intolerant nephrotic syndrome - Springer Link

Pediatr Nephrol (2011) 26:1255–1261 DOI 10.1007/s00467-011-1876-z

ORIGINAL ARTICLE

Novel multidrug therapy for children with cyclosporine-resistant or -intolerant nephrotic syndrome Tomomi Aizawa-Yashiro & Kazushi Tsuruga & Shojiro Watanabe & Eishin Oki & Etsuro Ito & Hiroshi Tanaka

Received: 2 February 2011 / Revised: 15 March 2011 / Accepted: 16 March 2011 / Published online: 9 April 2011 # IPNA 2011

Abstract An effective treatment for children with refractory nephrotic syndrome (NS), especially in those with cyclosporine (CsA)-resistant or CsA-intolerant NS, has yet to be established. Recently, the efficacy of multidrug therapy consisting of tacrolimus (Tac), mycophenolate mofetil (MMF) in combination with prednisolone (PDN) in adult patients with refractory NS has been reported. We successfully treated 14 consecutive children with refractory CsA-resistant or CsA-intolerant NS using combination therapy consisting of relatively low-dose Tac, mizoribine (MZR), which has a mechanism of action very similar to that of MMF, and PDN. There were no serious clinical toxicities. Of the 14 children, 9 with a mean age of 13.0 years had steroid-dependent NS (SDNS) and 5 with a mean age of 9.6 years had steroid-resistant NS (SRNS). All SDNS patients had minimal change disease (MCD), 4 with SRNS had focal segmental glomerulosclerosis (FSGS), and the remaining child had MCD on renal biopsy. All patients were in a prospective cohort, but were evaluated retrospectively. The mean follow-up from the initiation of multidrug therapy was 18.4 months in SDNS and 18.6 months in SRNS patients. At the last observation point, the calculated relapse rate and minimum dose of PDN required for

maintenance of clinical remission after the start of multidrug therapy were significantly decreased compared with those prior to this therapy, while on CsA, in SDNS patients (0.4±0.5 times/year vs 2.9±1.5 times/year, P=0.0077, and 0.3±0.2 mg/kg on alternate days vs 0.5±0.2 mg/kg on alternate days, P=0.0184 respectively). All SDNS and two SRNS patients (40%) achieved complete remission, allowing further decreases in the minimal doses of PDN required for maintenance of clinical remission in most our patients. However, one patient with FSGS remained refractory to multidrug therapy and subsequently developed end-stage renal disease. These clinical observations, although preliminary and involving a small number of patients, suggest that multidrug therapy consisting of relatively low-dose Tac, MZR, and PDN might be effective and safe for treating children with refractory CsA-resistant or CsA-intolerant NS. However, further studies involving larger numbers of patients are needed. Keywords Cyclosporine-intolerant . Cyclosporineresistant . Mizoribine . Multidrug therapy . Refractory nephrotic syndrome . Tacrolimus

Introduction T. Aizawa-Yashiro : K. Tsuruga : S. Watanabe : E. Oki : E. Ito : H. Tanaka (*) Department of Pediatrics, Hirosaki University Hospital, Hirosaki 036-8563, Japan e-mail: [email protected] H. Tanaka Department of School Health Science, Faculty of Education, Hirosaki University, Hirosaki, Japan

Since cyclosporine A (CsA) is reportedly effective for pediatric patients with refractory nephrotic syndrome (NS), of both the steroid-dependent relapsing (SDNS) and steroidresistant (SRNS) type, CsA may now serve as a first-line immunosuppressant for treating children with refractory NS [1–5]. However, CsA nephrotoxicity remains a major concern [1, 2], and some NS patients exhibit CsA resistance or CsA intolerance [6–8]. Treatment of such refractory NS

