There is currently a lack of published HER3 expression prevalence data among non-small cell lung cancer (NSCLC) patients. The estimation of HER3 expression prevalence in this population using archival tissue samples and the assessment of associated patient characteristics in real world (RW) data will ultimately inform clinical strategy and increase awareness among health care providers (HCPs) and the greater medical community to improve patient care.

The purpose of this study is to use archival tissue samples and RW data to generate HER3 expression prevalence data within the NSCLC population and by patient characteristics (e.g., ethnicity, histology, smoking status, age, prior treatment, etc.).

The primary objective of the study will analyze and assess archival tissue specimens and associated RW data to:

• Increase the understanding of HER3 expression in NSCLC among HCPs and the medical community
• Generate evidence to support future clinical strategies in this area

Inclusion Criteria:

• Age ≥18 years in US
• Histologically or cytologically documented advanced or metastatic NSCLC
• At least one sample available and evaluable for HER3 expression

Additional population-specific inclusion criteria:

For Cohort 1:

• Tissue sample collected on or after January 1, 2013

For Cohort 2:

• EGFRm NSCLC previously treated with a 3rd generation EGFR TKI
• 2 samples are available and evaluable for HER3 expression at 2 timepoints: one pre-treatment and one post-treatment, where the treatment is a 3rd generation TKI (defined as Osimertinib, Aumolertinib [formerly Almonertinib])

For Cohort 3:

• ALK+ NSCLC
• 2 samples are available and evaluable for HER3 expression at 2 timepoints: one pre-treatment and one post-treatment, where the treatment is a TKI

For Cohort 4:

• NSCLC harboring a KRAS p.G12C mutation or EGFR exon 20 insertion
• 2 samples are available and evaluable for HER3 expression at 2 timepoints: one pre-treatment and one post-treatment

Exclusion Criteria:

• Prior treatment with an anti-HER3 antibody or topoisomerase I inhibitor (single-agent or combination)
• Prior treatment with an antibody drug conjugate (ADC) that contains a topoisomerase I inhibitor
• Previous histologic or cytologic evidence of small cell or combined small cell/non-small cell disease

The EMR database provided by GRN, an oncology-focused, mission-driven hospital consortium comprised of 37 cancer centers, 85 hospitals and more than two million oncology patients across 13 USA states (New York, Massachusetts, Rhode Island, Maryland, Virginia, South Carolina, Florida, Indiana, Kentucky, Missouri, Arkansas, Kansas, Oklahoma), will be used as the data source for this study.