DeLLphi-305: Durvalumab Plus Tarlatamab Hits Overall Survival in First-Line ES-SCLC Maintenance
核心洞察
Amgen's phase III DeLLphi-305 trial met its primary overall survival endpoint for tarlatamab plus durvalumab versus durvalumab alone as first-line maintenance in extensive-stage small-cell lung cancer (搜索).
The 563-patient randomized study enrolled patients whose disease had not progressed after induction with durvalumab, platinum chemotherapy and etoposide, with PFS and ORR also significantly improved.
No numerical survival data, hazard ratios or safety tables were disclosed, and the full dataset is slated for presentation at an upcoming medical meeting and regulatory submission.
Amgen and AstraZeneca have reported positive high-level results from the phase III DeLLphi-305 trial, in which maintenance therapy with tarlatamab (Imdelltra) plus durvalumab (Imfinzi) significantly improved overall survival compared with durvalumab alone in patients with extensive-stage small-cell lung cancer (搜索) (ES-SCLC) whose disease had not progressed after induction chemoimmunotherapy.
The result, disclosed in a September 8, 2026 release, marks the first randomized phase III evidence that adding a DLL3 (搜索)-directed bispecific T-cell engager during the maintenance phase can extend survival in this disease. The trial also met the key secondary endpoint of progression-free survival, and objective response rate was significantly improved as well. Neither company released numerical data supporting the findings.
Trial Design and Patient Population
DeLLphi-305 is a global, randomized, open-label phase III study sponsored by Amgen, with partial funding and durvalumab supplied by AstraZeneca. Patients first received standard induction therapy consisting of durvalumab plus platinum chemotherapy — carboplatin or cisplatin — and etoposide. Those who completed induction without disease progression were then randomized 1:1 to maintenance durvalumab plus tarlatamab or durvalumab alone.
A total of 563 patients entered the randomized maintenance phase, with treatment continuing until progression or unacceptable toxicity. Overall survival served as the primary endpoint, with progression-free survival as a key secondary endpoint. Because every randomized patient had already demonstrated at least disease stability during standard induction, the trial specifically tests whether maintenance intensification — rather than a different induction regimen or a second-line strategy — can further extend survival.
The study population included patients with both treated and untreated asymptomatic brain metastases at baseline, a feature that increases the clinical relevance of the population given the frequency of central nervous system involvement in SCLC. No detailed intracranial efficacy data have been released.
Mechanistic Rationale for the Combination
Tarlatamab is a bispecific T-cell engager designed to bind DLL3 (搜索) on tumor cells and CD3 (搜索) on T cells, bringing cytotoxic T cells into proximity with DLL3-expressing cancer cells and activating immune-mediated tumor killing. According to the source, DLL3 is expressed on the surface of SCLC cells in approximately 85%–96% of patients, while expression in healthy cells is minimal — making it an attractive target in a disease with few actionable genomic drivers.
The combination with durvalumab is mechanistically complementary: durvalumab blocks PD-L1 (搜索)-mediated immune suppression, while tarlatamab directly redirects T cells toward DLL3 (搜索)-expressing tumor cells. DeLLphi-305 provides phase III evidence that this biological pairing can translate into a survival benefit.
Rationale for Earlier Use
Extensive-stage SCLC remains one of the most therapeutically challenging malignancies in thoracic oncology. Although the introduction of immune checkpoint inhibition into first-line platinum–etoposide chemotherapy improved survival and established immunotherapy as part of the standard backbone, the disease is still characterized by rapid progression, early relapse and limited long-term survival. According to the September 8, 2026 release, median overall survival with the current first-line standard remains approximately one year.
Because relapse can occur quickly, not all patients remain well enough to receive subsequent systemic therapy — a treatment-attrition problem that distinguishes SCLC from more indolent malignancies. DeLLphi-305 effectively asks whether DLL3 (搜索)-directed treatment should be given before that opportunity is lost, intensifying therapy during the period of disease control achieved with initial chemoimmunotherapy rather than waiting for clinically overt progression.
Safety and Monitoring Requirements
The topline announcement states that the overall safety and tolerability profile of durvalumab plus tarlatamab was consistent with the known profiles of the individual drugs, with no new safety signals identified. No detailed adverse-event table has been released; the eventual dataset will need to clarify rates of high-grade toxicity, discontinuation, treatment interruption, immune-mediated events and toxicities associated specifically with T-cell engagement.
Operational considerations may also affect implementation. Following tarlatamab administration on cycle 1 days 1 and 8, patients in DeLLphi-305 underwent healthcare-setting monitoring for one to two hours, extended to six to eight hours in certain regions including Europe. Such requirements may be manageable at major oncology centers but could influence use in lower-resource or geographically dispersed settings.
Competitive and Regulatory Landscape
If approved, the durvalumab–tarlatamab combination would enter an established first-line maintenance market. In October 2025, the FDA approved Jazz Pharmaceuticals' lurbinectedin (Zepzelca) in combination with Roche's atezolizumab (Tecentriq) as maintenance treatment for adults with ES-SCLC whose disease had not progressed following first-line induction with atezolizumab plus platinum chemotherapy and etoposide. That approval was based on the late-stage IMforte study, which showed the combination reduced the risk of disease progression or death by 46% and the risk of death by 27% versus atezolizumab alone, and led to the regimen's addition to the NCCN guidelines as a preferred option in this setting.
Durvalumab is already approved in extensive-stage disease in combination with platinum–etoposide based on CASPIAN, and in limited-stage SCLC after chemoradiotherapy based on ADRIATIC. The new results suggest a further role as the immunologic backbone onto which a DLL3 (搜索)-targeting agent can be layered during first-line maintenance.
Tarlatamab itself has been approved since 2024 for adults with ES-SCLC whose disease has progressed on or after platinum-based chemotherapy, and has become a standard of care in second-line disease. Amgen reported global sales of $546 million for the drug in the first half of 2026, up sharply from $215 million in the year-ago period.
Lung cancer remains the leading cause of cancer death globally, accounting for almost one in five cancer deaths. SCLC represents about 15% of lung cancers, with roughly two-thirds of patients diagnosed with the extensive-stage form; AstraZeneca estimates that approximately 195,000 people globally will be treated for ES-SCLC in 2026.
What Remains Unanswered
The current evidence is a high-level corporate disclosure rather than a fully presented phase III dataset. The oncology community still needs absolute median overall survival and progression-free survival differences, hazard ratios and confidence intervals, duration of response, subgroup outcomes, safety details, treatment discontinuation rates, subsequent therapies, quality-of-life data and intracranial outcomes.
The timing and magnitude of the survival curves will also matter, since a modest but statistically significant separation carries different clinical implications from a large and sustained survival advantage. Terms such as "unprecedented improvement" in the release reflect the sponsor's characterization of the results. The data are scheduled for presentation at a forthcoming medical meeting and will be submitted to global regulatory authorities.
Until those results are available, it is premature to define durvalumab plus tarlatamab as a new standard of care. What can already be concluded is that DeLLphi-305 has met the most consequential endpoint in extensive-stage SCLC: overall survival. If the full dataset confirms a substantial survival gain with manageable toxicity, the trial could reshape first-line treatment by transforming maintenance from continued checkpoint inhibition alone into an active dual-immunotherapy phase built around PD-L1 (搜索) blockade and DLL3 (搜索)-directed T-cell engagement.