Inclusion Criteria:

        Participants must meet all of the following criteria to be eligible for inclusion in this
        study.

          -  Sign and date the tissue informed consent form (ICF) and the main ICF, prior to the
             start of any study-specific qualification procedures.

          -  Male or female participants aged ≥18 years (follow local regulatory requirements if
             the legal age of consent for study participation is >18 years old).

          -  Histologically or cytologically documented locally advanced or metastatic NSCLC not
             amenable to curative surgery or radiation.

          -  Documentation of radiological disease progression while on/after receiving most recent
             treatment regimen for locally advanced or metastatic disease. Participants must have
             received both of the following:

               -  Prior treatment with osimertinib. Participants receiving an EGFR TKI at the time
                  of signing informed consent should continue to take the EGFR TKI until 5 days
                  prior to Cycle 1 Day 1. Participants in South Korea known to harbor a clinically
                  actionable genomic alteration in addition to EGFR mutation (e.g., anaplastic
                  lymphoma kinase [ALK] or ROS1 protocol oncogene 1 [ROS1] fusion) for which
                  treatment is available must have also received prior treatment with at least 1
                  approved genotype-directed therapy, unless unable (i.e., if contraindicated). No
                  new testing for these genomic alterations (e.g., ALK or ROS1 fusion) is required
                  for Screening.

               -  Systemic therapy with at least 1 platinum-based chemotherapy regimen.

          -  Documentation of an EGFR-activating mutation detected from tumor tissue or blood
             sample: exon 19 deletion or L858R.

          -  At least 1 measurable lesion confirmed by BICR as per RECIST v1.1

          -  Consented and willing to provide required tumor tissue of sufficient quantity and of
             adequate tumor tissue content. Required tumor tissue can be provided as either:

               -  Pretreatment tumor biopsy from at least 1 lesion not previously irradiated and
                  amenable to core biopsy OR

               -  Archival tumor tissue collected from a biopsy performed within 3 months prior to
                  signing of the tissue consent and since progression while on or after treatment
                  with the most recent cancer therapy regimen.

          -  Eastern Cooperative Oncology Group Performance Standard of 0 or 1 at Screening.

          -  Has adequate bone marrow reserve and organ function based on local laboratory data
             within 14 days prior to Cycle 1 Day 1:

               -  Platelet count : ≥100,000/mm^3 or ≥100 × 10^9/L (platelet transfusions are not
                  allowed up to 14 days prior to Cycle 1 Day 1 to meet eligibility)

               -  Hemoglobin: ≥9.0 g/dL (transfusion and/or growth factor support is allowed)

               -  Absolute neutrophil count: ≥1500/mm^3 or ≥1.5 × 10^9/L

               -  Serum creatinine (SCr) or creatinine clearance (CrCl): SCr ≤1.5 × upper limit of
                  normal (ULN), OR CrCl ≥30 mL/min as calculated using the Cockcroft-Gault equation
                  or measured CrCl

               -  Aspartate aminotransferase/alanine aminotransferase: ≤3 × ULN (if liver
                  metastases are present, ≤5 × ULN)

               -  Total bilirubin: ≤1.5 × ULN if no liver metastases (<3 × ULN in the presence of
                  documented Gilbert's syndrome [unconjugated hyperbilirubinemia] or liver
                  metastases)

               -  Serum albumin: ≥2.5 g/dL

               -  Prothrombin time (PT) or PT-International normalized ratio (INR) and activated
                  partial thromboplastin time (aPTT)/PTT: ≤1.5 × ULN, except for subjects on
                  coumarin-derivative anticoagulants or other similar anticoagulant therapy, who
                  must have PT-INR within therapeutic range as deemed appropriate by the
                  Investigator

        Exclusion Criteria:

        Participants meeting any exclusion criteria for this study will be excluded from this
        study.

          -  Any previous histologic or cytologic evidence of small cell OR combined small
             cell/non-small cell disease in the archival tumor tissue or pretreatment tumor biopsy.

          -  Any history of interstitial lung disease (including pulmonary fibrosis or radiation
             pneumonitis), has current interstitial lung disease (ILD), or is suspected to have
             such disease by imaging during screening.

          -  Clinically severe respiratory compromise (based on Investigator's assessment)
             resulting from intercurrent pulmonary illnesses including, but not limited to:

               -  Any underlying pulmonary disorder (eg, pulmonary emboli within 3 months prior to
                  the study enrollment, severe asthma, severe chronic obstructive pulmonary disease
                  [COPD]), restrictive lung disease, pleural effusion);

               -  Any autoimmune, connective tissue or inflammatory disorders with pulmonary
                  involvement (eg, rheumatoid arthritis, Sjogren's syndrome, sarcoidosis); OR prior
                  complete pneumonectomy.

          -  Is receiving chronic systemic corticosteroids dosed at >10 mg prednisone or equivalent
             anti-inflammatory or any form of immunosuppressive therapy prior to enrollment.
             Participants who require use of bronchodilators, inhaled or topical steroids, or local
             steroid injections may be included in the study.

          -  Evidence of any leptomeningeal disease.

          -  Evidence of clinically active spinal cord compression or brain metastases.

          -  Inadequate washout period prior to Cycle 1 Day 1, defined as:

               -  Whole brain radiation therapy <14 days or stereotactic brain radiation therapy <7
                  days;

               -  Any cytotoxic chemotherapy, investigational agent or other anticancer drug(s)
                  from a previous cancer treatment regimen or clinical study (other than EGFR TKI),
                  <14 days or 5 half-lives, whichever is longer;

               -  Monoclonal antibodies, other than immune checkpoint inhibitors, such as
                  bevacizumab (anti-VEGF) and cetuximab (anti-EGFR) <28 days;

               -  Immune checkpoint inhibitor therapy <21 days;

               -  Major surgery (excluding placement of vascular access) <28 days;

               -  Radiotherapy treatment to more than 30% of the bone marrow or with a wide field
                  of radiation <28 days or palliative radiation therapy <14 days; or

               -  Chloroquine or hydroxychloroquine <14 days.

          -  Prior treatment with an anti-human epidermal growth factor receptor 3 (HER3) antibody
             or single-agent topoisomerase I inhibitor.

          -  Prior treatment with an antibody drug conjugate (ADC) that consists of any
             topoisomerase I inhibitor

          -  Has unresolved toxicities from previous anticancer therapy, defined as toxicities
             (other than alopecia) not yet resolved to National Cancer Institute Common Terminology
             Criteria for Adverse Events (NCI-CTCAE) v5.0, Grade ≤1 or baseline. Participants with
             chronic Grade 2 toxicities may be eligible at the discretion of the Investigator after
             consultation with the Sponsor Medical Monitor or designee.

          -  Has history of other active malignancy within 3 years prior to enrollment, except:

               -  Adequately treated non-melanoma skin cancer;

               -  Superficial bladder tumors (Ta, Tis, T1);

               -  Adequately treated intraepithelial carcinoma of the cervix uteri;

               -  Low risk non-metastatic prostate cancer (with Gleason score <7, and following
                  local treatment or ongoing active surveillance);

               -  Any other curatively treated in situ disease.

          -  Uncontrolled or significant cardiovascular disease prior to Cycle 1 Day 1

          -  Active hepatitis B and/or hepatitis C infection, such as those with serologic evidence
             of viral infection within 28 days of Cycle 1 Day 1.

          -  Participant with any human immunodeficiency virus (HIV) infection.