Key Inclusion Criteria:

          -  Patient has pathologically (histologically or cytologically) proven diagnosis of small
             cell lung cancer

          -  Has limited-stage disease (stage Tx, T1-T4, N0-3, M0; AJCC staging, 8th edition), and
             can be safely treated with definitive radiation doses.

          -  Patient has not received any prior treatment for LS-SCLC.

          -  Patient has measurable disease as assessed according to RECIST v1.1 that is
             appropriate for selection as a target lesion for repeat measurement, as determined by
             local site investigator/radiology review

          -  ECOG Performance Status ≤ 2 assessed within 7 days before the first administration of
             study intervention, and must have a life expectancy of ≥ 12 weeks.

        Key Exclusion Criteria:

          -  Mixed small cell lung cancer histology. Note: mixed SCLC with the component of
             neuroendocrine carcinoma origin is considered eligible

          -  Have received surgical resection for LS-SCLC

          -  Any patient for whom the tumor is considered resectable by surgery or stereotactic
             body radiation therapy/stereotactic ablative radiotherapy should be considered
             ineligible

          -  Is expected to require any other form of antineoplastic therapy while on study.

          -  Prior therapy with an anti-PD-1, anti-PD-L1, anti-PD-L2, anti-TIGIT, or any other
             antibody or drug specifically targeting T-cell costimulation or checkpoint pathways

        Note: Other protocol-defined Inclusion/Exclusion criteria may appl