The US FDA has started its priority review of AstraZeneca’s Tagrisso for first-line non-small cell lung cancer (NSCLC), setting up a possible approval in the first half of 2018.
Third-generation EGFR inhibitor Tagrisso (osimertinib) is already approved as a follow-up to older drugs in the class, including AZ’s own Iressa (gefitinib) product and Roche’s Tarceva (erlotinib), but expansion into front-line use could dramatically increase its sales potential. It’s also under review for first line-use in the EU, having been filed there in November.
Tagrisso is already one of the fastest-growing new products in AZ’s portfolio, with sales rising 138% to $651m in the first nine months of the year, and AZ wants to position the drug as a new first-line standard of care in NSCLC that would propel it to blockbuster status. It has already overtaken Iressa, which brought in $398m in the same period.
The data backing the new application comes from the FLAURA trial in patients with metastatic NSCLC whose tumours have EGFR mutations (exon 19 deletions or exon 21 (L858R) substitution mutations), which showed that Tagrisso extended progression-free survival (PFS) compared to Iressa and Tarceva.
PFS in patients taking Tagrisso was 18.9 months compared to 10.2 months for those receiving the other drugs, while the objective response rate was 80% versus 76%, respectively.
AZ maintains that the extension in the time to tumour progression is clinically meaningful to patients and should be sufficient to support approval, although analysts have suggested that to ensure prescribing and to be a commercial success in first-line NSCLC Tagrisso may need positive overall survival data.
Oncologists in the US already seem primed to accept the drug as a new first-line option, however, as in September the National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology were updated to include the use of Tagrisso in the frontline treatment of patients with metastatic EGFR mutation-positive NSCLC.
There have been suggestions that Tagrisso should be used second-line as this gives two lines of therapy – and first-line agents have not been shown to work in patients who develop resistance to AZ’s new drug. On the other handy, others say this would deny patients the best front-line option, which would be unfair as a high proportion of first-line patients – up to one half – don’t develop T790M mutations.