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patients is a major challenge that remains to be overcome. Although tacrolimus (Tac) and/or mycophenolate mofetil (MMF) as an alternative to CsA may be useful in a portion of patients with refractory NS [6–12], therapy-related adverse events, i.e., hyperglycemia, hypertension, diarrhea, opportunistic infection, and calcineurin inhibitor-related nephrotoxicity, remain major concerns [8–10]. Recently, we successfully treated two children with focal segmental glomerulosclerosis (FSGS), who had formerly experienced therapy-related adverse events, with a combination regimen consisting of relatively low-dose Tac, mizoribine (MZR), which has a mechanism of action very similar to that of MMF, and prednisolone (PDN) [13]. Thus, we hypothesized that multidrug therapy consisting of two immunosuppressants with different mechanisms of action administered at relatively low doses, in combination with PDN, would be an effective and safe treatment in select patients with refractory NS [13], as postulated in a recent report describing successful treatment of adult NS patients using multidrug therapy comprising Tac, MMF, and PDN [14]. We have since used relatively low-dose Tac combined with MZR, when appropriate, to treat children with refractory NS. Herein, we report our single-center experience with a pilot study of novel multidrug therapy consisting of Tac, MZR, and PDN for 14 consecutive children with CsA-resistant or CsA-intolerant refractory NS.

Patients and methods Patients From December 2006 to July 2010, a total of 14 consecutive children with CsA-resistant or CsA-intolerant refractory NS were treated with a combination consisting of relatively low-dose Tac, MZR, and PDN for at least 20 weeks at the Department of Pediatrics Hirosaki University Hospital. Among the 14, 9 had SDNS and 5 had SRNS. The definition and criteria for diagnosing SDNS and SRNS, and for remission and relapse of NS were the same as those used in the International Study of Kidney Disease in Children [15]. Prior to the start of this novel therapy, treatment with CsA had proved ineffective, in terms of steroid-sparing effects and reducing the frequency of relapses in all of the SDNS patients and the antiproteinuric effect in all of the SRNS patients. Resistance to CsA therapy (CsA-resistant) was defined as persistence of nephrotic-range proteinuria and/or more than two relapses after at least 6 weeks of CsA therapy with an adequate calculated 0- to 4-h area under the concentration time curve (AUC0–4) of the drug at approximately 2,000 ng × h/ml [5, 16]. CsA intolerance was defined as difficulty maintaining

Pediatr Nephrol (2011) 26:1255–1261

a stable absorption profile of CsA, or the development of adverse events, including biopsy-proven nephrotoxicity and/or deterioration of the estimated glomerular filtration rate (GFR) [17] while on preprandial administration of an appropriate dose of the drug (up to 5 mg/kg daily). All the patients had a long history of refractory NS, and were on continuous PDN therapy. Moreover, they were suffering from therapy-related toxicity, such as steroid-induced obesity, short stature and osteoporosis, and/or CsA-related toxicity. Thus, we were very keen on the safe and effective treatment protocol for those patients. Also, we had experienced a rapid efficacy of CsA therapy with an adequate AUC0–4 in SDNS patients [5]. Thus, we decided to use the definition criteria of CsA-resistant or CsAintolerant based on a relatively short observation period of CsA treatment in this study. Renal biopsies were performed in all 14 patients before multidrug therapy. All SDNS and 1 SRNS patient had minimal-change disease (MCD), while 4 SRNS patients had typical lesions of FSGS. Two patients with SDNS who had received relatively long-term CsA treatment showed therapy-related nephrotoxicities, such as striped interstitial fibrosis with tubular atrophy. However, blood pressure and renal function were normal in all patients. Treatment protocol For patients with SDNS, remission was induced by escalating the dose of PDN (up to 60 mg/day). Then, Tac was started at 0.05 mg/kg once daily after the evening meal (up to 3 mg). The dose was adjusted according to a 12h post-dosing blood level of approximately 5 ng/ml [13, 18]. Next, MZR was added at 3 mg/kg once daily before breakfast (up to 150 mg). Thereafter, the MZR dose was adjusted for each individual to yield a peak blood drug level (2-h post-dosing) of approximately 1.0–2.0 μg/ml [13]. All patients had a long history of refractory NS, and were on continuous PDN therapy, administered according to our treatment protocol for SDNS [5]. After the start of Tac, the PDN dose was gradually tapered (0.2 mg/kg on alternate days per 4 weeks) down to the minimal dose required for maintenance of clinical remission, or discontinuation if possible, based on the clinical status of each patient. For patients with SRNS, although the administration protocols for Tac and MZR were the same as those for SDNS patients, PDN was maintained at a dose of 1.0 mg/kg daily (up to 60 mg/day) for 4 to 6 weeks, then reduced to 1.0 mg/ kg on alternate days and maintained for at least 12 weeks, followed by gradual tapering if possible. If relapse occurred during treatment, the dose of PDN was transiently increased (up to 60 mg/day) to treat the flares. This PDN treatment regimen was the same as that while on CsA prior to this multidrug treatment. Patients on angiotensin II receptor


