That was remarkably fast: Just nine days into its Gardasil 9 review, China's revamped drug regulator handed Merck's HPV vaccine a conditional green light—a new approval tool the agency is testing in its quest to speed new drugs to market.

It's a move that could further compress the living space of GlaxoSmithKline’s Cervarix, already pressed by Merck's previous version of Gardasil, which covered four HPV strains instead of the latest product's nine.

China’s Food and Drug Administration based its decision on Gardasil data that previously led to the quadrivalent shot’s Chinese approval last May, and for the latest approval, considered foreign clinical trial data specifically on Gardasil 9, the agency said in a Sunday announcement (Chinese). The conditional approval comes with requirements for additional studies and postmarketing surveillance.

Even in the U.S., conditional approval is a fairly new tool that has only gained popularity at the FDA in recent years. China's former CFDA largely followed its U.S. counterpart’s "accelerated approval" standards when the agency proposed its own conditional approval pathway in May 2017. The top government finalized that plan in principle last October—along with a provision that allows foreign clinical data into drug applications. But detailed guidance for those approvals just wrapped up public comment mid-January.

RELATED: China creates new drug regulator in biggest government overhaul in years

Under those new rules, Gardasil 9 took a smooth regulatory road toward its approval. After accepting Merck’s new drug application on April 20, the agency put the shot on its proposed expedited review list on April 23. A five-day window for comment followed, and the vaccine apparently immediately moved to its approval afterward. CFDA announced on Sunday that it had granted the conditional approval the day before.

GSK’s Cervarix and Merck’s previous version of Gardasil weren’t so lucky. At a time when the Chinese regulatory process was widely considered too slow, both vaccines took about 10 years to reach the Chinese market. To hasten the launch of novel drugs and to work through the notoriously large backlog of applications for clinical trial and new drug approvals, the Chinese agency made scores of game-changing new rules in recent months. Ruyi He, M.D., chief scientist of its Center for Drug Evaluation, has said on several occasions that by 2020 the agency plans to double the number of drug reviewers to 1,600 from 800—and that’s up from just about 170 in 2015.

Zooming into the HPV arena now, Gardasil 9 could pose an additional threat to Cervarix, which has already lost out to the Merck duo in major markets in the U.S. and Europe. China might be its last chance to garner a meaningful amount of sales.

RELATED: Gardasil 9 supply running short in the U.K., Merck reports

Cervarix was officially launched in China late last July, a year after it became the first HPV shot approved in the country. For the fourth quarter of 2017 and first quarter of 2018, Cervarix enjoyed sales of £62 million ($85 million) and £52 million, respectively, with both quarters' results more than double those of the same period of the previous year. The British pharma made it clear in its reports that the vaccine's overall growth was "driven by its recent launch in China."

Gardasil, which won its Chinese nod last May, was officially launched in November through local distributor Zhifei Biological Products. Given that Merck reported $2.31 billion in sales from the Gardasil family last year—up from $2.17 billion in 2016—China's early contribution wasn't singled out. But in revising an exclusive supply contract with Merck last September, Zhifei disclosed that it bought 542 million Chinese yuan ($85.6 million) worth of Gardasil in 2017. Another 1.37 billion yuan ($217 million) was planned for 2018, and 1.78 billion yuan and 2.23 billion yuan for the following two years.

It’s not clear whether Merck will tap Zhifei’s help again to market Gardasil 9 in China. But chances are high, given that the Chinese company also takes care of Merck’s hepatitis A vaccine Vaqta, pneumococcal vaccine Pneumovax 23, and pentavalent rotavirus vaccine RotaTeq, which was just greenlighted in China on April 12.

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