Study setback presents ominous signs for key osteoporosis drug class

Aug 20, 2009 (Datamonitor via COMTEX) -- LLY | Quote | Chart | News | PowerRating -- Eli Lilly has discontinued the development of osteoporosis drug arzoxifene after a recent study found that treatment with the second generation selective estrogen receptor modulator caused an increase in adverse events. The results raise further questions over the commercial potential of this drug class, with regulatory bodiesthe FDA likely to be increasingly concerned over their safety.

Following the results of the five-year GENERATIONS study, which involved 9,354 postmenopausal women, Eli Lilly announced that it will not be seeking FDA approval for its second generation selective estrogen receptor modulator (SERM) osteoporosis drug arzoxifene. Eli Lilly had hoped to launch arzoxifene as a follow-on product to its class leading Evista (raloxifene) prior to patent expiry in 2012. The Phase III study showed that while arzoxifene reduced vertebral fracture risk and invasive breast cancer, it did not have a significant effect on non-vertebral fractures and caused side-effects more frequently than placebo, including potentially fatal blood clots and , hot flushes and gynecological-related events.

In 2008, sales for SERMs reached $834m across the seven major markets (US, Japan, France, Germany, Italy, Spain, UK), with 64% of sales coming from the US. In the EU, uptake has been limited due to the poor efficacy on non-vertebral fractures and safety. Although several SERMs are currently in development, safety concerns have caused various FDA regulatory delays and Evista remains the only member of this class currently on the market. Most notably, Wyeth/Ligand's Conbriza/Viviant (bazedoxifene) and Pfizer/Ligand's Fablyn (lasofoxifene) have experienced numerous setbacks.

Wyeth's Conbriza and its combined SERM and estrogen therapy Aprela (bazedoxifene + conjugated estrogen, Wyeth) are now the closest SERMs to the US market. However, the results of arzoxifene's trial do not bode well for their prospects having highlighted further evidence of class-related safety issues. Previously, Evista has shown to cause similar serious cardiovascular events in patients. Nevertheless, should the FDA approve Conbriza and Aprela, Wyeth will be able to fully exploit the reduced competition. Assuming these drugs receive regulatory approval in this market, Datamonitor forecasts SERM class sales to reach a total of $969m sales in 2018 across the seven major markets.

For Eli Lilly, the withdrawal of arzoxifene substantially impacts its future osteoporosis franchise, which currently comprises Evista and Forteo (teriparatide) and was worth $1.4 billion in 2008 across the seven major markets. With the patent life of the franchise coming to an end, Eli Lilly will need to seek an alternative strategy to maintain its position in this lucrative therapy market, worth $9.6 billion globally in 2008.

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