blockers (ARB), which had been administered previously to manage a possible anti-proteinuric effect, were maintained on the same dose for the duration of therapy. Informed consent from the patients’ parents was obtained in writing prior to the study. Since all patients had refractory NS, the scheduled treatment duration with this novel multidrug regimen was relatively long. Clinical observations The minimal PDN dose required for maintenance of clinical remission, the calculated relapse rate (times per year), the GFR estimated using Schwartz’ formula [17] and therapyrelated adverse events were determined prior to initiating this novel multidrug therapy and at the latest observation point, at a mean interval of 18 months (range 5–41 months) after the start of this treatment. Complete remission (CR) was defined as a decrease in proteinuria to no more than 0.2 g of protein per day and an increase in serum albumin to more than 3.5 g/dl; partial remission (PR) as a proteinuria decrease of at least 50% below baseline and an increase in serum albumin to at least 2.5 g/dl [9]. Resistance to this therapy (no response, NR) was defined as persistence of nephrotic-range proteinuria after at least 16 weeks of treatment. Statistical analysis Data are expressed as means ± SD and were analyzed by Wilcoxon’s U test using Stat View Graphics (Abacus Concepts, Berkeley, CA, USA) computer software. A P value of less than 0.05 was considered statistically significant.

Results The clinical characteristics of our 14 study subjects with refractory NS are shown in Table 1. There were 7 boys and 2 girls, with a median age of 13.0 years (range 7.1– 21.1 years) in the SDNS group, and 2 boys and 3 girls with a median age of 9.6 years (range 5.2–14.8 years) in the SRNS group. Renal pathological evaluation prior to multidrug therapy showed MCD in 10 patients and FSGS in 4. Of these, 2 patients (Patients 1 and 8) with MCD showed CsA-related nephrotoxicity. Although all patients had normal blood pressure and renal function, all were being treated with an ARB before this study for anticipated anti-proteinuric effects. All patients completed at least 3 months of therapy and were included in the analysis of efficacy. The follow-up duration after the initiation of multidrug therapy ranged from 5 to 41 months. Prior to this multidrug therapy, a trial of cyclophosphamide at a dose of

