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Expert Interview

Slingshot members are talking to an expert! The topic is:

Discussing the Market Potential and Chances of Approval for FibroGen's (FGEN) Roxadustat Versus Akebia's (AKBA) Vadadustat for the Treatment of Anemia Associated with Chronic Kidney Disease (CKD)

Ticker(s): FGEN, AKBA

Who's the expert?

Name: Dr Edward Skolnik - MD

Institution: NYU


  • Director of Division of Nephrology, Norman S. Wikler Professor of Medicine & Professor of Pharmacology at NYU Langone.
  • In practice for 33 years, double board certified in Nephrology and Internal Medicine, and has extensive experience treating patients with CKD and FSGS.
  • Published a number of articles in peer reviewed journals and member of several professional organizations including The American Society for Clinical Investigation

Interview Questions

Please describe your experience treating patients with anemia associated with CKD. Roughly what percentage of your patients suffer from anemia associated with CKD? 

Added By: pjloria

Anemia in CKD patients is currently treated by iron pills, erythropoietin injections, red blood cell transfusions, vitamin B12 and folic acid supplements, or managing eating, diet, and nutrition. Which of these treatments do you use in your practice? How do you determine which treatment to use? Please discuss the safety and efficacy of each of these treatment options. 

Added By: pjloria

Vadadustat has been shown to inhibit hypoxia inducible factor-prolyl hydroxylase (HIF-PH), leading to stabilization and increased levels of HIFα. There are currently no approved therapies that utilize this mechanism of action. What are your opinions on this mechanism of action? Please compare the safety and efficacy of Vadadustat to treatments currently used.

Added By: pjloria

Roxadustat is an orally administered small molecule that corrects anemia by a different mechanism of action from that of ESAs. As a HIF-PH inhibitor, roxadustat activates a response that is naturally activated when the body responds to reduced oxygen levels in the blood, such as when a person adapts to high altitude.What are your opinions on this mechanism of action? Please compare the safety and efficacy of Roxadustat to treatments currently used.

Added By: pjloria

Roxadustat and Vadadustat are both HIF-PH inhibitors. Has the data suggested any significant differences in safety or efficacy between the two drugs? 

Added By: pjloria

How do you view the chances of approval for Vadadustat? For Roxadustat? 

Added By: pjloria

Assuming both are approved, what percentage of the market do you think each drug will attain and why? How do you see the market share for each drug changing over the next few years?

Added By: pjloria

Are there any other drugs in development that could disrupt the market? 

Added By: pjloria

Could you discuss the different dosing (TIW for Roxadustat vs. both daily and TIW for Vadadustat) in particular the possibility of tachyphylaxis with Vadadustat in the daily dosing as this graph is illustrating

Thanks to @Biomaven (Peter) for pointing it out.

Added By: maurice

Regarding the various HIF-PH enzymes (Prolyl Hydroxylases) PHD1, PHD2, and PHD3, Akebia's CEO postulates that the Hypoxia-Inducible Factor Stabilizers in development may be differentiated based on which of the 3 they hit. He mentioned that his drug, Vadadustat, may have lower peak EPO levels than Fibrogen & GSK's drug because it hits only the one (I believe he said PHD2) that creates a more moderate / stable EPO elevation. The others may hit 2 of the 3 or all 3. Is this a legitimate statement?

Added By: william gerber

Akebia's CEO claims potential safety differentiation with Vadadustat because it has not been shown to impact VEGF. Is this a major concern with the HIF stabilizers in development and, if so, do you think Vadadustat is differentiated in this regard?  If so, what is the biology behind the drug's differentiation with regard to VEGF. 

Added By: william gerber

Akebia's CEO claims potential advantage of Vadadustat because no drug-drug interactions have been seen with statins (CKD population is likely to have high % statin users).  Has DDI with statins been seen in other HIF stabilizers?  Is this a valid claim and, if so, what do you think the biology is behind this differentiation? 

Added By: william gerber

If the above questions do not address this, can you please describe what you believe may be the cost and resources implications of HIF stabilizers getting approved. For example, hospital/clinic visits for rhEPO infusions, blood transfusion, iron deficiency and any other costs like rhEPO storage vs oral HIF stabilizers.  How might these factors impact market uptake, formulary inclusion, etc.?

Added By: william gerber

Do you see any material differences in trial designs for Roxadustat, Vadadustat, Daprodustat, etc including endpoints, eligibility, exclusions?  Are there differences that could impact outcomes and/or labels? 

Added By: william gerber

What do you believe are the most important indicators/biomarkers for HIF stabilizer efficacy besides appropriate increase in Hb?  Various indicators cited by these companies include evidence of iron mobilization based on increase in total iron binding capacity (TIBC), reductions in hepcidin, lowering of Cystatin C (Cys-C) and improved/stabilized glomerular filtration rate (GFR).  Which ones are important and trustworthy (accuracy of measurement), if any?

Added By: william gerber

What are the potential implications of the total cholesterol-lowering effect of roxadustat for CKD and dialysis patients?

Added By: userb48c2f78

In your opinion, which investigational HIF product will be the first to be submitted for approval by the FDA, based upon the status of the key Phase 3 trials?  Fibrogen continues to report that it is on track to file an NDA for roxadustat in 2018.  Is this timeline realistic?

Added By: userb48c2f78

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