Combination of AstraZeneca's Imfinzi, tremelimumab fails to hit goals of third-line lung cancer study

AstraZeneca said Tuesday that the Phase III ARCTIC study investigating the combination of Imfinzi (durvalumab) and tremelimumab in patients with PD-L1 low/negative non-small-cell lung cancer failed to meet its primary endpoints of a significant and clinically-meaningful improvement in progression-free survival (PFS) and overall survival (OS) versus standard-of-care chemotherapy.

Chief medical officer Sean Bohen remarked "while we are disappointed that the combination…did not result in a statistically-significant survival benefit in this heavily pre-treated patient population, we are encouraged by the activity of Imfinzi monotherapy observed in this trial."

In the study, patients with locally-advanced or metastatic NSCLC who have received at least two prior treatments were randomised to receive Imfinzi plus tremelimumab, Imfinzi and tremelimumab monotherapies or standard-of-care chemotherapy. The trial comprised two parts, with the first comparing Imfinzi monotherapy versus standard-of-care chemotherapy in patients with PDL1-high NSCLC, and the second investigating the combination of Imfinzi and tremelimumab, as well as Imfinzi and tremelimumab monotherapies, versus standard-of-care chemotherapy in patients with PDL1-low/negative NSCLC.

AstraZeneca noted that while the first part of the trial was not powered for statistical significance, Imfinzi monotherapy showed a clinically-meaningful reduction in the risk of death compared to chemotherapy. Full data from the study will be presented at an upcoming medical meeting.

Last month, AstraZeneca announced that the final analysis of OS from the Phase III MYSTIC study of Imfinzi as monotherapy and in combination with the CTLA-4 inhibitor tremelimumab is now expected in the second half of 2018, delayed from the first half. Initial results from the trial showed that the combination failed to improve PFS in previously-untreated patients with EGFR and ALK wild-type locally-advanced or metastatic first-line NSCLC.

Although OS results from the MYSTIC trial may be positive, Deutsche Bank analyst Richard Parkes said expectations for this "should now be very low." Imfinzi, which inhibits PD-L1, gained FDA expanded approval in February to include the treatment of patients with unresectable Stage III NSCLC whose disease has not progressed following concurrent platinum-based chemotherapy and radiation therapy.

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