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1.5–2.0 mg/kg/day for 8–12 weeks had proved ineffective, in terms of steroid-sparing effects and reducing the frequency of relapses, in 6 of the 14 study patients. Intravenous methylprednisolone pulse therapy at a dose of 20–30 mg/kg daily (up to 1 g) on 3 consecutive days per week for 3 weeks had proved ineffective, in terms of antiproteinuric effects, in all SRNS patients. Thus, all patients were scheduled to receive an oral micro-emulsion formation of CsA, the administered dose of which was adjusted with the AUC0–4 of the drug at approximately 2,000 ng × hour/ml [5, 16]. However, after at least 6 weeks of CsA treatment, all patients were deemed to be CsA-resistant or CsA-intolerant, based on the following observations: more than two relapses in 5 patients (Patients 2, 5, 6, 7, and 9) with SDNS, unremitting proteinuria in 3 patients (Patients 10, 12, and 13) with SRNS, emergence of CsA-related adverse events in 2 patients (Patients 1 and 8) with SDNS and 1 patient (Patient 14) with SRNS, and unstable blood CsA levels despite an appropriate dose of the drug in 2 patients (Patients 3 and 4) with SDNS and 1 patient (Patient 11) with SRNS. The doses and blood levels of Tac and MZR in the study subjects are shown in Table 2. By the end of the 6-week treatment with this novel multidrug therapy, CR was achieved in all 9 patients with SDNS and 2 with SRNS. PR occurred in 1 patient with SRNS, while the other 2 remained refractory and were considered to have NR. Thus, prompt remission was achieved in 12 patients (86%) on multidrug therapy (11 CR and 1 PR). After 6 months of treatment (Patient 4 and 6 were at 5 months of treatment), 2 patients with SDNS experienced relapse while the remaining 7 patients were on CR. These 2 patients were successfully treated with transient dose escalation of PDN. In SRNS patients, the clinical status of each patient was same as after 6 weeks of treatment. At the latest observation point, a mean of 18 months, 5 patients with SDNS (56%) and 1 with SRNS (20%) showed sustained CR despite further PDN dose reduction. As a result, 2 patients (Patients 2 and 9) with SDNS and 1 with SRNS (Patient 10) were able to discontinue PDN. The remaining 7 patients with SDNS did not discontinue PDN during the observation period, because of pre-existing severe long-term steroid dependence. One patient (Patient 13) with SRNS, a 16year-old girl considered to have NR, progressed to endstage renal disease (ESRD) 12 months after starting multidrug therapy, and underwent renal transplantation. Unfortunately, she subsequently developed recurrent FSGS in the transplanted kidney. The remaining (Patient 14) patient with SRNS, an 8-year-old girl considered to have NR, discontinued multidrug therapy 12 weeks after starting because of a significantly increased urinary β2-microglobulin level. She had had a similar experience while being treated with CsA. She was then successfully managed

13.0 13.8 13.4 7.3 13.2 2.3 3.7 6.7 5.7

6.5 4.3 3.6 11.4 2.2

Male Male Male Male Female Male Male Male Female

Male Male Female Female Female

9.5 5.2 11.2 14.8 7.3

21.1 20.1 14.9 7.7 13.8 8.4 12.3 11.9 7.1 FSGS FSGS FSGS FSGS MCD

MCD MCD MCD MCD MCD MCD MCD MCD MCD MPT, MPT, MPT, MPT, MPT,

88 64 3 1a 2 50 76 56 2

CsA, PDN 34 CsA, PDN 3 CPA → CsA, PDN 47 CPA → CsA, PDN 12 CPA → CsA, PDN 1b

CsA, PDN CsA, PDN CsA, PDN CsA, PDN CsA, PDN CPA → CsA, PDN CPA → CsA, PDN CsA, PDN CPA → CsA, PDN Resistant Intolerant Resistant Resistant Intolerantd

Intolerantc Resistant Intolerant Intolerant Resistant Resistant Resistant Intolerantc Resistant

Duration on Response CsA (months) to CsA

CR CR PR NR NR

CR CR CR CR CR CR CR CR CR 137.5 107.1 139.3 74.7 149.0

98.1 100.6 156.6 119.3 133.0 125.7 184.4 113.3 117.7 40 32 39 32 11

38 36 9 5 28 5 41 15 32

Response to Estimated GFR Latest observation point multidrug therapy (ml/min/1.73m2) from multidrug therapy (months)

d

c

b

a

A significant increase in the urinary β2-microglobulin level soon after CsA administration

Biopsy-proven CsA-related nephrotoxicity

Patient 14 was deemed to be CsA-intorelant at 4 weeks of treatment because of the development of significant urinary β2-microglobulin elevation soon after the initiation of CsA

Patient 4 was deemed to be CsA-intolerant at 4 weeks of treatment because of severe steroid dependency-induced early relapses while on an unstable blood level of CsA

