Study Evaluating Tarlatamab After Chemoradiotherapy in Limited-Stage Small-Cell Lung Cancer (LS-SCLC)

Inclusion Criteria: -Participants are eligible to be included in the study only if all of the following criteria apply:

• Participant has provided informed consent prior to initiation of any study specificactivities/procedures.

• Age ≥ 18 years (or ≥ legal age within the country if it is older than 18 years).

• Histologically or cytologically confirmed small-cell lung cancer (SCLC).

• Diagnosed and treated for LS-SCLC with concurrent chemotherapy and radiotherapy.

• Has completed chemoradiotherapy without progression per Response Evaluation Criteriain Solid Tumors v1.1 (RECIST 1.1.) (ie, achieved complete response [CR], partialresponse [PR], or stable disease [SD]).

• Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) of 0 or 1.

• Minimum life expectancy of 12 weeks.

• Adequate organ function.

• Toxicities attributed to concurrent chemoradiotherapy resolved to grade ≤ 1, unlessotherwise specified. Excluding alopecia or fatigue.

Exclusion Criteria: -Participants are excluded from the study if any of the following criteria apply:

Disease Related

• Extensive-stage SCLC (ES-SCLC).

• Any previous diagnosis of transformed non-small-cell lung cancer (NSCLC), epidermalgrowth factor receptor (EGFR) activating mutation positive NSCLC that hastransformed to SCLC, or mixed SCLC NSCLC histology.

• Evidence of interstitial lung disease or active, non-infectious pneumonitis. OtherMedical Conditions

• History of other malignancy within the past 2 years, with certain exceptions.

• History of solid organ transplantation.

• Myocardial infarction and/or symptomatic congestive heart failure (New York HeartAssociation > class II) within 6 months prior to first dose of study treatment.

• History of arterial thrombosis (eg, stroke or transient ischemic attack) within 6months prior to first dose of study treatment.

• Exclusion of human immunodeficiency virus (HIV) and/or hepatitis infection based oncriteria per protocol.

• Participant with symptoms and/or clinical signs and/or radiographic signs thatindicate an acute and/or uncontrolled active systemic infection within 7 days priorto the first dose of study treatment.

Prior/Concomitant Therapy

• Received sequential chemotherapy and thoracic radiotherapy (no overlap of thoracicradiotherapy with chemotherapy) during chemoradiation.

• Prior therapy with any selective inhibitor of the delta-like ligand 3 (DLL3)pathway.

• Prior history of severe or life-threatening events from any immune-mediated therapy.

• Receiving another anti-cancer therapy. Adjuvant hormonal therapy for resected breastcancer is permitted.

• Receiving systemic corticosteroid therapy or any other form of immunosuppressivetherapy within 7 days prior to enrollment.

• Major surgical procedures within 28 days prior to first dose of study treatment.

• Treatment with live virus, including live-attenuated vaccination, within 14 daysprior to the first dose of study treatment. Inactive vaccines and live viralnon-replicating vaccines within 3 days prior to first dose of study treatment.

Prior/Concurrent Clinical Study Experience

• Treatment in an alternative investigational trial within 28 days prior to enrollment.

Other Exclusions

• Female participants of childbearing potential unwilling to use protocol specifiedmethod of contraception during treatment and for an additional 60 days after thelast dose of study treatment.

• Female participants who are breastfeeding or who plan to breastfeed while on studythrough 60 days after the last dose of study treatment.

• Female participants planning to become pregnant or donate eggs while on studythrough 60 days after the last dose of study treatment.

• Female participants of childbearing potential with a positive pregnancy testassessed at screening by a highly sensitive serum pregnancy test.

• Male participants with a female partner of childbearing potential who are unwillingto practice sexual abstinence (refrain from heterosexual intercourse) or usecontraception during treatment and for an additional 60 days after the last dose ofstudy treatment.

• Male participants with a pregnant partner who are unwilling to practice abstinenceor use a condom during treatment and for an additional 60 days after the last doseof study treatment.

• Male participants unwilling to abstain from donating sperm during treatment and foran additional 60 days after the last dose of study treatment.

• Participant has known sensitivity to any of the products or components to beadministered during dosing.

• Participant likely to not be available to complete all protocol-required studyvisits or procedures, and/or to comply with all required study procedures to thebest of the participant and investigator's knowledge.

• History or evidence of any other clinically significant disorder, condition, ordisease (with the exception of those outlined above) that, in the opinion of theinvestigator or Amgen physician, if consulted, would pose a risk to participantsafety or interfere with the study evaluation, procedures or completion.