
338.20 ± 75.22
333.80 ± 95.15
320.63 ± 58.12
379.72 ± 115.93
290.50 ± 66.07
341.88 ± 76.06
STP, g/L
46.24 ± 4.91
49.46 ± 8.02
53.13 ± 9.98a
51.69 ± 8.49
58.68 ± 6.97b
56.35 ± 8.73
61.00 ± 9.36c
61.43 ± 9.19c
SAlb, g/L
24.11 ± 3.51
26.21 ± 5.27
31.38 ± 6.65a
28.78 ± 6.64
35.44 ± 6.33b
32.89 ± 6.86b
38.72 ± 7.81c
38.10 ± 8.73c
TC, mmol/L
7.63 ± 2.60
7.21 ± 1.74
7.91 ± 2.68
7.21 ± 2.01
6.01 ± 3.31b
6.25 ± 2.24b
5.45 ± 2.40c
5.70 ± 1.49c
TG, mmol/L
2.84 ± 1.53
3.31 ± 1.70
3.80 ± 2.91
3.54 ± 2.62
2.74 ± 1.36
2.50 ± 0.92
2.21 ± 1.05
2.62 ± 0.98
FBG: fasting blood glucose, BUN: blood urea nitrogen, Scr: serum creatinine, eGFR: estimated glomerular filtration rate, STP: total serum protein, SAlb: serum albumin, TC: total cholesterol, TG: total triglyceride, CTX: cyclophosphamide. a, b, c: P −BH value < 0.05 at the 2nd, 6th and 12th month respectively versus baseline levels. Continuous variables are presented as mean ± standard deviation.
The extent of urinary protein excretion decrease from baseline levels was significantly greater in the low-dose multitarget group than in the CTX group (−4800.48 ± 3002.65 mg/24h versus −1663.32 ± 4113.98 mg/24h in the second month, P − BH P − BH Figure 2 ]. In addition, the extent of serum albumin increase from baseline levels was also greater in the low-dose multitarget group than in the CTX group, although the difference was not significant (7.22 ± 4.42 g/L versus 2.57 ± 6.67 g/L in the second month, P − BH P − BH P − BH Figure 3 ].
Figure 2.: Change of urine protein excretion (mean ± standard deviation, mg/24h) from baseline levels at each follow-up evaluation in two groups. P −BH (adjusted by Benjamini-Hochberg method) versus the low-dose multitarget group. CTX, cyclophosphamide.
Figure 3.: Change of serum albumin (mean ± standard deviation, g/L) from baseline levels at each follow-up evaluation in two groups. P −BH (adjusted by Benjamini-Hochberg method) versus the low-dose multitarget group. CTX, cyclophosphamide.
At the same time, serum albumin levels significantly increased from 24.11 ± 3.51 g/L at baseline to 31.38 ± 6.65 g/L in the second month, 35.44 ± 6.33 g/L in the sixth month, and 38.72 ± 7.81 g/L in the twelfth month, respectively (P − BH Table 2 ]. In contrast, in the CTX group, the serum albumin levels started increasing significantly after the sixth month, from 26.21 ± 5.27 g/L at baseline to 32.89 ± 6.86 g/L in the sixth month (P − BH P − BH Table 2 ].
In addition, a significant decrease in total cholesterol levels was observed in the sixth and twelfth months in both groups, from 7.63 ± 2.60 mmol/L at baseline to 6.01 ± 3.31 mmol/L in the sixth month (P − BH P − BH Table 2 ); from 7.21 ± 1.74 mmol/L at baseline to 6.25 ± 2.24 mmol/L in the sixth month (P − BH P − BH Table 2 ].
The levels of blood urea nitrogen (BUN), Scr, and eGFR remained stable during the follow-up [Table 2 ].
Remission and relapse
In the Kaplan-Meier analysis, the median time to achieve partial remission was 4.5 months (95% CI: 2.66–6.33 months) in the low-dose multitarget group and 6.5 months (95% CI: 3.75–9.25 months) in the CTX group. The median time to complete remission was 25.5 months (95% CI: 18.48–32.51 months) in the low-dose multitarget group and 18.0 months (95% CI: 12.67–23.32 months) in the CTX group. However, the log-rank test revealed no significant difference in the cumulative partial or complete remission rates between both groups [Figure 4 and 5 ].
