Key Inclusion Criteria:  Provision of signed and dated, written informed consent before any study specific procedures, sampling and analyses Histological or cytological confirmation of advanced and/or metastatic stage IIIB/IV NSCLC Radiological documentation of disease progression while on a previous continuous (at least 30 days) treatment with an EGFR TKI monotherapy (including, but not limited to, osimertinib, afatinib, gefitinib, or erlotinib)  Patients must fulfill one of the following:  Confirmation that the tumor harbors an EGFR mutation known to be associated with EGFR TKI sensitivity (including, but not limited to, exon 19 deletion, L858R, or L861Q) Documented partial or complete response or a significant and durable stable disease (at least 6 months), based on the RECIST or WHO criteria, after treatment of an EGFR TKI  Key Exclusion Criteria:  Treatment with any of the following:  An EGFR TKI, including but not limited to osimertinib, afatinib, gefitinib, or erlotinib within 8 days of the first dose of study treatment. Any cytotoxic chemotherapy, investigational agents, or anticancer drugs for the treatment of advanced NSCLC, between prior EGFR TKI treatment and BBT-176 treatment Major surgery (excluding placement of vascular access) within 4 weeks of the first dose of study treatment Radiotherapy with a limited field of radiation for palliation within 1 week of the first dose of study treatment Patients receiving radiation to more than 30% of the bone marrow or with a wide field of radiation within 6 weeks of the first dose of study treatment Any unresolved toxicities from prior therapy greater than NCI Common Terminology Criteria for Adverse Events (CTCAE v5.0) Grade 1 at the time of starting study treatment, with the exception of alopecia and Grade 2 neuropathy related to prior platinum-therapy Spinal cord compression or brain metastases, unless asymptomatic and stable