AstraZeneca wins speedy FDA review for Imfinzi to challenge Roche in small cell lung cancer

In their separate trials, the Imfinzi-chemo combo appeared to do better than the Tecentriq pairing in new small cell lung cancer patients with brain metastases, SVB Leerink analyst Daina Graybosch noted. (AstraZeneca)

The FDA has put AstraZeneca’s Imfinzi in the fast lane toward a potential nod in previously untreated small cell lung cancer, where Roche’s Tecentriq has been the sole player since March.

Thanks to an FDA priority review, Imfinzi is now looking at an early decision by the first quarter of 2020 for its use in first-line extensive-stage SCLC, AstraZeneca said Friday.

AZ filed the new application with positive phase 3 results showing Imfinzi, in tandem with standard chemotherapy, could cut the risk of death by 27% compared with chemo alone.

Survival benefits from the two PD-L1 inhibitors in separate trials appear comparable. In the Caspian study, the Imfinzi-chemo regimen prolonged patients’ lives by 13 months, versus 10.3 months for the chemo arm. In the IMpower133 study, patients on solo chemo also lived a median 10.3 months, while those on the Tecentriq cocktail survived 12.3 months, which Roche said translates into a 30% reduction in the risk of death.

If ultimately approved, Imfinzi could offer physicians the flexibility of choosing between two platinum-based chemos, carboplatin or cisplatin, to pair with Imfinzi and another chemo drug etoposide. In comparison, Tecentriq’s approval is only for use alongside carboplatin.

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When AZ first reported the top-line data at the World Conference on Lung Cancer annual meeting in September, SVB Leerink analyst Daina Graybosch also noted that patients with brain metastases performed better on Imfinzi than Tecentriq. In Caspian, Imfinzi-chemo cut the risk of death by 31% in 55 brain metastases patients, while in IMpower133, the Tecentriq regimen performed almost on par with chemo in 35 such patients.

SCLC is a badly needed win for AZ even though it only accounts for about 15% of all lung cancer cases. While Imfinzi has enjoyed success as a treatment for unresectable stage 3 non-small cell lung cancer, it flopped against chemo in the all-important Mystic study pairing it with AZ’s own CTLA4 inhibitor tremelimumab. The Imfinzi+tremelimumab+chemo combo also failed to meet statistical success at an interim analysis in Caspian, Graybosch noted in the September report, though AZ is continuing the trial for final overall survival analysis.

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Meanwhile, Merck & Co.’s PD-1 king Keytruda is also being tested alongside chemo in frontline ES-SCLC in the Keynote-604 study, which could read out before year-end.  

Dubbing it “the most important near-term catalyst” for Keytruda, Graybosch argued the indication offers Merck an opportunity to further build loyalty among oncologists. The SVB Leerink analyst estimates the total frontline U.S. SCLC market for PD-1/L1s could be worth about $1.2 billion a year.