Figure 4.: Cumulative probability of partial remission in two groups. CTX, cyclophosphamide.
Figure 5.: Cumulative probability of complete remission in two groups. CTX, cyclophosphamide.
The median follow-up time of this study was 14.5 months (12.0–52.5 months). Two patients who received glucocorticoids plus CTX therapy relapsed during this period and then achieved complete remission after switching to the glucocorticoids plus mycophenolate mofetil treatment for 14 and 4 months, respectively.
Anti-PLA2R antibody
Serum anti-PLA2R antibodies were measured using ELISA in patients enrolled after 2018. A positive PLA2R test was defined as ELISA titer ≥ 20 Ru/mL. The positive rate of serum anti-PLA2R antibodies decreased from 75.0% to 12.5% after treatment, and the serum anti-PLA2R antibodies all tested negative in patients who achieved remission [Table 3 ].
Table 3 -
Urine protein excretion and serum anti-PLA2R antibody
Group
Case No.
Baseline
After treatment
Urine protein Excretion (mg/24h)
anti-PLA2R antibody (Ru/mL)
Urine protein Excretion (mg/24h)
anti-PLA2R antibody (Ru/mL)
Low-dose multitarget group
1
4364.60
3.15
163.68
2.40
2
6743.80
53.54
171.12
2.46
3
13717.00
30.44
539.74
2.36
4
11445.93
80.32
662.40
2.09
5
5633.80
70.63
257.54
6.74
CTX group
6
10347.90
18.29
8634.20
28.69
7
14803.20
175.13
2927.40
12.29
8
11500.71
29.91
1760.72
2.33
Adverse effects of treatment
One aspect we focused on in this study was the potential treatment disadvantage on blood glucose levels. As illustrated in Figure 6 , the HbA1c levels increased in the CTX group significantly after treatment, from 6.40% ± 1.12% at baseline to 8.00% ± 0.91% in the second month (P − BH P − BH Table 4 ] and mostly occurred within the first six months after treatment. There were 15 infections in the low-dose multitarget group, of which 7 occurred in one patient due to underlying bronchiectasis. Additionally, 12 infections occurred in the CTX group during the follow-up. Nausea or vomiting, Cushing syndrome, and a decrease in white blood cell count were observed in patients treated with glucocorticoids plus CTX therapy. One patient with pre-existing atherosclerosis in the low-dose multitarget group died from acute cerebral infarction.
Figure 6.: HbA1c (%) levels at each follow-up evaluation in two groups. P −BH (adjusted by Benjamini-Hochberg method) versus the baseline value in each group. HbA1c, glycated hemoglobin. CTX, cyclophosphamide.
Table 4 -
Adverse events in patients with T2DM
Characteristics
Low-dose multitarget group (n = 14)
CTX group (n = 14)
Infection events, N
Pneumonia
7
6
Acute urinary tract infection
7
4
Herpes zoster or varicella
1
2
Nausea or vomiting, N
0
3
WBC < 4×109 /L, N
0
1
Cushing syndrome, N
0
5
Death, n
1
0
N: number of events, n: number of patients, CTX: cyclophosphamide, T2DM: type 2 diabetes mellitus.
DISCUSSION
Until now, most non-diabetic kidney disease (NDKD) studies have focused on clinical and pathological characteristics. To our knowledge, there is no RCT on pMN coexisting with diabetes. Furthermore, only a few retrospective studies have reported immunosuppressive agents’ effects on remission rate and glucose control in patients with such diseases. Therefore, we designed and conducted this retrospective study to evaluate the efficacy and safety of the combination of glucocorticoids, tacrolimus, and mycophenolate mofetil in patients diagnosed with pMN and T2DM.
Tacrolimus suppresses immune response by inhibiting T cell activation and suppressing interleukin-2 (IL-2) transcriptions.[ 18 ] In addition, tacrolimus can improve podocyte damage by restoring actin cytoskeleton distribution and increasing the expression of synaptopodin and podocin.[ 19 ] Mycophenolate mofetil can inhibit inosine monophosphate dehydrogenase (IMPDH) type Ⅱ, which is expressed in activated lymphocytes, and induce apoptosis of activated T-lymphocytes.[ 20 ] Thus, the combination therapy was speculated to synchronously mitigate the immune response, inflammation, and podocyte lesions that are crucial to the underlying pathogenesis of pMN.
