Tarlatamab improved cough, breathlessness and chest pain against chemotherapy in the DeLLphi-304 patient-reported outcomes

Dyspnoea improved in 22% of patients on tarlatamab against 7% on chemotherapy

The largest separation between the two arms at 19 weeks was in breathlessness. Twenty-two per cent of patients receiving tarlatamab achieved symptom improvement, against 7% of those receiving standard-of-care chemotherapy. Global health status improved in 23% against 15%.

These are proportions of patients achieving improvement at a single timepoint rather than mean scores, and the abstract reports them without confidence intervals or P values. The comparison rests on the questionnaire responses of a population in which symptom burden is high at entry: extensive-stage small cell lung cancer is described by the authors as associated with a high symptom burden and impaired health-related quality of life. The analysis was prespecified in the trial protocol.

Cough, chest pain and physical functioning moved in the same direction

Cough improved in 35% of the tarlatamab group against 26% of the chemotherapy group, chest pain in 19% against 10%, and physical functioning in 13% against 8%. The direction of the difference was the same for every measure the abstract names, and the size of the difference varied from 5 percentage points for physical functioning to 15 for dyspnoea.

Alongside the improvement rates, the analysis reports that tarlatamab delayed deterioration in symptoms, in physical functioning and in pain at worst relative to chemotherapy. The abstract states the direction of those three time-to-deterioration results and gives neither the median times nor the hazard ratios behind them.

“In addition to its previously reported antitumor activity, tarlatamab demonstrated clinically meaningful improvements in symptoms and HRQoL compared with SoC.”Mountzios et al., Lung Cancer (2026)

Patients on tarlatamab reported being less bothered by treatment side effects

The FACT-G GP5 results indicated that patients receiving tarlatamab were less bothered by treatment side effects over time. The abstract states that finding and attaches no figures to it.

That result is worth separating from the symptom scales above, because it concerns side effects of treatment rather than symptoms of the disease. It is also the one result in the abstract for which no comparison against chemotherapy is stated: the sentence reports the tarlatamab group over time and stops there.

Compliance above 69% through 19 weeks, and an open-label design behind every score

Completion of the QLQ-C30 and QLQ-LC13 questionnaires remained above 69% through 19 weeks. The abstract reports no compliance figure beyond that point, and no compliance rate for the other instruments it names.

DeLLphi-304 is an open-label trial. Patients and investigators knew which treatment was being received while these questionnaires were completed, and that applies to every proportion quoted above. The authors present the results as support for a favourable benefit-risk profile for tarlatamab in patients previously treated for extensive-stage small cell lung cancer, alongside antitumour activity reported previously.