AstraZeneca's Imfinzi improves PFS in Phase III study of patients with Stage III NSCLC

AstraZeneca's MedImmune unit unveiled Phase III study data from a planned interim analysis at the European Society of Medical Oncology (ESMO) congress showing that Imfinzi (durvalumab) significantly prolonged progression-free survival (PFS) in patients with Stage III unresectable non-small-cell lung cancer (NSCLC) who did not progress following platinum-based chemotherapy plus radiation therapy. In the PACIFIC trial, Imfinzi was found to extend PFS by more than 11 months versus placebo.

AstraZeneca chief medical officer Sean Bohen remarked that "as the first immuno-oncology medicine to achieve improvement in [PFS] in this setting, [Imfinzi] is showing clear potential to become a new standard of care" for this patient population. The company reported in May that the study had met one of its primary endpoints, noting at the time that the PD-L1 inhibitor is the first immuno-oncology medicine to show superior PFS as sequential treatment in patients with locally-advanced, unresectable NSCLC who had not progressed following standard platinum-based chemotherapy concurrent with radiation therapy.

The trial enrolled 713 patients who were randomly assigned to treatment with Imfinzi or placebo. The co-primary endpoints were PFS and overall survival (OS), while secondary endpoints included landmark PFS and OS, objective response rate (ORR) and duration of response. 

Results, which were also published in the NEJM, indicated that median PFS in the Imfinzi group was 16.8 months, compared to 5.6 months in the placebo arm. AstraZeneca noted that the benefit for PFS was observed across all pre-specified subgroups, including PD-L1 expression status. 

AstraZeneca also reported that median duration of response was not reached in the Imfinzi group, but was 13.8 months for placebo, while the ORRs in the two arms were 28.4 percent and 16 percent, respectively. The drugmaker indicated that OS remains under analysis in the trial.

FirstWord reports in this therapy area - KOL Insight NSCLC: Find out how KOLs expect the market to evolve, which pipeline treatments are most promising, and which clinical trials will shape treatment decisions. Learn more.

Imfinzi was awarded accelerated approval earlier this year for the treatment of certain patients with locally advanced or metastatic urothelial carcinoma. More recently, the therapy was granted breakthrough therapy status for use in patients with locally advanced, unresectable NSCLC whose disease had not progressed following platinum-based chemoradiotherapy. However, in July, AstraZeneca announced initial results from the Phase III MYSTIC study, with the combination of Imfinzi and its experimental CTLA-4 inhibitor tremelimumab failing to improve PFS versus platinum-based standard-of-care chemotherapy in previously-untreated patients with metastatic first-line NSCLC.

Analysts estimate that Imfinzi could amass more than $8.1 billion in revenue by 2023 for use as monotherapy or in combination with another immunotherapy. Jefferies analysts indicated that the treatment could generate up to $1.7 billion in sales for treating patients with Stage III lung cancer. 

AstraZeneca separately presented late-stage study data at the ESMO congress, demonstrating that Tagrisso (osimertinib) prolonged PFS in previously untreated adults with EGFR-mutated NSCLC. 

For related analysis, see ViewPoints: ESMO 2017 – expectations high for AstraZeneca's PACIFIC data.

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