Amgen's Imdelltra with Imfinzi cut the risk of death by 58% in small cell lung cancer, a Phase 3 trial found
Patients lived a median 21.1 months on the pair against 12.7 months on Imfinzi alone, and nearly 80% were alive at one year against 53%. FDA has not approved the drug for this use.
Amgen’s Imdelltra, given with AstraZeneca’s Imfinzi, cut the risk of death by 58% in people with extensive stage small cell lung cancer, Amgen said on Oct 24. The results come from DeLLphi-305, a Phase 3 trial, at a median follow up of about 16 months.
The data were presented at the European Society for Medical Oncology Congress 2026 and published the same day in The New England Journal of Medicine, Amgen says. These are interim results.
Who was in the trial
Small cell lung cancer makes up about 13% to 15% of the more than 2.6 million lung cancers found worldwide each year, per Amgen.
Before the trial, every patient got Imfinzi (durvalumab) with platinum chemo and etoposide. The trial tested what comes next, called maintenance. Median survival from the start of maintenance has been about one year, Amgen says.
DeLLphi-305 enrolled 563 patients whose cancer had not grown after that first round. Half added Imdelltra (tarlatamab) to Imfinzi. The other half stayed on Imfinzi alone. Patients and doctors knew which treatment each patient got, per the trial listing on ClinicalTrials.gov.
The trial allowed patients whose cancer had spread to the brain, treated or not, as long as it caused no symptoms.
What the trial showed
The main goal was overall survival, per Amgen.
→ Median survival was 21.1 months on the pair against 12.7 months on Imfinzi alone. → At one year, nearly 80% of patients on the pair were alive, against 53%. → Median time before the cancer grew or the patient died was 7.4 months against 1.9 months. → Tumors shrank in 26.4% of patients on the pair against 4.1%.
Amgen says the survival gains held across the groups it planned to check in advance, including patients whose cancer had spread to the brain or liver.
Side effects
Grade 3 or worse side effects tied to treatment hit 20.9% of patients on the pair against 10.8% on Imfinzi alone, per Amgen.
Cytokine release syndrome, an immune overreaction that can cause fever and low blood pressure, hit 49.6% of patients who got Imdelltra. Almost all cases were mild or moderate, with one severe case. ICANS, a nervous system side effect, hit 1.1%, with no severe cases.
What it means for patients now
FDA approved Imdelltra for adults whose extensive stage small cell lung cancer grew during or after platinum chemo. It is not approved as a first treatment, which is how this trial used it. Amgen says it will take the results to regulators worldwide. It gave no filing date.
The drug carries a boxed warning for cytokine release syndrome and nervous system side effects, including ICANS. Under the current US label, patients are watched for 6 to 8 hours after each of the first two doses. They are told to stay within an hour of a hospital for 48 hours after each, with a caregiver.
In DeLLphi-305, monitoring after those two doses lasted 1 to 2 hours, or 6 to 8 hours in some regions including Europe, per Amgen.
Amgen also reported longer follow up from earlier trials. In DeLLphi-304, patients who had already been treated lived a median 13.6 months on Imdelltra against 8.4 months on chemo.
What to watch
These are interim results from an open label trial, sponsored by Amgen with partial funding from AstraZeneca. Final survival data and any FDA filing will show whether the gap holds and whether the pair becomes a first treatment.
FDA
