AstraZeneca and research arm MedImmune have announced a longer wait for survival data from a closely-watched trial testing Imfinzi in advanced lung cancer.

The Phase III MYSTIC trial is evaluating Imfinzi (durvalumab) as monotherapy and in combination with tremelimumab, versus platinum-based standard-of-care (SoC) chemotherapy in previously-untreated patients with metastatic (Stage IV) 1st-line non-small cell lung cancer (NSCLC).

The drug giant had been expecting results in the first half of the year, but said in a statement that “based on current predictions, the final analysis of overall survival (OS) is now expected in the second half of 2018”.

Results are eagerly anticipated in light of the high-profile failure of Imfinzi plus tremelimumab to hit progression-free survival targets in a wider lung cancer patient population in the Mystic trial.

As a secondary endpoint, although not formally tested, Imfinzi monotherapy would not have met a pre-specified threshold of PFS benefit over standard of care in this disease setting, AZ said at the time.

Imfinzi is a human monoclonal antibody that blocks the interaction of PD-L1 with PD-1 and CD80, countering the tumour's immune-evading tactics and releasing the inhibition of immune responses.

In February this year, the drug won US approval for the treatment of patients with unresectable Stage III NSCLC whose disease has not progressed following concurrent platinum-based chemotherapy and radiation therapy.

Imfinzi has also received accelerated approval in the US for the treatment of patients with locally advanced or metastatic urothelial carcinoma, who have disease progression during or following platinum-containing chemotherapy, or whose disease has progressed within 12 months of receiving platinum-containing chemotherapy before (neoadjuvant) or after (adjuvant) surgery.

The drug is also currently under review in Europe.