DeLLphi-301: Tarlatamab phase 2 trial in small cell lung cancer (SCLC)—Efficacy and safety analyzed by presence of brain metastasis.

8015 Background: Brain metastases affect 40%–70% of patients with SCLC. Tarlatamab, a BiTE (bispecific T-cell engager) immunotherapy targeting delta-like ligand 3, demonstrated durable responses and promising survival outcomes in patients with previously treated SCLC (10 mg Q2W) (DeLLphi-301; NCT05060016; Ahn M-J, N Engl J Med 2023). Here, tarlatamab efficacy and safety in patients with baseline brain metastases from DeLLphi-301 are reported. Methods: The DeLLphi-301 study design has been published. Patients with treated, stable, asymptomatic brain metastases were included. Subgroup analyses for efficacy (blinded independent central review BICR assessments) and safety by presence or absence of baseline brain metastases were performed. Intracranial activity was assessed. Post enrollment, brain imaging was performed if clinically indicated. Results: As of 27 June 2023, 186 patients had received tarlatamab (ECOG PS: 0–1; median prior lines of therapy: 2; median follow-up: 13.6 months). 29% of patients (54/186) had treated and stable brain metastases at baseline. Most patients (91%) with brain metastases had received prior local radiotherapy; 6% each had received surgery only or both radiotherapy and surgery. Overall systemic objective response rate (ORR; RECIST 1.1) was 45.3% in patients with brain metastases and 32.6% in patients without brain metastases (Table). Any grade immune effector cell associated neurotoxicity syndrome and associated neurological events occurred in 24.1% of patients with brain metastases and in 13.6% of patients without brain metastases; grade ≥ 3 events occurred in the 100 mg group only: 9.4% and 1.8%, respectively, and did not lead to tarlatamab discontinuation in any patient with brain metastases. Analysis of intracranial activity will be presented. Conclusions: Tarlatamab showed promising efficacy and a favorable benefit-risk profile in patients with previously treated SCLC and stable brain metastases. Clinical trial information: NCT05060016 . Table: see text