Facing Cubicin generic threat, Merck's anti-infectives biz gets a nudge with new C. diff-fighter Zinplava

Merck building

The anti-infectives field is heating up--and Merck’s the latest Big Pharma player to win approval for a new entrant.

The New Jersey pharma giant Friday snagged a green light for Zinplava, a med meant to reduce comebacks of Clostridium difficile infection--better known as C. diff--in adults. The go-ahead followed an FDA delay; in July, the regulator asked for more data and analyses on the med from Merck's trials and simultaneously pushed back Zinplava's PDUFA date by three months.

Now, Zinplava will join a Merck anti-infectives portfolio that took shape with its early 2015 purchase of Cubist Pharmaceuticals. That buy brought in a range of meds that included the blockbuster antibiotic Cubicin, which fights antibiotic-resistant infections, instantly making Merck an established player in the field.

But with Cubicin's patent protection eroded in court--and the Supreme Court's decision in May not to take up the case--Merck will need Zinplava more than ever. Cubicin brought in $649 million in the first half of this year, but Hospira's copycat could make its debut by year's end.

For its part, however, Zinplava won’t hit numbers anywhere near Cubicin’s, analysts predict. The Thomson Reuters Cortellis database late last year pegged 2020 Zinplava sales at $350 million. Cubicin follow-up Zerbaxa, approved in late 2014, made its debut with estimates of $560 million in 2018 sales. 

Zinplava also faces the prospect of competition not only from other drugs, but also from vaccines that might prevent C. Diff altogether. Pfizer and Sanofi are each working on versions, and smaller vaccine makers are in the mix, too.

Meanwhile, Merck isn’t the only major drugmaker to be dabbling in anti-infectives. Demand for them is growing as bacteria evolve to withstand current treatments. Allergan boasts a pair of relative newcomers in antibiotics Avycaz and Dalvance, and Pfizer in August agreed to shell out up to $1.5 billion for AstraZeneca’s antibiotics stable.

In fact, one analyst predicted that Avycaz' early--and plentiful--sales could convince others to jump into the field. The gram-negative antibiotic’s early success “bodes well” for other gram-negative products coming up through the pipeline, “especially the ones that work on bugs for which all current options fail," Evercore ISI analyst Umer Raffat wrote in a note to clients.

Merck in-licensed Zinplava from Medarex in 2009, just before Bristol-Myers Squibb snapped up that drugmaker for $2.4 billion. 

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