• Aged ≥ 20 years.

• Pathologically or cytologically confirmed diagnosis of non-small cell lung cancer whose stage is IIIB, IIIC, IVA, or IVB according to the AJCC Cancer Staging System, 8th Edition.

• The tumor harbors an exon 19 deletion or exon 21 L858R mutation in EGFR, confirmed locally.

• Patient must have a documented Globo H H-score of at least 100 using a validated central IHC assay.

• Patient must have received 3±1 months of first-line erlotinib therapy under a stable dosage of 150 mg/day, have achieved SD or PR before randomization (as confirmed by the Investigator), and plan to continue the erlotinib treatment at 150 mg/day.

• At least one measurable tumor lesion according to RECIST version 1.1 as assessed by the Investigator (local radiological image assessment).

• Life expectancy ≥ 6 months.

• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.

• Organ Function Requirements - Subjects must have adequate organ functions as defined below:

‣ AST/ALT ≤ 3X ULN (upper limit of normal); AST/ALT ≤ 5X ULN in the presence of liver metastases

⁃ Total bilirubin ≤ 2.0 X ULN

⁃ Serum creatinine ≤ 1.5X ULN

⁃ ANC ≥ 1,500 /µL

⁃ Platelets ≥ 100,000/µL

⁃ All eligible patients of childbearing potential must use effective contraception during study treatment, and for at least 2 months after the last dose of OBI-833/OBI-821 and for at least 2 weeks after the last dose of erlotinib. Subjects not of childbearing potential (i.e., permanently sterilized, postmenopausal) can be included in the study. Postmenopausal is defined as 12 months with no menses without an alternative medical cause.

⁃ Understand and provide a written informed consent document according to institutional guidelines.