Implementing a safe and effective process to deliver tarlatamab bispecific antibody treatment for patients with small cell cancer across a community healthcare system.

581 Background: Tarlatamab, a bispecific DLL3-CD3 antibody, was FDA approved in May 2024. The benefit of this treatment was shown in the DeLLphi-301 and DeLLphi-304 studies, however, very few patients were enrolled from US sites. Herein we report the implementation of a safe and effective process to deliver this treatment in a community healthcare setting with data on the first 17 patients treated from July 2024 through May 2025. Methods: Our evaluation process includes an initial evaluation of candidacy for treatment by a thoracic medical oncologist in the thoracic multidisciplinary team at the tertiary center for candidacy of treatment. Patients are evaluated for performance status, comorbid conditions, actively progressing brain metastases, and discussion of logistical treatment considerations. Patients are treated at the tertiary community hospital with cycle 1, day 1 and cycle 1, day 8 dosing followed by a mandatory 48-hour admission to Step Down Unit for monitoring for cytokine release syndrome (CRS) and ICANS. Nursing is trained to evaluate for CRS/ICANS during the admission. Standing orders are used: for grade 1 CRS/ICANS, treatment with acetaminophen +/- dexamethasone (D), for > grade 1 CRS/ICANS, D and tocilizumab (T). With cycle 1, day 15 treatment and thereafter, patients may be treated at their local outpatient infusion centers under care of their primary oncologist. Results: 17 patients have been treated to date, patient characteristics are listed in Table 1 in comparison to the patients enrolled to the DeLLphi-301 trial. 82% had Medicare or Medicaid insurance. Average distance from patient home to the tertiary center was 74 miles. 76% of patients experienced grade 1 or 2 CRS, no patients experienced grade > 2. 53% of patients experienced grade 1 or 2 ICANS, no patients experienced grade > 2. T use was given to 47% of patients, 35% after day 1 and 18% after day 8. 76 % of patients were able to receive cycle 1 day 15 dose and further dosing as outpatient. Of patients assessed for response, ORR was 23%, median PFS was 3.8 m (range 1-9+ m). Conclusions: Our structured process of delivering tarlatamab in a community healthcare system was safe and effective. Patients were older, had worse ECOG PS, were more likely to have brain metastases, and were less responsive to therapy than seen in DeLLphi-301. Rates of CRS and T use were high and may limit ability to move to a fully outpatient treatment delivery process in this setting. Patient characteristics. DeLLphi-301, n = 100 Baptist Cohort, n = 17 Age (median) 64 (35 - 82) 68 (50 – 82) Sex 72% male 41% male White/Asian/Black 58%, 41%, 0% 76%, 0%, 24% ECOG PS 100% 0-1 71% 0-1; 29% 2-3 Median (IQR) prior lines of therapy 2 (1-6) 2 (1-4) Brain metastases 23% 53%