FibroGen has not even filed its AstraZeneca-partnered oral anemia drug roxadustat for U.S. approval. But the collaborators have already scored their second nod for the blockbuster hopeful in China.

Last December, the pair made a rare—if not only—case out of roxadustat by racking up its first-in-class approval in China before any other country. At that time, Chinese authorities greenlighted the drug for patients on dialysis. With this second approval, it’s now allowed to treat the larger nondialysis-dependent group.

Assuming a green light across the chronic kidney disease population was close, SVB Leerink analyst Geoffrey Porges has projected roxadustat sales could reach $1 billion in China alone by 2025.

The current approval is primarily based on a phase 3 trial that showed roxadustat could increase patients’ hemoglobin levels by a mean of 1.9 g/dL, compared with a reduction of 0.4 g/dL among patients on placebo. In a previous China-specific trial on dialysis-dependent patients, the drug produced a numerically greater hemoglobin improvement versus Johnson & Johnson and Amgen’s Epogen/Procrit.

Because FibroGen was relocating its Chinese manufacturing site, the drugmakers couldn’t immediately launch roxadustat in China, and they’re still eyeing an official rollout later this year. But AstraZeneca has already been preparing for talks with the Chinese government to include roxadustat on the country’s National Reimbursement Drug List. Results of those talks are expected around the end of this year, Leon Wong, AstraZeneca’s EVP in charge of China and emerging markets told investors on a conference call in July.

China’s National Healthcare Security Administration—the watchdog of national medical insurance—unveiled an update to the list on Tuesday and said negotiations are underway to add another 128 drugs.

As the NRDL process is still pending, AstraZeneca "will also explore other market access strategies such as Critical Disease Insurance, ad hoc negotiations with individual provinces, and national tendering," a company spokesman told FiercePharma.

In the U.S., the spokesman said a filing is still on track within 2019. FibroGen, the drug application holder, previously said it was expecting an FDA submission in September or October. At least in China, "we believe that we are several years ahead of our competitors," he said.

Roxadustat is the first in the hypoxia-inducible factor prolyl hydroxylase inhibitor class to win an approval anywhere. Its second Chinese nod came just as GlaxoSmithKline picked Japan to be its first country to file for its rival drug daprodustat. Astellas, which holds roxadustat rights in Japan, filed for local approval in October, and Mitsubishi Tanabe, through a collaboration with Akebia Therapeutics, is awaiting a Japanese decision on their contender, vadadustat.

The hope for roxadustat is to upend standard erythropoiesis-stimulating agents (ESAs) like Epogen. Besides efficacy, the main upside for the FibroGen-AZ drug could lie in its cardiovascular safety profile, as a black box warning for CV harm is shared among all ESAs.

But investors were confused when FibroGen in May said a pooled analysis found the drug only showed "no clinically meaningful difference" versus placebo in the nondialysis-dependent population or to ESA in dialysis-dependent patients.

That analysis covered seven different trials, Wolfe Research analyst Tim Anderson said in a recent note. And because it’s a complex dataset encompassing multiple studies, analysts at Jefferies previously said the confusing readout was not as negative as investors had feared.

In all, the companies have reported positive results from 12 of roxadustat's 15 phase 3 trials, FibroGen said in May.

"Obviously we have to have conversations with the regulators about how we do the analysis, what analysis we look at, and ultimately looking at totality of all the safety data, not just the CV risk, before we decide on the path forward," Mene Pangalos, AstraZeneca’s EVP of R&D BioPharmaceuticals, said during a June conversation with Anderson.

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