A Study to Assess Adverse Events, Change in Disease Activity of Intravenous Telisotuzumab Adizutecan in Combination With Osimertinib as First-Line Treatment in Adult Participants With Locally Advanced Unresectable or Metastatic EGFR-Mutated Non-Squamous Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is a common type of lung cancer where abnormal cells in the lungs grow out of control. The purpose of this study is to assess adverse events and change in disease activity "when telisotuzumab adizutecan is given in combination with a fixed dose of osimertinib (Osi)or standard of care (Osi plus platinum/pemetrexed chemotherapy). Telisotuzumab adizutecan is an investigational drug being developed for the treatment of NSCLC. Osi is a drug approved for the treatment of NSCLC. This study will be divided into two stages, in the first stage participants will receive increasing doses of telisotuzumab adizutecan with Osi. Participants will then be randomized into 4 groups called treatment arms where 3 groups will receive 1 of 3 doses of telisotuzumab adizutecan from from the dose escalation phase with Osi, or standard of care (Osi plus chemotherapy). In the second stage participants will receive the optimal dose of telisotuzumab adizutecan, from the previous stage, with Osi, or SOC. Approximately 854 adult participants with 1L estimated glomerular filtration rate (EGFR) mut (mutated) not sufficient quantity (NSq) NSCLC will be enrolled in the study in 200 sites worldwide. In Stage 1, during dose escalation participants will receive increasing intravenous (IV) doses of telisotuzumab adizutecan with oral Osi tablets. participants will receive 1 of 3 doses of telisotuzumab adizutecan with Osi, or standard of care (Osi plus chemotherapy). In stage 2 participants will receive the optimal dose of IV telisotuzumab adizutecanin with oral Osi tablet, or SOC. The study will run for a duration of approximately 76 months. There may be higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular visits during the study at an approved institution (hospital or clinic). The effect of the treatment will be frequently checked by medical assessments, blood tests, questionnaires and side effects.