Adding a bit of zing to Thursday, Merck announced it was halting Phase III trials of its experimental osteoporosis drug odanacatib because the data monitoring committee's interim check of its five-year study showed “robust efficacy and a favorable risk-benefit profile” among more than 16,000 participants.
Safety data has yet to be released, but analysts are hopeful that Merck's drug could be a boon for the category for two reasons: first, Bernstein analyst Tim Anderson pegged the osteoporosis market at $8 billion before generics stepped in. Second, the drug works differently from bisphosphonates like Boniva, Reclast and Fosamax. These drugs have triggered concern at the FDA that long-term use of these drugs may be linked to a higher risk of fractures, cancer and jaw erosion. Merck's osteoporosis candidate is a cathepsin-K inhibitor, meaning it focuses on the primary enzyme that digests proteins that are part of regular bone renewal. Bone breakdown and rebuilding is a natural process, but it becomes a problem when it becomes lopsided and more bone is broken down than replaced.
However, being new doesn't mean cathepsin-K inhibition is without baggage: Novartis halted exploration of its cathepsin-K inhibitor, balicatib, because it was linked to a hardening of the skin.
“The outstanding question is what safety issues require follow-up, particularly given odanacatib's placebo-like safety profile over five years of follow-up in Phase II,” Leerink Swann analyst Seamus Fernandez wrote in a research report Thursday. Fernandez said a successful drug could have peak sales of $975 million in 2020 with a global sales potential of over $3 billion.
Bernstein's Anderson is also positive about Merck's prospects, but cautioned that the initial results are only as compared with a placebo and said “it will be critical to see how the fracture data with odanacatib stacks up versus existing therapies.” His Thursday report forecast sales of about $418 million in 2016, reaching $1.5 billion by 2020, with the potential to take a bite out of Lilly's Evista, Novartis' Reclast and Amgen's Prolia
Merck said in a statement that it will go forward with a previously announced blinded extension trial and will publish results from the recently terminated study in 2013. The company expects to submit odanacatib to the FDA next year.