Amgen's Imdelltra with Imfinzi cut lung cancer death risk by 58 percent

What happened

Amgen said on Saturday 24 October that its drug Imdelltra, given with AstraZeneca's Imfinzi, cut the risk of death by 58 percent in a Phase 3 trial in extensive-stage small cell lung cancer. ^{[1, 2]}

The trial, DeLLphi-305, enrolled 563 patients whose cancer had not grown after first treatment with Imfinzi, platinum chemotherapy and etoposide. Half then took both drugs as maintenance, the treatment that follows; half took Imfinzi alone. The results were presented at the ESMO Congress in Madrid and published the same day in The New England Journal of Medicine, the companies said. ^{[1, 2, 3, 4]}

Median survival, the point by which half the patients had died, was 21.1 months with the pair and 12.7 months with Imfinzi alone. The hazard ratio, the relative risk of death at any moment, was 0.42. At one year, 79 percent of patients on both drugs were alive, against 53 percent, AstraZeneca said. ^{[1, 2, 4]}

Why it matters

Median survival in this disease is about one year from the start of maintenance treatment, and only about 40 percent of patients reach a second line of therapy, Amgen wrote. In the United States, Imdelltra is approved only after platinum chemotherapy has stopped working. This trial moved it to the first course of treatment. ^[1]

Side effects and open questions

Serious side effects linked to treatment, grade 3 or higher, struck 20.9 percent of patients on both drugs and 10.8 percent on Imfinzi alone, nearly twice the rate by the desk's arithmetic. Counting every serious event, related to treatment or not, the rates were 46.8 and 40.6 percent, Targeted Oncology reported. ^{[1, 4, 5]}

Cytokine release syndrome, an immune overreaction that heads the warnings on Imdelltra's US label, was reported in 49.6 percent of patients on the pair, Amgen said. Most cases were grade 1 or 2, with one grade 3 case. No patient on the combination died of a treatment effect, against two on Imfinzi alone, OncLive reported. ^{[1, 4]}

The figures come from a planned interim analysis at about 16 months of follow-up. Amgen said the benefit held across prespecified subgroups; OncLive reported a hazard ratio of 0.82 among the 75 patients enrolled in the Americas, with a range that includes no difference. Reports also differ on stopping: OncLive put tarlatamab discontinuation for treatment effects at 3.2 percent, Targeted Oncology at 5.7 percent for any side effect. ^{[1, 4, 5]}

What settles it next

No regulator has approved the combination: Amgen's release says the use discussed is investigational and not part of the US label. Jay Bradner, Amgen's head of research and development, said the company is 'moving with urgency to share these results with regulatory authorities worldwide.' ^[1]

The ESMO Congress runs to Tuesday 27 October, OncLive's reference list shows. A second Phase 3 trial, DeLLphi-312, tests Imdelltra with Imfinzi and chemotherapy from the very first treatment, Amgen's release says. ^{[1, 4]}

Who it reaches

Amgen (AMGN) is direct: it makes Imdelltra and sponsors the trial. AstraZeneca (AZN) is adjacent: it partly funded the trial and supplied Imfinzi, the partner drug, both companies said. ^{[1, 2, 6]}

Zai Lab (ZLAB) is adjacent: its 8-K of Thursday 6 August says Amgen began enrolling DeLLphi-313 in April, testing Zai Lab's DLL3 drug zocilurtatug pelitecan with Imdelltra. Zai Lab also said that drug's first-line data would be presented at ESMO 2026. ^{[7, 1]}