Previous studies have revealed that the remission rate of patients with pMN treated with ACEI/ARB is < 10% in the sixth month, which is significantly lower than those treated using tacrolimus.[ 21 ] Moreover, remission, especially complete remission, rarely occurs spontaneously within six months in patients with massive proteinuria. Meanwhile, the risk of infections and thromboembolic events in patients with diabetes mellitus (DM), which is much higher than in those without DM,[ 22 ] will further increase because controlling renal hypertension, hypoalbuminemia, and hyperlipidemia is challenging in patients with pMN who have not achieved remission.[ 23 ] Severe complications, such as acute myocardial infarction, cerebral infarction, and massive pulmonary embolism, can lead to a significant decline in quality of life, paralysis, or death of the patients. Furthermore, it does not result in better preservation of kidney function; however, early treatment shortens nephropathy duration.[ 24 ] Therefore, immunosuppressive therapy was initiated immediately after diagnosis rather than after six months of ACEI/ARB treatment. As recommended in the 2020 KDIGO Clinical Practice Guideline for Diabetes Management in Chronic Kidney Disease,[ 25 ] all the patients in our study received ACEI/ARB at the maximum tolerable dose to decrease urinary protein excretion and control blood pressure by suppressing aberrant activation of the renin-angiotensin-aldosterone system (RAAS).
Our results revealed that glucocorticoids plus CTX therapy and combination therapy of glucocorticoids, tacrolimus, and mycophenolate mofetil significantly reduce urine protein excretion, increase serum albumin levels, and favor remission in patients with pMN and T2DM. However, the reduction in urinary protein excretion of patients treated with combination therapy was significantly higher than that in patients treated with glucocorticoids plus CTX therapy, especially in the first two months of treatment, consistent with previous reports.[ 14 , 21 ] These findings suggest that glucocorticoids plus tacrolimus or tacrolimus monotherapy may have more advantages in decreasing the levels of urinary protein excretion over ACEI, ARB, and cyclophosphamide regimens for patients with pMN and T2DM. Furthermore, the urinary protein level is significantly positively correlated with progression to ESKD and is an independent risk factor for kidney disease progression,[ 26 ] remission, even partial, can significantly improve the long-term prognosis of patients with pMN.[ 27 ] In addition, serum albumin increase from baseline value was also greater in the low-dose multitarget group than in the CTX group, although the difference was not significant, which might be attributed to the relatively small sample size of the study. As such, the combination of glucocorticoids, tacrolimus, and mycophenolate mofetil is a potential alternative therapeutic regimen for patients with pMN coexisting with T2DM due to its superiority in decreasing urinary protein excretion, increasing plasma albumin, alleviating edema symptoms, and reducing thrombosis risks, thereby improving quality of life.
The remission rate was key to evaluating the efficacy of both regimens in this study. An observational study in India included 16 patients with pMN and T2DM, and 18% of them achieved remission after six months of using the Modified Ponticelli (MP) regimen. Patients who did not achieve remission switched to tacrolimus and mycophenolate mofetil therapy due to persistent cytopenias, worsened diabetes, and recurrent infections.[ 13 ] High doses of glucocorticoids and cyclophosphamide in the MP regimen may have contributed to the low remission rates in the study in India, accompanied by a higher risk of frequent and severe adverse effects, thereby limiting their clinical application. Our study revealed that patients receiving combination therapy of glucocorticoids, tacrolimus, and mycophenolate mofetil had a shorter time to achieve partial remission than patients receiving glucocorticoids plus CTX therapy. However, no significant difference was observed between the cumulative remission rates of both groups. DM may also make achieving complete remission challenging.[ 28 ]
Treatment-related adverse effects were another important aspect that required attention in our study. Studies have indicated that patients treated with tacrolimus had a higher risk of nephrotoxicity, increased Scr, and reduced eGFR.[ 29 ] Previous studies have revealed that the nephrotoxicity caused by calcineurin inhibitors is time- and dose-dependent and the tolerability of tacrolimus appears to improve with dose reduction.[ 30 ] However, Scr and eGFR remained stable in patients with pMN coexisting with T2DM who received tacrolimus in our study. The follow-up of our study was relatively short, with a median of 14.5 months (12.0–52.5 months), and the initial dosage of tacrolimus was 0.05 mg/kg/d. At the same time, all the patients had normal renal functions before treatment with tacrolimus. These may be why our patients did not experience nephrotoxicity. The risk of potential nephrotoxicity using tacrolimus for an extended period should be investigated in further studies.
