['small cell lung cancer', 'extensive-stage small cell lung cancer']
['ipilimumab', 'nivolumab']

        Inclusion Criteria:

          -  Signed Written Informed Consent

          -  Willing and able to comply with scheduled visits, treatment schedule, laboratory tests
             and other requirements of the study.

          -  Patients with Small Cell Lung Cancer (SCLC) documented by histology or cytology from
             brushing, washing, or needle aspiration of a defined lesion, but not from sputum
             cytology alone

          -  Have presented at initial diagnosis with extensive-stage disease

          -  Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) 0 or 1

          -  Have received 4-6 cycles of platinum-based first-line chemotherapy and have an ongoing
             response of complete response (CR), partial response (PR), or stable disease (SD)
             after completion of chemotherapy. Acceptable combinations, as recommended per National
             Comprehensive Cancer Network (NCCN) guidelines, include cisplatin or carboplatin
             combined with either etoposide or irinotecan; As an exception to the above criterion,
             participants receiving only 3 cycles of chemotherapy due to toxicity are eligible, if
             they have an ongoing PR or CR after the 3rd cycle; Participants who have received > 6
             cycles of platinum-based first-line chemotherapy are not eligible.

          -  Participants must initiate study treatment with thoracic radiation therapy less than
             or equal to 8 weeks (56 days) from the last dose of platinum-based first line
             chemotherapy.

          -  Whenever possible, a formalin-fixed, paraffin-embedded (FFPE) tumor tissue block or 10
             unstained slides of tumor sample (archival or recent) for biomarker evaluation should
             be made available and submitted to the central lab for correlative studies.

          -  Participant re-enrollment: This study permits the re-enrollment of a participant who
             has discontinued the study due to pre-treatment failure (i.e., participant has not
             been treated). If re-enrolled, the participant must be re-consented.

          -  Men and women at least 18 years of age

          -  Women of childbearing potential (WOCBP) must have a negative serum or urine pregnancy
             test within 24 hours prior to the start of thoracic radiation therapy

          -  Women must not be breastfeeding.

          -  WOCBP must agree to follow instructions for method(s) of contraception for the
             duration of treatment with study drug(s) plus 5 half-lives of study drug (half-life up
             to 25 days) plus 30 days (duration of ovulatory cycle) for a total of 5 months
             post-treatment completion.

          -  Males who are sexually active with WOCBP must agree to follow instructions for
             method(s) of contraception for the duration of treatment with study drug (s) plus 5
             half-lives of the study drug (half-life up to 25 days) plus 90 days (duration of sperm
             turnover) for a total of 7 months post-treatment completion.

          -  Additional criteria may apply

        Exclusion Criteria:

          -  Participants with previous brain metastases are eligible provided that they are
             treated and asymptomatic not requiring steroids or anticonvulsants, and have stable
             disease at the screening tumor assessment. A 4 week disease stable interval as
             confirmed by MRI or CT brain with contrast is required after treatment of brain
             metastases before initiation of thoracic radiation therapy. In addition, participants
             must have been either off corticosteroids, or on a stable or decreasing dose of 10 mg
             daily prednisone (or equivalent).

          -  Participants who have received prior chest radiation which at the discretion of the
             treating radiation oncologist precludes delivery of protocol radiation therapy

          -  Carcinomatous meningitis

          -  Pleural effusion that cannot be controlled with appropriate interventions

          -  All toxicities attributed to prior anti-cancer therapy must have been resolved to
             Grade 1 (NCI CTCAE Version 4) or baseline before administration of study drug(s) other
             than: Patients with toxicities attributed to prior anti-cancer therapy that either are
             not expected to resolve and/or result in long-lasting sequelae, such as neuropathy
             after platinum-based therapy, or are not expected to interfere with treatment on
             study, such as fatigue,alopecia, or grade 2 hematologic toxicity are eligible.

          -  Women who are pregnant or breastfeeding

          -  Active, known, or suspected autoimmune disease. Patients with an autoimmune
             paraneoplastic syndrome requiring concurrent immunosuppressive treatment are excluded.
             Patients with type I diabetes mellitus, hypothyroidism only requiring hormone
             replacement, skin disorders (such as vitiligo, psoriasis, or alopecia) not requiring
             systemic treatment, or conditions not expected to recur in the absence of an external
             trigger are permitted to enroll.

          -  A condition requiring systemic treatment with either corticosteroids (> 10 mg daily
             prednisone equivalent) or other immunosuppressive medications within 14 days of
             randomization. Corticosteroids with minimal systemic absorption (inhaled or topical
             steroids) and adrenal replacement steroid doses > 10 mg daily prednisone equivalent
             are permitted in the absence of active autoimmune disease.

          -  Prior therapy with anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137, or anti-CTLA-4
             antibody (including ipilimumab or any other antibody or drug specifically targeting T
             cell co-stimulation or checkpoint pathways)

          -  Interstitial lung disease that is symptomatic or may interfere with the detection or
             management of suspected drug-related pulmonary toxicity

          -  Any patient requiring supplemental oxygen therapy

          -  Previous malignancies (except non-melanoma skin cancers, and the following in situ
             cancers: bladder, gastric, colon, endometrial, cervical/dysplasia, melanoma, or
             breast) unless a complete remission was achieved at least 2 years prior to study entry
             AND no additional therapy is required during the study period

          -  Known medical condition that, in the investigator's opinion, would increase the risk
             associated with study participation or study drug(s) administration or interfere with
             the interpretation of safety results

          -  Major surgery or significant traumatic injury that is not recovered at least 14 days
             before the initiation of thoracic radiation therapy.

          -  Positive test for hepatitis B virus (HBV) using HBV surface antigen (HBVsAg) test or
             positive test for hepatitis C virus (HCV) using HCV ribonucleic acid (RNA) or HCV
             antibody test indicating acute or chronic infection

          -  Individuals with a positive test for HCV antibody but no detection of HCV RNA
             indicating no current infection are eligible

          -  Known medical history of testing positive for human immunodeficiency virus (HIV) or
             known medical history of acquired immunodeficiency syndrome (AIDS)

          -  Inadequate hematologic function according to study guidelines

          -  Inadequate hepatic function according to study guidelines

          -  History of allergy or hypersensitivity to any of the study drugs or study drug
             components

          -  Additional criteria may apply
      