Blog entry by Meguid El Nahas

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by Meguid El Nahas - Wednesday, 1 May 2013, 11:13 AM
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FDA Limits Duration, Usage of Tolvaptan Due to Possible Liver Injury

ROCKVILLE, Md -- April 30, 2013 -- The US Food and Drug Administration (FDA) has determined that the drug tolvaptan (Samsca) should not be used for longer than 30 days and should not be used in patients with underlying liver disease because it can cause liver injury, potentially requiring liver transplant or death. An increased risk of liver injury was observed in recent large clinical trials evaluating tolvaptan for a new use in patients with autosomal dominant polycystic kidney disease (ADPKD)

The FDA has worked with the manufacturer to revise the tolvaptan drug label to include these new limitations.

The tolvaptan drug label has been updated to include the following information:

• Limitation of the duration of tolvaptan treatment to 30 days (Dosage and Administration and Warnings and Precautions sections)

• Removal of the indication for use in patients with cirrhosis. Use of tolvaptan in patients with underlying liver disease, including cirrhosis, should be avoided because the ability to recover from liver injury may be impaired (Indications and Usage and Use in Specific Populations sections).

• Description of liver injuries seen in clinical trials of patients with ADPKD.

• Recommendation to discontinue tolvaptan in patients with symptoms of liver injury.

Data Summary

Tolvaptan was approved in May 2009 for the treatment of clinically significant euvolemic and hypervolemic hyponatremia. Patients should be in a hospital for initiation and re-initiation of therapy to evaluate the therapeutic response before subsequently receiving tolvaptan in the outpatient setting.

Tolvaptan is being studied for another indication: delay in progression of renal disease in adult patients with ADPKD. Three cases of serious liver injury attributed to tolvaptan were observed in a placebo-controlled trial in ADPKD and its open-label extension study, indicating the potential for the drug to cause liver injury that could progress to liver failure.

In addition, tolvaptan was associated with an increased incidence of ALT elevations greater than 3 times the upper limit of normal: 42 of 958 (4.4%) patients in the tolvaptan group versus 5 of 484 (1.0%) patients in the placebo group. The serious liver injury cases were consistent with Hy’s law.

Analysis of safety information in the clinical trials that supported the hyponatremia indication (and in other populations such as those with heart failure) did not demonstrate hepatotoxicity. However, the controlled hyponatremia trials were of short duration --about 30 days.

Although the FDA has received spontaneous post-marketing reports of elevated liver enzymes and other liver events in patients taking tolvaptan, these reports are difficult to interpret because many of the patients had underlying disease that can be associated with elevated liver enzymes or liver injury (cirrhosis, heart failure or cancer).

Based on the cases of liver injury in patients participating in the ADPKD trials, the FDA worked with the manufacturer to revise the tolvaptan drug label to include the above information, to reduce the potential for serious liver injury.

Comment:

Another drug bites the dust...and reminds us all that post-marketing surveillance is key to ascertain the safety of new medications.

The TEMPO study of Tolvaptan in ADPKD showed a marginal benefit on CKD progression.

Enthusiasts and those prompted by the sponsor/Pharma claimed a breakthrough in ADPKD management, in spite of the fact that the benefit on CKD progression was minimal (see OLA Blog TEMPO TEMPERED).

So now it seems that whilst the BENEFIT is marginal,  the RISK, side effects, is potentially high.

Back to the drawing board with the management of ADPKD; mTOR antagonists also have a bad/high RISK v BENEFIT profile!

For alternative therapeutic interventions to slow cysts progression and CKD in ADPKD, see the excellent review by Chang & Ong in Nephron:

3 hopeful strategies for ADPKD: 1. reduce intracellular cAMP manipulations, 2. inhibit cell proliferation, 3. reduce tubular fluid secretion.

http://www.ncbi.nlm.nih.gov/pubmed/22205396

Also more mundane interventios such as BP control and RAAS inhibition: HALT_PKD trial: The HALT-PKD study (underway) may tell us all we need to know that to slow the progression of ADPKD we need to optimise BP control...but that combination ACEi + ARB may not be such a good idea after all....this trial may have been overtaken by the negative outcomes of trials of maximum/combined RAAS inhibition (such as ONTARGET and ALTITUDE). Is it still a viable option????

The ADPKD trials story also reminds us of the value of surrogate markers; intervention such as mTOR antagonists and VAPTANS (TOLVAPTAN) reduce cyst size and their expansion...BUT...hardly affect kidney function....!!!! surrogates...surrogates...surrogates....are NO substitutes for HARD ENDPOINTS.

Finally, manipulating key intracellular mediators such as cAMP (Tolvaptan), mTOR (Sirolimus and everolimus) or even key mediators such as the RAA system may do more harm than good!

So far the lessons of clinical translation in ADPKD:

What works in rats and mice doesnt always translate safely and effectively into humans...!!!

[ Modified: Thursday, 1 January 1970, 1:00 AM ]