Worsened diabetes caused by glucocorticoids and tacrolimus was observed in both groups. In patients with known DM, glucocorticoids can exacerbate hyperglycemia by decreasing peripheral insulin sensitivity, increasing hepatic glucose production, and inhibiting the production and secretion of pancreatic insulin.[ 31 , 32 ] The diabetogenicity of calcineurin inhibitors has also been confirmed in animals and humans.[ 33 ] In an open-label, randomized, multicenter study, 33.6% of patients who received tacrolimus after a kidney transplant developed new-onset DM or impaired fasting blood glucose six months after commencing treatment.[ 34 ] In our study, HbA1c, a useful clinical parameter for monitoring long-term blood glucose control, was significantly higher in the CTX group in the second and sixth month of treatment, which may be attributed to the higher glucocorticoid used (1 mg/kg/d) in the CTX group compared to 10 mg/d in the low-dose multitarget group. It is challenging to decide which therapy is more suitable for patients with diabetes without convincing results from long-term RCTs. Researchers have recently discovered that B-cell anomalies are vital to MN pathogenesis. Studies have revealed that rituximab is safer than glucocorticoids plus cyclophosphamide and superior to cyclosporine in maintaining proteinuria remission.[ 35 , 36 ] Furthermore, rituximab has no significant influence on blood glucose, making it more suitable for patients with pMN coexisting with diabetes; however, there has been no RCT addressing this concern so far.
Infections were another adverse effect in patients with diabetes receiving glucocorticoids or immunosuppressive therapy. In our study, the most frequently involved organs were the lungs and the urinary system. Herpes zoster infection also accounted for a large proportion. The infection events were higher in the combination therapy group than in the glucocorticoids plus cyclophosphamide therapy group due to repeated infections in the same patient with bronchiectasis. Other side effects, such as leucopenia, nausea or vomiting, and Cushing syndrome, were observed in patients receiving glucocorticoids plus cyclophosphamide therapy.
Several limitations should be considered in this study. First, its retrospective nature and the relatively small sample size would inevitably bring some bias in evaluating the efficacy and safety of both regimens. Second, the relatively short follow-up makes it challenging to determine relapse and long-term complication risks. Third, our study did not include patients with impaired renal function.
In conclusion, our results suggested that glucocorticoids plus cyclophosphamide and glucocorticoids, tacrolimus, and mycophenolate mofetil combination therapies were useful therapeutic options in treating patients with pMN coexisting with T2DM, and the combination therapy seems to be more effective in proteinuria reduction. However, long-term studies are required to evaluate this regimen's influence on blood glucose.
Financial support and sponsorship
This work was supported by the National Natural Science Foundation of China (Nos. 82170697) and the Natural Science Foundation of Shaanxi Province (No. 2022JM-472).
Authors contribution
Jia L and Fu R developed the initial study and analysis plan. Wang L, Ma X, and Ge H performed the study. Wang H, Chen Z, Cui C, and Huo Y completed all data collection. Zhang L gave useful suggestions on the analysis data. Wang Y and Xue X completed the data analysis. The initial manuscript was drafted by Wang Y. Tian X reviewed and edited the manuscript. All authors read and commented on previous versions of the manuscript, and finally approved the final manuscript.
Ethics approval and consent to participate
Xi'an Jiaotong University Health Science Center (Xi'an, China) approved the study and the approval number was No. [2021] 049. All the participants provided informed written consent before the study.
Conflicts of interest
Xuefei Tian is an Editorial Board Member of the journal. The article was subject to the journal's standard procedures, with peer review handled independently of this member and his research group.
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