Amgen Drug Combination Cuts Lung Cancer Death Risk by 58%

A combination of two immunotherapy drugs reduced the risk of death by 58% among patients with extensive-stage small cell lung cancer, according to Phase 3 trial results released October 24, 2026. Amgen's Imdelltra, combined with AstraZeneca's Imfinzi, extended median overall survival to 21.1 months, compared with 12.7 months for patients receiving Imfinzi alone as maintenance treatment after initial chemotherapy and immunotherapy.

The DeLLphi-305 trial evaluated patients whose cancer had not progressed after initial treatment with Imfinzi, platinum-based chemotherapy and etoposide. According to Amgen, the combination also reduced the risk of disease progression or death by 66%, extending median progression-free survival to 7.4 months from 1.9 months with Imfinzi alone.

Nearly 80% of patients receiving the combination remained alive after one year, compared with 53% of those treated with Imfinzi alone. The objective response rate was 26.4% for the combination, versus 4.1% for Imfinzi alone, according to the trial results presented at the European Society for Medical Oncology Congress 2026 and published simultaneously in The New England Journal of Medicine.

Amgen Chief Medical Officer Dr. Paul Burton described the findings as potentially transformative for treatment standards in an interview with CNBC.

"I think there are moments in medicine when you see a piece of data that is so profound that it's going to transform the standard of care for patients, and I think, honestly, we're at that moment," said Dr. Paul Burton, Amgen's chief medical officer.

Burton said the results could change how clinicians manage this aggressive cancer, which frequently progresses despite initial treatment.

"The combination has the potential to take on one of the most aggressive cancers that we deal with today, and almost convert it into a chronic disease," he said, adding that "these data say that's a possibility."

Small cell lung cancer is difficult to control because the disease often returns or advances within months, even when chemotherapy initially works. According to the trial's lead investigator, Dr. Jacob Sands, associate chief of the Lowe Center for Thoracic Oncology at Dana-Farber Cancer Institute, existing immunotherapies have delivered long-lasting disease control for only a subset of patients.

Sands said the combination's benefits extended across prespecified patient subgroups, including those with brain or liver metastases, which are associated with poorer outcomes.

"For a disease where durable survival has remained extremely difficult to achieve, the magnitude and consistency of benefit in DeLLphi-305 are striking," said Dr. Jacob Sands, associate chief of the Lowe Center for Thoracic Oncology at Dana-Farber Cancer Institute.

Sands said the results support efforts to improve disease control and survival by introducing effective treatments earlier in the course of care. Longer follow-up could also clarify whether the observed survival benefit continues to grow.

"Importantly, the benefit was seen across clinically relevant groups, including patients with brain metastases. Today's remarkable results demonstrate substantial progress in our work to achieve meaningfully longer disease control and survival for patients with extensive-stage small cell lung cancer, further highlighting the importance of effective treatment at the earliest possible opportunity," Sands said.

The trial findings could expand the role of Imdelltra, which is currently approved for patients whose small cell lung cancer progresses during or after platinum-based chemotherapy. Researchers tested whether adding it to maintenance treatment could improve outcomes compared with continuing Imfinzi alone.

Amgen reported that the combination's safety profile was consistent with the known safety profiles of the individual drugs. Grade 3 or higher treatment-related adverse events occurred in 20.9% of patients receiving the combination, compared with 10.8% of those receiving Imfinzi alone.

Cytokine release syndrome occurred in 49.6% of patients treated with Imdelltra, predominantly at Grade 1 or Grade 2 severity. One patient experienced a Grade 3 event, and no Grade 4 or higher events were reported. Immune effector cell-associated neurotoxicity syndrome occurred in 1.1% of patients, with no Grade 3 or higher cases.

Imdelltra works by binding to DLL3 on cancer cells and CD3 on T cells, bringing immune cells into contact with tumors. Imfinzi blocks PD-L1, a protein that cancer cells use to evade immune defenses, allowing the medicines to target the disease through complementary mechanisms.

Additional results presented at the same congress indicated sustained survival benefits in other treatment settings. In the Phase 1b DeLLphi-303 trial, updated data after a median follow-up of 30.8 months showed median overall survival of 37.9 months from the start of first-line maintenance therapy with Imdelltra plus standard-of-care anti-PD-L1 treatment. At two years, 58.1% of patients remained alive.

In the Phase 3 DeLLphi-304 trial, updated results after 23 months of follow-up showed median survival of 13.6 months with Imdelltra among previously treated patients, compared with 8.4 months with chemotherapy, representing a 38% reduction in the risk of death.

Amgen also reported commercial growth for Imdelltra, which generated $288 million in sales during the second quarter, an increase of 115% from a year earlier. Global sales reached $627 million in 2025.

Small cell lung cancer accounts for approximately 31,000 new cases annually in the United States, and an estimated 60% to 70% of patients are diagnosed with extensive-stage disease, according to the trial background reported by CNBC.