A Study of Lazertinib in Participants With Epidermal Growth Factor Receptor (EGFR) Mutation Positive Advanced Non-Small Cell Lung Cancer (NSCLC)

Inclusion Criteria:

* Females should agree to use adequate contraceptive measure, should not be breast feeding and must have a negative pregnancy test prior to start of dosing if of child-bearing potential or must have evidence of non-child-bearing potential by fulfilling one of following criteria at screening; Post-menopausal defined as aged more than 50 years and ameorrhoeic for at least 12 months following cessation of all exogenous hormonal treatments; Documentation of irreversible surgical sterilization by hysterectomy, bilateral oophorectomy or bilateral salpingectomy but not tubal ligation; Women under 50 years old would be considered postmenopausal if they have been ameorrhoeic for at least 12 months following cessation of exogenous hormonal treatment, and have serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels in postmenopausal range for the institution
* Male participants who have not undergone a vasectomy must agree to use barrier contraception that is, condoms, and refrain from donating sperm until 3 months after last drug is taken
* During the study, and for 3 months after receiving the last dose of study drug, female participants must agree not to donate eggs (ova, oocytes) and male participants must agree not to donate sperm for the purposes of assisted reproduction
* In Part D: Participants outside Korea with histologically or cytologically (that is, using pleural effusion, ascites) confirmed Non-Small Cell Lung Cancer (NSCLC) with previously diagnosed epidermal growth factor receptor single activating mutation positive (EGFRm+), and who have had progressive disease on prior epidermal growth factor receptor- Tyrosine kinase inhibitor (EGFR-TKI) therapy
* Eastern Cooperative Oncology Group (ECOG) performance status 0 to 1 with no deterioration over the previous 2 weeks and a minimum life expectancy of 3 months

Exclusion Criteria:

* An unapproved investigational product from another clinical study within 30 days of the first dose of study treatment
* Treatment with an EGFR TKIs (example: erlotinib or gefitinib) within 8 days or approximately 5x half-life, whichever is the longer, of the first dose of study treatment or other investigational products within approved indication of marketed product (if sufficient wash-out time has not occurred due to schedule or PK properties, an alternative appropriate wash-out time based on known duration of time to reversibility of drug related adverse events could be agreed upon by sponsor and the Investigator)
* Any cytotoxic chemotherapy or other anticancer drugs for the treatment of advanced NSCLC from a previous treatment regimen within 14 days of the first dose of study treatment
* Symptomatic spinal cord compression (if steroid treatment is not required within at least 2 weeks prior to the start of the study treatment then the participant may be enrolled)
* Brain metastases with symptomatic and/or requiring emergency treatment (example; Steroid for at least 2 weeks prior to start of study treatment)