Inclusion Criteria:

          -  Have confirmed diagnosis of stage IV non-small cell lung cancer (NSCLC) according to
             the American Joint Committee on Cancer Staging Handbook.

          -  Determined to have detectable mutations in codons 12 or 13 of the kirsten rat sarcoma
             (KRAS) oncogene by an investigational assay at the study central laboratory. A KRAS
             positive mutation result in codons 12 or 13 of the KRAS oncogene from tumor tissue per
             local laboratory will be permitted in no more than 10% of randomized participants.

          -  Have progressed after platinum-based chemotherapy (with or without maintenance
             therapy) AND have received one additional therapy which may include an immune
             checkpoint inhibitor or other anti-cancer therapy for advanced and/or metastatic
             disease OR is judged by the physician as ineligible for further standard second-line
             chemotherapy. Participants who have progressed after platinum-based chemotherapy and
             an immune checkpoint inhibitor (immunotherapy) e.g. pembrolizumab or nivolumab alone
             or in combination with other agents are eligible.

          -  Have measureable disease as defined by the Response Evaluation Criteria in Solid
             Tumors (RECIST 1.1).

          -  Have a performance status (PS) of 0 to 1 on the Eastern Cooperative Oncology Group
             (ECOG) scale.

          -  Have discontinued all previous therapies for cancer (including chemotherapy,
             radiotherapy, immunotherapy, and investigational therapy) for at least 21 days for
             myelosuppressive agents or 14 days for nonmyelosuppressive agents prior to receiving
             study drug.

        Exclusion Criteria:

          -  Have received treatment with a drug that has not received regulatory approval for any
             indication within 14 or 21 days of the initial dose of study drug for a
             nonmyelosuppressive or myelosuppressive agent, respectively.

          -  Have a personal history of any of the following conditions: presyncope or syncope of
             either unexplained or cardiovascular etiology, ventricular arrhythmia (including but
             not limited to ventricular tachycardia and ventricular fibrillation), or sudden
             cardiac arrest.

          -  Have the presence of unstable central nervous system (CNS) metastasis. History of CNS
             metastasis or stable CNS metastases is allowed (no longer requiring active therapy
             such as steroid medications). Participants with a history of CNS metastases must have
             a brain scan (for example, magnetic resonance imaging [MRI]) within 28 days of
             randomization to document stability, even if there have been no changes in symptoms.

          -  Have previously completed or withdrawn from this study or any other study
             investigating a cyclin-dependent kinase 4 (CDK4) and cyclin-dependent kinase 6 (CDK6)
             inhibitors, or have received treatment with a prior CDK4 and CDK6 inhibitors.