Pfizer plans to launch the over-active bladder therapy Toviaz (fesoterodine fumarate) during the first half of 2009, about three years ahead of the expected generic competition to its current OAB franchise Detrol (tolterodine).

Toviaz cleared FDA Oct. 31 after a protracted review. The approval, however, still comes in time for Pfizer to build the new brand before its first Detrol patent expires in September 2012. Fesoterodine is a metabolite of tolterodine.

Pfizer licensed Toviaz from Schwarz in 2006. The agreement gave Pfizer rights to the drug in the U.S. for $100 million up-front, plus up to $110 million in potential product milestones (¹ Also see "Pfizer To Acquire Urology Agent Fesoterodine From Schwarz" - Pink Sheet, 13 April, 2006.).

The agreement also resolved pending patent litigation between the two firms, and includes a provision under which Schwarz will receive royalties on Detrol sales once Toviaz is launched (See ² Also see "Schwarz Shops Fesoterodine to Pfizer" - In Vivo, 1 May, 2006.).

The NDA for fesoterodine was pending in both the U.S. and EU before the deal with Pfizer. The application was approved in the EU in April 2007, but FDA issued an "approvable letter" in February 2007. That April, Pfizer cited manufacturing shortfalls on the part of Schwarz and projected it would not be able to launch the drug until 2009 (³ Also see "Pfizer Blames Fesoterodine Partner Schwarz For Launch Delay" - Pink Sheet, 20 April, 2007.).

The Detrol franchise is a significant contributor for Pfizer: worldwide sales totaled $901 million for the first three quarters of the year, up 4 percent. The U.S. market accounts for almost two-thirds of that amount ($604 million). Pfizer does not break out sales of fesoterodine in Europe.

Although growth of Detrol has slowed, Pfizer estimates that one in six Americans suffers OAB, many of whom go untreated or under-treated.

Two doses approved by FDA

Toviaz is indicated to treat OAB symptoms such as urge urinary incontinence, urgency and frequency of urination. It is approved for once-daily use in 4 mg and 8 mg doses. The label recommends 4 mg as a starting dose, with an increase to the 8 mg tablet to be based on individual response and tolerability.

The NDA included a pair of 12-week, randomized, placebo-controlled Phase III trials in which fesoterodine demonstrated a statistically significant and clinically meaningful improvement in decreasing the number of times participants needed to urinate and the number of leaking episodes each day, FDA said.

The majority of trial subjects were female with a mean age of 58. In the two trials, 554 patients received fesoterodine 4 mg daily, 566 received 8 mg daily of the study drug, and 554 received placebo. Pfizer said the 8 mg arm demonstrated up to an 88 percent reduction median reduction in urge urinary incontinence, compared with 50 percent for placebo recipients.

The most common side effects were dry mouth, reported by 19 percent in the 4 mg treatment arm, and 35 percent in the 8 mg arm. Less than 1 percent of participants, however, discontinued fesoterodine treatment due to dry mouth, Pfizer noted.

The drug also was tested for up to three years in open-label studies, demonstrating an adverse-event profile similar to the other studies, the company added.

Schwarz was purchased by Belgium's UCB in September 2006 in a deal that did not otherwise affect the agreement for fesoterodine (⁴ Also see "May The Schwarz Be With You: UCB Proposes $5.6 Bil. Acquisition" - Pink Sheet, 25 September, 2006.).

-Joseph Haas (j.haas@elsevier.com)

Pfizer Toviaz Clears FDA For OAB: Three-Year Window To Establish Detrol Successor

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