- AstraZeneca said a combination of Imfinzi and chemotherapy kept lung cancer from getting worse in newly diagnosed patients better than chemotherapy alone. A triple combination of Imfinzi, chemo, and a second immuno-oncology agent called tremelimumab also performed better than chemo alone.
- Investors are closely watching the results from this trial, called POSEIDON, as it could make AstraZeneca competitive with Merck & Co. in the first-line lung cancer setting. A similar trial of Bristol-Myers Squibb's Opdivo also had positive results last week.
- AstraZeneca did not release detailed safety and efficacy results. Oncologists will want to see data on Imfinzi's magnitude of benefit as well as side effects before deciding whether to use it instead of Merck's Keytruda.
The first round in first-line non-small cell lung cancer went to Keytruda (pembrolizumab). Adding the Merck drug, which is now the company's biggest seller, to chemotherapy has been able to cut the risk of death by up to 51% depending on the tumor type.
Other agents in Keytruda's drug class have been unable to keep up. Imfinzi (durvalumab) and Opdivo (nivolumab) struggled to gain ground in lung cancer, having only secured approval for patients who progressed after receiving chemo.
But that could all change based on the results of two trials that read out in the past week.The latest was AstraZeneca's POSEIDON study, which tested two experimental regimens — Imfinzi and chemo, along with Imfinzi, tremelimumab and chemo — against chemo alone, in newly diagnosed patients with metastatic lung cancer.
Like Imfinzi, Keytruda and Opdivo, tremelimumab fights cancer by stimulating an immune response to tumor cells, though it uses a different mechanism of action.
The primary analysis compared the Imfinzi/chemo combination against chemo alone, in which the combination was able to keep patients from relapsing longer than chemo. A secondary analysis showed the Imfinzi/tremelimumab combination also delayed progression, according to AstraZeneca.
The U.K. pharma giant also said both combinations did not trigger any safety concerns. The triple combination "delivered a broadly similar safety profile to the Imfinzi and chemotherapy combination and did not result in increased discontinuation of therapy."
That is significant because tremelimumab is in the same drug class as Bristol-Myers' Yervoy (iplimumab), a class called CTLA-4 inhibitors, and Yervoy has strong warnings on its label about "severe and fatal immune-mediated adverse reactions."
The safety signals haven't discouraged Bristol-Myers from pushing its own combination of Opdivo, low-dose Yervoy and chemo in a similar-looking trial called CheckMate-9LA. Last week, the company announced that trial met its primary goal by showing the triple combination delayed death in lung cancer patients who had never been treated.
Both Bristol-Myers and AstraZeneca said they will present fuller details from their trials at upcoming medical meetings, which could have them competing for attention at next year's American Society for Clinical Oncology meeting. With survival data in hand, Bristol-Myers might have the upper hand if AstraZeneca's trial isn't complete enough to provide any.
Conversely, should AstraZeneca be able to show similar benefit to Keytruda using only Imfinzi and chemotherapy, it would likely have an advantage over Bristol-Myers based on side-effect profile.