Multicentre Clinical Study to Evaluate the Effect of Personalized Therapy on Patients With Immunoglobulin A Nephropathy.

BACKGROUND AND RATIONALE. Idiopathic Immunoglobulin A nephropathy (IgAN) is the most common biopsy-proven glomerulonephritis in the world. It is more prevalent in Asia than in Europe and the US. Approximately 40% of IgAN patients reach end-stage kidney disease (ESKD) 20 years after their kidney biopsy. The high prevalence of ESKD shows that IgAN has a significant economic impact in the all countries because renal replacement therapy is costly. Moreover, the disease's onset in the second and third decades of life represents a social challenge because young adult patients are very active and highly productive in the workplace. This challenge is one more reason to move from a generalized therapy for all patients to a personalized therapy.

The first edition of the KDIGO guidelines, published in 2012, suggested different therapeutic approaches for IgAN patients based on the clinical setting. However, the KDIGO guidelines do not consider the presence of active (endocapillary and extracapillary lesions) and chronic (tubulointerstitial lesions) renal lesions at the time of the kidney biopsy for therapy decision. The investigators of the clinical study in IgAN patients (CLIgAN) will consider for the patient's stratification the type of renal lesions, preliminarily, and then the clinical parameters as estimated glomerular filtration rate (eGFR) and proteinuria because the categorization of proteinuria and eGFR is not enough for a complete diagnosis of the disease.

AIMS. Considering the critical role of kidney biopsy, in the CLIgAN study the investigators plan to evaluate (i) the effect of corticosteroids combined with RASBs in IgAN patients with active renal lesions (ACIgAN) versus RASBs for 3 months followed by oral corticosteroids to determine whether the renal lesions are reversed by immediate corticosteroid therapy; (ii) the effect of SGLT2i in patients with chronic or moderate renal lesions (CHRONIgAN) to determine whether a delay of the ESKD onset is achieved; (iii) after the prediction of ESKD through the IgAN CDSS tool (DialCheck), to determine whether personalized therapy delays the impairment of the renal function; (iv) finally, on a small cohort of active and chronic IgAN patients enrolled in the CLIgAN study, a cutting edge-molecular study will be conducted to evaluate the effect of precision therapy (PRECIgAN).

STUDY DESIGN. The investigators have designed a prospective, multicentre, open-label clinical study that includes two multicentre randomized controlled trials (RCTs) based on the kidney biopsy report.

In the first RCT, patients with active renal lesions (E1 and/or C1), daily proteinuria >0.5 g and GFR ≥ 30 ml/min/1.72 m2 will be enrolled. They will be randomized to receive corticosteroids combined with RASBs in the experimental arm or RASBs alone in the control arm. Aim of this trial is to demostrate the benefit of corticosteroids in patients with active renal lesions.

In the second RCT, patients with chronic renal lesions (T1,2) and patients with moderate renal lesions (M0,1; S0,1; T0; E0; C0) at high or very high CKD risk (proteinuria> 0.5 g/day and GFR ≥ 30ml/min/1.73 m2) will be enrolled. They will be randomized to receive SGLT2 inhibitor (SGLT2i) combined with RASBs (experimental arm) or RASBs combined with corticosteroids (control arm). Aim of this trial is demostrate the benefit of SGLT2i combined with RASBs.

In conclusion, we have designed two RCTs (i) to study personalized therapy in biopsy-proven IgAN patients and (II) to monitor the outcomes to look at whether personalized therapy may delay the time to reach the ESKD predicted by our IgAN tool.

RECRUITMENT AND FOLLOW-UP. Renal Units will be involved in the enrollment of IgAN patients during a period of three years. The follow-up study to measure the outcomes will consist of regular visits at the prescribed times and to collect clinical and laboratory data and information on drug adherence. At the end of the trial, each patient will receive a final visit in the outpatient section.

OTHER MEAUSURES. Age, body mass index, eradication of infectious foci, or concurrent antibiotic therapy to prevent infections or to avoid the transformation of a trivial infection into a severe complication will be considered. Covid-19 vaccination will be done in all patients who will receive corticosteroids therapy. In addition, home and life conditions and culture will be analyzed. Regular daily exercise to prevent obesity and cardiovascular disease will be prescribed.

Dietary counseling. Patients with CKD stage 1 and 2 will observe the Mediterranean diet combined with reduced intake of proteins (1.0 - 0.8 g/kg bw/day). A reduced intake of proteins (0.6 - 0.8 g/kg bw/day) will also be prescribed to patients with CKD stage 3. Salt intake will be limited to 1.5 g/day. Dietary compliance will be assessed by measuring daily urinary sodium and urea excretion. Physical activity will be observed for 30 min. every day, primarily in the morning.