SDNS, steroid-dependent nephrotic syndrome; SRNS, steroid-resistant nephrotic syndrome; MCD, minimal change disease; FSGS, focal segmental glomerulosclerosis; MPT, methylprednisolone pulse therapy; CPA, cyclophosphamide; CsA, cyclosporine A; CR, complete remission; PR, partial remission; NR, no response

SDNS 1 2 3 4 5 6 7 8 9 SRNS 10 11 12 13 14

Patient number Gender Age at onset Age at multidrug Renal Previous (years) therapy started pathology immunosuppressants (years)

Table 1 Demographic characteristics of 14 children with refractory nephrotic syndrome who received multidrug therapy consisting of tacrolimus, mozoribine, and prednisolone

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Table 2 The doses and blood levels of tacrolimus and mizoribine in the 14 study patients Variable

SDNS group (n=9)

SRNS group (n=5)

Age at onset (years) Age at multidrug therapy started (years) Tac dose (mg/kg/day) Trough blood level of the drug (ng/ml)a MZR dose (mg/kg/day) Peak blood level of the drug (μg/ml)b

8.8±4.6 (2.3–13.8) 13.0±5.1 (7.1–21.1) 0.066±0.022 (0.040–0.105) 3.73±1.98 (2.2–7.2) 3.66±1.95 (2.02–8.33) 1.64±0.92 (0.47–3.52)

5.6±3.6 (2.2–11.4) 9.6±3.7 (5.2–14.8) 0.054±0.027 (0.021–0.083) 4.12±2.58 (2.0–8.3) 3.95±2.28 (2.28–7.89) 1.45±0.37 (1.08–2.03)

Tac, tacrolimus; MZR, mizoribine; SDNS, steroid-dependent nephrotic syndrome; SRNS, steroid-resistant nephrotic syndrome a

Obtained 12 h after drug administration

b

Obtained 2 h after the drug administration

by doubling high-dose MZR combined with ARB plus an aldosterone blocker without recurrence of urinary β2microglobulin elevation. These study results indicate that with multidrug treatment, both the calculated relapse rate and the minimum dose of PDN required for maintenance of clinical remission in SDNS patients can be significantly decreased, as shown by the post-treatment evaluation conducted a mean of 18 months after starting multidrug therapy. Comparisons were made with the respective values obtained at the pretreatment evaluation (0.4±0.5 times per year vs 2.9±1.5 times per year, P=0.0077, and 0.3±0.2 mg/kg on alternate days vs 0.5±0.2 mg/kg on alternate days, P=0.0184 respectively; Table 3). The estimated GFR at the posttreatment evaluation showed no tendency to decrease compared with the pretreatment evaluation (P=0.2636). On the other hand, among the SRNS patients, although 3 achieved CR or PR, 2 remained refractory. In the 3 patients who were responsive to the treatment, the minimum dose of PDN required for maintenance of CR or PR decreased, although the decrease did not reach statistical significance.

None of the study patients showed a decrease in the estimated GFR except for 1 SRNS patient (Patient 13, who developed ESRD, as described above). No serious adverse effects, such as major or minor infections due to multidrug therapy, liver dysfunction, hypertension or hyperglycemia, were observed in any of our patients, except for 1 patient (Patient 14) with SRNS who showed a transient increase in urinary β2-microgloblin after 2 months of treatment, necessitating discontinuation of multidrug therapy. This patient had had a similar experience while on CsA therapy, as described above.

Discussion Recent advances in the treatment of refractory NS resistant or intolerant to CsA suggest that Tac may be an effective alternative to CsA [6–10]. Gulati et al. recently reported that CR was achieved in 16 of 19 children with SRNS receiving 12-month Tac treatment (84%) [8]. However, their study cohort included only 4 patients who were

Table 3 Pre- and post-treatment with multidrug therapy results in 14 children with refractory nephrotic syndrome Variable

Pre-treatment

Post-treatmenta

SDNS Calculated relapse rate (times/year) Minimum dose of prednisolone (mg/kg/alternate days)

2.9±1.5 (1.4–5.0) 0.5±0.2 (0.1–0.6)

