Sunday, December 1, 2013

Go #TeamTolvaptan

This is just a picture of the ballot
go to RFN to cast you ballot.
One of my favorite end-of-the-year traditions is Renal Fellow Network's top nephrology stories of the year. Make sure you vote. The authors did a great job selecting 2013's top stories of nephrology somehow they forgot the Omontys allergic reaction, voluntary recall and abandonment of peginesatide.

(I thought of one more but it escapes me, I'll update this post when I remember it.)

Looking over the list, I think the story of the year is Tolvaptan's failure to FDA gain approval for ADPKD. If Tolvaptan gains FDA approval in the next year or two following re-submission this story will quickly be forgotten. But if the future goes the other way, if Otsuka abandons tolvaptan for ADPKD and decides to remain in the limited ghetto of inpatient management of hyponatremia that would be a tragedy.

Part of what gets my blood boiling is the raging hypocrisy that the very same organization that approved:
  • Zemplar (paricalcitol)
  • Hecterol (doxercalciferol)
  • Renagel (sevelamer)
  • Renvela (sevelamer again)
  • Fosrenal (lanthium carbonate)
  • Sensipar (cinacalcet)
(all drugs that have never been shown to help a patient but merely to improve some biochemical target. Hell, even sevelamer and cinacalcet tried and failed to show reduced mortality and they remain on the market) had the gall to deny tolvaptan for ADPKD.

ADPKD slowed cyst growth and slowed the progression of kidney disease. Not just for one year but for three years! It joins ACEi/ARBs and insulin in the pantheon of drugs that can slow the progression of CKD (though bicarbonate and allopurionol are walking toward the door). Denying it was preposterous.

The other part of my rage comes from possibilities of having tolvaptan available as an outpatient option for patients. I certainly want this drug available for ADPKD but turning it from a limited duration in-patient drug to a chronic outpatient therapy will completely remake the cost structure.

The price will remain high but it will no longer be $300/pill. Let us say $1000 per month. The TEMPO trial used 120 mg per day, so a month worth would be 120 pills. That would go a long way if you were interested in using tolvaptan for aquaresis. This drug is effective at increasing urine output by a mechanism totally novel to us. We are being given control over one of the fundamental control levers of the kidney. There are only limited number of these levers:
Look it how useful the drugs are that affect these hormones. The list is full of all-stars. Tolvaptan has already been proven a winner in ADPKD and maybe useful in CHF. Tolvaptan failed a pivotal trial called EVEREST, but the drug did increase diuresis, fluid loss, and the effects were long lasting. Tolvaptan failed one trial on heart failure, but alternative patient selection or dosing regimens could turn this turkey into another critical tool for heart failure. We need to have this drug available to see where it can be useful because today we are primitives.

If the FDA approves it, the fact that it failed its first application will be quickly forgotten, but if Otsuka decides to retreat from this breakthrough and live happily ever after correcting mild asymptomatic hyponatremia nephrology will be a poorer place.
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