Another failed trial for AstraZeneca’s CTLA4 inhibitor tremelimumab – this time in small cell lung cancer (SCLC) – has ushered the drug another step towards the grave.
The latest miss for the companion drug to AZ’s PD-L1 inhibitor Imfinzi (durvalumab) in a phase 3 trial involved patients with previously-untreated, extensive-stage SCLC, a group which accounts for around 15% of all lung cancer cases.
Last year, the study – called CASPIAN – showed that Imfinzi added to standard of care chemotherapy resulted in improved overall survival (OS) compared to chemo alone. However, adding tremelimumab to the regimen didn’t provide any improvement on this outcome over Imfinzi and chemo given alone.
It’s a familiar pattern – Imfinzi works (mostly), and tremelimumab brings nothing extra to the table – and the failure of the combination in SCLC follows similar strike-outs in non-small cell lung cancer, bladder cancer and other tumour types.
AZ notes the CTLA4 inhibitor remains in clinical trials in combination with Imfinzi in NSCLC, SCLC, bladder cancer, head and neck cancer and liver cancer.
The data for Imfinzi is nevertheless still a plus overall for AZ as it allows it to challenge Roche’s PD-L1 inhibitor Tecentriq (atezolizumab), which was approved for first-line SCLC last year and is still the only checkpoint inhibitor licensed for this use.
The data for Tecentriq and Imfinzi in extensive-stage SCLC look pretty comparable, although AZ claims its drug seems to have stronger response duration data, and has data with a broader range of chemo drugs.
The FDA is due to deliver a verdict on Imfinzi in extensive-stage SCLC in the first half of 2020, with decision in Europe and Japan – and a regulatory filing in China – expected before year-end. It’s already been approved for this indication in Singapore.
Analysts have suggested the indication could add another $800m-plus to peak sales for Imfinzi, which accelerated last year to almost $1.5bn thanks largely to wider use in NSCLC as well as bladder cancer.
“We are pleased to see the sustained and meaningful survival benefit of Imfinzi for patients with small cell lung cancer after more than two years median follow up,” commented AZ’s head of oncology R&D José Baselga.
“We have already received the first global regulatory approval for Imfinzi with etoposide plus either carboplatin or cisplatin and remain on track for more approvals soon as we provide patients an important new first-line treatment option,” he added.
Both Roche and AZ will however be looking over their shoulders at Merck & Co/MSD – already reigning supreme with Keytruda (pembrolizumab) in NSCLC – which has approval for third-line SCLC and has a first-line phase 3 trial nearing completion.