0.4±0.5 (0–1.1)* 0.3±0.2 (0.1–0.6)**

138.8±16.5 (112.7–165)

127.6±27.6 (98.1–184.4)

0.4±0.3 (0–0.8) 128.4±40.5 (77.4–172.7)

0.3±0.2 (0.1–0.6) 121.5±30.5 (74.7–149.0)

Estimated GFR (ml/min/1.73 m2) SRNS Minimum dose of prednisolone (mg/kg/alternate days) Estimated GFR (ml/min/1.73 m2)

SDNS, steroid-dependent nephrotic syndrome; SRNS, steroid-resistant nephrotic syndrome *P value < 0.01 **P value < 0.05 a

Data obtained after a mean interval of 18 months after starting the therapy

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deemed to be CsA-resistant. Since treatment of patients with refractory NS is a major challenge that has yet to be overcome, we conducted this pilot trial of a multidrug regimen, consisting of relatively low-dose Tac administered once-daily plus MZR and PDN, to treat children with refractory NS. Moreover, 2 children with SDNS who showed biopsy-proven CsA-related nephrotoxicity were recruited as CsA-intolerant patients. Thus, all patients were judged as having NS that was difficult to treat. Tac is a calcineurin inhibitor, sharing a potentially nephrotoxic action with CsA [9, 14]. In this context, we previously reported daily, single-dose administration of Tac to be an effective and safe treatment in young patients with lupus nephritis [18]. Based on this clinical experience, we speculated that once-daily administration of the calcineurin inhibitor Tac might be beneficial for preventing progression of chronic nephrotoxicity, and that once-daily administration of low doses of Tac following our protocol could shorten exposure to the drug, although this remains speculative [13, 18]. We believe that the development of an optimal Tac treatment strategy for refractory NS, with administration of the lowest possible dose of Tac, would minimize treatment toxicity while maintaining efficacy [18]. Although we did not examine histological alterations following Tac treatment in this study, Tac was welltolerated in all study participants with stable estimated GFR values, except for 1 patient with SRNS. Also, none of the common Tac-related adverse events, such as severe diarrhea [8], occurred in this cohort. This may, partly, be attributable to the relatively low-dose Tac administered only once per day in our treatment protocol. On the other hand, the purine synthesis inhibitor, MZR, has a mode of action similar to that of MMF, and reportedly exhibits relatively low clinical toxicity in patients with NS [19, 20]. However, MZR has also been reported to have low clinical efficacy, as the sole immunosuppressant, for treating NS [19]. Interestingly, aside from its immunosuppressive effect, MZR also appears to have a beneficial effect against calcineurin inhibitors, CsA-induced intimal hyperplasia, and perivascular inflammatory cell infiltration in rat models [21, 22]. Moreover, Takeuchi et al. reported that MZR directly prevents podocyte injury in experimental puromycin aminonucleoside-induced nephropathy [23]. We recently documented significant suppression of intraglomerular and interstitial macrophage infiltration accompanied by significant suppression of chronicity indices following MZR treatment in patients with lupus nephritis [24]. Thus, we speculate that these histological observations might further support the use of MZR in the treatment of selected patients with glomerular diseases, especially those treated with calcineurin inhibitors, such as CsA or Tac. Our treatment protocol, adding MZR to Tac plus PDN treatment, might be beneficial for preventing calcineurin


