Blog entry by Meguid El Nahas

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by Meguid El Nahas - Friday, 20 July 2012, 9:08 AM
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This study by Giovanni Stallone1,etal published early online -NDT Advance Access published July 10, 2012 added to the 3 previously published studies about the role of Rapamycin for the treatment of ADPKD.

Rapamycin for treatment of type I autosomal dominant polycystic kidney disease (RAPYD-study): a randomized, controlled study

In this prospective, open-label randomized clinical trial, 55 ADPKD patients followed in the outpatient clinic of the two participating centres (University of Foggia and Bari, Italy) were enrolled between November 2007 and November 2008. The duration of the planned follow-up was
24 months.
The inclusion criteria were clinical, genetic and ultrasonographic diagnosis of type I ADPKD, age between 18 and 65 years and an estimated glomerular filtration rate (eGFR) between 40 and 80 mL/min/1.73 m2, evaluated by the abbreviated Modification of Diet in Renal Disease (MDRD) formula

The primary objectives were to assess whether rapamycin may reduce the progressive increase in single cyst and total kidney volume in type I ADPKD and the decline in renal function and to identify the optimal rapamycin dose to achieve the beneficial results without incurring inmajor side effects.
After a screening assessment, all patients entered a run-in phase of 2 months in which eGFR and 24 h proteinuria were evaluated every 2 weeks. At the beginning of this period, in patients already treated with angiotensin-converting enzyme inhibitors (ACE-I) and angiotensin II receptor blockers (ARBs), these drugs were withdrawn for at least 4 weeks before performing the laboratory tests.

At the end of the run-in phase, all eligible patients were randomly assigned to ramipril alone (Group A) or ramipril plus high-dose rapamycin (Group B) or ramipril plus low-dose rapamycin (Group C). In Group B, rapamycin administration was given with a loading dose of 3 mg. The maintenance dose was 1 mg/day aiming at a blood trough level between 6 and 8 ng/mL. In Group C, the patients did not receive a
loading dose and the maintenance dose of rapamycin was 1 mg/day to reach a blood trough level between 2 and 4 ng/mL.
Magnetic resonance imaging technique .All patients recruited for our study underwent a standardized magnetic resonance imaging (MRI) examination at the baseline (T = 0) and after 24 months of initiation of drug therapy (T = 24) with the same MRI scanner.
Genetic analysis
DNA isolation and linkage analysis. Genomic DNA was derived from whole blood using Purelink Genomic DNA Mini kit (Invitrogen), according to the manufacturer’s protocol.
Epidermal growth factor urinary concentration:
was evaluated by ELISA and the results were normalized to urine creatinine excretion.
Results:
The mean rapamycin trough levels were 6.4 ± 0.3 ng/mL for Group B and 3.2 ± 0.4 ng/mL for Group C. The differences between the two groups were statistically significant at each time point for Group C.
Primary outcomes:
In all three groups of patients, They observed an increased total kidney volume. Specifically,
in Groups A and B, there was a statistically significant increase in kidney volume after 24 months of treatment (P = 0.003 and 0.02, respectively), while in Group C, the increase failed to reach the statistical significance However, they did not observe any significant difference in change of kidney volume among the three study groups at the end of the observational period.
On the contrary, the cyst volume was increased in Group A patients after 24 months of treatment (P < 0.0001 versus basal), whereas it was significantly reduced in Group B (P < 0.0001 versus basal) and Group C (P <0.0001 versus basal) Also, in the case of single cyst volume, they did not observe any
significant difference among the three study groups at the end of the observational period.
Renal function analysis. They observed a decline in estimated creatinine clearance in Group A patients (P = 0.01, T24 versus T0),whereas in Groups B and C after 24 months, they observed
a slight increase in GFR, although the differences did not reach statistical significance .
The changes in the estimated creatinine clearance in the three groups at
the end were not significantly different.
EGF urine excretion. an increased EGF urinary excretion in Group A patients (P =0.001 versus T0) was observed, whereas the treatment groups were characterized by a significant reduction after 24 months
(Group B: P = 0.0001 versus T0; Group C: P = 0.0001 versus T0)
In conclusion:
The results of this pilot study suggest that rapamycin treatment at a dose effectively inhibiting p70S6 kinase in circulating PBMCs does not significantly slow down cyst growth and renal function decline featuring the natural history of ADPKD

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