Severe adverse events. Infections, impaired glucose tolerance, weight gain, hypoglycemia will be monitored during the follow-up.

VARIABLES OF THE DISEASE. Kidney biopsy will be scored according to the Oxford classification because it is a simple method for predicting renal outcomes and for differentiating active and chronic renal lesions. Therefore, the kidney biopsy will be the principal key-note, not only for diagnosis but also for personalized therapy, because active renal lesions will be treated with immediate corticosteroid therapy before lesions become chronic. In some RCTs IgAN patients received six months of RASBs treatment before their enrollment for corticosteroid therapy. In our opinion this approach is not correct because the acute renal lesions evolve in the chronic stage and are no-responsive to corticosteroid therapy. Therefore, the aim of the first RCT is early treatment of the active renal lesions because they are responsible for altered GFR and proteinuria.

The definition of remission or no response of the MESTC lesions to therapy in published studies is inconsistent. Therefore, high-quality clinical trials with a large sample size are necessary to define the response of histological renal lesions to corticosteroids in biopsy-proven IgAN. The kidney biopsy will be analyzed using digital histopathologic analysis coupled with machine-learning tools. At least eight glomeruli will be available for a correct diagnosis. Renal tissue sections will be stained with hematoxylin and eosin, periodic acid-Schiff and methenamine silver. The last edition of the Oxford classification (MESTC) will be used for scoring the renal lesions.

Three independent renal pathologists, blinded to the study results, will score the lesions in the kidney biopsy using the Aperio System. The histology report will be necessary for the enrollment of patients. No larger RCT has confirmed that the disease improves when clinical decisions are made in a short time in the presence of the MESTC score.

• Serum creatinine will be measured using enzymatic methods calibrated to the National Institute of Standards and Technology's (NIST) liquid chromatography isotope dilution mass spectrometry method. eGFR creatinine will be evaluated by the CKD-EPI formula. Moreover, the slope of eGFR (16) will be calculated. Patients, categorized in CKD stages 1 to 3, will be included in the clinical study.
• Proteinuria. Patients will collect 24 hour urine for proteinuria. Values of >0.5 g/ day will be considered abnormal. Proteinuria reduction (geometric mean of 30% within 6 months), time-average proteinuria (TA-P) and slope of proteinuria will be evaluated.

Serum creatinine, proteinuria, age and hypertension have a lower weight when histological lesions are not considered. This finding highlights the importance of the kidney biopsy, not only for diagnosis but for personalized treatment.

• Blood hypertension is defined when values are > 130/80 mmHg or in subjects treated with anti-hypertensive drugs.
• For hyperuricemia allopurinol therapy is recommended.

SAMPLE SIZE CALCULATION.

ACIgAN. Data from the literature show a difference in renal survival between corticosteroids and controls when the researchers assumed a difference of 50% in the primary end point (i.e. in the between-arms difference of delta 24 hour proteinuria from baseline to 6 months) as clinically relevant. We assume that a mean delta proteinuria (±SD) from baseline to 6 months in patients treated with Ramipril alone (control arm) is 0.6±1.0 g/24 hours versus a mean delta proteinuria (±SD) from baseline to 6 months in patients treated with Ramipril and corticosteroids (experimental arm) 1.2±1.0 g/24 hours. Based on these assumptions, we calculated a sample size of 132 patients (66 patients per group including a 10% dropout rate) for a power of 90%, a two-sided significance level of 0.05 and 3 years of recruitment. If the number of the enrolled patients will be insufficient, the recruitment period will be extended for two years. At 4 months, all patients of the control arm who will display a 24 hour proteinuria >0.5g will be switched to the experimental treatment and will receive corticosteroids combined with RASBs for 4 months. They will be followed-up until the study termination.

CHRONIgAN. Data from the literature suggest a difference of renal survival between SGLT2is and controls. Here we assume a difference of 40% in the primary end point (i.e. in the between-arms difference of delta 24 hour proteinuria from baseline to 6 months) as clinically relevant. We assume that a mean delta proteinuria (±SD) from baseline to 6 months in patients with Ramipril alone is 0.6±1.0 g/24 hours versus a mean delta proteinuria (±SD) from baseline to 6 months in patients treated with SGLT-2 inhibitor and Ramipril (1.0±1.0 g/24 hours). Based on these assumptions, we have calculated a sample size of 294 patients (147 patients per group including a 10% dropout rate) for a power of 90%, a two-sided significance level of 0.05 and 3 years of recruitment. If the time-recruitment will be insufficient, the recruitment period will be extended for two years. At 6 months, all patients of the control arm who will display a 24 hour proteinuria >0.5 g will be switched to the experimental treatment (SGLT-2 inhibitor combined with Ramipril). They will be followed-up until the study termination.