AZ's Imfinzi on target in small cell lung cancer, sets up Roche rivalry

AstraZeneca’s Imfinzi cancer immunotherapy has hit the mark in a phase 3 trial in extensive-stage small cell lung cancer, setting up a potential rivalry with Roche’s PD-L1 class drug Tecentriq (atezolizumab).

The UK pharma said that at a planned interim analysis an independent data monitoring committee concluded the trial had met its primary endpoint by showing a statistically significant, and clinically meaningful improvement in overall survival (OS) compared with standard of care.

AZ said that Imfinzi (durvalumab) plus standard of care etoposide and platinum-based chemotherapy had outperformed a standard of care control arm, but gave no details about the performance of a combination of Imfinzi, AZ’s CTLA 4 class immunotherapy tremelimumab, and chemotherapy.

The trial is testing Imfinzi plus platinum-based chemotherapy options or the combination of Imfinzi, tremelimumab and chemotherapy, compared with chemotherapy alone.

AZ said that no new safety issues had emerged in the trial, with side effects in line with those seen in previous trials.

CASPIAN will continue to the final analysis of OS for the combination of dual immune checkpoint blockade with chemotherapy.

Should AZ decide results are strong enough to file in a new indication, this sets up a potential rivalry with Roche’s PD-L1 class immunotherapy, Tecentriq (atezolizumab), which was approved in extensive-stage small cell lung cancer in March.

While it’s not good form to compare results from separate clinical trials, Tecentriq in combination with chemotherapy was approved on the basis of results showing a median OS of 12.3 months in the treatment arm.

This was compared with 10.3 months in an arm treated with placebo and chemotherapy – enough to convince regulators to approve it, but nevertheless a fairly narrow gap in performance in this group of very sick patients.

Imfinzi’s success will likely depend on the margin of OS benefit – while there will be no head-to-head data available, a much larger survival benefit could make doctors likely to prescribe it.

Imfinzi is also being tested following concurrent chemoradiation therapy in limited-stage SCLC in the Phase III ADRIATIC trial.

It is already approved for unresectable, Stage III non-small cell lung cancer in more than 45 countries, including the US, EU and Japan, based on the phase III PACIFIC trial.

AZ's José Baselga

José Baselga, AZ's executive vice president of oncology R&D said: “The phase 3 CASPIAN results offer new hope for patients who are facing the devastating diagnosis of small cell lung cancer, and for whom new medicines are urgently needed.

“This is the first trial offering the flexibility of combining immunotherapy with different platinum-based regimens in small cell lung cancer, expanding treatment options.”