Independent educational summary. This page summarises the PMDA document “Points to Consider for the Efficacy Evaluation of Drug for IgA Nephropathy (Early Consideration)” in plain language. Clinical Biostats created it by editing and summarising the document; it is not an official PMDA publication and is not legal or regulatory advice. Consult the official document for its full wording and context. PMDA provides the English version for reference purposes; if it differs from the Japanese original, the Japanese original prevails.
In Plain Language
IgA nephropathy can gradually damage the kidneys, but trials that wait for severe kidney failure to occur may take a long time. For trials in people with mild to moderate renal dysfunction, the document recommends setting eGFR slope or change in eGFR from baseline, based on an observation period of at least two years, as the primary endpoint. It also describes a possible role for urine protein-to-creatinine ratio (UPCR), a measure of protein in urine, when its effect and eGFR results observed up to that timepoint can reasonably predict a clinically meaningful eGFR result over two years or more. The document sets out basic considerations rather than a single trial design for every drug. Its purpose is to support development in Japan, including participation in global trials, while recognising that individual plans depend on the drug and its clinical positioning.
What This Guidance Covers
The document presents basic considerations for evaluating the efficacy of drugs being developed for IgA nephropathy, with particular attention to eGFR and UPCR. IgA nephropathy is described as a primary kidney inflammation involving deposits of immunoglobulin A (IgA) in the glomeruli, the filtering structures in the kidneys, and persistent blood and protein in the urine, without an underlying disease that could cause the condition.
The endpoint discussion is directed especially to clinical trials in patients with mild to moderate renal dysfunction. The document notes that trials for IgA nephropathy often include patients with relatively early chronic kidney disease (CKD), corresponding to eGFR of at least 30 mL/min/1.73m2. It says that the Japanese Guideline for Clinical Evaluation of Drugs for Early Chronic Kidney Disease defines early CKD as CKD with eGFR ≥30 mL/min/1.73m2. That definition provides context for the population discussed; the document does not set out a detailed eligibility rule for every IgA nephropathy trial.
The document focuses on efficacy evaluation and does not prescribe a complete protocol or a universal design for a particular product. It says that a specific clinical-trial design should be determined in view of the drug’s characteristics and clinical positioning. It also encourages sponsors to use PMDA consultations. The document notes that its considerations may change as new knowledge becomes available.
Why It Matters
The document describes IgA nephropathy as a serious disease: it reports that approximately 40% of patients progress to end-stage renal disease (ESRD) within 20 years of diagnosis. ESRD is the severe kidney-disease outcome discussed in the document, and the established endpoint for clinical evaluation of CKD is ESRD necessitating renal replacement therapy. However, trials using ESRD as their primary endpoint require a long period.
At the time of the document, the source describes treatment options and evidence gaps. Dilazep hydrochloride hydrate was approved in Japan for reducing urinary protein in IgA nephropathy with mild to moderate renal dysfunction, but the effect of long-term administration on suppressing progression of renal dysfunction remained unclear. Renin-angiotensin system inhibitors, corticosteroids, and immunosuppressants were also used, but their effects on improving renal prognosis in IgA nephropathy had not been verified, and standard treatment had not been established.
Against that background, clinical development has explored measures that could provide evidence sooner than waiting for ESRD events. The document discusses eGFR change from baseline, eGFR slope, and UPCR as possible surrogate endpoints. A surrogate endpoint is a measured outcome used in place of a later clinical outcome when it may provide information about that outcome. The document’s central concern is how to assess efficacy without losing sight of whether earlier measurements can reasonably anticipate a meaningful longer-term effect on kidney function.
Key Recommendations
For trials in mild to moderate renal dysfunction, consider an eGFR-based primary endpoint. In light of the Japanese clinical evaluation guidelines it discusses, the document recommends that clinical trials for IgA nephropathy with mild to moderate renal dysfunction set either eGFR slope or change in eGFR from baseline as the primary endpoint, based on an observation period of at least two years.
When using eGFR slope, use the total slope from treatment start. The document specifies that eGFR slope should be the total slope from the start of drug administration. This qualification is part of the endpoint consideration, rather than an optional alternative described in the document.
UPCR-based results may provide evidence in a particular evidentiary situation. The document allows that it may be possible to demonstrate a certain level of efficacy when the magnitude of the effect on UPCR over an observation period such as nine months, together with eGFR slope or change in eGFR from baseline observed up to that timepoint, can reasonably predict that results from at least two years of observation will show a clinically meaningful magnitude of effect on eGFR slope or change in eGFR from baseline. The possibility is conditional: it is not a general statement that a UPCR result at nine months alone establishes efficacy.
Consider the possible relevance of conditional approval only in the stated context. The document says that, given that treatment for IgA nephropathy is not established at present, the conditional approval system for drugs may potentially be applicable when clinical-trial results are determined to demonstrate a certain level of efficacy and safety of the investigational drug. For consultations about applying that system, it points to PMDA’s consultation system in accordance with the Director’s Notification named in the document.
