Approvable Letter Mania

I am beginning to believe that there have been a flood of approvable letters, though I haven’t gone back over the years to count the rate – but my gut tells me that the rate has increased.  It is a little difficult to determine for sure because the FDA does not announce approvable letters, only companies announce them.  Their contents are proprietary to the company, meaning they don’t have to tell us what is in them.  But with news last week I looked at the year for one company – Wyeth. 

If you need an update on what an approvable letter means, check out my posting on What Does Approvable Mean as well as  past postings on approvable letters. 

This week Wyeth announced another approvable letter – this one for Pristiq, a serotonin-norepinephrine reuptake inhibitor, currently under review as a treatment for moderate-to-severe hot flashes and night sweats associated with menopause. 

I say "another" because not only is it another in what feels like a spate of FDA-issued approvable letters, but because it is another approvable letter for Wyeth, which received one earlier this year for Pristiq for major depressive disorder.   While this one did not require further clinical study, it was received in January, 2007 and Wyeth is not anticipating submitting a response until August. 

And then in April of this year, Wyeth announced an approvable letter for bazedoxifene, a selective estrogen receptor modulator (SERM) for the prevention of postmenopausal osteoporosis.   In that one, there were a few issues at stake, including a plant inspection:

The approvable letter indicates, among other things, that before the New Drug Application (NDA) can be approved:

• FDA must receive and analyze, as part of its benefit-risk assessment, final safety and efficacy data from the recently completed Phase 3 treatment study of bazedoxifene, which was discussed during the Company’s earnings call last week.      
• FDA must complete an acceptable establishment evaluation for the manufacturing and testing facilities for bazedoxifene.  The FDA concluded its general re-inspection of Wyeth’s Guayama facility in early April, and Wyeth has provided a written response to the FDA’s observations.  We believe the situation at the Guayama facility will be resolved without affecting the timing of new product launches.

In this latest one, it was not good news.  As you will remember from past postings about approvable letters, the matters that the FDA would like to have resolved can be relatively minor and involve little time, or can involve new trials that mean added expense and time before approval.  In this case, the agency asked the company for more data from a randomized, placebo-controlled clinical trial of a duration of one year or more conducted in postmenopausal women.  Also in April, the company announced that the PDUFA date for Torisel™ (temsirolimus), Wyeth’s investigational treatment for advanced renal cell carcinoma (RCC) had been extended by three months (until July).  It was originally filed with a priority status.  No word on that front yet that I could tell, but July is slipping away.   

The impact of this latest approvable letter on Wyeth’s trading was a 10% tumble according to PharmaTimes. 

It would be an interesting exercise, and one I intend to undertake when I have a moment, to see if the FDA has issued more approvable letters this year than they have approval letters.  If someone already knows the answer, I’d love to hear from you!