inhibitor-related nephrotoxicity, although this remains to be examined in future studies. Since the mechanisms of action of calcineurin inhibitors and MZR are probably complementary, we hypothesized that combination therapy using low-dose Tac administered once-daily and MZR might be a beneficial alternative to CsA for the treatment of refractory NS in childhood [13], as postulated in a recent report describing the successful treatment of adult NS patients using multidrug therapy comprising Tac, MMF, and PDN [14]. Since therapy related-adverse events are a major therapeutic dilemma in the immunosuppressive treatment of patients with refractory NS, the optimal treatment strategy for managing refractory NS, especially in pediatric patients, remains controversial [13]. Regarding combination therapy consisting of Tac plus MMF in adult lupus patients, the incidence of therapy-related adverse events necessitating discontinuation of these drugs is reportedly high [25]. The present pilot study was conducted based on our previous clinical experiences with this novel multidrug therapy. We examined daily, single-dose administration of relatively low doses of Tac and MZR combined with PDN in two children with CsA-resistant FSGS who had therapy-related adverse events [13]. Our treatment protocol proved to be welltolerated in most of the present study patients. Thus, we believe our clinical observations to be useful for physicians managing NS patients, including patients with persistent sequelae after previous aggressive immunosuppressive treatment. This study has limitations. First, the study population was a clinically (i.e., gender, age, and disease duration) and histologically heterogeneous patient group from a single center with a short follow-up. These variations may have influenced the results. Second, the study was retrospective and involved a small number of patients without histological reevaluation. The retrospective nature of this study involving a small number of patients limits the power of analysis. Repeat biopsy is needed in future studies. Also, optimal doses and blood levels of Tac and MZR remain to be elucidated. Despite these limitations, we believe that this multidrug therapy with relatively low doses of Tac and MZR administered once daily in combination with PDN might be an effective and safe treatment for selected patients with CsA-resistant and/or CsA-intolerant refractory NS. However, the long-term efficacy and safety of this regimen remains unclear, and the therapeutic mechanisms underlying the effects of this regimen remain to be determined. No definite conclusions can be drawn based on our preliminary experiences. Further studies involving larger numbers of patients are needed to confirm the longterm efficacy and safety of multidrug therapy consisting of relatively low doses of Tac and MZR administered oncedaily in combination with PDN.


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Conflict of interest None declared. 14.

References 1. Hino S, Takemura T, Okada M, Murakami K, Yagi K, Fukushim K, Yoshioka K (1998) Follow-up study of children with nephrotic syndrome treated with a long-term moderate dose of cyclosporine. Am J Kidney Dis 31:932–939 2. Inoue Y, Iijima K, Nakamura H, Yoshikawa N (1999) Two-year cyclosporine treatment in children with steroid-dependent nephrotic syndrome. Pediatr Nephrol 13:33–38 3. El-Husseini A, El-Basuony F, Mahmoud I, Sheashaa H, Sabry A, Hassan R, Taha N, Hassan N, Sayed-Ahamad N, Sobh M (2005) Long-term effects of cyclosporine in children with idiopathic nephrotic syndrome: a single-centre experience. Nephrol Dial Transplant 20:2433–2438 4. Hamasaki Y, Yoshikawa N, Hattori S, Sasaki S, Iijima K, Nakanishi K, Matsuyama T, Ishikura K, Yata N, Kaneko T, Honda M (2009) Cyclosporine and steroid therapy in children with steroid-resistant nephrotic syndrome. Pediatr Nephrol 24:2177–2185 5. Suzuki K, Oki E, Tsuruga K, Aizawa-Yashiro T, Ito E, Tanaka H (2010) Benefits of once-daily administration of cyclosporine A for children with steroid-dependent, relapsing nephrotic syndrome. Tohoku J Exp Med 220:183–186 6. Bhimma R, Adhikari M, Asharam K, Connolly C (2006) Management of steroid-resistant focal segmental glomerulosclerosis in children using tacrolimus. Am J Nephrol 26:544–551 7. Suzuki K, Tsugawa K, Tanaka H (2006) Tacrolimus for the treatment of focal segmental glomerulosclerosis resistant to cyclosporine A. Pediatr Nephrol 21:1913–1914 8. Gulati S, Prasad N, Sharma RK, Kumar A, Gupta A, Baburaj VP (2008) Tacrolimus: a new therapy steroid-resistant nephrotic syndrome in children. Nephrol Dial Transplant 23:910–913 9. Butani L, Ramsamooj R (2009) Experience with tacrolimus in children with steroid-resistant nephrotic syndrome. Pediatr Nephrol 24:1517–1523 10. Roberti I, Vyas S (2010) Long-term outcome of children with steroid-resistant nephrotic syndrome treated with tacrolimus. Pediatr Nephrol 25:1117–1124 11. Cattran DC, Wang MM, Appel G, Matalon A, Briggs W (2004) Mycophenolate mofetil in the treatment of focal segmental glomerulosclerosis. Clin Nephrol 62:405–411 12. Okada M, Sigimoto K, Yagi K, Yanagida H, Tabata N, Takemura T (2007) Mycophenolate mofetil therapy for children with intractable nephrotic syndrome. Pediatr Int 49:933–937 13. Oki E, Tsuruga K, Kudo M, Tsugawa K, Suzuki K, Tanaka H (2009) A novel multidrug therapy for difficult cyclosporine-