The document presents these points as basic considerations for efficacy evaluation, not as a complete set of design instructions. In particular, it does not give a numerical UPCR threshold, a numerical minimum effect size for eGFR, or a single required observation schedule for every investigational drug.
Practical Implications
Interpretation: For sponsors and study teams, the primary-endpoint recommendation makes the planned observation period and kidney-function assessment central to trial planning. A protocol using eGFR slope should align the endpoint definition with the document’s stated starting point: the total slope from the start of drug administration. If the primary endpoint is change in eGFR from baseline, the plan should retain that endpoint and its observation period as the document describes them.
Interpretation: A shorter-term UPCR result may be relevant to an efficacy argument, but the document attaches an important predictive condition. Teams considering this route would need to assess whether the observed UPCR effect and eGFR evidence available up to the same timepoint can reasonably predict a clinically meaningful result in eGFR over two years or more. The document does not supply a universal rule or threshold for making that assessment, so the condition should not be reduced to “a decrease in UPCR is enough.”
For statisticians and clinical researchers, this means distinguishing the measurements and time horizons involved: UPCR is a urine protein measure, while eGFR slope and change from baseline describe kidney-function measures. The longer-term eGFR result remains the outcome whose clinically meaningful effect the shorter-term evidence is expected to predict in the conditional scenario described. Clinical operations teams may need to plan follow-up and data collection around the selected endpoint and observation period.
Interpretation: Regulatory and development teams should treat the endpoint approach as dependent on the product. The document explicitly says that a specific design should be determined based on the drug’s characteristics and clinical positioning, and strongly recommends use of PMDA consultations. The mention of possible conditional approval is not a statement that any particular trial result will qualify; the document connects that possibility to results showing a certain level of both efficacy and safety, and refers applicants to the named consultation system.
Technical Details
The endpoint considerations can be read as two related pathways:
For a clinical trial in IgA nephropathy with mild to moderate renal dysfunction, the document recommends setting eGFR slope or change in eGFR from baseline as the primary endpoint, based on an observation period of at least two years.
The eGFR slope should be the total slope from the start of drug administration.
For observation periods such as nine months, consider whether the UPCR effect and eGFR slope or change in eGFR observed up to that timepoint can reasonably predict a clinically meaningful eGFR effect over at least two years. Only in that circumstance does the document say it may be possible to demonstrate a certain level of efficacy.
The document’s discussion of surrogate endpoints reflects the challenge that ESRD-based trials require long follow-up. It notes that the Japanese Guideline for Clinical Evaluation of Drugs for Early Chronic Kidney Disease discusses observation periods and clinically meaningful effect sizes for eGFR slope, and the possibility of using reduction in albuminuria or proteinuria as a surrogate endpoint. For IgA nephropathy, it further reports that the guideline, based on a meta-analysis of randomized controlled trials, notes that early reduction in UPCR may potentially be used as a surrogate endpoint. Those statements provide context for the document’s conditional position; they do not add a fixed threshold to the recommendations presented here.
Who Should Read It
This document is relevant to sponsors planning clinical development for drugs intended to treat IgA nephropathy, particularly when trials include patients with mild to moderate renal dysfunction. Biostatisticians and clinical researchers may find it useful when considering endpoint choice, follow-up duration, and the relationship between early UPCR and eGFR findings and longer-term kidney-function results. Clinical operations teams, medical writers, investigators, and regulatory affairs staff may also use it to understand the endpoint considerations and the need to tailor study design to the drug’s characteristics and clinical positioning. It is especially relevant when a development program is considering participation in global clinical trials or a discussion with PMDA about an individual development plan.
Official PMDA Source
- Official title: Points to Consider for the Efficacy Evaluation of Drugs for IgA Nephropathy(Early Consideration)
- Issuing body: Pharmaceuticals and Medical Devices Agency, Office of New Drug I
- Date on the cover: December 24, 2025
- PMDA PDF: Official PMDA PDF
- PMDA list page: PMDA Early Consideration documents
Source: Pharmaceuticals and Medical Devices Agency (PMDA) website, PMDA list page. This page was created by editing and summarising the PMDA document.
Readers should consult the official document; this summary does not replace it. PMDA describes Early Consideration documents as reference information reflecting its views when published, which may change as scientific knowledge develops. The English version is supplied for reference, and the Japanese original takes precedence if the two versions are inconsistent.
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Key Takeaways
- For IgA nephropathy trials in mild to moderate renal dysfunction, the document recommends setting eGFR slope or change in eGFR from baseline as the primary endpoint, based on an observation period of at least two years.
- When eGFR slope is used, the document specifies the total slope from the start of drug administration.
- UPCR and eGFR results observed at an earlier timepoint may support a certain level of efficacy only when they can reasonably predict a clinically meaningful eGFR result over two years or more.
- Specific trial designs depend on the investigational drug and its clinical positioning; the document strongly recommends PMDA consultations.
- The document says conditional approval may potentially be applicable in the stated context of results demonstrating a certain level of efficacy and safety, but it does not establish a universal eligibility rule.