Amgen AMGN announced positive results from a phase III study that evaluated its lung cancer therapy Imdelltra (tarlatamab) in combination with AstraZeneca’s AZN blockbuster immunotherapy Imfinzi (durvalumab) for certain patients with extensive-stage (ES) small-cell lung cancer (SCLC).
The study, called DeLLphi-305, assessed the combination regimen against Imfinzi alone as a first-line maintenance treatment for ES-SCLC patients whose cancer had not progressed following induction treatment with Imfinzi plus platinum chemotherapy and etoposide.
Amgen and AstraZeneca reported that the study achieved its primary endpoint of overall survival and met a key secondary endpoint of progression-free survival (PFS). While neither company provided numerical data supporting the results, both mentioned that the study did not identify any new safety concerns.
DeLLphi-305 is sponsored by Amgen, with partial funding and Imfinzi provided by AstraZeneca.
AZN & AMGN Target a Wider Market Opportunity
Lung cancer is the leading cause of cancer death globally, accounting for almost one in five cancer deaths. The companies estimate that SCLC accounts for about 15% of lung cancers, with roughly two-thirds of patients diagnosed with the ES form. AstraZeneca estimates that approximately 195,000 people globally will be treated for ES-SCLC in 2026.
If approved, the Imfinzi-Imdelltra combination would face established competition in the first-line maintenance market. In October 2025, the FDA approved Jazz Pharmaceuticals’ JAZZ Zepzelca (lurbinectedin) in combination with Roche’s RHHBY Tecentriq (atezolizumab) as a maintenance treatment for adults with ES-SCLC whose disease has not progressed following first-line induction therapy with Tecentriq plus platinum chemotherapy and etoposide.
The approval was based on results from the late-stage IMforte study, which showed that the combination reduced the risk of disease progression or death by 46% and the risk of death by 27% versus Tecentriq alone. These results also led to the addition of the regimen to the NCCN guidelines as a preferred treatment option in this setting.
AMGN, AZN Stock Performance
Year to date, shares of Amgen have gained nearly 20%, while those of AstraZeneca have lost about 15%. During the same period, the industry has climbed 6%.
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Imdelltra: An Emerging Revenue Driver for Amgen
A bispecific T-cell engager (BiTE) drug, Imdelltra is currently approved for adults with ES-SCLC whose disease has progressed on or after platinum-based chemotherapy. Since its approval in 2024, the drug has emerged as a standard-of-care treatment in second-line ES-SCLC. Imdelltra has quickly gained commercial traction, with global sales of $546 million in the first half of 2026, up sharply from $215 million in the year-ago period.
The latest DeLLphi-305 results could provide an important new growth opportunity for Imdelltra. A potential expansion into first-line maintenance could significantly broaden the drug’s addressable patient population, given the larger number of patients treated in earlier lines of therapy. The opportunity could become even larger over time, as Amgen is pursuing a comprehensive clinical development program evaluating Imdelltra in both ES and limited-stage (LS) SCLC across different treatment settings.
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Imfinzi: A Key Growth Driver for AstraZeneca
Imfinzi is already a key growth driver for AstraZeneca, with first-half 2026 revenues rising 31% year over year to $3.55 billion. The drug has an increasingly broad commercial footprint, with approvals spanning multiple tumor types and disease settings, including lung cancer, hepatocellular carcinoma (liver cancer), biliary tract cancer, endometrial cancer, bladder cancer and gastric cancer.
Imfinzi is being evaluated in phase III studies in earlier settings in its approved indications. The latest DeLLphi-305 results are particularly relevant because they could further strengthen Imfinzi's position as the backbone of first-line treatment for SCLC. Imfinzi is already approved as induction therapy for first-line ES-SCLC. A successful combination with Imdelltra could therefore reinforce Imfinzi's position in SCLC and provide another avenue for extending its use in this market.
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Zacks Rank
Amgen currently carries a Zacks Rank #3 (Hold), while AstraZeneca is ranked #4 (Sell). You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.
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