15.

16.

17. 18.

19.

20. 21.

22.

23.

24.

25.

resistant focal segmental glomerulosclerosis. Pediatr Nephrol 24:773–775 Ballarin J, Poveda R, Ara J, Perez L, Calero C, Grinyo JM, Romero R (2007) Treatment of idiopathic membranous nephropathy with the combination of steroids, tacrolimus and mycophenolate mofetil: results of a pilot study. Nephrol Dial Transplant 22:3196–3201 International Study of Kidney Disease in Children (1981) The primary nephrotic syndrome in children: identification of patients with minimal change nephrotic syndrome from initial response to prednisone: a report of the International Study of Kidney Disease in Children. J Pediatr 98:561–564 Takeda A, Horike K, Onoda H, Ohtsuka Y, Yoshida A, Uchida K, Morozumi K (2007) Benefits of cyclosporine absorption profiling in nephrotic syndrome: preprandial once-daily administration of cyclosporine microemulsion improves slow absorption and can standardize the absorption profile. Nephrology (Carlton) 12:197– 204 Schwartz GJ (1992) Does kL/Pcr estimate GFR, or does GFR determine k? Pediatr Nephrol 6:512–515 Tanaka H, Oki E, Tsuruga K, Yashiro T, Hanada I, Ito E (2009) Management of young patients with lupus nephritis using tacrolimus administered as a single daily dose. Clin Nephrol 72:430–436 Yoshioka K, Ohashi Y, Sakai T, Ito H, Yoshikawa N, Nakamura H, Tanizawa T, Wada H, Maki S (2000) A multicenter trial of mizoribine compared with placebo in children with frequently relapsing nephrotic syndrome. Kidney Int 58:317–324 Honda M (2002) Nephrotic syndrome and mizoribine in children. Pediatr Int 44:210–216 Shimizu H, Takahashi M, Takeda S, Tahara K, Inoue S, Nakamata Y, Kaneko T, Takeyoshi I, Morishita Y, Kobayashi E (2003) Effect of conversion from cyclosporine A to mizoribine on transplant arteriosclerosis in rat aortic allograft models. Microsurgery 23:454–457 Hara S, Umino D, Someya T, Fujinaga S, Ohtomo Y, Murakami H, Shimizu T (2009) Protective effects of mizoribine on cyclosporine A nephropathy in rats. Pediatr Res 66:524–527 Takeuchi S, Hiromura K, Tomioka M, Takahashi S, Sakairi T, Maeshima A, Kaneko Y, Kuroiwa T, Nojima Y (2010) The immunosuppressive drug mizoribine directory prevents podocyte injury in puromycin aminosucleoside nephrosis. Nephron Exp Nephrol 116:e3–e10 Tanaka H, Oki E, Tsuruga K, Aizawa-Yashiro T, Ito Y, Sato N, Kawasaki Y, Suzuki J (2010) Mizoribine attenuates renal injury and macrophage infiltration in patients with severe lupus nephritis. Clin Rheumatol 29:1049–1054 Lanata CM, Mahmood T, Fine DM, Petri M (2010) Combination therapy of mycophenolate mofetil and tacrolimus in lupus nephritis. Lupus 19:935–940